JPH06326396A - Laser controlling device - Google Patents

Abstract

PURPOSE:To contrive the improvement of the accuracy of a semiconductor laser in the stabilization of light output of the laser and to reduce the failure rate of the laser without making an abnormal current or the like flow in the stabilization by a method wherein a laser controlling device is provided with a photodetecting means, a current-voltage conversion means, a comparison means, integrating means and a voltage-current conversion means. CONSTITUTION:Light output of a semiconductor laser 344 is detected by a photodetecting means 260, an output current of this means 260 is converted into a voltage by a current-voltage conversion means 232, the voltage is compared with a reference voltage of a comparison means 234 and thereafter, charge and discharge are performed by integrating means R40 and CO7 responding to the compared result and moreover, charged voltages of the means R40 and CO7 are converted into a current by a voltage-current conversion means 257 and the current is fed to the laser 344. Thereby, the laser can be controlled with high accuracy and in a stable state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser control device for stabilizing the light output of a semiconductor laser.

[0002]

2. Description of the Related Art In recent years, semiconductor lasers have been applied in various fields, and it is an important condition to stabilize the laser light amount in any field. In particular,
When the light output of a semiconductor laser is switched in multiple stages and used properly, stabilization of the light output at the time of this switching is an important issue. Further, since the semiconductor laser has a large temperature dependency, even a slight temperature change causes a large change in the light output, which makes it more difficult to stabilize the light output.

By the way, the semiconductor laser has a property of being easily damaged by an abnormal current and an abnormal voltage. Conventionally, an abnormal current or an abnormal voltage may be applied to the semiconductor laser when the laser light amount is stabilized, and the damage rate of the semiconductor laser is large. Further, conventionally, a modulation transistor has been used for modulation of a semiconductor laser. Normally, the modulation frequency of this modulation transistor is about 4 to 10 MHz, and fast response is required. Therefore, the modulation transistor is used for high frequency. However, there is a problem in that a high-frequency transistor causes a power loss in relation to the junction capacitance, and a large-current transistor must be arranged to compensate for this power loss.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and aims to improve the accuracy in stabilizing the optical output of a semiconductor laser and to prevent abnormal current from flowing during the stabilization. It is an object of the present invention to provide a laser control device capable of significantly reducing the failure rate of a semiconductor laser, reducing power loss, having good responsiveness, and capable of controlling minute optical output.

[0005]

According to a first aspect of the present invention, there is provided a laser control means for detecting a semiconductor laser output, a current-voltage conversion means for converting an output current of the light detection means into a voltage. Comparing means for comparing the output voltage of the current-voltage converting means with a reference voltage, integrating means for charging / discharging according to the output of the comparing means, and converting the voltage charged in the integrating means into a current. It has a voltage-current conversion means for supplying the semiconductor laser.

According to a second aspect of the present invention, in the laser control device, the integrating means has a switching means, and when the light quantity stabilizing operation of the semiconductor laser is performed, the switching means is turned on so that the laser modulating operation is performed. When performing, the switching means is turned off.

According to a third aspect of the laser control apparatus, the light quantity of the semiconductor laser is set by changing the reference voltage.

According to a fourth aspect of the present invention, in the laser control device, the voltage-current converting means has a current driving means for causing a current equal to or lower than a threshold current at which the semiconductor laser causes optical oscillation to flow through the semiconductor laser. The current driving means is constantly driven when the laser is modulated.

[0009]

According to the laser control device of the present invention, the light output of the semiconductor laser is detected by the light detecting means, the output current of the light detecting means is converted into the voltage by the current-voltage converting means, and the comparing means is operated. After comparison with the reference voltage, charging and discharging are performed by the integrating means according to the comparison result, and the charging voltage of the integrating means is converted into current by the voltage-current converting means and supplied to the semiconductor laser. .

Therefore, the light output of the semiconductor laser is controlled so as to be constant, so that the light output can be stabilized with extremely high accuracy regardless of temperature fluctuations. In particular, since the comparison means has a systematic characteristic, it is possible to improve the stabilization of the comparison judgment and contribute to the accuracy improvement of the stabilization of the optical output.

Further, when the semiconductor laser is turned on, the current is gradually increased by the function of the integrating means in a considerably slow time, so that no abnormal current flows in the semiconductor laser and the failure rate of the semiconductor laser is increased. Significantly reduced.

Further, since the light output setting reference voltage and the light output of the semiconductor laser are in a proportional relationship, an accurate light output can be set.

According to another aspect of the laser control device of the present invention, the switching means provided in the integrating means is turned on during the light quantity stabilizing operation of the semiconductor laser and turned off during the modulating operation. The optical output can be reliably stabilized.

According to the laser control device of the third aspect, since the light quantity of the semiconductor laser is set by changing the reference voltage, it is possible to control the minute light output by changing the reference voltage.

According to the fourth aspect of the laser control device, when the semiconductor laser is modulated, the current driving means operates to supply the semiconductor laser with a current equal to or lower than the threshold current that causes optical oscillation. The semiconductor laser can be controlled by using the current drive means in a state in which the response is good without power loss.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram of a system for recording information on a recording medium with a laser beam. Host side system 1 that delivers information (computer,
Information from the word processor main body or the like) is given to the data control unit 2. The data control unit 2 converts the information given by the host-side system 1 into dot-corresponding data and stores it in the page memory.

The stored dot image data is sent to the print controller 100.

In the print control unit 100, the input dot image data is written on a recording medium by modulating the laser beam to develop and transfer the dot image data, and the dot image data is printed on a recording sheet.

FIG. 2 is a detailed view of the mechanism of the printer 300 having a video interface. The printer 300 incorporates the print control unit 100 of FIG.

In FIG. 2, 300 is a printer main body,
Reference numeral 301 denotes a photoconductor as an image carrier for recording information with a laser beam, and 302 denotes the photoconductor 301.
This is a static elimination lamp for eliminating the electric charges in the initial state from the plurality of red LEDs. Reference numeral 303 denotes a charge eliminating lamp for increasing transfer efficiency, which is similar to the charge eliminating lamp 302.
It is composed of a plurality of red LEDs. 304 is a charging charger for uniformly charging the photoconductor 301 to a predetermined potential, 305 is a transfer charger for transferring the toner developed on the photoconductor 301 to a sheet, 306
Is a peeling charger for separating the paper after transfer from the photoconductor.

Reference numeral 307 denotes a developing device for developing an electrostatic latent image written by a laser beam on the photoconductor 301, and 308 is a constituent element of the developing device 307. A magnet roller for adhering to the electrostatic latent image on 301 and rotating in the direction of the arrow.

Reference numeral 309 is an auto toner probe for contacting the developer on the magnet roller to measure the toner specific density of the developer, and 310 is a cleaning for removing the toner remaining on the photoconductor 301 after transfer. It is a blade.

Reference numeral 311 denotes a laser scanner unit for recording the video data inputted from the data control unit on the photoconductor 301 by scanning and modulating the laser beam, and 312 denotes a laser beam from a laser diode for the photoconductor. An octahedron polygon mirror 313 for guiding on the surface 301, a scan motor 313 for rotating the polygon mirror 312 at high speed, and a reference numeral 314 for the photoconductor 3
F.theta. Lens for keeping the scanning speed of the laser beam on 01 constant. Reference numerals 315 and 316 denote the laser beam from the scanner unit 311 and the photosensitive member 3.
This is a reflection mirror for leading to 01.

317 is an upper cassette that can store 500 sheets of paper, 318 is an upper sheet feeding roller for taking out the sheets one by one from the upper cassette 317, and 319 is a detection that the upper cassette 317 has run out of sheets. Upper paperless switch, 320 indicates the upper cassette 317
Is an upper cassette size detection switch composed of 4 bits for detecting a size identification mark provided in the. Reference numeral 321 denotes a lower-stage paper feeding roller, 323 denotes a lower-stage paperless switch, and 324 denotes a lower-stage cassette size detection switch. In addition, the upper side has a structure in which a lower side can store 250 sheets and a cassette can be used.

Reference numeral 326 denotes a manual feed switch for detecting a sheet inserted from the manual feed guide 325, 327.
Is a manual paper feed roller for carrying the paper after the insertion is confirmed by the manual feed switch 326, and 328 is a manual stop switch for detecting the paper carried by the manual paper feed roller 327.

Reference numeral 329 is a registration roller for synchronizing the image developed on the photosensitive member 301 with the sheet.
330 is a conveyor belt for conveying the sheet separated by the peeling charger 306 to the fixing device, 331 is a fixing device for fixing the toner on the transferred sheet,
332 is a fixing roller, 333 is a heater lamp for heating the fixing roller, 334 is a thermistor for detecting the surface temperature of the fixing roller, 335 is a discharge roller, and 336 is discharged from the fixing device 331. A paper discharge switch for detecting paper.

Reference numeral 337 is a cooling fan for cooling the inside of the printer 300, 338 is a high voltage transformer for generating high voltage applied to the charging charger 304, the transfer charger 305, the peeling charger 306, the developing device and the magnet roller 308, respectively. Reference numeral 339 is a power supply device that generates a DC voltage used for each control, and 340 is a PC board unit that controls the printer 300.

Reference numeral 342 denotes a drum temperature sensor provided near the photoconductor 301 for detecting the temperature of the photoconductor 301, which uses a thermistor having a very small thermal resistance.

FIG. 3 shows the photoconductor 3 using a laser beam.
FIG. 3 is a perspective view showing an outline of a portion for recording information on 01. In FIG. 3, the laser beam emitted from the semiconductor laser 344 is corrected into parallel light by the collimator lens 343, and the parallel light is reflected by the polygon mirror 313.
It is applied to one side of the octahedron. Polygon mirror 31
Since 3 is rotated at a high speed in the arrow direction by the scan motor 312, the laser beam incident on the polygon mirror is scanned from the left to the right in the beam scanning range 348 through the f.theta. Lens 314. It A part of the laser beam within the beam scanning range 348 is guided to the beam detector 346 by the reflection mirror 345. Therefore, one of the polygon mirrors 313 has one surface.
The beam detector 346 detects the laser beam being scanned every horizontal scanning. The laser beam not incident on the reflection mirror 345 within the beam scanning range 348 is applied to the photoconductor 301. In FIG. 3, reference numeral 349 shows a portion where the laser beam is scanned on the photoconductor 301. Reference numeral 304 denotes a charging charger, and 347 denotes a sheet. As shown in FIG. 2, in the actual printer, the laser beam passing through the f.theta.
Instead of being illuminated at 1, the reflective mirrors 315 and 31
Although it is guided to the photoconductor 301 by being reflected by 6, the reflecting mirrors 315 and 316 are not shown in FIG. 3 for convenience. It is shown as if the laser beam passing through the f.theta. lens 314 is directly irradiated onto the photoconductor 301.

Now, the structure of the reflection mirror 345 will be described with reference to FIG. As shown in the figure, the reflection mirror 345 is mounted on a supporting member 456 located outside the beam incident area by a screw 455 via a leaf spring 454, and a fine adjustment screw 457 is attached to the lower portion of the leaf spring 454. It is provided so that the angle of the reflection mirror 345 can be changed.

The laser scanner unit shown in FIGS. 3 and 42 is shielded from the outside so that the scanning beam does not leak, as is apparent from the view shown in FIG. Then, the detection result of the beam detection by the beam detector 346 is displayed at an appropriate position on the scanning panel shown in FIG.

FIG. 4 shows the pass sensor 39 before the registration rollers.
It is explanatory drawing of FIG. The manual stop switch 328 shown in FIG. 2 detects only the manually fed paper, whereas
The purpose of the pre-registration roller pass sensor 394 is to detect the paper when the cassette is fed. In FIG. 4, the paper fed from the upper cassette 317 and the lower cassette 321 by either the upper paper feed roller 318 or the lower paper feed roller 322 is fed to the registration roller 329 along the paper guide plate. It At this time, if the paper is fed correctly, the light emitted from the light emitting diode 393 is blocked by the paper and the pass sensor 3 before the registration roller is cut off.
Since the light does not enter 94, the fed paper can be confirmed. If the paper cannot be fed correctly, the paper will
Since the position of the pre-registration roller pass sensor has not been reached, it can be recognized that the paper has not been fed because the light from the light emitting diode 393 is continuously incident on the pre-registration roller pass sensor.

FIG. 5 is a schematic view of the reversing tray 381 which is an optional unit. In the normal printer 300,
As shown in FIG. 2, a non-inverted tray 397 is attached. When such a non-reversed type is used, the first print sheet is at the bottom side, so the data must be sent from the last page from the information delivery device (host system 1). There is a drawback that the method of filing information in the system 1 becomes complicated. Therefore, the inversion tray 381 is indispensable for compensating the above-mentioned drawbacks.

In FIG. 5, the paper sheet that has passed through the paper discharge roller 335 of the printer 300 is conveyed rollers 382 and 383.
Thus, the tray 384 is accommodated in a mold that is the reverse of the one when it passed through the paper discharge roller 335. Therefore, since the print side of the paper is on the lower side, the first page is on the bottom side, but when the paper is taken out of the tray 384 and the print side of the paper is on the front side, the first page is on the top Page becomes the lower side, and the above-mentioned drawbacks of the non-inverting tray 397 can be solved.
In the figure, numeral 385 is a paper stopper which can be slid according to the length of the printing paper in the carrying direction. 388 is a paper pressing actuator for preventing floating of the paper stored in the tray, 395 is a paper discharge switch for confirming that the paper is normally stored in the tray 384, and 391 is presence / absence of paper in the tray 384. The light emitting diode 392 for confirming is a tray sensor on the light receiving side. When the sheet 390 is in the tray 384, the tray sensor 392 is not illuminated, and when the sheet 390 is not present, the tray sensor 392 is illuminated and thus the sheet 3 is exposed.
The presence or absence of 90 can be detected.

FIG. 44 shows another example of the paper presence / absence and paper full detection unit. This is provided with an actuator 388 centered around a rotation fulcrum 386 and a lever 398 continuously provided above, and the tip of the lever 398 is urged in one direction by a solenoid 389 as a separating means and a coil 387 as a releasing means. The lever 398 is moved depending on the state where the paper is stored in the paper storage unit 390, and the state at this time is detected by the detection means, for example, the plurality of sensors 401 and 402. In various states of the actuator 388, the position of a1 is "paper full", the position of a2 is "paper present", and the position of a3 is "no paper". The separating means 389 is configured so that at least the paper 390 is discharged to the paper discharge tray 3.
The actuator 388 is separated while being discharged and moved into the inside 84, and the solenoid 389 is turned off in synchronization with the status signal at that time when the paper is to be detected, for example, during the printing operation or during the stop, and the actuator 388 is separated. Is released, and the detection operation is performed. Therefore, the paper 39
The discharge tip of 0 does not collide with the actuator 388, and the discharge operation is not hindered.

It should be noted that the paper sent to the paper discharge tray is 1
A sheet discharge memory counter (RAM 107 of FIG. 3) whose contents are detected by the sheet discharge switch 395 for each sheet and which will be described later
Is counted and the number of sheets is detected. When the "paper is full" is displayed on the tray full lamp 358 of FIG. 6, the memory counter is cleared.

FIG. 6 is a detailed view of the operation panel of the printer 300.

In FIG. 6, 350 is the top cover of the printer 300, 351 is the front cover, and 352 is the front cover.
The front cover 351 serves as a maintenance cover, and is opened in the direction of the arrow for processing when a paper jam, toner replenishment, etc. occur. Further, although the maintenance cover 352 has a structure that can be opened at the upper part, it can be opened only when the front cover 351 is opened in the direction of the arrow to prevent erroneous operation by the operator. .

Reference numeral 353 is a 6-digit mechanical counter, and 1
It is incremented by 1 for each print on a sheet of paper. 354 is a select switch for selecting online / offline,
355 corresponds to the select switch 354, a select lamp that lights up when online, 356 is a one-digit seven-segment LED that is a numeric display for displaying error contents during a service call, a mode number during a maintenance mode, and 357. A power lamp indicating that the printer 300 is powered on, a reference numeral 358 indicates a tray full lamp indicating that the reversing tray unit 381 is full of printing paper, and a reference numeral 359 indicates a color indicating details of the operating state of the printer. The LCD displays are shown respectively.
The total counter 353 to LCD display 359 described above are always operated or displayed.
Next, a portion that cannot be operated unless the maintenance cover 352 is opened will be described. The following parts are operated only by service personnel.

Reference numeral 403 is a maintenance switch for selecting the maintenance mode and replacement mode, 406 is an indicator lamp indicating that the maintenance mode is in effect, 407 is an indicator lamp indicating that the replacement mode is in effect, and 404 is each mode. A selection switch for selecting the operation mode NO, 408 is a selection lamp indicating that the selection operation by the selection switch 404 is possible, and 405 is a test print mode selection and operation in each of the above-mentioned maintenance, replacement, and test print mode states. , A main exposure adjusting volume 360, which will be described later, and a reference numeral 361, a shadow exposure adjusting volume. Both the 360 and 361 volumes are
The structure is such that the adjustment driver is inserted and turned, and it cannot be turned by hand with the maintenance cover 352 opened.

FIG. 7 is a detailed view of the LCD display 359, and the function of each display segment will be described below.

Reference numerals 371 and 372 are segments that indicate the standby and ready states of the printer 300. Both lights 371 and 372 when waiting for the fixing device ready, only 371 lights when ready, and 371 and 372 during printing operation.
Turn off both lights.

Reference numeral 373 blinks when a jam of the sheet feeding portion occurs, and the segment indicating the sheet feeding state also blinks at the same time.
That is, the manual feed designation 365 flashes in the manual feed mode, the upper cassette 364 blinks in the upper cassette mode, and the lower cassette 363 blinks in the lower cassette. 374 blinks in the case of a conveyance system (registration roller 329 or later) jam.
At this time, the paper feed segment blinks at the same time as the paper feed jam. 375 blinks when the toner collected by the cleaning blade 310 in FIG. 2 is full in the toner bag (not shown). Reference numeral 376 blinks when the toner hopper (not shown) of the developing device 307 runs out of toner. 377 and 378 blink when a serviceman error described later occurs. 379 blinks when an operator call described later occurs. 380 blinks when there is no paper in the selected cassette. 362 displays the size of the selected paper. For example, if the upper cassette side is selected and A4 portrait paper cassette is selected, A4-R is lit, and if A6 is selected in the manual feed mode, A6 is lit. 363 is lit when the lower cassette is selected, 364 is lit when the upper cassette is selected, and 365 is lit when manual feeding is selected. Reference numeral 366 represents the shape of the printer 300, which is always lit, 367 represents the photoconductor 301, which is always lit, 368 represents the upper shape of the printer 300, which is always lit except when the conveyance unit is jammed, and 369 is a conveyance unit jam. (When the 374 is blinking), the 368 is alternately turned on. Reference numeral 370 denotes five segments that display the sheet conveyance state, and one segment moves from the right side to the left side while lighting up.

FIG. 8 shows the data control unit 2 in FIG.
3 is a schematic block diagram of FIG. The data control unit 2 stores the character code information and the image information sent from the host-side system 1 in the page memory 20 corresponding to the printing area on the paper of the printer 300 after the data conversion after the data conversion. Further, the stored data on the page memory 20 is sent to the printer 300 to perform a printing operation.

The data control unit 2 is configured to receive two types of information. That is, one is character code information (JIS8 unit code or the like). In this case, the character generator 15 generates a character pattern corresponding to the character code, and the dot information of the character pattern is stored in the page memory 20. . The other is image information,
In this case, since the dot information has already been input, it is stored in the page memory 20 as it is. Or later,
An outline of the data control unit 2 will be described with reference to FIG.

Information from the host system 1 is sent to the interface 50 via the signal line SO1, and the information is stored in the data latch 3.

Interface 50 and host system 1
The signal line SO2 is sent from the host-side system 1. Data strobe signal and other control signal lines S
O3 is a busy signal and status signal line from the data control device.

The format of the information sent from the host system 1 is shown in FIGS. 9 and 10. The format example of FIG. 9 is a format for character code information,
A character identification code indicating character code information and a paper size code indicating the size of the paper to be printed are included at the beginning of one page. After that, character code data is entered in the order of the 1st line, the 2nd line ... Nth line, and the END code indicating the end of the data of the page is entered at the end. Again 1
The character code data for a line is a code that indicates the character size,
It consists of a character code and an LF code that represents the delimitation of one line of data.

FIG. 10 shows a format in the case of image information, in which the image identification code indicating the image information and the paper size identification code indicating the size of the paper to be printed are at the beginning of the data for one page. After that, image data is entered in the order of 1 line, 2 lines ... M lines. Further, since the data of one line is designated by the paper size identification data, the data control section 2 can automatically discriminate it by counting the designated data. There is.

Input information from the distributor 4 is processed as follows. The output line SO is always output from the distributor 4 to the decoder 5.
The information entered in the distributor 4 is input by the number 4. First, regarding the case of character code information, when the character identification code of FIG. 9 is input to the decoder 5, the output of the decoder 5 is input to the main control unit 6 via the signal line SO5. The main control unit 6 determines that the input information is character code information, and instructs the distributor 4 via the signal line SO6 to input the next paper size data to the page code buffer control circuit 7. Therefore, the paper size data is input from the distributor 4 to the page code buffer control circuit via the data line SO7. Next line 1 and 2 ...
The data up to the nth row is input from the distributor 4 to the page code buffer via the data line SO8. At this time, the character code data is stored in the memory area on the page code buffer 9 designated by the address counter 8. When the input of the character code information for one page is completed in the page code buffer and the END code of FIG. 9 is detected by the decoder 5, signal lines SO5 and SO9 are used to enable the main control unit 6 and the page code buffer control circuit 7, respectively.
Report D code detection. When the page buffer control circuit 7 confirms that the character code input for one page to the page code buffer is completed by the signal line SO9, the data is stored in the page memory 20 in dot units.

The correspondence between the memory space on the page memory 20 and the paper is shown in FIG. In FIG. 11, broken lines indicate the outside of each sheet. That is, 25 is the leading edge of the sheet (common to all sizes), 24 is the left edge of the sheet (common to each size), and 28 is A5.
Right edge of size paper, 27 is right edge of A4 size paper, 26
Indicates the right end of the A3 size paper, 31 indicates the rear end of the A5 size paper, 30 indicates the rear end of the A4 size paper, and 29 indicates the rear end of the A3 size paper. Reference numeral 32 indicates a point of the address ADR (0,0) of the read address counter 19 and the write address counter 18. ADR here
(0,0) means that the vertical address (ADRV) and the horizontal address (ADRH) are both "0". That is, as shown in FIG. 12, the write address counter 18 and the read address counter 19 have a vertical address (ADRV) and a horizontal address (ADR).
H), ADRV represents a vertical address (arrow b in FIG. 11), and ADRH represents a horizontal address (arrow c in FIG. 11).

43 is the last horizontal address (A3HE) of A3 size paper, 44 is the horizontal address of A4 size paper (A4HE), and 45 is the horizontal address of A5 size paper (A5HE). Similarly, 46 represents the last vertical address (A3VE) of A3 size paper, 47 represents the A4 size vertical address (A4VE), and 48 represents the A5 size vertical address (A5VE). 33 is A3 size vertical address ADRV = 0, horizontal address ADRH = A3
HE points ADR (O, A3HE), 34 are similarly ADR (O, A4HE), and 35 are ADR (O, A5).
HE) is shown respectively. 36 is an A3 size vertical address ADRV = (A3VE), a horizontal address ADRH.
= O point ADR (A3VE, O), 37 similarly ADR (A4VE, O), 38 ADR (A5V
E, 0) respectively. Reference numeral 39 is an A3 size vertical address ADRV = A3VE and a horizontal address ADRH = A3.
HE points ADR (A3VE, A3HE), similarly 40 for ADR (A4VE, A4HE), 41
ADR (A5VE, A5HE) is shown respectively. The dot image of the character pattern is stored in the page memory 20 having the above memory space as follows. The character size data of the first line is read from the page code buffer 9 to the page code buffer control circuit 7 via the signal line S10. The type of character size in this embodiment is basically two types of fonts of 40 × 40 and 32 × 32 dots, and the page code buffer control circuit 7 discriminates the character size from the read character size code. The determination signal is sent to the page memory control circuit 17 via the signal line S11 and to the character generator 15 via the signal line S13. The page memory control circuit 17 controls the line feed pitch and the character pitch according to the character size discrimination signal, and the character generator 15 switches the character size area.

The character code after the character size data is 1
The data is transferred to the area designated by the row address counter 11 in the row buffer 10 having the memory capacity for the row. When the transfer of the character code data for one line to the line buffer 10 is completed, the line address counter 11 returns to the initial address (0). First, the first line (line 57 in FIG. 11) in the vertical direction of the character font is written to the page memory 20. Here, the line / scan counter 13
Is set to the initial value (0, 0), and the value of the write address counter 18 is ADR (0, 0).
The character code data in the line buffer 10 is sequentially read from the leading digit in a constant cycle, and the line counter 1
3 are sequentially latched by the output latch 12 in order to synchronize with 3. When the leading character code (“T” character in this embodiment) is latched by the output latch 12, the character code and the output of the line / scan counter 13 are combined by the combining circuit 14 and the character pattern selection code of the character generator 15 is generated. Is input to the character generator 15. Here, the structure of the line / scan counter 13 will be described. The upper 6 bits are a counter for counting scanning lines, that is, a vertical counter of a character pattern, and 0 for a character of 40 × 40 dots.
39 plus, counting for the line feed pitch control line and returning to "0". The lower 3 bits are a horizontal counter of the character pattern, and in the case of a font of 40 × 40 dots, count 0 to 4 plus the character pitch control and return to “0” (the output of the character generator 15 is 8).
Because of bit parallel).

The operation when the font size is 40.times.40, the horizontal spacing between characters is 8 bits, and the vertical spacing between characters is 8 bits will be described below. When the leading character code ("T") is set in the output latch 12 as described above, the character code and the output of the line / scan counter 13 are combined by the combining circuit 14 and used as the character pattern selection code of the character generator 15. , Is input to the character generator 15. At this time, since the value of the line / scan counter is (0, 0), the character generator 15 outputs the character pattern in the vertical “0” line and the horizontal “0” -th data (8 bits). ) Is output. The output data of the character generator 15 is temporarily latched by the output latch 16 in order to synchronize the writing to the page memory 20, and is written to the address on the page memory 20 designated by the write address counter 18 by the page memory control circuit 17. Be done. In this case, since the value of the write address counter 18 is ADR (0,0), it is written to the addresses of the vertical address "0" and the horizontal address "0". When the writing of the 1-byte character pattern is completed, the value of the line / scan counter changes to (0, 1), and the value of the write address counter 18 also changes to ADR (0, 1). . Therefore, the vertical "0" line data and the horizontal "1" data of the character pattern are output to the output of the character generator 15, and after being latched in the output latch 16 as described above,
It is written in the address ADR (0,1) of the page memory 20. In this way, the vertical direction of one character pattern is "0".
When the writing of the last (“4” th data) of the line is completed, the value of the line / scan counter is (0, 5), and the write address counter 18 is ADR.
It becomes (0, 5). The horizontal spacing between characters is 8 dots (1
Character generator 1
All of the outputs of page memory 5 are forcibly set to "0" by the command from the page code buffer control circuit 7, and the page memory 2
"0" is written to the ADR (0,5) address of 0, and after the writing operation is completed, the row address counter is incremented by "1" and the next character code is set in the output latch 12 from the row buffer 10. . Also, the line / scan counter is (0,
0), the write address counter 18 is ADR (0, 6)
become. Therefore, the next character pattern of "0" is "0" in the vertical direction.
The writing operation of the data of the line to the page memory 20 is performed. At this time, the write address counter 18 is ADR
(0,6), (0,7), (0,8), (0,9),
Count up sequentially with (0, A), each O
The character pattern data of is written in the address designated by the write address counter 18. Then, when the value of the write address counter 18 becomes (0, B) and the value of the line / scan counter 13 becomes (0, 5), "0" is written in the page memory 20 as described above, and the write operation is performed. After the operation is completed, the row address counter is incremented by "1", and the next character code is set in the output latch 12 from the row buffer 10.

Further, the line / scan counter 13 is (0, 0), and the write address counter 18 is ADR.
It becomes (0, C). In this manner, the character pattern data of the vertical "0" line is sequentially written to the page memory 20, and the output of the line buffer 10 is "L".
When the "F" code is output, the "LF" code detection signal is sent through the output line S14 to the page code buffer control circuit 7
The writing operation of the character pattern from the character generator 15 is stopped. After that, the write address counter 18 is sequentially incremented by "1" to forcibly write "0" in the page memory 20. And
When the value of the write address counter 18 is the value of ADR (0, A3HE) when the A3 size is currently designated, that is, 33 points in FIG. 11, after the forced "0" write operation, the write address counter 18 is ADR (1,0),
The row address counters 11, 18 (0) and the line / scan counter 13 are set to (1, 0), respectively.
Then, the character code "T" at the beginning of the row buffer 10 is set in the output latch 12 again. Then, the character pattern data of the vertical “1” line of the character pattern is written to the page memory 20. Similarly, when the writing operation up to the lines "2", "3" ... "39" in the vertical direction of the character pattern is completed, the write address counter 18 sets the ADR (28, 0), the row address counter 11
Is (0), the line / scan counter 13 is (28,
0) respectively. With the above, the writing operation of the character pattern data for one line is completed, but since the line feed pitch is every 48 lines, "0" is forcibly written in the page memory 20 for the remaining 8 lines. When the writing of "0" for 8 lines is completed, the address value of the write address counter 18 is at the point 61 in FIG. 11, that is, the row address counter 11 at ADR (30, 0).
Is (0), the line / scan counter has an initial value (0,
0) respectively. This completes all writing operations including the line feed pitch for one line. Then, the character code data of the next second line is transferred from the page code buffer 9 to the line buffer 10. When the transfer of the character code data is completed, the row address counter 11 returns to the initial address (0). After that, the writing of the character pattern data of the second line is performed by the same operation as the writing of the character pattern data of the first line. Therefore, when the writing operation of the character pattern data of the second line is completed, the address value of the write address counter is ADR (60, 0), the row address counter 11 is (0), and the line / scan counter is (0,
0) respectively. In this way, the character code of each line is sequentially patterned and the pattern data is written on the page memory 20. Then, "E" indicating the last line
When the ND "code is detected from the line buffer, the data writing operation of the character pattern is stopped. Then, the page code buffer control circuit 7 forces the output of the character generator 15 to" 0 "via the signal line S13. At the same time, the completion of writing the character pattern data is notified to the page memory control circuit 17. Page memory control circuit 17
Then, after receiving the write end signal, forcibly up to the final memory address (in the case of A3 size, FIG. 1139 point ADR (A3VE, A3HE)) for the remaining memory area in the page memory 20 designated by the paper size. To "0"
Write in. Then, "0" is written at the 39th point in FIG. 11 to complete the operation of writing the character pattern data for one page of the designated paper size into the page memory 20. Then, the write address counter 18 displays ADR (0,
0), the row address counter 11 is initialized to (0), and the line / scan counter 13 is initialized to (0, 0).

Next, a case where the data sent from the host system 1 is image information will be described. When the image identification code of FIG. 10 is input to the decoder 5, the output of the decoder 5 is input to the main control unit 6 via the signal line S05.
The main control unit 6 determines that the input information is image information, and instructs the distributor 4 via the signal line S06 to input the next paper size data to the page memory control circuit 17. Therefore, the paper size data is input from the distributor 4 to the page memory control circuit 17 via the data line S07. Image data up to the next image data 1, 2, ... M is input from the distributor 4 to the page memory 20 via the data line S15. The method of inputting image data to the page memory 20 is as follows. When the page memory control circuit receives the paper size identification code, the next succeeding image data is transferred to the 32 point (address ADR (0,
0)) to write from the write address counter 18
Set to DR (0,0). The data length of one line in the horizontal direction is determined by referring to the table in the page memory control circuit 17 based on the paper size identification code. Therefore, if the paper size of the image information to be input to the page memory 20 is A4, the data length of one line is a value up to 44 points (A4HE) in FIG. 11, that is, "A4HE". Host system 1
Since the length of the image information sent from each line is of course "A4HE", the data length of the image data 1, image data 2, ... Image data m in FIG. 10 is "A4HE".
11 and the image data number m is the value of 47 points in FIG. 11, that is, “A4VE”. Therefore, the image data 1 in FIG.
32 points ADR (0,0) to 34 points AD
R (0, A4HE), image data 2 is a 51-point line, image data 3 is a 52-point line ... Image data m is a 37-point line, so the final address is 40
It becomes the point ADR (A4VE, A4HE). In this way, the image information is written in the page memory 20 while controlling the write address counter 18.

In the character pattern data 13 thus written in the page memory 20, the data at the addresses indicated by the read address counter 19 are sequentially output.
1, the gate circuit 23, the interface 22 to send the data to be printed to the print control unit through the interface bus S17. In FIG. 8, S17 is a status data line from the print control unit, S18 is a command data line for designating an operation mode to the print control unit, S19 and S20 are strobe signal lines for sending command data and print data, and S21. Is a busy signal line from the print controller, S22 is a horizontal synchronizing signal line from the print controller, S2
3 is a page end signal line for notifying the end of print data, S24 is a ready signal line of the print control unit, S25
Is a print request signal line for informing a printable state, S26 is a select signal line (2 lines) for specifying the data content of the data line in the interface bus S17, and S27 is an instruction to the print control section to start the print operation. This is a print start signal line.

The data transmission to the print control unit will be described in more detail. For the printing from the data control unit 2, the print control unit sends the horizontal synchronizing signal S22 to the start signal line S27. According to this horizontal synchronization signal S22, first, the line of 32 points in FIG.
The data of the 51-point line are sequentially transmitted, so that the read address counter 19 also sequentially changes the address line by line in accordance with the horizontal synchronizing signal S22, and the page from the print control unit is read. This operation is repeated until the end signal S23 is received, the data in the designated area of the page memory 20 is sent to the print control unit, and the page end signal S2 is sent.
When 3 is received, the data transmission is forcibly stopped. The print control unit outputs the page end signal S23 at the same timing as the horizontal synchronizing signal S22.
Further, in correspondence with the memory address in FIG. 11, the print control unit outputs at the same timing as 46 points in the last line A3 of the memory area of the paper size or 47 points in A4, or at a timing before that.

Further, in the page memory control circuit 17, when the sending of print data from the page memory 20 is started,
The values of the read address counter 19 and the write address counter 18 are constantly compared, and the read address counter 1
If the value of 9 is larger, it is controlled so as to permit the writing operation to the memory area where the transmission of the data is completed. Therefore, the loss of the writing time to the page memory 20 becomes very small.

FIG. 13 is a block diagram of the print controller 100 shown in FIG. In FIG. 13, 101 is a microprocessor for controlling each unit in the print control unit 100, 102 is an interrupt control circuit for controlling an interrupt to the microprocessor 101, and a command from the interface circuit 122. Signal line S30, page end signal line S2 from the print data write control circuit 19
9. Time-out signal line S2 from the general-purpose timer 103
The interrupt request signal from each of the 8 is transmitted to the microprocessor 101. Reference numeral 103 is a general-purpose timer that generates a basic timing signal for controlling the paper conveyance process and the drum rotation process. The general-purpose timer 103 is set to 10 msec in this embodiment. A ROM (Read Only Memory) 104 stores all control programs for operating the print control unit 100.
Reference numeral 105 is also a ROM and stores a data table different from that of the ROM 104. The contents of the data table are shown in FIG. In FIG. 45, the address (4000,4
001) is data for top margin control in the case of paper size A3, and addresses (4002, 4003) are data for bottom margin control and addresses (4004, 400).
5) Left margin control data and address (40
064007) contains write margin control data. Similarly, the address (4008-4
00F) includes the top, bottom, and
Contains left and right margin control data. Margin control data corresponding to various paper sizes are stored up to the address (4087). Then, these margin control data are used as set data of a margin control counter in a print data writing control circuit 119 described later.

Up to addresses (4100 to 41FF),
It contains a table of command codes for specifying the operation from the data control unit 2 and is used for checking the command code from the data control unit 2. The contents of the command are a top / bottom margin change table, a top margin adjustment table, a cassette top / bottom adjustment table, a cassette / manual feed adjustment table, and the like. Address (4200-42
Up to FF), data on the charging characteristics of the photosensitive drum 301 are stored, and five types of data A to F are stored. Then, this data is used for temperature correction control of the charging charger 304 described later. Address (4300-43
Up to FF), a replacement data table is provided, which includes the photosensitive drum 301, the developer in the developing device 307, and the fixing roller 3.
Contains 32 exchange cycle data.

Up to addresses (4400 to 47FF),
It is a control timer table that contains various timer values for printing such as process timing, paper feed timing, and the like.

Reference numeral 106 denotes a RAM (random access memory), which is a working memory, in which, as shown in FIG. 46, timers (TIM) A, B, ...
E, paper size register (stores cassette size data by signals of cassette size detection switches 320 and 324 described later), statuses 1 to 6 and other contents. The microprocessor 101 is
The cassette size stored in the paper size register is compared with the size of the recording information (image data etc.) sent from the external device from the data control unit 2, and if the cassette size is larger, the printing control in the subsequent stage is performed. A print operation command is issued to the unit 100. Therefore, it is possible to print even if the printing paper is larger than the information size sent from the outside, and the utilization can be improved. 107 is a non-volatile R
The data in the memory is retained even when the power is cut off by AM. The data contents in the non-volatile RAM are shown in FIG. Address in FIG. 45 (6000)
Indicates the drum characteristic NO input from the operation unit according to the exchange mode, and the address (6100) contains the jam information when a jam occurs. Used to prevent forgetting to process paper. Address (6200) is in reverse tray 3
At the discharge tray counter that counts the paper in 81,
Every time one sheet is fed to the reversing tray 381, the count is incremented by one. When the count value reaches the specified value, the tray becomes full and the operator is instructed to take out the paper from the tray. Further, the paper discharge tray counter is automatically cleared when the paper is taken out from the tray by the operator. Therefore, the power source is OF
Even if F is performed, the number of sheets remaining in the tray is held by this counter.

The address (6300) is a drum replacement counter, which counts up by 1 for each printing. When the value of this counter reaches the value of the replacement table (drum) of FIG. 45, the operator is informed of the replacement of the drum by the display of the operation unit.

The address (6400) is a developer exchange counter, which is incremented by 1 for each print as in the drum exchange, and when the value of this counter reaches the value of the exchange table (developer) of FIG. 45. Display on the operation unit.

The address (6500) is a fixing roller replacement counter, which is incremented by 1 for each printing as in the drum replacement, and when it reaches the value of the replacement table (fixing roller) in FIG.

Reference numeral 108 denotes a power supply sequence circuit, which has a function of preventing an erroneous operation when the power of the nonvolatile RAM 107 is turned on or off. Reference numeral 399 is a power supply device that supplies power to the control unit. An input / output port 110 outputs display data to the operation display unit 111 and reads each operation switch data and the like. Reference numeral 112 is an input port for reading input data from each detector 113 in the print control unit 100. 116 is a motor, a high-voltage power supply lamp,
Drive elements such as solenoids, fans, and heaters are shown. 11
Reference numeral 5 is a drive circuit for the drive element 116, and 114 is an output port for supplying an output signal to the drive circuit 115. Reference numeral 312 is a laser scan motor for operating a laser beam, 118 is a drive circuit thereof, and 117
Is an input / output port for supplying a drive control signal to the drive circuit.

Reference numeral 344 is a semiconductor laser, 120 is a laser modulation circuit as a laser control device for performing control including light modulation of the semiconductor laser, and 346 is a beam detector for detecting a light beam operated by the laser scan motor. Yes, a PIN diode that responds quickly is used. Reference numeral 121 is a high-speed comparator for converting the analog signal from the beam detector into a digital signal to generate a horizontal synchronizing pulse.
01 is a print data write control circuit that performs control such as writing to a predetermined position on 01 and generation of test pattern print data. An interface circuit 122 controls output of status data to the data control unit 2 and reception of command data and print data from the data control unit 2.

The details of the main blocks in FIG. 13 will be described below. FIG. 14 is a detailed circuit diagram of the various detectors 113 shown in FIG. In FIG. 14, signals from various detectors are input to the multiplexer 139. In the multiplexer, the input signal 11 of FIG.
Entered in 2.

Reference numeral 320 denotes an upper cassette size detection switch, which is composed of four switches, and the combination of these switches indicates the paper size. 324 is
The lower cassette size detection switch has the same structure as the upper cassette size detection switch. 319
Is a switch for the upper paper of the cassette, which is turned on when there is no more paper in the cassette. Reference numeral 323 is a lower paperless switch. Reference numeral 123 denotes a pass sensor before the registration roller, which uses a cds light receiving element. In this sensor, a bias voltage is applied through a resistor, and the output voltage changes depending on the presence or absence of paper (not shown). Therefore, by inputting the output to the comparator 124 to which the reference voltage Vref1 is applied,
A signal for determining the presence or absence of paper is obtained.

Reference numeral 326 is a manual feed switch for detecting the paper from the manual feed guide 325, 336 is a paper ejection switch in the fixing roller portion, and 395 is a paper ejection switch in the paper ejection tray portion. 125 is a toner-free detection switch for detecting the absence of toner in the toner box, 126
Indicates a toner full detection switch that operates when the toner is full in the toner bag.

Reference numeral 127 is a sensor for detecting the toner specific density of the developer (probe density detection sensor), which uses a photodiode. A bias voltage is applied to this sensor through a resistor, and the output voltage changes depending on the toner concentration. Therefore, the output of the comparator 12
Since the reference voltage Vref2 is applied to the other input terminal of the comparator 128 by inputting to the
A signal of 1 or 0 is obtained when the toner density is equal to or higher than the specified value.

Reference numeral 129 indicates that the front cover is opened and closed.
A door switch for turning on / off, a temperature fuse 130 provided in the fixing device, and a driving power source (+2).
4VB) is an MC relay that turns ON / OFF. Since one of the temperature fuses 130 is connected to the power supply +24 VA, when the temperature fuse 130 is melted due to an abnormality of the fixing device, the MC relay 131 is turned off and the driving power supply is turned off. The temperature fuse 130 is connected to the resistor RO1, and one of the resistors RO1 has a resistor R1.
It is connected to O2 and the input of the comparator 132. The reference voltage Vref is applied to the other input of the comparator 132.
3 is applied. Therefore, when the temperature fuse 130 is blown, the input of the comparator 132 becomes OV. Therefore, the fusing detection signal of the temperature fuse is output to the output of the comparator 132. 133 is a destination changeover switch. Specifically, it is turned on by turning on / off this switch.
The state is domestic (A and B sizes), and OFF is for the United States (legal and letter sizes). Therefore, for example, even if the combination of codes by the upper or lower cassette size switches (4) is the same, either the domestic or US paper size is selected depending on the state of this switch.

Reference numeral 134 denotes a jam reset switch,
It is installed in the front cover. This switch is a switch that is turned on for the purpose of confirmation after an operator clears a jam or replaces a toner bag when an operator call occurs when paper jam or toner is full. Therefore, if this switch is not turned on after the above processing, the display of the operation unit for jam or full toner is not cleared. Reference numeral 392 is a paper discharge tray sensor for detecting the paper in the tray in FIG. A thermistor 334 detects the temperature of the fixing device, and is controlled so that the temperature detected by the thermistor becomes constant. The output of the thermistor 334 is the resistance RO3 and the comparator 13
It is connected to the input side of 6,137. Therefore, the input voltage of the comparator changes as the resistance value of the thermistor 334 changes with temperature. That is, the higher the temperature, the higher the input voltage. The voltage divided by the resistors RO6 and RO7 is applied to the other input terminal of the comparator 136, and the output of the comparator 136 changes depending on whether it is higher or lower than the divided reference voltage. Further, a resistor RO8 is provided at a connection point of the resistors RO6 and RO7.
Are connected, and one of them is connected to the collector of the transistor 138. Therefore, this transistor 13
8 is turned on by the input signal (power save signal) S3, the reference voltage of the comparator 136 is lowered by the resistor RO8, and the temperature control of the fixing device is performed by the transistor 1
It is lower than when 38 is OFF. Therefore, the power consumption of the fixing device is reduced, and the power saving state is set.
Further, the reference voltage of the comparator 137 is the resistors RO4 and RO.
Given by a partial pressure of 5. Since the reference voltage of the comparator 137 is set to be considerably lower than the reference voltage of the comparator 136, it is possible to detect the temperature drop of the fixing device due to the heater burnout during the operation of the printer or the failure of the heater drive circuit. . One of the outputs S33 of the comparator 136 is input to the multiplexer 139, and the microprocessor 101
Read by This input signal is used to detect the ready state of the fixing device. The other is used as a drive signal for the fuser heater lamp 333 of FIG.

Reference numeral 342 is a drum temperature sensor for detecting the temperature near the photoconductor 301. The output side of the thermistor 342 is connected to the resistor R58 and the input of the operational amplifier 270. Therefore, the resistance value of the thermistor 342 also changes due to the temperature change near the photoconductor 301. Therefore,
The input voltage of the operational amplifier 270 also changes. Operational amplifier 2
The output voltage of 70 is low when the temperature of the photoconductor 301 is low, and is high when the temperature of the photoconductor 301 is high.
The operational amplifier 270 is a voltage follower,
The output is connected to the input of the A / D converter 271. Then, the A / D converter 271 converts the output voltage of the operational amplifier 270 into a digital value, and the microprocessor 10 passes through the multiplexer 139.
Let 1 read. The A / D-converted temperature data of the photoconductor 301 is used for charging correction of the photoconductor 301 described later. 440 is a cassette upper / lower stage adjustment switch,
441 is a cassette / manual feed adjustment switch, 442
Is a top margin adjustment switch.

FIG. 15 shows a drive circuit 115 in FIG.
3 is a detailed block diagram of an output element 116 and FIG. In FIG. 15, reference numeral 141 denotes a developing device motor, which uses a DC-driven hall motor. Reference numeral 140 denotes a driver for the developing device motor, which performs PLL control. 143
Is a fuser motor, and a DC-driven hall motor is used. 142 is a driver for the fixing unit motor 143, which performs PLL control. A fan motor 145 for cooling the inside of the machine uses a DC-driven hall motor. Reference numeral 144 denotes a driver for the cooling fan motor, which does not perform PLL speed control like the above-mentioned developing device and fixing device driver. Reference numeral 147 is a motor for driving the photosensitive drum 301, which uses a four-phase pulse motor. Reference numeral 146 is a driver of the drum motor 147, which adopts a constant current 1-2 phase excitation method. It should be noted that the driving is performed at a speed of about 1200 PPS in a portion where vibration is less likely to occur. 149 is a registration roller 32
9 and a registration motor for driving the manual feed roller 327, which is a pulse motor. Reference numeral 148 is a driver for the registration motor, which uses a constant voltage two-phase excitation method. The speed is about 400 PPS.

The registration motor 149 rotates the registration roller 329 when the rotation direction is normal, and rotates the registration roller 327 when it is reversed. These are transmitted via a one-way clutch.

Reference numeral 151 is a sheet feeding motor for driving the lower sheet feeding roller 322 and the upper sheet feeding roller 318, which is a pulse motor. In the same way as above, forward and reverse rotations are transmitted via the one-way clutch. Reference numeral 150 is a driver for the paper feed motor 151, and the registration motor driver 14
As in No. 8, constant voltage two-phase excitation is used. Speed is 400
It is about PPS.

Reference numeral 302 denotes a static elimination lamp for removing the residual charge on the photoconductor 301 before charging, and a plurality of red LEDs.
It is composed of. R10 is a current control resistor of the static elimination lamp 302, and 152 is a driver of the static elimination lamp 302. Reference numeral 303 denotes a pre-transfer charge eliminating lamp that is placed before the transfer charger to increase transfer efficiency, and is composed of a plurality of red LEDs. R11 is a current control resistor of the pre-transfer charge eliminating lamp, and 153 is a driver of the pre-transfer charge eliminating lamp. Reference numeral 158 denotes a solenoid of a blade for collecting toner, and when the solenoid is turned on, the blade 310 is pressed against the photoconductor 301. 154
Is a driver of the blade solenoid 158. 1
Reference numeral 59 denotes a toner replenishing motor for replenishing toner from the toner hopper to the developing device 307. By rotating the toner replenishing motor, toner is replenished from the toner hopper to the developing device 307. This toner replenishment motor 1
The operation of 59 operates according to the output of the probe concentration detection sensor of FIG. A driver 155 for the toner replenishment motor 159. Reference numeral 131 is an MC relay that works in conjunction with the door switch similar to that shown in FIG.
56 is the driver. As shown in FIG. 15, the power supply side common such as the motor and the lamp which omits the MC relay 131 is connected to the contact 163 of the MC relay 131, and the other of the contacts is connected to the + 24VB power supply. Therefore, when the MC relay 131 is turned on, the motor and the lamp can be operated.

Reference numeral 304 denotes a charging charger, and the case of the charger is connected to the ground of the machine body. The charger corona discharge wire is connected to the output terminal of the charging high-voltage power supply 160 of the high-voltage power supply 338, and the high-voltage output ON / OFF signal line S35 and the high-voltage output current are input to the charging high-voltage power supply. An analog control signal line S36 to be changed is connected. Further, the analog control signal line S36 is connected to the D / A converter 165, and the data of the charging voltage control data line S37 from the microprocessor 101 converts the analog voltage into an analog voltage by the D / A converter 165 and outputs the high voltage power source for charging. Control the current. 306 is a peeling charger, a peeling charger 30
6 is connected to the output of the peeling high-voltage power supply 161. The peeling high-voltage power supply has an AC output. Reference numeral 305 denotes a transfer charger for transferring the developed toner on the photoconductor 301 to a sheet, and the transfer charger is connected to the output of the transfer high-voltage power supply 62. The high-voltage power supply for transfer is
In addition to the transfer charger output, a developing device bias power source is also incorporated, and its output line S38 is connected to the developing device magnet roller 308. With this voltage, a bias voltage is applied to the magnet roller 308 to give a developing bias. Reference numeral 33 is a heater ramp of the fixing device, one side of which is connected to one of the AC 100V power sources.
The other is connected to the second contact 164 of the MC relay 131, and one of them is connected to the heater drive circuit 166. Therefore, the heater lamp 333 is the MC relay 1
It operates only when 31 is ON. Also, heater drive circuit 1
Two input signals S33 and S39 are input to 66, and S33 is the thermistor 334 in the fixing device shown in FIG.
And a density control signal for the fixing device. S3
9 is a heater lamp 3 from the microprocessor 101
33 is a compulsory OFF signal.

FIG. 16 is a detailed circuit diagram of the laser scan motor 312 and its drive circuit 118 in FIG. In FIG. 16, reference numeral 312 is a circuit diagram inside the laser scan motor. L02, L03, and L04 represent motor coils, and 180, 181, and 182 are Hall elements that detect the position of the rotor of the motor. 18
3, 184, 185 are the hall elements 180, 181,
182 is a comparator, the output of which is the drive circuit 1
Power transistors 171, 172, 173 for driving the motor coils L02, L03, L04 in 18
Is connected to the base of resistors through resistors R26, R27, and R28. In addition, the power transistors 171, 17
Base resistors R23, R24, and R25 are connected between the bases and the emitters of 2,173, respectively. As the rotor of the motor rotates, the Hall elements 180, 1
81, 182 are turned on in the order of 180, 181, 182. Therefore, the outputs of the comparators 183, 184 and 185 also become LOW level in the order of 183, 184 and 185.
Therefore, the power transistors are turned on in the order of 173, 172, and 171 and the drive voltage is applied in the order of L02, L03, L04, so that the laser scan motor 31
2 rotates. The output of the comparator 185 is passed through the diode D02, the resistor R30 and the capacitor C0.
6, input to the frequency dividing counter 175 through the waveform shaping circuit by the inverter 174. Frequency divider counter 175
The outputs of the output terminals Q1 and Q2 are connected to motor speed switching gates 176 and 177, and the output of the speed switching gate is passed through an OR gate 178 to the FG input of the PLL (phase lock loop) control IC. It is connected. The speed switching gates 176 and 177 are also provided.
The output of the speed control signal line S40 and its inverted output are connected to one of the inputs. Therefore, S40 is LOW
In the case of the level, the switching gate 177 becomes effective and the output of Q1 of the frequency division counter is FG of the PLL control IC 167.
When S40 is at the HIGH level, the switching gate 176 is enabled and the Q2 output of the frequency dividing counter 175 is input to the FG input of the PLL control IC 167. The input / output signals of the PLL control IC 167 will be briefly described below. The P / S terminals (PLAY / STOP) are at the HIG level.
Stop at H level and start at LOW level.
In the case of HIGH level, the outputs of both terminals of AGC and APC are HIGH level. FGIN is a rotary motor pulse signal input from the motor to be controlled, and N1 and N2 are this IC
33/45 is a signal for switching the number of rotations of the motor, CPOUT is a crystal reference frequency output signal, CPIN is a reference frequency input, and LD is a lock detection signal for the motor. H when the rotation speed is within the lock range
IGH level, and LOW level otherwise.
AFC is the output of the speed control system of the motor.
Bit D / A converter output, APC is a phase control system output of the motor and is an 8-bit D / A converter output inside the PLLIC. X connected to the PLLIC167
01 is a crystal oscillator for generating a reference frequency, C01, C02
Is an oscillating capacitor.

AFC, APC of PLL control IC 167
The output terminal of is composed of resistors R12 and R13, and is connected to the-side input terminal of the operational amplifier 168. To the + input terminal of the operational amplifier 168, apply + 12V to the resistor R1.
The voltage divided by 4 and R15 is applied. The resistor R16 and the capacitor C03 form a negative feedback circuit, and the capacitor C03 particularly functions as a high pass filter. Therefore, the amplification degree of the operational amplifier 168 has a characteristic of attenuating an input having a certain frequency or higher.
The output of the operational amplifier 168 is connected to the + input terminal of the pulse width modulation type switching regulator IC 169. Reference numeral 169 is a pulse width modulation type switching regulator IC which is a general commercial product. The IC 169, the power transistor 170, the diode D01, the coil L01, and the capacitor C05 form a down switching regulator circuit. In the input / output of the IC 169, the-terminal is a comparison reference voltage terminal, and the reference voltage obtained by dividing the voltage of the reference voltage output terminal VREF inside the IC 169 by the resistors R17 and R18 is applied. The DEADTIME terminal regulates the maximum pulse width of the output, and a voltage obtained by dividing the VREF by resistors R19 and R20 is applied. C1 and C2 are output terminals, and the pulse width changes according to the voltage value of the + input terminal. That is, when the + side input terminal voltage is lower than the − side input terminal voltage, the pulse width of C1 and C2 on the LOW level side becomes small, and the ON width of the power transistor 170 also becomes small. Therefore, the voltage across the capacitor C05 also decreases. On the contrary, when the + side input terminal voltage is higher than the-side input terminal voltage, the pulse width of C1 and C2 is increased and the capacitor C0
The voltage across 5 also increases.

The rotation speed control of the scan motor 312 will be described below.

Rotation start signal S4 of the scan motor 312
When 2 becomes LOW level, both AFC and APC outputs of the PLL control IC 167 are LOW level until the above-mentioned lock signal S41 is output. Therefore, the output of the operational amplifier 168 is HIGH level voltage. To be done. Therefore, the output pulse width of the regulator IC 169 is large, and the voltage across the capacitor C05 is about + 16V. Since any one of the Hall elements 180, 181, 182 is turned on at the position where the rotor of the motor is stopped, the motor coils L02, L03,
Of L04, the coils corresponding to the hall elements 180, 181, 182 are excited and the scan motor 312 starts rotating. Then, the scan motor 312 accelerates its rotation. Now the level of the speed control signal line S40 is HIGH
Therefore, the Q2 output of the frequency division counter 175 is
It is added to the FG input terminal of the PLL control IC 167. Therefore, the frequency division counter 175 functions as an 8 frequency division circuit. The frequency of the signal applied to FGIN is PLLIC1.
When it reaches about 96% of the reference frequency inside 69, the lock signal LD S41 becomes HIGH, and the AFC and APC output levels are not fixed to the LOW level (OV) but switched to the output voltage of the PLLIC internal D / A converter. Therefore, thereafter, the scan motor 312 is controlled by the speed control system output AFC and the phase control system output APC so as to have a constant speed.

Further, in this embodiment, a certain fixed time (about 5
Min) When the print command does not come from the data control unit 2, the scan motor enters the standby state and the speed control line S
The output of 40 becomes LOW level. Therefore, the frequency divider 175
Is divided by 4 from the previous divided by 8, so that the scan motor has a rotation speed of 4/8, that is, 1/2. In order to prevent the reliability problem of the bearings of the motor from occurring during high speed rotation for a long time, the half speed control as described above is performed. In this embodiment, the speed is about 12,000 rpm during printing operation, that is, high speed rotation, and about 6000 rpm during standby.

FIG. 17 shows the laser modulation circuit 1 in FIG.
20 is a detailed circuit diagram of the semiconductor laser 20 and the semiconductor laser 344. FIG. Figure 1
In FIG. 7, 344 is a semiconductor laser diode which is a light beam generating means which is a light beam generating means, the structure of which is a laser diode 259 and a monitoring photodiode which is a light detecting means for monitoring the output beam intensity from the laser diode 259. It consists of 260. 257 is a high frequency transistor which is a voltage-current conversion means (or a first current drive means) and performs optical modulation of the laser diode 259 (control means). A resistor R50 is a current detecting resistor, 258 is a transistor (level selecting means) which is a second current driving means for supplying a bias current to the laser diode 259, R51 is its current limiting resistance, and R52 is a base current of the transistor 258. It is a limiting resistance. 254, 255, and 256 are high-speed analog switches for applying modulation to the laser diode 259, and each analog switch has an H gate (G).
When an IGH level voltage is applied, the resistance between the drain (D) and the source (S) becomes low and the ON state is achieved. When a LOW level voltage is applied to the gate (G), it becomes a high resistance and is turned off. The output power from the laser 259 has three levels in this laser printer. The first is the portion corresponding to the white background on the paper, and is the photoconductor 30.
Output P for removing the charged electric charge of 1 almost completely
When the analog switch 254 is turned on at (ON), the laser diode 259 becomes the output P (ON). The second is a portion corresponding to a black background on the paper, and in order to keep the charged electric charge on the photoconductor 301 as it is, the analog switch 256 is turned on in the output “0” state, that is, the output P (OFF). The output of the laser diode 259 is OFF, that is, P (OFF). Third
Is for increasing the print density of one dot line at the output P (SH) between the first output P (ON) and the second output P (OFF). By turning on the analog switch 255, the laser The diode 259 has the output P
(SH) (details of P (SH) will be described later).

The resistors R42 and R43 are analog switches 2
Short-circuit protection resistors 249, 250, 251 at the time of ON / OFF change of 54, 255, 256 are gate drivers of the analog switches 254, 255, 256. C
09, C10, C11 are capacitors for speeding up, and R47, R48, R49 are the gate driver 2
Input resistances of 49, 250, and 251.

Reference numeral 246 denotes a 3-NAND gate, which outputs L when all three gate inputs become HIGH level.
The OW level is reached, the analog switch 254 is turned on, and the laser diode 259 is in the output P (ON) state. The first of the three input gates is the inverter 2
It is connected to the output of 53 and the input of the inverter 253 is the print data signal S47 (L for printing at HIGH level).
Is not printed at OW level). The second is connected to the output of the inverter 252 and
The input of 2 is connected to the shadow signal S48 (shadow ON at HIGH level, OFF at LOW). The third is connected to a laser enable signal S49 (laser enable at HIGH level, laser forced OFF at LOW). Therefore, the output of the NAND gate 246 is L
The condition for reaching the OW level is the laser enable signal S4.
9 is HIGH, the shadow signal S48 is LOW, and the print data signal S47 is LOW. Next, 247 is 3N
When all three gate inputs in the AND gate become HIGH level, the output becomes LOW level, the analog switch 255 is turned ON, and the laser diode 25
9 is in the output P (SH) state. Of the three input gates, the first is the shadow signal S48 and the second is the inverted signal of the print data signal S47, the inverter 253.
The third is connected to the laser enable signal S49, respectively. Therefore, the NAND gate 2
The condition that the output of 47 is LOW level is that the laser enable signal S49 is HIGH and the shadow signal S48 is H.
This is when the IGH and print data signal S47 is LOW.
Next, 248 is a 2OR gate, and when either one of the two gate inputs becomes the LOW level, the output becomes the LOW level, and the analog switch 256
Is turned on, and the laser diode 259 enters the OFF state output P (OFF) state.

A sample and hold IC 245 is used to control the output of the laser diode 259 to the shadow output P (SH). AN
ALOG-INPUT is an analog voltage input for sampling, SAMPLEC is a connection terminal of the holding capacitor CO8, and STROBE is a sampling strobe signal terminal, which is connected to the sample strobe signal S46. Reference numeral 237 denotes an FET-input operational amplifier, which constitutes a voltage follower circuit. DO3 is a Zener diode and regulates the output of the laser diode 259 to be within the maximum rating. Further, the resistor R40 and the capacitor CO7 constitute an integrating circuit as an integrating means, and the resistor R41 is a discharging resistor for discharging the electric charge of the capacitor CO7 at a constant rate. Reference numeral 236 is an analog switch as switching means, and its gate (G) is connected to the buffer 244.
The sample signal S45 is input to the input of No. 4. 253
Is a transistor for level conversion, and R39 functions as a current limiting resistor when the capacitor CO7 is charged. R38
Is a base current limiting resistor of the transistor 235, and 234 is a comparator which is a comparing means. This comparator has hysteresis characteristics due to the functions of the resistors R34 and R35. The output voltage of the laser monitor amplifier 232 is applied to the + input side of the comparator 234 through the resistor R34. 232 is a photodiode 2 that detects the optical output from the laser diode 259.
An amplifier with an output of 60, which serves as a current-voltage conversion means. The resistors R32, R33 and VRO1 are resistors that regulate the amplification degree of the operational amplifier 232. Therefore, the amplification degree of the operational amplifier 232 can be changed by changing the volume VRO1. R31
Is the photodiode 2 in the semiconductor laser 344.
60 is a load resistance for output, and the photodiode 260
A voltage proportional to the output current of is obtained. FIG. 19 shows the relationship between the short circuit current Is and the light output Po of the photodiode 260. In FIG. 19, Is is the monitor current, Po
Indicates the optical output of the laser diode 259. The P
Output of (ON) is about 6mw, output of P (SH) is about 4m
w and P (OFF) are 0. Also LA-A, L
AB represents the monitor characteristics of two types of laser diodes. Normally, the volume VR01 is adjusted so that the output voltage of the operational amplifier 232 is about 3 V when the laser diode light output is 6 mw. Therefore, the characteristics of both graphs LA-A and LA-B in FIG. 19 can be adjusted by the volume VR01. 238 is a comparator for confirming whether the laser diode 259 is emitting light,
The output voltage of the operational amplifier 232 is applied to the + side input. A voltage (in this case, set to about 2.0V) is applied to the-side by being divided by resistors R36 and R37. Therefore, the laser diode 259 emits light, the output of about 2 mw bell changes from the LOW level to the HIGH level, and the laser ready signal S43 is output. Further, a laser light amount setting voltage is applied to the-side input terminal of the comparator 234. The set voltage is given from either analog switch 240 or 241. That is, the analog switch 240
Becomes ON when the laser output P (ON) is set, and the output voltage of the voltage follower 239 is applied to the-side input of the comparator 234. Voltage Follower 2
A voltage is input to the input terminal of 39 by being divided by the main exposure adjusting volume 360 which is the first voltage changing means and the resistor R45, and the voltage of the main exposure adjusting volume 360 is changed. The voltage at the side terminal also changes. Also analog switch 24
1 is turned on when the laser output P (SH) is set, and the output voltage of the voltage follower 239 is set to the resistance R.
The voltage divided by 46 and the shadow exposure adjusting volume 361 which is the second voltage varying means is applied to the-side input terminal of the comparator 234. The voltage follower 239, the analog switches 240 and 241,
The main exposure adjustment volume 360, the resistor R45, the shadow exposure adjustment volume 361, and the resistor R46 constitute the light output setting means. A circuit that compares the voltage detected by the monitor photodiode 260 and amplified by the monitor amplifier 324 with the set voltage by the comparator 234 and integrates the comparison value is called an optical output stabilizing unit.

Then, the analog switches 240, 2
The switching of 41 is switched by the main exposure setting signal S44. That is, the main exposure setting signal S44 is L
In the case of OW level, the output level of the inverter 242 is H
It becomes the IGH level and the analog switch 241 is turned on. Further, when the main exposure setting signal S44 is HIGH level, the output of the buffer 243 becomes HIGH level and the analog switch 240 is turned on. The outputs (S side) of the analog switches 240 and 241 are also input to the voltage follower 261 and are used to correct the threshold level of the horizontal sync pulse detection comparator of the beam detection circuit, which will be described later.
An output S50 of 1 is used.

Next, the current-output characteristics of the laser diode used in this printer will be described. Figure 1
8 is a graph of the IF-Po characteristic. TC = 0 ° C is the IF-Po characteristic when the case temperature of the laser diode 344 is 0 ° C, and TC = 25 ° C is the case temperature of 25 ° C.
TC = 50 ° C. is the IF-Po characteristic when the case temperature is 50 ° C. Taking the case temperature TC = 25 ° C. as an example, when the current IF flowing in the laser diode 259 is gradually increased from 0, the optical output Po starts to be output from a point of about 50 mA. Then, at the point of IF = 68 mA, the optical output of P (ON) is 6 mw. Therefore, T
Even when C = 0 ° C., the point at which the optical output Po starts to be output is about 40 mA.
When the laser enable signal S49 is at the HIGH level, the bias current I
FB is supplied to reduce the power loss of the laser modulation transistor 257. Therefore, the laser modulation transistor 257 is connected to the bias current IF.
The action of B ensures extremely stable operation even at high temperatures. Further, when the amount of change in current required to modulate the laser is, for example, TC = 25 ° C., the value of IF25−IFB is sufficient and the current of IF25 is directly supplied to the transistor 2
The accuracy of the light quantity stabilizing operation, which will be described later, can be considerably improved as compared with the case of driving with 57. Further, as is apparent from the graph, the output of the laser diode itself changes considerably depending on the temperature, so that the light quantity stabilizing circuit is required. This laser light quantity stabilizing circuit detects the light quantity from the laser diode 259 with the monitor photodiode 260 and detects the light quantity.
Is controlled so that the short-circuit current Is is always constant.
This is because, as is apparent from FIG. 19, the monitor short circuit current Is and the optical output Po of the laser diode 259 have a perfect proportional relationship, so that if the monitor current Is is kept constant, the optical output Po is always kept constant. . Further, since the drift of the photodiode 260 due to the temperature is very small, the change amount of the light output can be ignored even if the temperature changes. Next, the operation of the above optical output stabilizing circuit will be described with reference to FIGS. 17 and 20.

In FIG. 20, the laser enable signal S
When both 49 and the sample signal S45 become HIGH level, the transistor 258 of FIG. 17 is turned ON, and a bias current (about 30 mA) flows through the laser diode 259 through the resistor R51. At this time, since the print data signal S47 and the shadow signal S48 are both at the LOW level, only the gate 246 of the gates 246, 247, 248 is at the HIGH level, so that the output is at the LOW level and the analog switch is turned on. 25
Of the 4,255,256 analog switch 254 is O
It becomes N state. Further, the analog signal 236 is turned on when the sample signal S45 becomes HIGH. At this time, since the capacitor CO7 is not yet charged, the output of the op amp 237 is OV, and the base of the laser modulation transistor 257 is also OV. Therefore, at this time point, only the bias current flows in the laser diode 249, and the laser diode does not emit light as can be seen from the characteristics of FIG.
Photodiode 26 for laser diode monitor
Since the laser does not emit light at 0, the monitor current I
s is 0, and the output of the op amp 232 is OV.
Is output, the output of the comparator 234 is LO
The transistor is turned to the W level and the transistor 235 is turned off. Since the transistor 235 is off, the capacitor C07 is charged through the resistors R39 and R40.
The time constants of the resistors R39 and R40 and the capacitor CO7 when charged are selected to be about 20 to 50 msec.
If this value is very small, the response of the stabilization circuit is too fast,
The laser light output level fluctuates greatly. On the other hand, if it is too large, the response becomes poor and it takes time for the light output to stabilize. As the capacitor CO7 is charged, the output voltage of the voltage follower 237 also gradually rises. Therefore, a current flows through the collector as the base voltage of the laser modulation transistor 257 rises. At this time, the collector current Ic of the transistor 257 has a current value of {VB-VBE (SAT)} / R50. In the laser diode 259, an added current IF of the bias current IFB from the transistor 258 and the current Ic from the transistor 257 flows. Then, when the current Ic increases and the forward current IF of the laser diode 259 reaches about 50 mA (TC = 25 ° C.), the laser diode 259 emits light. When the laser diode 259 emits light, the monitor current of the monitor photodiode 260 flows according to the emitted light output, and the + input terminal voltage of the operational amplifier 232 rises, and the output voltage also has a value obtained by amplifying the input voltage. Is output. The amplification degree of the operational amplifier 232 is equal to that of the operational amplifier 23 with respect to the output 1 mw of the laser diode 259.
Volume V in advance so that the output voltage of 2 becomes about 0.5V
Since it is adjusted by R01, the optical output of the laser diode 259 increases, and the optical output of the operational amplifier 2 is about 2 mw.
When the output voltage of 32 becomes about 1 V, the output signal of the comparator 238, that is, the laser ready signal S43 changes from LOW to HIGH level. And the comparator 23
The main exposure setting signal S44 is LO
Because of the W level, the shadow exposure level (light output P (SH)) voltage is applied through the analog switch 241. This voltage is set according to the sensitivity characteristic of the photoconductor 301, and the shadow exposure level voltage is set by the shadow exposure setting volume 361 in the operation unit. Now, it is assumed that the voltage is 2.0 V corresponding to the average value of the optical output of 4 mw. Therefore, when the optical output of the laser diode 259 rises and the + input terminal voltage of the comparator 234 becomes 2.0 V or more, the transistor 235 turns on and the capacitor C
O7 is discharged through the resistor R40. Therefore, the base voltage of the laser modulation transistor 257 also drops, and the optical output of the laser diode 259 becomes 4 mw or less. When the optical output of the laser diode 259 becomes 4 mw or less, the + side input terminal voltage of the comparator 234 also becomes 2.
The voltage becomes 0 V or less, and the transistor 235 is turned off again. Then, the capacitor CO7 is again connected to the resistors R39 and R4.
Charged up through 0. Then, the laser diode 259 fluctuates the optical output again around 4 mw, and the comparator 234 repeats ON / OFF operation at a constant cycle. Incidentally, this comparator 234
Has a hysteresis characteristic, the comparison judgment is stabilized and a reliable judgment can be made. Then, due to the integration effect of the resistors R39 and R40, the capacitor CO
The voltage across 7 approaches the value of VO1 in FIG. 20 and stabilizes.
After the laser ready signal S43 becomes HIGH level, the microprocessor 101 outputs a sample strobe signal S46 of shadow level after a predetermined time t6 has passed through the output port. When the sample strobe signal is output, the sample hold IC 245
The voltage VO1 (FIG. 20) of the capacitor C07 input to the NALOG-INPUT input terminal is sampled and held, and the voltage is stored in the hold capacitor CO8. Therefore, after the sample strobe signal is turned off, the control voltage VO1 for outputting the shadow level P (SH) is continuously output to the output OUT of the sample hold IC.

Next, when the sample hold operation for the shadow level P (SH) is completed, the microprocessor 101
Sets the main exposure setting signal S44 to HI through the output port.
Switch to GH level. Therefore, the
The output voltage of the voltage follower 239 is applied to the side input terminal through the analog switch 240. The main exposure level (light output P (ON)) voltage is output to the output of the voltage follower 239. This voltage is a voltage set by the main exposure setting potentiometer 360 in the operation unit according to the sensitivity characteristic of the photoconductor 301. At this time, a voltage of 3.0V corresponding to the average light output of 6 mw is output. Be present. Therefore, the comparator 234
Output becomes low level because the − side input terminal is switched to 3.0 V, and the transistor 235 is turned off. Therefore, when the capacitor CO7 is further charged up, the base voltage of the laser modulation transistor also rises and the light output of the laser diode 259 also increases. And the optical output of the laser diode 259 is 6
At around mw, the output voltage V23 of the operational amplifier 232
2 becomes about 3V. Output voltage of operational amplifier 232 is 3V
As described above, the output of the comparator 234 changes to HIGH as in the case of setting the shadow level described above, and the transistor 2
35 is turned on, and the capacitor CO7 is discharged through the resistor R40. Therefore, the base voltage of the laser modulation transistor 257 also drops, and the optical output of the laser diode 259 becomes 6 mw or less. When the optical output of the laser diode 259 becomes 6 mw or less, the + side input terminal voltage of the comparator 234 also becomes 3.0 V or less, and the transistor 235 is turned off again. Then, the capacitor CO7 is charged up again through the resistors R39 and R40, and the optical output of the laser diode 259 is 6 mw.
That's all. In this way, the comparator 234 turns ON / O mainly when the optical output of the laser diode 259 is around 6 mw.
The operation of the FF is repeated at a constant cycle. And the resistor R3
The voltage of the capacitor CO7 approaches VO2 in FIG. 20 and stabilizes due to the integration effect of 9 and R40. When the setting of the main exposure level is completed, the microprocessor 101 starts the operation of a sampling timer, which will be described later, and writes the print data to the photoconductor 301.
The sample timer is triggered one after another at a constant cycle T each time a laser beam detection signal, which will be described later, arrives, and outputs the sampling signal S45 only in a portion other than the print data writing operation, that is, the section of FIG. 20a. Since the sample signal S45 is at the LOW level in the section of the print data S47 and the shadow data S48, the analog switch 236 is turned off. Therefore, print data D4
7 and the shadow signal S48 causes the laser diode 259 to be modulated.
The optical output level of 59 is P (ON), P as described above.
There are three levels, (SH) and P (OFF). That is, the first is that the print data signal S47 is OFF, that is, LO
When the shadow signal is OFF at the W level, that is, at the LOW level (white as the output of printing), the NAND gate 246 is established and only the analog switch 254 is turned ON.
Therefore, the main exposure level voltage V02 is applied to the base of the modulation transistor 257, and the optical output of the laser diode 259 becomes P (ON) = 6 mw. The second is NA when the print data signal S47 is OFF and the shadow signal is ON (halftone as the print output).
The ND gate 247 is established, only the analog switch 255 is turned on, the output voltage V01 of the sample hold IC 245 is applied to the base of the modulation transistor 257, and the optical output of the laser diode 259 is P (S).
H) = 4 mw. Thirdly, the print data signal S47 is O
N, when the shadow signal is OFF (black as the print output), the OR gate 248 is established and only the analog switch 256 is turned ON. Therefore, the base of the modulation transistor 257 is shot by GND and becomes OV, so that the optical output of the laser diode 259 is P (OFF).
= 0 and no light is emitted. In this way, the first printing is performed. When printing is completed, the microprocessor 101 outputs the main exposure setting signal S4 through the output port.
4 to the LOW level again, and the shadow exposure level P (S
H) is reset. Therefore, the voltage of the minus side input terminal of the comparator 234 becomes 2.0V which is the set voltage of the shadow exposure level. Therefore, the transistor 235 is turned on, the capacitor CO7 is discharged, and the VCO7 becomes smaller. Here, in explaining the light output stabilizing operation of the laser diode, it is assumed that the case temperature of the laser diode 344 is increased by ΔT during the second printing operation. As is clear from the characteristic diagram of FIG. 18, when the case temperature rises, the IF-Po characteristic curve of the laser diode shifts to the right, and when the same current is applied to the laser diode 259, the optical output Po decreases. I will end up. Therefore, in order to obtain the same optical output, the IF
Must be increased by the current ΔIF corresponding to the shift of the characteristic curve to the right. Therefore, the voltage VCO7 of the capacitor CO7 is set to V03 which is higher than the first set voltage V01 by the voltage ΔV1 corresponding to the above ΔIF, and the optical output of the laser diode 259 becomes the same as the first set P (SH) = 4 mw. Is set. Then, similarly to the first time, the shadow exposure level P (ON) is set in the sample hold IC 245 by the sample strobe signal S46. Also at this time, the laser diode 344
The operation corresponds to the case temperature rise of the capacitor C
The voltage of 07 is V which is higher by the correction voltage ΔV2 due to the temperature rise.
04 is set, and after the setting, the second printing is performed. In this way, the shadow exposure level P (SH) and the main exposure level P (ON) are very accurately maintained at constant levels by the function of the stabilizing circuit, so that high quality printing can be performed. Incidentally, the main exposure level P (ON) is such that the light quantity stabilizing operation is performed so that the light output is always kept constant except during the writing of the print data as described above. Regarding the shadow exposure level, the sample hold operation is performed before the start of printing of each print, and the light quantity stabilizing operation during the print writing operation like the main exposure level is not performed. This is because the circuit becomes complicated and expensive, and the shadow level is auxiliary compared to the fluctuation of the main exposure level, and even if the shadow level slightly fluctuates, the print quality is not so affected. When changing the setting voltage input to the comparator 234 according to the sensitivity characteristic of the photoconductor 201, the main exposure setting volume 3 is set.
Adjust 60 by changing. The main exposure setting volume 360 is adapted to change the input voltage of the voltage follower 239. Therefore, the light output setting voltage at P (ON) can be adjusted by changing the main exposure setting knob 360. On the other hand, the light output setting voltage at P (SH) is the output voltage of the voltage follower 239 divided by the resistor R46 and the shadow exposure setting volume 361. Therefore, by adjusting the main exposure setting volume 360, when P (ON), P (S
The light output setting voltage at H) changes proportionally, and the constant relationship between the recording density and the applied voltage can be maintained. Therefore, the adjustment is simplified without the need for the complicated operation of adjusting the set voltage at the time of P (ON) and P (SH) together as in the conventional case.

FIG. 21 shows the beam detection circuit 1 in FIG.
21 is a detailed circuit diagram of the beam detector 21 and the beam detector 346. FIG. Figure 21
346 is a beam detector, which uses a PIN diode having a very fast response. The beam detector 346 serves as a reference pulse when writing print data on the photoconductor 301 as shown in FIG. 3, and its pulse width and pulse generation position must be very accurate. Therefore, if the pulse width, the position where the pulse is generated, or the like changes for each beam scanning due to the rotation of the polygon mirror 313, the writing start point on the photoconductor 301 changes and the print quality deteriorates. The anode side of the beam detector 346 is connected to the-side input terminal of the high speed comparator 262, which is a comparison means, through load resistors R52 and R55.
A resistor R53 is connected to the + side input terminal of the comparator 262.
And the voltage divided by R54 is applied through the resistor R56. A noise removing capacitor C12 is connected in parallel to the resistor R54. Further, R57 is a positive feedback resistor for providing a hysteresis characteristic, and C13 is a feedback capacitor for performing high-speed feedback and improving the output waveform. Further, the threshold variable voltage S50 is applied to the + side input of the comparator 262 through the diode D40 and the resistor R57. The threshold variable voltage S50 is the output of the analog switch 240 or the analog switch 241 (the output of the light output setting means) (see FIG. 17). FIG. 22 shows the relationship between the-side terminal input waveform of the comparator 262, that is, the output waveform of the beam detector 346 and the + side terminal voltage of the comparator 262, and the relationship between the output waveform of the comparator 262 at that time. When the laser beam passes over the beam detector 346 at a high speed, a pulse current flows from the beam detector (PIN diode), and a-side input terminal of the comparator 262 has a pulse shown in FIG.
The waveform of b is input. If the threshold variable voltage S50 is not applied to the voltage at the + side input terminal of the comparator 262 and a low voltage V06 is always applied, the output waveform of the comparator 262 is the output indicated by the dotted line in the case of the waveform a. In the case of the waveform b, the output waveform shown by the solid line is obtained. Here, the waveform a is the photoconductor 3
When the sensitivity of 01 is low and the laser output during the main exposure is 6 mw or more, the waveform b shows the case where the sensitivity of the photoconductor is high and the laser output is 6 mw or less. As can be seen from this output waveform, when the + side voltage of the comparator 262 is kept constant, the output waveform changes significantly depending on the amount of light incident on the beam detector 346. Therefore, when the light quantity of the laser beam is large by using the threshold variable voltage S50, it is V0 when it is smaller than the voltage of V05.
As shown in FIG.
As shown in, the output waveform can be kept almost constant.

FIG. 23 is a block diagram of the beam detector (PIN diode) 346. In FIG. 23, 410 is a light receiving element, 411 is an electrode wire, 412 is a mask plate, 413.
Is a laser scanning beam, 414 is a light receiving element mounting base,
Reference numerals 415 denote output lead wires, respectively. The PIN diode used in this embodiment has a light receiving element shape of 2.5 × 2.
It has a length of 5 mm and a response time of 4 nsec. The laser beam 413 is scanned by the rotation of the polygon mirror 313 at a constant speed in the arrow direction of FIG. When the laser beam 413 passes over the light receiving element 410, an output current flows according to the optical output of the laser beam 413. At this time, the comparator 262 of FIG.
The input waveform of the side input terminal is the waveform shown in FIG. Figure 2
4, the input waveform 1 is a waveform when there is no mask on the light receiving element 410, and noise is generated before and after the output waveform.
This is mainly intended for the case where the light receiving element 410 itself is used for detecting light at a very low speed even when detecting light that is originally stationary or scanning.
There are quite a lot of elements whose end faces have poor parallelism, and the output current becomes unstable when the laser beam passes through the end faces. Therefore, in order to solve these problems, a mask 412 which does not allow the laser beam 413 to pass therethrough is attached on the light receiving surface of the light receiving element 410 to prevent the output waveform from breaking on the end face when the beam passes. As shown in FIG. 23, the mask 412 has a structure in which a square window is opened in the end surface portion of the light receiving element 410 and a portion not including the lead-out portion of the electrode wire 411, and the laser beam 413 passes through the square window portion. Light is applied to the light receiving element 410 only when the light is being received. With such a structure, the accuracy of the window portion of the mask, in particular, the parallelism is increased, so that the comparator 2
As the input waveform to 62, a waveform containing no noise can be obtained like the input waveform 2 in FIG.

FIG. 25 is a detailed circuit diagram of the print data writing control circuit 119 in FIG. The main function of the print data writing control circuit 119 is to print the print data S57 from the interface circuit 122 so as to write the print data S57 in a predetermined area on the photoconductor 301 in accordance with the size of the paper to be printed. Serial conversion is performed and the laser modulation circuit 120 outputs the converted data. Further, a shadow signal for improving the print quality is generated from the data content of the print data S57 and is sent to the laser modulation circuit 120 together with the print data. Further, the laser modulation circuit 120 sends out a necessary signal when setting the optical output. Further, a timing signal for controlling the transmission from the print data control unit 2 is transmitted to the interface circuit 122. The other is to generate a test print pattern required for maintenance.

In FIG. 25, reference numeral 186 is an input / output port for sending and receiving signals necessary for control in the laser modulation circuit 120 and the print data write control circuit 119, and 187 and 188 are print data write commands. It is a counter / timer that controls the insertion position, test pattern generation, laser light output sampling, and the like. A crystal oscillator 189 serves as a reference clock for the image clock pulse and has an oscillation frequency of about 32 MHz. A circuit 190 for generating an image clock generates a pulse (about 8 MHz) corresponding to one dot of the minimum modulation unit of the laser beam. 191 is a byte unit (8 bits) received from the interface circuit
Control counter for converting the print data of
Reference numeral 192 is a circuit for generating a test pattern used during maintenance, 211 is a multiplexer for selecting test pattern data and print data from the interface circuit 122, and 210 is a shift for converting the 8-bit parallel data from the multiplexer 211 into serial data. Registers 213 and 214 are line memories for temporarily storing print data and have a memory capacity of 4096 bits, 212.
Is an address counter for the line memories 213 and 214, and 215 is a decoder for producing a signal for controlling the test pattern generating circuit. 226, 227, 2
Reference numeral 28 is a flip-flop for adjusting the timing of sending the print data and the shadow data.

The details of the counters 187 and 188 will now be described. 275 is a counter that determines the laser light amount correction timing for each line (horizontal scanning line) and counts based on the reference clock signal S53.
A sample signal S75 used for light amount correction and line start is generated. Reference numeral 276 is a counter for horizontal recording start positioning, which is Q from the control counter 191.
7 output (video 1 dot unit signal) S83 is counted and a horizontal recording start position (left margin) signal S84 is output. Reference numeral 277 is a counter for determining the horizontal recording end position, which is the video 8-dot unit signal S8.
The count is performed based on 3, and the data write end position (write margin) signal S85 is output. A vertical recording start positioning counter 278 counts on the basis of the output of the gate 198 having two inputs, the paper leading edge position (page top) signal S74 output from the input / output port 186 and the Q output of the flip-flop 204. The page top count output S76 is generated. 279
Is a vertical recording end positioning counter, which counts based on the output of the gate 198 and outputs a page end count signal S77 in the same manner as described above. A vertical test pattern control counter 280 counts based on the Q output of the flip-flop 240 and outputs a test pattern control signal S79.

FIG. 26 is a detailed circuit diagram of the interface circuit 122 shown in FIG. 263 in FIG.
Is an input / output port that receives command data and a print start command signal from the data control unit 2 and sends status data and a ready state signal of the print control unit to the data control unit 2, and 264 is both a command and a print. 8 for data
Bit latch, 265 is an interface data bus S
59 transceiver / receiver. 266 is a data selection signal S for designating the data on the data bus S59.
A decoder for 60, 269 is a BUSY signal control circuit for controlling the data transmission timing to the data control unit 2 when receiving command data and print data, respectively.

Next, details of the interface signal will be described. In FIG. 26, S59 is a bidirectional 8-bit data bus, and S60 is a data selection signal on the data bus S59 which selects data on the data bus S59 by a combination of two signals, IDCOM and IDSTA. S61 is a signal indicating that the print control unit 100 is in a ready state by IPRDY, and S62 is a data control unit 2 by IPREQ.
A signal for permitting the transmission of the print start signal IPRNT, S63 is IPEND, and the data control unit 2 side stops the transmission of the print data by receiving this signal. S6
Reference numeral 4 denotes IHSYN, which is a transmission request signal for one line of print data,
S65 is an IPRNT print start command signal, and S30 is a command and print data strobe signal, abbreviated as IST.
B and S66 are signals IBSY for permitting transmission of the strobe signal S30 and permitting reading of status data on the data control unit 2 side.

Commands and print data are sent by transceiver /
It is output to the output line S72 of the receiver 265 when the status identification signal S68 is OFF. Output line S
The data on 72 is latched in the data latch 264 by the strobe signal S30. In the case of command data, the command data is latched by the input / output port 263, and the specified operation of the command is executed after the command is identified. In the case of print data, it is sent from the output line S59 to the print data write control circuit. The status data is transmitted as follows. When the status request command is received by the print controller 100, the status content corresponding to the command is set in the status data output S71 of the input / output port 263. The set status data S71 is the transceiver / receiver 2
65 is input. The input data is output onto the data bus S59 when the status identification signal S68 is ON.

Details of commands and statuses used in the print control unit 100 are shown in FIGS. 27 and 28, respectively.
In FIG. 27, SR1 to 6 are status 1 to 1 in FIG.
6 is a status request command, PSON is a power save command for reducing the power consumption of the fixing device 331, PSOF is a command for canceling the power save state, and when not recording, the power saving command PSON reduces the power consumption of the fixing device 331. To reduce power consumption,
During recording, the power can be fixed to the toner by increasing the power to a normal value by the power save cancel command PSOF. CSTU is a cassette upper sheet feed designation command, CSTL is a lower tray designation command, VSYNC is a command for instructing start of print data transmission from the data control unit 2, MF1 to 9 are manual feed mode designation commands, and T
BM1 to 4 are tops that specify the print start position on the paper.
The bottom margin designation command and SOF are commands for forcibly turning off shadow exposure.

In FIG. 28, a status indicating that the paper is being fed and the paper is being conveyed into the printer while the paper is being conveyed, and the select switch ON indicates that the select switch 354 of the operation unit has been pressed. Status, VSYN
The C request is a status indicating that the print control unit 100 has received the print start command and is ready to receive the print data, the manual feed is a status indicating that the paper feed mode is the manual feed state, and the cassette upper / lower cassette feeds. The status indicating the status of the selected cassette in the paper mode, the top / bottom margin is the status indicating the status of the top / bottom margin selected by the top / bottom margin commands (TBM1 to 4), the cassette size (upper row) and The cassette size (bottom) is a status that indicates the size code of each installed cassette. Test / maintenance indicates the status of test / maintenance, data resend request indicates that reprinting is necessary due to jam, etc., status indicating that the printer is in warm-up state of the fixing unit during the wait, During power saving, the power save command (PSON) indicates that the power save mode is set. The operator call indicates that the operator call factor of status 4 has occurred. Serviceman call indicates that the status 5 serviceman call factor has occurred. Tray full indicates that the output tray has more than the specified number of sheets and the tray is full. Toner bag replacement indicates that the toner bag is full of toner. Paper jam indicates that the paper is jammed inside the machine. No toner means that there is no toner in the toner hopper. Open cover indicates that the front door is not closed. The timing error indicates that the transfer of print data has been hindered. The failure of the fixing device indicates that the fixing device has an abnormality such as a breakage of the heater of the fixing device or a break in the temperature FUSE. A laser failure indicates that the laser diode has not reached the specified power or the beam detector cannot detect the beam. The scan motor failure indicates that the scan motor does not reach the specified rotation speed even after a lapse of a certain time at the start-up, or the scan motor has deviated from the specified rotation speed for some reason after reaching the specified rotation speed. The heat roller replacement means that the fixing device roller counter in FIG. 15 has reached a specified value and the fixing roller needs to be replaced. Similarly, the drum replacement indicates that the drum replacement counter reaches the specified value and the drum replacement is required, and the developer replacement similarly indicates that the developer replacement counter reaches the specified value and the developer replacement is required. .

FIG. 29 shows one scanning range of the laser beam including the beam scanning section 349 on the photoconductor 301 in FIG. 3 and a position such as a beam detection position and a data writing position within the scanning range. It is a figure showing the relationship. In FIG. 29, 416 is a beam scanning start point, and 417 is a beam scanning end point. The beam reaching the beam scanning end point 417 is the beam next to the beam scanning start point 416 at time 0 by the next surface of the polygon mirror 313. Start scanning. 418
Indicates the beam detection start point of the beam detector 346, and 42
Reference numeral 8 indicates a left end surface of the photosensitive drum, and reference numeral 429 indicates a right end surface thereof. 419 is a left end surface of the sheet of the sheet size A3, 42
0 also represents the right end face. Reference numeral 421 represents the left end surface of the paper of paper size A3, and 420 represents the same right end surface. Reference numeral 421 indicates a data writing start point of the same A3 size paper, and 422 indicates a data writing end point.

Reference numeral 423 denotes the left end surface of the paper of paper size A6, 4
Reference numeral 24 is a right end surface, 425 is a data writing start point of the same size, and 426 is a data writing end point. Reference numeral 427 represents the center point of the paper.

D4 is the distance from the beam scanning 418 to the A3 size writing start point, d5 is the same distance to the A6 size writing start point, and d6 is the A6 size writing end point 4 as well.
26, and d7 represents the distance to the A3 size writing end point. d8 is A from the beam detection point 418
The size of 3 sizes represents the distance to the right end surface 420 of the sheet. Also d
Reference numeral 3 represents the range of one scanning of the beam. d14, d9, d1
0 indicates the effective print range in A3 and A6, respectively. As is clear from this figure, since the paper feed of this printer is always fed around the paper center point 427, the print writing start point from the beam detector position 418 differs depending on each paper size. Detector 3
It is necessary to write data after a lapse of time corresponding to the distance from the beam detection by 46 to each writing start point. Instead of performing such control, since this printer does not employ a sheet edge feed mechanism, it is possible to print on the entire surface of the sheet. In this embodiment, the left and right margins of the paper and the right margin are set to 3 mm, but this can be set to 0. In addition, a conventional printer that performs edge-feeding conveyance usually requires a margin of about 8 to 10 mm, which has a drawback that a considerably large portion on the paper cannot be printed.

FIG. 30 shows the paper size and print area portion of FIG. 29 not only in the horizontal direction but on the entire surface of the paper. In FIG. 30, 436 is A6 paper and 437 is A paper.
Represents 3 sheets. 419, 420, 421, 422, 42
29 for 3,424,425,426,427.
Shows the same position as. Reference numeral 430 represents the leading edge of the sheet, 432 the data writing start point in the vertical direction of the sheet, 431 the trailing edge of the A3 size sheet, and 433 the A3 size data writing end point. 434 is an A6 size sheet rear end, and 435 is an A6 size sheet.
Indicates the end point of writing size data.

Next, with reference to the time charts of FIGS. 31 and 32, the operation of the above-mentioned constituent device will be described.

Ready signal IPRDY of the print controller 100
O (S61) is ready for printing. At the same time, the print start signal IPREQO (S62) becomes active. Next, the laser enable signal LDON1 (S
49) rises to "1". With this signal S49, FIG.
The transistor 258 of is turned on. At this time, FIG.
The data flip-flops 226 to 228 are not set, and therefore the print data signal S47 and the shadow signal S48 are both "0". Since the laser enable S49 is "1", the print data is "0", and the shadow signal S48 is "0", the gate 246 of FIG. 17 is established, and the analog switch 254 is turned on, which causes the laser diode 259 to emit light. . Then, the monitor photodiode 260 operates and the operational amplifier 2
The operational amplifier 239 operates via 32, and the laser ready signal LRDY1 (S43) is generated. Next, the sample signal SMPTO (S75) is generated from the counter 275 in synchronization with the horizontal synchronizing signal HSYO (S54). This signal S75 defines the paper size 416 in FIG.
It is used to set a time corresponding to a distance d3 (distance of one line) between ˜417. As a result, the light amount is corrected for each line and is used as a line start signal. That is, this signal S75 causes
Of the gate 193 of FIG. 17 is opened, the sample signal S45 is generated from the gate 194, and the sample signal S45 turns on the analog switch 236 via the gate 244 of FIG. 17, so that the correction signal is given to the laser diode 259. Thus, the light amount correction for each line is performed. PTCTO (S76) is an output signal of a counter (page top counter) that determines the leading edge of the paper, PEC.
TO (S77) is an output signal of a counter (page end counter) that determines the end position of the paper. When it is time to write an image, the status of the VSYNC request is sent to the external device. As a result, a VSYNC command is output, and when it is received, PTOP (S73) is output and the number of HSYNC lines is started from that point. In the same manner, specify up to which line (end position) to write from that position. A top margin nT and a hot margin nE are provided so that the designated value can be changed. When the above-mentioned designation is made, the PTOP signal is output before the leading edge of the sheet when VSYNC comes. For example, if a blank space of 5 mm is required, the number of lines including it is counted. If the top value is 10 mm, the data corresponding to that value is set in the timer. Similarly, the position of the bottom can be determined. When the data is set in the timer, the gate is opened from there to count, and the counter rises at the end of counting. In this way, it is the gate 201 of FIG. 25 that determines where to write from.
Is. LSTO (S78) is the Q output of the flip-flop 204 for synchronization and is set by HSYNC and reset when the sample timer signal rises. This reset line is included in the LDON signal (S49) in FIG. 25, and the reset line does not normally work and can be forcibly reset.
Upon resetting, the Q output of the flip-flop 204 is generated, and the clock generation circuit 190 operates to count the clocks from the oscillator 189. The clock generation circuit 190 divides the clock from the oscillator 189 into four and outputs a bit unit signal only while the line start signal LST is set. This output has two types of signals S with different phases.
82 and S87. As a result, one line is synchronized. VDAT1 is a print data signal (S4
In 7), it is output as serial data by the operation of the P / S conversion shift register 210. That is, the P / S conversion shift register 210 operates by the signal S82 from the clock generation circuit 190, but when the load signal is not applied, the output S86 is "0" (no laser writing) and the load signal. Data D when S88 is entered
5 to D12 are serially converted and output. At this time, the gates 207 to 209 load the data in 8 bits once in a cycle. Here, the generation timing of the load signal will be described. When there is a place to actually write, data is set every time the paper size changes, and the counter that controls this is the left margin counter 276 in FIG. 25 (data is d9 and d10 in FIG. 29).
And a write margin counter 277 (data is d in FIG. 29).
11 and d12). In this case, the set defines the distance between the left side and the right side based on the center of the paper. When the LST signal (S78) is output in synchronization with the HSYNC signal, the flip-flop 196 is set, which opens the game 198 and causes the counter 276 to start counting. In this case, the video clock is not counted every 1 bit but every 8 bits. The count output that appears every 8 bits is the left margin NLm and the right margin NRm.
When set in accordance with, the counting is performed in synchronization with the LST signal (S78). Then, it is started when the set number is output. Therefore, the gate 201 determines the vertical direction and the gate 199 determines the horizontal direction, and writing is performed at the point when both gate outputs become (1, 1). At this timing, the load signal is output and the data S86 is serially converted and transmitted from the shift register 210.

Line memory out signal LMOT (S8
0) is the output of the OR gate 222. This controls which data of the line memories 213 and 214 is sent. That is, the transmission timing is controlled by the flip-flop 203. That is, the output state of the flip-flop 203 changes every time a clock pulse is applied, and the gates 220 and 221 are alternately opened, whereby the output DOUT of the line memory 213 or 214 is alternately read. The writing timing to the line memories 213 and 214 is also controlled because the gates 217.218 are opened alternately. This is done in order to facilitate the processing by enabling simultaneous writing and reading of data when the shadow method described later is adopted.

Next, regarding LDAON1 (S81), FIG.
The description will be made with reference to FIG.

In this type of recording apparatus, the normal photoconductor 3
When the laser is not radiated over the entire surface of 01 in the axial direction, for example, it often prints only on a small size paper (B5, A4, etc. such as the paper 458 shown in FIG. 43), and therefore both ends not used. Toner and the like will not adhere to the portions near the spaces between the portions. Further, there is an unused area even for a large size sheet (for example, the sheet 461 in FIG. 43) (the used area is also within the shaded area 459 for the small size sheet 458). If a region where the toner does not adhere is provided for a long time like this, the problem that the contact resistance of the blade in the non-adhered part becomes large and the surface of the photoconductor is scratched at the stage of scraping the adhered toner by the blade after the recording is completed, is there. Therefore, in this apparatus, as shown in the time chart of FIG. 31, the line data ON signal LDAON1 (S81) is output immediately after the printing of one sheet of paper is completed.
Is generated and the print data signal VDAT is generated within this generation period.
1 (S47) is forcibly applied, and by this operation, lines (images) 460 and 463 extending over the entire surface in the axial direction of the photoconductor as shown in FIG. 43 are written after the printing of one sheet of paper is completed. The above drawbacks are eliminated. In this case, the timing of writing the line data is the data LDATn- immediately before the final stage data LDATn in the data of the line memory out signal LMOT1 (S80).
It is generated when a predetermined time tx has elapsed from the fall of 1. It should be noted that such a line is not always written periodically after printing for each sheet, and is set to be written for each lot (for example, every 10 sheets or every 100 sheets). May be.

Next, with reference to FIGS. 33 to 36 as well, a method (also referred to as a shadow method) used for making characters and the like easy to see by adding a "shadow" to a character to be printed will be described in detail. I will describe.

Whether or not to generate the shadow signal S48 is judged by various gates 220 to 225 for alternately inputting the data of the line memories 213 and 214, three flip-flops 226 to 228 and a gate 23 on the output side thereof.
Done by 1. Among them, flip-flop 22
7 contributes to the shadow discrimination based on the level change in the horizontal direction (line direction), and the flip-flop 228 contributes to the shadow discrimination based on the level change in the vertical direction (vertical direction). That is, if the serial data to be written is read from the line memory 213 and this sets the flip-flop 226, the previous data in the line direction is stored in the flip-flop 227, so that, for example, the current data is "0". The shadow signal S48 is output when the previous data is "1". Similarly, the data on the previous line and the data on the current line are compared by the gate 223. For example, when the data on the current line is "0", the data at the same horizontal position on the previous line is "1". When set, a shadow signal is generated. Both flip-flops 227, 22
A shadow signal also occurs when 8 is set. This state is changed to the shadow out signal SOUT1 (S8 of FIG. 32).
6), the print data signal VDAT1 (S47) and the shadow signal SDAT1 (S48).

FIG. 33 shows a conventional development pattern when the shadow method is not used, and FIG. 34 shows a development pattern when the shadow method is used. In this way, when the characters “Sho” are printed,
Since a shadow is attached to, it becomes very easy to see.

In FIG. 36, the vertical line S1 and the horizontal line S2 are crossed,
The characteristic diagrams PAT1 and PAT2 showing the relationship between the exposure position and the exposure energy are shown in the upper right region of the figure, the characteristic diagram Q showing the relation between the surface potential of the photoconductor and the exposure energy is shown in the upper left region of the figure, and the exposure position and the surface potential are shown in the lower left region of the figure. Characteristic diagram R
1 and R2 are shown respectively. In this figure,
3 and FIG. 34, the Y direction “14 to 21” is extracted in the X direction “8”. As shown in FIG. 33, the characteristics PAT1 and R1 of the pattern shown in FIG.
The characteristics PAT2 and R2 of the pattern shown in FIG. 4 are different. It can be seen that the width D2 of the characteristic diagram R2 of FIG. 34 is larger than the width D1 of the characteristic diagram R1 of FIG. 36 at a certain development level L in terms of the developing characteristic. FIG. 35 is a characteristic diagram showing the relationship between the exposure position and the exposure energy. The energy of P (ON) at the time of laser irradiation is, for example, 6 mw, and P (S at the time of shadow portion creation).
The energy of H) is, for example, 4 mw.

The above shadow methods are summarized as follows.

In the case of recording recording information (character information or the like) on a recording photosensitive member by beam scanning in correspondence with a difference in beam intensity, serial binary input data is converted into a beam having first and second intensities. (P (ON) and P (OF
F)), recording is performed, and when the input data has a specific relationship, it is replaced with the beam having the first or second intensity and the third beam positioned at the middle of the first or second intensity is used. Recording is performed by using an intensity (halftone) beam, and the determination of this specific relationship is made by (a) when the beam scanning is sequentially performed for each horizontal line.
It is determined that the binary data on the horizontal line changes from significant recorded data (data for forming characters) to involuntary recorded data (data that does not contribute to character formation), and the involuntary recorded data immediately after the change. Scanning the part with a beam of a third intensity and (b) comparing the data of the current line in the horizontal line with the data of the previous line in the vertical direction corresponding to that position, and in the same manner as in (a) above. When changing from the significant recorded data to the insignificant recorded data, the involuntary recorded portion immediately after the change is scanned with the beam having the third intensity.

When the shadow is added, it may be adopted regardless of the type of recording information (for example, character information and image information), but it is preferable to use this method only when handling character information. In this case, as shown in the flow chart of FIG.
If it is character information, it shifts to "shadow" ON flow, and if it is something other than character information (for example, image information), "shadow" is not activated and is automatically performed. I am trying to make it. The command in this case is "SONF Shadow ON / OF" shown in FIG.
F ". Or on the panel, "Shadow ON / O
An “FF” switch may be provided to allow the operator to make an arbitrary selection.

When the shadow method as described above is used, a "shadow" can be added when the record information is character information, so that the print quality can be improved. In particular, at the time of high-density beam recording, it is possible to prevent the line "blurring" due to the reduction in the print density of the 1-dot line, which is a drawback of the conventional recording method using the binary beam intensity, and as a result, the print density of the 1-dot line becomes high. The printing quality can be improved even for high-dot Kanji fonts such as a 40 × 40 dot configuration. In addition, the “face runout” of the polygon mirror
Since the permissible range of the vertical deflection of the beam on the photoconductor can be widened, there is an advantage that the polygon mirror can be easily processed and the cost is reduced.

The shadow may be applied to simple graphic information other than character information.

Next, the charge correction will be described with reference to the flowcharts of FIGS. 37 to 41 and 59.

FIG. 37 shows an example of the structure of the charging high-voltage power supply circuit 160. This is a high-voltage power supply ON / O.
A voltage control circuit 445 whose operation is controlled by the FF signal S35, a step-up transformer 446 which applies a frequency output to the primary side by the voltage control circuit 445 and generates a high voltage output from the secondary side, and an output of the step-up transformer 446. High-voltage rectifier circuit 447 that rectifies the voltage and applies a rectified output to the charger 304, a current / voltage converter circuit 450 that inputs a current flowing in the charger 304 and converts it into a voltage, and this current / voltage converter circuit 450. Is used as one input and the output of the control reference voltage generation circuit 448 is used as the other input. The control reference voltage generation circuit 448 is controlled by the analog control signal S36 and outputs different control reference voltages. With such a configuration, the output frequency of the voltage control circuit 445 is determined based on the output from the control reference voltage generation circuit 448, a high voltage output is generated based on this, and the current of the charging charger at this time is determined. The output voltage is applied to the current / voltage conversion circuit 450, the output voltage and the reference voltage are compared by the operational amplifier 449, and the control operation is performed so that they match each other, so that the output applied voltage can be stabilized.

Now, the contents of the analog control signal S36 will be described in detail.

As shown in FIG. 38, the photoconductor 301 has the characteristic that the surface potential changes significantly with temperature change. In the figure, the horizontal axis represents temperature and the vertical axis represents the surface potential change amount ΔVO. The drum types 451, 452, 453 are shown.
Each has different characteristics. Further, FIG. 39 is a characteristic diagram showing a relationship between the drum inflow current 1D of each of the drums 451, 452, 453 and the surface potential VO at a temperature of 25 ° C., and is a proportional straight line. Therefore, in order to keep the surface potential constant, it is sufficient to change the drum inflow current ID. For example, the characteristic 45 in FIG.
In order to maintain the surface potential of 800 V for the first drum, the inflow current change amount ΔI corresponding to the surface potential change amount ΔVO.
It can be seen that it is necessary to subtract only the amount D and increase the inflow current variation amount ΔID ′ corresponding to the surface potential ΔVO′0 for the drum having the characteristic 453 (various characteristic data of the photoconductor are stored in the RAM 107. Exist). Here, since the inflow current ID and the output current have a correspondence relationship as shown in FIG. 40, the analog signal (input voltage) S36 to the control reference voltage generating circuit 44 in the charging high-voltage power supply circuit 160 is set to 2
The inflow current ID can be adjusted by changing V, 4V, and 6V. FIG. 41 shows the relationship between the analog input current (the output voltage of the D / A converter 165 of FIG. 15 and temperature).
Temperature of the temperature sensor 342 (thermistor of FIG. 14)
Is detected by the analog control signal S corresponding to the temperature change.
36 may be applied.

The charging correction is carried out based on the contents as described above, and its operation will be described with reference to FIG. When the thermistor 342 shown in FIG. 14 detects the temperature of the drum, the A / D converter 271 converts it into a digital signal, and when the data conversion is completed, the temperature data DTn and the temperature data DT25 of the drum when the temperature is 25 ° C. are subtracted. The read value DΔT is read. Next, the standard data DV25 at the temperature of 25 ° C. is read, and DV25 + DΔV is calculated,
The calculation result DVn is output to the D / A converter 165. Then, referring to the RAM 107, the drum characteristic data of the address "6000" shown in FIG.
And the feedback error data DΔV is read. Next, read the reference data DV25 when the temperature is 25 ° C,
The calculation of DV25 + DΔV is performed, and the calculation result DVn is output to the D / A converter 165. Then, Vn is applied to the analog input of the charging high-voltage power supply 160 (S36).
At the same time, the control input signal S35 of the charging high-voltage power supply 160 is turned on.
Correction is performed with the N state. The above correction is repeated every time the temperature changes to keep the surface potential of the drum constant.

The operator can externally specify the characteristics of various photoconductors (drums) stored in the nonvolatile RAM 107. That is, as shown in the flow chart of FIG. 63 (indicated by a circle C), when it is determined whether or not the drum is replaced, if the drum is replaced, the drum characteristic NO is set to turn on the test key. After that, the drum characteristic NO is written in the drum characteristic NO area of the nonvolatile RAM 107. Therefore, thereafter, the characteristics of the currently used drum are always selected, and the correction is performed based on this.

When the above-described charging correction is performed, the charging potential of the photoconductor is kept constant even if the temperature of the photoconductor changes due to the change of the external environment and the temperature rise in the gas. It is possible to prevent the occurrence of defects such as fog due to a decrease in charging potential, a decrease in print density or an increase in charging potential, and it is possible to always provide clear printing. Further, in this embodiment, the information corresponding to the temperature characteristics of the photoconductor is input (externally set) to perform the correction in accordance therewith, so that the temperature correction of the charging characteristics can be performed with extremely high accuracy. Therefore, variations in the temperature characteristics of the photoconductor itself can be alleviated, and there is also an advantage that the range of specifications of the photoconductor can be expanded.

The operation of the entire apparatus will be described with reference to the flowcharts of FIGS. 47 to 59 and the time charts of FIGS. 60 to 62.

The door switch 129 is turned off after the power is turned on.
F, paper discharge switch 336 is OFF, manual stop switch 328 is OFF, pass sensor 123 is OF
It is confirmed that the F and temperature fuses 130 are not disconnected, and whether the discharge tray 384 is full (FULL), and whether the test print mode, the maintenance mode, or the replacement mode is selected. If there is no problem in each, the MC relay 131 is turned on, the fuser heater lamp 333 is turned on, the scan motor 312 is turned on, and the timer A (TIMA) is started. Timer ATI
When the MA counts the predetermined time t1, the drum motor,
The mechanical unit such as the developing device motor is turned on, and when the TIMA counts the predetermined time t2, the laser 344 is turned on. When the time t25 is counted by TIMA, it is determined whether or not the laser is ready. If YES (Y), then TIMA = t26 is timed and the transfer charger, the laser, the developing device motor, and the developing sleeve bias are turned off. Further, when the time TIMA = t27 has elapsed, the drum motor, the heat roller motor, the discharging lamp and the pre-transfer discharging lamp are turned off. Next, TIMA = t29
It is judged at the timing of whether the scan motor is ready or the HSYNC is ready. If YES (Y), TIMA is stopped (above FIG. 47).

Next, "tray full in status 4" is determined, "toner back replacement" and "toner-free" are determined. After removing the paper, set the "tray full" flag to "0", reset the paper discharge tray counter, and if "toner back replacement" is performed, the reset will be performed when the condition returns to the original state, even if the toner is replenished. Reset will be performed when it returns. After passing through the above flow, it is next determined whether or not "power saving" in "status 3", and if no (N), then "no paper" in "status 4" is determined. , Yes (Y), it is judged whether or not "Detection of absence of cassette paper is ON", and No (N)
If so, the "no paper" flag is set to "0", and if "fixing device ready", the "status wait in progress" flag is set to "0". Then IPRDY ON, IPREQ ON,
Whether "power is being saved" or "no paper" is determined, and if there is no problem, TIMA starts. T
At IMA = t01, the registration motor 149 reversely rotates and TI
The registration motor stops at MA = t02. At this stage, the leading edge of the paper is held by the paper feed roller. Next, it is determined whether or not it is "manual feed", and if it is no (N), "IPRN"
It is determined whether or not it is “T ON”, and if YES (Y), it is “IPREQ OFF”. Next, timer E (TI
ME) is operating, and if it is operating, “T
"IME = t30" is determined, and if YES (Y), T
The IME stops, and the transfer charger 305, the peeling (peeling) charger 306, the developing device motor 141, and the fixing device motor 143 are turned on. "TIME = t3
If it is not "0", TIME is stopped and the process moves to the flow of the circular frame F (above FIG. 48).

Next, TIMA is started, the blade solenoid 158 is turned on, and at "TIMA = tl", the developing device motor 141, the discharging lamp 302, the pre-transfer discharging lamp 303, and the drum motor 147 are turned on.
When "TIMA = t2", the transfer charger 305 and the fixing device motor 143 are turned on.

The peeling charger 30 with "TIMA = t3"
6 is turned on, and when "TIMA = t4", TI
Restart MA from "0". Next, "bypass"
It is determined whether the cassette is in the upper stage or the lower stage. If the cassette is in the upper stage, the sheet feeding motor 151 is rotated in the normal direction to perform sheet feeding in the upper stage, and if it is in the lower stage, the sheet feeding motor 1 is waited until “TIMA = t5”.
51 is reversed to feed the lower sheet. Next, "TIMA = t
When "5", the laser 344 is turned on, and "TIMA =
At “t6”, the charging charger 304 is turned on.
At "TIMA = t7", check whether the laser is ready or not. If yes (Y), select "VS" in "Status 1".
The "YNC request" flag is set to "1". After that, the timer B (TIMB) is started to shift to the flow of the circular frame G (above FIG. 49).

Next, at "TIMA = t31", the feed motor 1
51 is stopped, "VSYNC command reception" is discriminated, and if YES (Y), it is discriminated whether "TIMB <t32". If YES (Y), TIMB is stopped and "page top", The "page end counter" starts counting and image writing processing is performed. Timer C, D
Start (TIMC, D), and then "TIMA = t3
At 4 ", TIMA is stopped and the paper feed motor 151 is stopped. Next, register motor 1 with "TIMC / D = t35".
49 forward rotation, turning on the counter 354 ON, "TIM
C / D = t36 ”determines whether the toner density is high or low. When the density is low, the toner supply motor 159 is turned on.
If "yes" (Y), "IPEND pulse" for image writing is output. After that, each counter is incremented by +1 and each state is displayed in the case of "replacement of gravel", "drum replacement", "developer replacement", and "heat roller replacement". If the determination result of “receive VSYNC command” is no (N), “TIM
B = t46 ”, charger 304 OFF,“ TIM
B = t47 "laser 344, peeling charger 304
When OFF, "TIMB = t47", the laser 344, the peeling charger 306, and the developing device motor 141 are turned off.
F, the transfer charger 305 and the fuser motor 143 are turned off at "TIMB = t48", and "TIMB = t4".
9 ", the drum motor 147, the static elimination lamp 302, and the pre-transfer static elimination lamp 303 are turned off, respectively, and" TIMB = t5 ".
When it is "0", the blade solenoid 158 is turned off. or,
In the flow of "TIMB <t32", if NO (N), then "TIMB <t33" is determined, and if NO (N), TIMB stop and TIMA start are performed. After that, the blade solenoid 158 is turned on, and the "TIMA
= Tl ”, the developing device motor 141 and the drum motor 1
47, the static elimination lamp 302, and the pre-transfer static elimination lamp 303 are turned on. Then, when "TIMA = t2", the transfer charger 305 and the fuser motor 143 are turned on,
When “TIMA = t3”, peeling charger 306 is turned ON.
And Next, it is determined whether or not "TIMA = t4", and the timer A is once stopped and then restarted. Then, the developing device motor 141 and the transfer charger 30
5, the peeling charger 306 and the fixing device motor 143 are turned on. Laser 344 at "TIMA = t5"
ON, charging charger 304O when "TIMA = t6"
N, "TIMA = t7" is used to determine whether the laser is ready or not. If YES (Y), the TIMA is stopped (above FIG. 50).

[Toner full detection switch 126] O
It is determined whether or not it is N, and if it is ON, it is displayed, and if it is not ON, it is determined whether or not the "toner absence detection switch 125" is ON and the display is performed. Next, it is determined whether or not it is "manual feed 1," and if it is not manual feed, then it is determined that "no paper in the specified cassette". If there is no paper, a display to that effect and STPF
Set (stop flag) to "1". Then timer E
Start (TIME). If the stop flag is "1", STPF is set to "0" and print ready IPRDY is turned off. When STPF is not 1, it is determined whether or not "manual feed 1". If "manual feed 1", TIME stop, manual stop switch 3
28 OFF, manual feed “O”, TIMB stop, cassette paper out detection switch ON or not is determined, then the print request IPREQ is turned ON, and the flow shifts to the round frame I in FIG. 48 (above FIG. 51). ).

Next, the contents of the timer interrupt in each flow will be described with reference to FIGS. 52 and 53. This determines whether or not each of the timers A, B, C, D, and E is operating, and counts up when each is operating. The port input reading part reads all input information. Then, the timer is stopped at "TIMC / D = t38", it is determined whether or not "TIME = t39", and the operation of the timer E (TIME) is continued thereafter.
The "toner supply motor 159" and the "registration motor 149" are stopped every time. Next, "TIME = t
After "4", it is determined whether or not "TIMA is in operation" (this is to determine whether or not the next sheet of paper is printed). If TIMA is operating, stop TIME. After that, the charging charger 304 is turned off when “TIME = t41”, and the laser 3 is turned when “TIME = t42”.
44, the peeling charger 306, and the developing device motor 141 are turned off. When "TIME = t43", the transfer charger 305 and the fuser motor 143 are turned off,
At “TIME = t44”, the drum motor 147, the static elimination lamp 302, and the pre-transfer static elimination lamp 303 are turned off (see FIG. 52 above). When "TIME = t45", the blade solenoid 158 is turned off, TIME is stopped, whether "fixer temperature is normal" is determined, "is fuser temperature fuse stage", "scan motor 312 ready", and "door switch 129 is off". Is performed, and various processes are performed depending on each state.

Next, the contents of the command interrupt in each flow will be described with reference to FIG. When the command interrupt processing is started, it is judged whether or not there is a "parity error". If there is an error, the flag of "status DATA 81" becomes "1" and an "illegal command error" occurs.
If it is not a "parity error,""statorrequest."
Is within the range of SR1 to SR6, and if it is within the range, an output corresponding to any of them is generated. If it does not correspond to any of the "status requests", it is judged whether or not it is "top / bottom margin", and if so, "top / bottom margin" is specified and "1" is set in the "status set", and "DATA21" ~ 11 "is designated. If it is not "top / bottom margin", it is determined whether "manual feed designation" is made. If the result is YES (Y), then manual feed display and paper size display are performed, and the paper size register is set. Then, the manual feed status set becomes status 1 and "DATA 41"
The flag goes to "1", and then the flow goes to the status 4 where the paper out flag goes to "0". If it is not "manual feed designation", it is judged whether it is "cassette designation". If it is "cassette designation", the upper / lower display paper size is displayed, the paper size register is set, the manual feed status is reset, and status 1 is set. , DTA41 flag “0”, it is determined whether there is no cassette paper, and if there is no paper, the flag becomes “1”. If it is not "cassette designation", it is determined whether "select lamp is lit", whether online select lamp (external device, for example, designated by the host side) is lit, and yes (Y)
If so, the select lamp is lit, and if it is not selected, it is determined whether or not the select lamp is off,
If yes, the select lamp goes off, no (N)
In the case of, the process moves to the next flow.

Next, the flow charts shown in FIGS. 55 to 58 will be described.

In FIG. 55, "power save" is included in addition to the above-mentioned "shadow method". If "power save is in progress", the scan motor 312 is turned off, the fixing device is controlled to the power save temperature, and "status 3" is displayed. The power save flag is set to "1", and when the power save is released, the scan motor 312 is turned on and the fixing device is controlled to the normal temperature.
If "status 3 power saving flag 0" is set and "image data transfer is started", the flow proceeds to the flow shown in FIGS. 56, 57 and 58.

The paper size register is read, the top margin table data (D1) of the specified paper size is read, and it is determined whether the top / bottom margin designation is 5 mm or not. The margin change table data D2 is read. Next, the calculation of the top margin table data D1 + margin change table data D2 is performed, and the content of the top margin adjustment switch (442 in FIG. 14) is read. Next, the top margin adjustment table data D3 corresponding to the switch is read, the margin adjustment table data D3 is added to or subtracted from the values of D1 and (D1 + D2), and the calculation result D4 is set in the page top counter 278. Then, the bottom margin table data D5 of the designated paper size is read, it is determined whether the top / bottom margin designation is 5 mm, and if no (N), the top / bottom margin change table data D2 is read and the bottom Margin table data D5 and margin change table data D2
Is subtracted from the top margin adjustment switch 442.
Is read, and the top margin adjustment table data D3 corresponding to the switch is read. Next, the margin adjustment table data D3 is added to the value of D5 or (D5-D2).
Is added and subtracted, and the operation result D4 is added to the page counter 279
Set to. Next, the write margin table data D7 of the designated paper size is read, and the cassette / manual feed is determined. If the cassette is selected, it is determined whether it is the upper (reference) or not, and if it is not the upper, the lower is selected. The contents of the cassette upper / lower adjustment switch (440 in FIG. 14) are read and the cassette upper / lower corresponding to the switch is read. The adjustment table data D8 is read. The value of D7 is added to or subtracted from D8, and the calculation result D9 or D7 is set in the write margin counter 277. When manual feed is specified, the cassette / manual feed adjustment switch (4 in Fig. 14
Read the contents of 41) and read the contents of the cassette /
The manual feed adjustment table data D10 is read, and then D
The adjustment table data D10 is added to or subtracted from the value of 7, and the calculation result D11 is set in the write margin counter 277.

Next, the left margin table data D12 of the designated paper size is read, the cassette / manual feed is discriminated, and if it is a cassette, it is discriminated whether it is the upper stage (reference) or not. It is determined to be the lower stage, the contents of the cassette upper / lower stage adjustment switch 440 are read, and the cassette upper / lower stage adjustment table data D8 corresponding to the switch is read.
Is read. The data D8 is added to or subtracted from the value of D12, and the calculation result D13 or the data D12 is set in the left margin counter 276. If it is a manual feed, the contents of the cassette / manual feed adjustment switch 441 are read, the cassette / manual feed adjustment table data D10 corresponding to the switch is read, the data D10 and the value of the data D12 are added and subtracted, and the calculation result is obtained. D14
Is set in the left margin counter 276.

Details of the cassette paper printing in the above-mentioned flow are shown in the time chart of FIG. When the print start signal IPRNTφ (S65) is output, the print start permission signal IPREQφ (S62) rises. After that, the developing device motor 141 and the like are turned on, and the paper feeding motor 151 operates between times t4 and t8 to convey the paper in the cassette. At this time, the laser diode 344 is turned on at time t5.
Is turned on, and data writing is started from time t7 (the shaded period from time t7 to tll is the data writing period). At time t9, the registration motor 149 rotates to transfer the write data to the photoconductor onto the paper. Data writing is performed until time t11 when IPREQ φ (S62) falls, and after the time t11 has elapsed, the registration motor 149 continues to rotate and stops. The laser diode 344 then turns off at time t14.

61 and 62 are time charts for explaining the operation of the manual sheet printing. In the following description, parts different from the case of the above-mentioned cassette paper printing will be described.

61 and 62, the sheet feeding motor 151 is not used and the registration motor 149 is rotated in the reverse direction to drive the sheet feeding roller, which is used for conveying the sheet. The forward rotation drives the registration roller. I have to. Also, both start print command I after the "manual feed command" comes.
PREQφ (S62) is set to rise. FIG. 61
Shows the case where the paper is set in the manual feed guide before the "manual feed command" is generated. When the manual feed switch 326 is turned ON by the paper setting, after that, the registration motor 149 slightly rotates backward at time t01 and the leading edge of the paper is added. It stops in the jammed state, and at the time when the "manual feed command" is issued and IPREQ φ (S62) rises, the registration motor again rotates in the reverse direction and the sheet is conveyed to the transfer position and stopped. Therefore, it is possible to print on the paper from the cassette before the "manual feed command" is issued. In FIG. 59, the paper is set in the manual feed guide and the manual field switch 326 is turned on after the “manual feed command” is issued first. In this case, the registration motor 149 is continuously operated after the elapse of the predetermined time t01. It is rotated in the reverse direction and conveyed to the transfer position.
In either case, the manual stop switch 328
Although the registration motor 149 is stopped at a time t21 after a lapse of a predetermined period from the turning off (time t20), even if the paper set in the manual feed guide is longer than the displayed size. No "jam" will occur. In the case of cassette paper, such consideration is not necessary because the size is specified. Therefore, even if the cassette paper runs out, it is possible to print by preparing a paper size larger than the size of the information to be printed, and it is also possible to use a paper size that does not meet the standard. Increase the utilization of.

A circular frame A, which shifts from the flow of FIG. 47,
The contents of the flows of B and C will be described with reference to FIG. 63.

When the test print mode is selected, the display moves to the end of the circle A and the print specified by the print mode NO is executed via the test key. When the maintenance mode is selected, the flow moves to the frame B,
When the operation of the maintenance mode of NO designated through the test key is executed and the replacement mode is selected, the circular frame C
Then, it is determined whether "drum replacement", "developer replacement", or "heat roller replacement" is performed, and "drum characteristic NO set", "developer replacement NO set", and "heat roller NO set", respectively. ", The predetermined data is processed in the non-volatile RAM 107 via the test key.

64 to 66 are correspondence diagrams in which the displayed numbers are associated with their respective contents.

[0149]

According to the first aspect of the present invention, it is possible to provide a laser control device capable of controlling a semiconductor laser with extremely high accuracy and in a stable state.

According to the second aspect of the present invention, it is possible to provide a laser control device capable of reliably stabilizing the light output by the operation of the switching means.

According to the third aspect of the present invention, it is possible to provide a laser control device capable of minutely controlling the light output of the semiconductor laser.

According to the fourth aspect of the present invention, it is possible to provide a laser control device capable of controlling a semiconductor laser in a state of good response while preventing power loss.

[Brief description of drawings]

FIG. 1 is a system block diagram showing a relationship between a device according to the present invention and an external device.

FIG. 2 is a schematic sectional view of a print control unit (printer) in the system diagram.

FIG. 3 is a schematic perspective view showing the relationship between the laser scanner unit and the recording photoconductor in FIG.

FIG. 4 is a schematic view showing a paper feeding portion in FIG.

FIG. 5 is a schematic diagram showing an example of a paper discharge unit in FIG.

FIG. 6 is a plan view showing an operation panel unit of the apparatus of this embodiment.

FIG. 7 is an enlarged plan view of the display unit in FIG.

8 is a block diagram showing an example of a data control unit of FIG. 1. FIG.

FIG. 9 is a format diagram of data handled by a data control unit.

FIG. 10 is a format diagram of data handled by a data control unit.

FIG. 11 is a correspondence diagram between a region of a recording unit in the data control unit and a sheet.

FIG. 12 is a format diagram of data handled by a data control unit.

FIG. 13 is a block diagram of a print control unit in FIG.

FIG. 14 is a detailed circuit diagram of each detector in FIG.

15 is a block diagram showing details of a drive circuit and output elements in FIG.

16 is a circuit diagram showing details of a motor drive circuit and a laser scan motor in FIG.

17 is a detailed circuit diagram showing a laser modulation circuit and a semiconductor laser in FIG.

FIG. 18 is a characteristic diagram showing a relationship between a semiconductor laser and light output.

FIG. 19 is a characteristic diagram showing a relationship between a semiconductor laser and light output.

20 is a time chart for explaining the operation of the circuit in FIG.

21 is a detailed circuit diagram showing a beam detection circuit and a beam detector in FIG.

22 is a waveform diagram for explaining the operation of the circuit in FIG.

FIG. 23 is a diagram showing an example of a structure of the beam detector.

FIG. 24 is a waveform diagram for explaining the operation of the circuit in FIG.

25 is a detailed circuit diagram of the print data writing control circuit in FIG.

FIG. 26 is a circuit diagram of the interface circuit in FIG.

FIG. 27 is a diagram showing the relationship between command abbreviations and functions used in the device of this embodiment.

FIG. 28 is an explanatory diagram showing the contents of the status used in the device of this embodiment.

FIG. 29 is a relationship diagram of a beam scanning position and a data writing position and the like on the recording photoconductor in FIG.

30 is a plan view showing a print area portion of the entire surface of the paper including the paper size of FIG. 29. FIG.

FIG. 31 is a time chart for explaining the operation of the circuit of FIG. 25.

FIG. 32 is a time chart for explaining the operation of the circuit of FIG. 25.

FIG. 33 is a print pattern diagram printed on a sheet.

FIG. 34 is a print pattern diagram printed on a sheet.

FIG. 35 is a characteristic diagram showing the relationship between the exposure position and the exposure energy, the surface potential, and the exposure energy and the exposure position for explaining the exposure control operation in the circuit of FIG. 25.

FIG. 36 is a characteristic diagram showing the relationship between the exposure position and the exposure energy, the surface potential, and the exposure energy and the exposure position for explaining the exposure control operation in the circuit of FIG. 25.

FIG. 37 is a detailed block diagram of the charging high-voltage power supply in FIG. 15.

38 is a characteristic diagram for explaining the operation of the circuit of FIG. 37. FIG.

39 is a characteristic diagram for explaining the operation of the circuit of FIG. 37. FIG.

FIG. 40 is a characteristic diagram for explaining the operation of the circuit of FIG. 37.

41 is a characteristic diagram for explaining the operation of the circuit in FIG. 37. FIG.

42 is a schematic view showing the relationship between the laser scanner unit and the recording photoconductor in FIG.

FIG. 43 is an explanatory diagram showing a relationship between a recording photoconductor and a sheet.

FIG. 44 is a side view showing a modified example of the paper discharge tray shown in FIG. 5.

45 is a detailed diagram of data recorded in each recording device in FIG. 13. FIG.

FIG. 46 is a detailed diagram of data recorded in each recording device in FIG. 13.

FIG. 47 is a flow chart for explaining the overall operation of the device of this embodiment.

FIG. 48 is a flow chart for explaining the overall operation of the device of this embodiment.

FIG. 49 is a flow chart for explaining the overall operation of the device of this embodiment.

FIG. 50 is a flowchart for explaining the overall operation of the device of this embodiment.

FIG. 51 is a flowchart for explaining the overall operation of the device of this embodiment.

FIG. 52 is a flow chart for explaining the overall operation of the device of this embodiment.

FIG. 53 is a flowchart for explaining the overall operation of the device of this embodiment.

FIG. 54 is a flowchart for explaining the overall operation of the device of this embodiment.

FIG. 55 is a flow chart for explaining the overall operation of the device of this embodiment.

FIG. 56 is a flow chart for explaining the overall operation of the device of this embodiment.

FIG. 57 is a flow chart for explaining the overall operation of the device of this embodiment.

FIG. 58 is a flow chart for explaining the overall operation of the device of this embodiment.

FIG. 59 is a flow chart for explaining the overall operation of the device of this embodiment.

FIG. 60 is a time chart for explaining the operation of the device of this embodiment.

FIG. 61 is a time chart for explaining the operation of the device of this embodiment.

FIG. 62 is a time chart for explaining the operation of the device of this embodiment.

FIG. 63 is a flowchart for explaining the operation of the device of this embodiment.

FIG. 64 is a relational diagram showing the contents of the device numbers in the device of the present embodiment.

[Fig. 65] Fig. 65 is a relationship diagram showing the contents of the device numbers in the device of the present embodiment.

FIG. 66 is a relational diagram showing the contents of the device numbers in the device of the present embodiment.

[Explanation of symbols]

 120 Laser Modulation Circuit 236 Analog Switch 259 Laser Diode 260 Photodiode 257 High Frequency Transistor 344 Semiconductor Laser

Claims (4)

[Claims] 1. A photodetector for detecting an output of a semiconductor laser, a current-voltage converter for converting an output current of the photodetector into a voltage, and an output voltage and a reference voltage of the current-voltage converter. Comparing means for comparing, integrating means for charging / discharging according to the output of the comparing means, and voltage-current converting means for converting the voltage charged in the integrating means into a current and supplying it to the semiconductor laser. Laser control device characterized by. 2. The integrating means has a switching means, and when the light quantity stabilizing operation of the semiconductor laser is performed, the switching means is turned on, and when the laser modulating operation is performed, the switching means is turned off. The laser control device according to claim 1, wherein the laser control device is in a state. 3. The laser control device according to claim 1, wherein the light amount of the semiconductor laser is set by changing the reference voltage. 4. The voltage-current converting means has a current driving means for causing a current equal to or lower than a threshold current at which the semiconductor laser causes optical oscillation to flow in the semiconductor laser, and when the semiconductor laser is modulated, 3. The laser control device according to claim 2, wherein the current drive means is constantly driven.