JP2531767B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to printing such as a laser printer including a step of scanning a laser beam to form an electrostatic latent image on a photoconductor. The present invention relates to an image forming apparatus suitable for the apparatus.

(Prior Art) In the case of a conventional image forming apparatus of this type, for example, as shown in FIG. 25, a printing side 1 is composed of a printer 2 and a host side 3 is composed of a controller 4. Then, by issuing a status signal from the printer 2 to the controller 4 and issuing a command from the controller 4 to the printer 2, the system status can be checked by the system status. Further, the controller 4 causes the printer 2 to perform a control operation. Command is sent to control the printer 2. In the control operation of the printer 2, the printer 2 outputs a horizontal synchronizing signal to the controller 4, and the controller 4 outputs a video data signal based on the horizontal synchronizing signal.
It is designed to be sent to.

However, when the video data signal is transmitted from the controller 4 of the host side 3 to the printing side 1, the video data signal is transmitted based on the horizontal synchronizing signal output from the printing side 1, so that the recording of the paper is performed. There was a problem that there was a high rate of position variation.

(Problems to be Solved by the Invention) That is, in the case of the conventional image forming apparatus, the video data signal is sent from the host side to the printing side based on only the horizontal synchronizing signal output from the printing side. Therefore, for example, in a laser printer, when the laser beam is scanned by the printer unit to form an electrostatic latent image on the photoconductor, the time required for the arithmetic processing on the host side affects the host side to the printing side. There may be a delay in the transmission timing of the video data signal. As a result, conventionally, there has been a problem that the rate of occurrence of variations in the recording position of the paper increases.

In the case where the host side synchronizes the synchronizing signal from the printer with the video clock signal of the host, even if there is a mechanical dislocation of each component in the printer, this will be shipped to the printer. Couldn't be adjusted before. Therefore, when the user purchases a printer, prints it by connecting it to the host, and if the print area deviates from the desired area due to the above reasons, the print operation is executed many times and the print area matches the desired area. As described above, it is necessary to change the setting condition, which complicates the operation.

The present invention has been made in view of the above problems, and an object thereof is to provide an image forming apparatus in which variations in the recording position of a sheet are eliminated, and to further set a printing area as a desired area. An object of the present invention is to provide an image forming apparatus which has been adjusted at the time of purchase without requiring a troublesome operation such as changing setting conditions.

[Structure of the Invention] (Means for Solving Problems) In order to achieve the above-mentioned object, the present invention, based on print data output from an external device, forms an image corresponding to the print data on an image carrier. In the image forming apparatus formed on the
The apparatus further comprises: a generating unit for generating a video clock signal for requesting the external device to send print data; and a supplying unit for supplying the external apparatus with the video clock signal generated by the generating unit, The external device, based on the video clock signal supplied from the supply means,
The print data is output to the image forming apparatus.

(Operation) With such a configuration, when a video data signal is sent from the host side to the print side, the video from the print side does not have to be processed by the host side for the purpose of sending the video data signal. The video data signal is sent from the host side to the printing side in synchronization with the clock signal. Therefore, for example, in the case of a laser printer, on the printing side, the error in the electrostatic latent image forming operation due to the laser beam disappears, and the variation in the recording position of the paper is eliminated.

(Embodiment) FIG. 1 is a schematic diagram showing an embodiment of an image forming apparatus to which the present invention is applied.

The image forming apparatus according to this embodiment has two colors forming the printing side.
The LBP 199 and the host system 500 (an external device such as an electronic computer or a word processor) are connected via a transmission controller (interface circuit or the like) not shown. Then, the two-color LBP199 receives two types of dot image data by the host system 500, modulates two laser beams, respectively, and executes writing on the photoconductor (image bearing member), and the written 2 Each type of dot image data is independently developed and transferred onto recording paper.

That is, this two-color laser beam printer (Laser Beam P
rinter, hereinafter referred to as 2-color LBP) 199, the photoconductor 200
In the peripheral portion of the first charging device 201, the first surface potential sensor 202, the first developing device 203, the second charging device 204, the second surface potential sensor 205, as shown in order along the rotation direction indicated by the arrow. A second developing device 206, a pre-transfer charger 207, a transfer charger 208, a peeling charger 209,
The cleaner 210 and the static eliminator 211 are provided, and the first laser beam 309 is irradiated between the first surface potential sensor 202 and the first developing device 203 to the photoconductor 200 to perform the first exposure, In addition, the second surface potential sensor 205 and the second developing device 206
The second laser beam 310 is radiated between them to perform the second exposure.

The control unit of the two-color LBP of this embodiment has a block configuration as shown in FIG.

The control unit of this two-color LBP uses the CPU 501 as the control center,
A ROM 502 storing a system program, a ROM 503 storing a data table, a RAM 504 used as a working memory, a timer 505, an I / O data input / output device 506, and a print data writing control circuit 513. The interface circuit 519 is basically provided.

The contents of the data table stored in the ROM 503 are, as shown in FIG. 3, the first color top margin control data, the addresses (4002), (40) at the addresses (4000), (4001).
03) contains the second color top margin control data, and addresses (4004) and (4005) contain the left margin control data.

Address (4006) (4007) has bottom margin control data for paper size A3, address (4008) (4009)
Contains the write margin control data of the same paper size. Below, tables corresponding to various paper sizes are similarly stored up to the address (4083).

Top margin coarse adjustment data from address (4090), top margin fine adjustment data from address (40B0), left margin coarse adjustment data from address (40D0), and left margin fine adjustment from address (4100). Data and address (4120) contain 2-beam scanning length correction data, which are data corresponding to the switches 1 to n, respectively.

The margin control data, the coarse adjustment data, and the fine adjustment data are used as set data for the margin control counter and the binary counter of the print data writing control circuit 513 described later.

The first for red toner at address (6000) (6001)
The developing bias data and the addresses (6002) and (6003) contain the second developing bias data. Similarly, the first and second developing bias data of blue toner, green toner, and black toner are stored up to the address (600F), and are used as set data for developing bias control of the process control circuit 522 described later.

Addresses (6100) and (6101) contain target surface potential table data for the first charging potential control, which is the reference value of 25 ° C.

The address (6102) (6103) contains convergence time error table data, and represents the allowable control range for the target surface potential.

Addresses (6104) and (6105) contain initial control output table data, which is the set value of the first charging charger to be output first during warming up.

The address (6106) (6107) contains the minimum correction table data.

Address (6108) (6109) contains surface potential limit table data, addresses (610A) (610B) contains control output upper limit table data, and addresses (610C) (610D) contains control output lower limit table data. The surface potential limit table data, the control output upper limit table data, and the control output lower limit table data are used for self-diagnosis of the control system.

Similarly, the table corresponding to the second charging potential control is stored up to the address (611B). The address (6120) contains charging potential temperature correction table data in the temperature range of 10 to 40 ° C., which is the temperature correction data for the target surface potential table data of 25 ° C.

The timer 505 is a general-purpose timer, and generates a basic timing signal for controlling the paper conveyance process and the photoconductor rotation process.

In the input / output device 506, output of display data to the operation display unit 507, input of various switch data and the like, input of each detector 508 in the control unit, drive circuit 509 for driving the drive element 510 such as motor, clutch and solenoid. To the drive circuit 511 for driving the laser scan motor 512 for scanning the two laser beams, and the output of the high voltage power supply 523 or the like in response to the input of the detection signal of the potential sensor, the temperature sensor or the like. Input and output of the process control circuit 522 to be controlled.

The print data writing control circuit 513 includes a first semiconductor laser 30 as a laser light source for writing the first color image data.
The first laser modulation circuit 514 that performs the optical modulation of 2 and the second laser modulation circuit 521 that performs the optical modulation of the second semiconductor laser 303 as the laser light source for writing the image data of the second color are driven and controlled. Write control is performed at a predetermined position so that an electrostatic latent image is formed on the photoconductor by exposing and scanning the photoconductor based on the print data of the video image transferred from the host system 500. At that time, the beam detector 518 using the PIN diode of high-speed response detects one of the two light beams scanned by the laser scan motor, and the beam detector 517 uses the beam detector. The analog signal from 518 is digitized by a high-speed comparator to create a horizontal synchronizing pulse, which is sent to the print data writing control circuit 513.

The interface circuit 519 outputs status data to the host system 500 and receives command data and print data from the host system 500.

In addition, a power supply device 520 is provided to supply power to each part of these control units.

Details of main blocks in FIG. 2 will be described below.

FIG. 4 is a diagram showing details of interface signals between the interface circuit 519 and the host system 500 in FIG. In the figure, D7-DO is an 8-bit bidirectional data bus, and IDSTA is a selection signal of the data bus, which is used as a status data bus to the host system 500 or as a command data bus from the host system 500. Or select. ISTB is a strobe signal for latching the command data in the interface circuit, and IBSY is a signal for permitting transmission of the strobe signal ISTB and permitting reading of status data.

IHSYN1 is a horizontal sync signal for the first color, and requests transmission of one line of print data.

IVCLK1 is a video clock signal for the first color, and requests transmission of one dot of print data.

IPEND1 is the page end signal of the first color to notify the end of the line.

The host system 500 uses the IHSYN1 and IVCLK1 to output the video data signal IV of the dot image data of the first color.
Send DAT1 and stop sending when IPEND1 is received.

Similarly, IHSYN2 is the horizontal sync signal of the second color, IVCLK2 is the video clock signal of the second color, IPEND2 is the page end signal of the second color, and the host system 500 is the IHSYN2, IVC.
The video data signal IVDAT2 of the second color dot image data is transmitted based on LK2, and the transmission is stopped when IPEND2 is received. The video data signals IVDAT1 and IVDAT2 are sent to the print data writing control circuit. The above relationship is shown in FIG.

IPRDY is a signal notifying that the two-color LBP199 is ready, IPREQ is a signal that allows the host system 500 to send a print start signal IPRNT, IPRME is a prime signal that initializes the two-color LBP199, and IPOW is two-color LBP199. Is a signal indicating that power is being supplied.

Next, details of commands and statuses used in the two-color LBP199 are shown in FIGS. 6 and 7, respectively.

In FIG. 6, SR1 to SR7 are status 1 in FIG.
Status request command corresponding to ~ 7, CSTU is upper sheet feed designation command of cassette, CSTL is lower stage designation command, VSYNC is command to start sending print data from host system 500, SP1, SP2, DP1 are print mode Command for specifying SP1, SP1 prints only the first color, SP2
Is a mode for designating a printing operation for only the second color, and DP1 is a mode for designating a printing operation for both the first color and the second color. MF1 to 9 indicate manual mode designation commands, respectively.

In FIG. 7, a status indicating that the paper is being fed and the paper is being conveyed in the two-color LBP199 while the paper is being conveyed. For the VSYNC request, the two-color LBP199 receives the print start command and receives the print data. Status indicating that the paper feed mode is enabled, manual status indicates that the paper feed mode is the manual feed status, upper / lower cassettes indicate the status of the selected cassette in the cassette paper feed mode, and printing mode first color , 2nd color, 2 colors are the status showing the selected print mode status, cassette size (upper row) and cassette size (lower row) are the status code showing the size code of the installed cassette, toner color (first color) ) And toner color (second color) are statuses indicating the toner color code of the developing device, and test / maintenance is test / maintenance Status indicating that the printer is in the status of printing, a data resend request indicates the status when reprinting is necessary due to a jam, etc.
Indicates that the fixing device is in the warm-up state, and operator call indicates that the operator call factor of status 5 has occurred. Serviceman call indicates that the status 6 serviceman call factor has occurred. Toner bag replacement indicates that the toner bag is full of toner. No paper indicates that there is no paper in the specified cassette, and paper jam indicates that paper has jammed inside the machine. No 1st color toner is 1st
No toner in the developing unit, no toner in the second color means no toner in the second developing unit, first laser failure causes the first laser diode to not reach the specified output, or A second laser failure, indicating that the beam detector cannot detect the beam, indicates that the second laser diode has not reached the specified power. The scan motor failure indicates that the scan motor has not reached the specified number of times even after a certain period of time has passed during the normal operation, or has deviated from the specified number of revolutions for some reason after the specified number of revolutions. Indicates that the surface potential of the photoconductor cannot be detected, and the number of retransmitted sheets indicates the number of sheets to be reprinted when the data resend request status occurs.

FIG. 8 is a detailed circuit diagram of the first laser modulation circuit 514, the first semiconductor laser 302, the second laser modulation circuit 521, and the second semiconductor laser 303 in FIG. First, the first laser modulation circuit 514 and the first semiconductor laser 302 will be described.

In FIG. 8, reference numeral 302 denotes a first semiconductor laser diode, which is composed of a laser diode 812a that emits light and a monitor photodiode 811a that monitors the output beam intensity from the laser diode.

809a is a high frequency transistor, and the first laser diode 81
Light modulation of 2a is performed. Resistor R29a is a current detection resistor, 810a
Is a transistor for supplying a bias current to the first laser diode 812a, R30a is its current limiting resistor, R27a is the base current limiting resistor of the transistor 810a, and 817a is an inverter. The first laser diode enable signal LDON10 is input to the input of the inverter 817a, and this signal is the LO signal.
Transistor 810a turns on when it becomes the W level,
A bias current flows through the first laser diode 812a. 80
Reference numerals 7a and 808a are high-speed analog switches for applying modulation to the first laser diode 812a. Each analog switch has a low voltage between its drain (D) and source (S) when a high level voltage is applied to its gate (G). It becomes a resistance and turns on. When a LOW level voltage is applied to the gate (G), the resistance becomes high and the state becomes OFF. R21a is a short circuit protection resistor when the analog switches 807a and 808a turn ON and OFF, 813a and 813a
Reference numeral 14a is a gate driver for the analog switches 807a and 808a. CO2a and CO3a are speed-up capacitors, R
24a and R25a are input resistors of the gate drivers 813a and 814a. 815a and 816a are EXCLUSIVE-OR gates, which change depending on the output of the 2AND gate 820a. 2 AND gate 820a is 2
When either of the two gate inputs goes low, the output goes low and the EXCLUSIVE-OR gate 815a output goes low, turning on the analog switch 807a.
Then, the first laser diode 812a is turned on. Said
The condition that the output of the AND gate 820a becomes LOW level is when the first video data signal IVDAT10 is LOW level or the first sample signal SAMP10 is LOW level. 2AND
When both gate inputs are high level, the EXCLUSIV
The output of the E-OR gate 816a becomes low level, the analog switch 808a is turned on, and the first laser diode 812a
Turns off.

Reference numeral 806a is an operational amplifier, which constitutes a voltage follower circuit. DO1 is a Zener diode and is regulated so that the output of the first laser diode 812a is within the maximum rating. In addition, the resistor R19a and CO1a form an integrator circuit,
R20a is a discharge resistor for discharging the electric charge of the capacitor CO1a at a constant rate. 804a is an analog switch, the gate (G) of which is connected to the inverter 805a, and the first sample signal SAMP10 is input to the input of the inverter 805a. Reference numeral 803a serves as a level conversion transistor, R22a serves as a base current limiting resistance of the transistor 803a, and R18a serves as a current limiting resistance when the capacitor CO1a is charged. 802a is a comparator, and this comparator has resistors R14a and R15a
Has a hysteresis characteristic.

The output voltage of the first laser monitor amplifier 801a is applied to the + input side of the comparator 802a through the resistor R14a. Reference numeral 801a is an amplifier for the output of the photodiode 811a which detects the light output from the first laser diode 812a. The resistors R12a, R13a, and VRO1a are resistors that regulate the amplification degree of the operational amplifier 801a. Therefore, the amplification degree of the operational amplifier 801a can be changed by changing VRO1a. R11a is a load resistor for output of the photodiode in the first laser diode, and a voltage proportional to the output current of the photodiode 811a is obtained across the resistor R11a. Since the output current of the photodiode 811a is proportional to the optical output of the laser diode 812a, by changing the volume VRO1a, the laser diode 8
The light output of 12a can be adjusted.

Reference numeral 818a is a comparator for confirming whether the first laser diode is emitting light, and the output voltage of the operational amplifier 801a is applied to one side input. A voltage divided by the resistors R16a and R17a is applied to the + input. Therefore, when the first laser diode 812a emits light and the output becomes equal to or higher than the voltage divided by the resistors R16a and R17a, the output level of the comparator 818a changes from the HIGH level to the LOW level, and the first laser ready signal LRDY10.
Is output.

A laser light quantity setting voltage is applied to one input terminal of the comparator 802a. The output of the voltage follower 819 is applied to the set voltage. The + input terminal of the voltage follower 819 has an exposure adjustment volume 821 and a resistor.
The voltage divided by R31 is input, and the output voltage of the voltage follower 819 also changes by changing the exposure adjustment volume 821.

Next, the first laser modulation circuit 514 and the first laser diode 3
The operation of 02 will be described. First, when the first laser diode enable signal LDON10 goes low, a bias current flows through the first laser diode 812a. Next, when the first sample signal SAMP10 goes low, the analog switch 804
Although a and 807a are turned on, since the capacitor CO1a is not charged, the output of the voltage follower 806a is OV, and the modulation transistor 809a does not turn on. Therefore, a current is flowing to the first laser diode 812a to the extent that it does not emit light. At this time, since no current flows in the first photodiode 811a, the output of the comparator 802a becomes LOW level and the transistor 803a becomes OFF, so that the resistor R18
The capacitor CO1a is charged through a and R19a.
This charging resistor R18a, R19a, capacitor CO1
Select a time constant of 20 to 50 msec.

If this value is very small, the response of the stabilizing circuit is too fast, and the fluctuation of the optical output level of the laser becomes large. On the other hand, if it is too large, the responsiveness deteriorates and it takes time for the optical output to stabilize. By charging the capacitor CO1a, the output voltage of the voltage follower 806a also gradually rises. Therefore, a current flows through the collector as the base voltage of the laser modulation transistor 809a rises. The first laser diode 812a has a bias current from the transistor 810a and the transistor 809a.
When the added current of the collector current from the first laser diode 812a exceeds the threshold current of the first laser diode 812a, the first laser diode 812a emits light. When the first laser diode 812a emits light, a current flows through the monitor second photodiode 811a, the + input terminal voltage of the operational amplifier 801a rises, and a value obtained by increasing the output voltage and the input voltage is output. The output voltage of the operational amplifier 801a is
When the voltage is divided by the resistors R16a and R17a or more, the output of the comparator 818a, that is, the first laser ready signal LRDY10
Goes from HIGH to LOW level. And comparator 802a
When the output voltage of the operational amplifier 801a becomes equal to or higher than one input terminal voltage, that is, the first laser light amount setting voltage, the output of the comparator 802a changes from LOW to HIGH level, the transistor 803a turns ON, and the capacitor CO1a is discharged through the resistor R19a. It Therefore, the modulation transistor 80
The base voltage of 9a also drops, and the optical output of the first laser diode drops. When the light output of the first laser diode decreases, the + input terminal voltage of the comparator 802a also becomes less than or equal to the first laser light amount setting voltage, and the transistor 803a turns off again.
Then, the capacitor CO1a is charged up again through the resistors R18a and R19a. In this way, the first laser diode 812a
Once the optical output of reaches the first laser light amount setting voltage,
After that, the comparator 802a slowly repeats ON-OFF near the first laser light amount setting voltage, and the first laser diode 8
The optical output of 12a is stable.

CPU501 sends 1st laser ready signal LRD via I / O port
When it is confirmed that Y10 has become LOW level, the operation of the sample timer to be described later is started and the first sample signal SAMP10 is kept LOW for a certain period outside the printing area for each line.
At the level, the analog switches 804a and 807a are turned on to stabilize the laser light amount.

Next, when the two-color LBP199 is ready for printing and the first video data signal VDAT10 is sent from the host system 500, the analog switches 807a and 808a are alternately turned on and off according to the first video data signal VDAT10. The laser diode 812a is modulated by the modulation transistor 809a, and the dot image data is written on the photoconductor 200.

The details of the first laser modulation circuit 514 and the first semiconductor laser 302 have been described above.
The semiconductor laser 303 has the same structure. Light amount setting voltage of the second laser diode 812b, that is, the comparator 802b
The output of the voltage follower 819 is applied to one input terminal of the. Therefore, by changing the exposure adjustment volume 821, the output voltage of the voltage follower 819 also changes, so that one input terminal voltage of the comparators 802a and 802b changes at the same time. Therefore, the light output of the first laser diode 812a and the light output of the second laser diode 812b can be adjusted simultaneously by making the exposure volume 821 variable.

FIG. 9 is a detailed circuit diagram of the beam detection circuit 517 and the beam detector 518 shown in FIG. In FIG. 9, reference numeral 518 denotes a beam detector which uses a PIN diode having a very fast response. In addition, this beam detector 518 is
It serves as a reference pulse when writing print data to, and the position where this pulse is generated must always be stable.

The anode side of the beam detector 518 is load resistor R41 and resistor R4.
It is connected to the-side input terminal of the high-speed comparator 825 through 4. Further, the voltage divided by the resistors R42 and R43 is applied to the + side input terminal of the high speed comparator 825 through R45. A noise removing capacitor C10 is connected in parallel to the resistor R43. Further, R46 is a positive feedback resistor for providing a hysteresis characteristic, and C11 is a feedback capacitor for performing high-speed feedback and improving the output waveform.

Next, the operation will be described. When the laser beam passes over the beam detector 518 at high speed, a pulse current flows through the beam detector 518, and a positive pulse voltage is generated at the-side input terminal of the comparator 825. This pulse voltage is the comparator 825
The negative pulse (beam detection signal) HSYO is output to the output of the comparator 825 as compared with the + side input terminal voltage of. This beam detection signal HSYO is input to the print data writing control circuit 513, and the signals other than those necessary are thinned out and the host system 50 outputs the horizontal synchronization signals IHSYN1 and IHSYN2 shown in FIG.
Output to 0. In other words, this beam detection signal HSYO becomes a synchronization signal.

FIG. 10 is a diagram showing a scanning range of the laser beam light on the photoconductor 200 once, and a positional relationship such as a beam detection position and a data writing position falling within the scanning range.

In FIG. 10, 900 is a beam scanning start point, 901 is a beam scanning end point, and the beam reaching the beam scanning end point 901 is the beam next to the beam start point 900 at time 0 due to the next surface of the polygon mirror. To start. 902 is a beam detector 51
8 shows the beam detection start point, 903 is the left end surface of the photoconductor, 91
Similarly, 0 indicates the right end face. 904 is the left edge of the paper, 909
Represents the right end surface of the paper size A3, and 907 represents the right end surface of the paper size A6. 905 is the data writing start point (printing start point), 9
08 is the data writing end point (printing end point) for paper size A3,
906 is the data writing end point for paper size A6 (printing end point)
Represents

d ₂ is the distance from the beam detection point 902 to the writing start point, d ₃
Is the distance to the A6 size writing end point, and d ₄ is the distance to the A3 size writing end point. Further, d ₁ represents the range of one scanning of the beam.

d _5, d ₆ shows the effective print range in the A6 and A3, respectively. As can be seen from this drawing, the paper feed of this printer is always carried out with the left end face of the paper as a reference, so the printing start point 905 from the beam detection device 902 is the same for each paper size. Therefore, the data may be written after a time corresponding to the distance from the beam detector 518 beam detection to the writing start point.

FIG. 11 shows the paper size and print area portion of FIG. 10 not only in the horizontal direction but also in the entire paper.

In FIG. 11, 917 is A6 paper and 918 is A3 paper. 904, 905, 906, 907, 908 and 909 show the same positions as in FIG.

911 is the leading edge of the paper, 913 is the data writing start point in the vertical direction of the paper, 912 is the trailing edge of the A3 size paper, and 916 is the A3 size data writing end point. 915 is the rear edge of A6 size paper, 914
Indicates the end point of writing A6 size data.

FIG. 12 shows the print data writing control circuit 513 shown in FIG.
3 is a detailed circuit diagram of FIG. This print data writing control circuit 513
The main function of the photoconductor 20 is to match the size of the paper on which the print data from the host system 500 is printed.
It is sent to the laser modulation circuits 514 and 521 to write in the area above 0. It also sends out the signals necessary for the laser light output stabilizing circuits of the laser modulation circuits 514 and 521. Also host system
A timing signal necessary for sending print data is sent to 500.

In FIG. 12, reference numeral 830 is an input / output port for sending and receiving signals necessary for control in the laser modulation circuits 514 and 521 and the print data writing control circuit 513. The 831 is composed of a counter / timer that controls writing of print data, laser light output sampling, etc. The operation mode and preset values of the counter / timer can be programmed by the CPU 501. is there.

865 is a laser light output sample timer, and the gate input G6 is the beam detection signal HSY which is the output of the beam detector circuit 517.
O is input, and the beam detection signal HSYO is from LOW
The timer operation starts after the HIGH level is reached, and when the timer operation ends, the beam detector is used to detect the next beam.
It is set to end before 518.

Therefore, the timer 865 is activated each time the beam detection signal HSYO is input to the gate input G6. A clock of 1500 KHz is input to the clock input CK6 of the timer 865. The output SMPTO of the timer 865 is input to one of the 2OR gates 877, and the output of the 2OR gate 877 is the first sample signal.
As the SAMP10 and the second sample signal SAMP20, a 2NAND gate is provided to the first laser modulation circuit 514 and the second laser modulation circuit 517, respectively.
Sent via 886,887. The output first laser diode enable signal LDON11 of the I / O port 830 is input to the other input of the 2NAND gate 886 so that the first sample signal SAMP10 can be independently prohibited. Similarly,
The output second laser diode enable signal LDON21 of the I / O port 830 is input to the other input of the 2NAND gate 887, so that the second sample signal SAMP20 can be independently prohibited. In addition, I / is connected to the other input of 2OR gate 877.
The output laser test signal LDTS1 of the O port 830 is input, and by setting the laser test signal LDTS1 to the high level, the first semiconductor laser 302 and the second semiconductor laser 30
3 can be set to forced light emission. I / O port 830 has a first laser ready signal LRDY10 and a second laser ready signal L
RDY20 is input, and the
By determining the first and second laser ready signals, it is possible to confirm whether or not each laser is emitting light.

866 is a D type F / F that generates a line start signal LST1
Then, the beam detection signal HSYO is set, and the rising edge of the sample timer output SMPTO is reset. 867 is a D-type F / F that generates a beam detection ready signal LDOT1 and is an I / O port 8
Entered in 30. The D type F / F 866,867 is also reset by the output of the 2OR gate 869. The input of the 2OR gate 869 is the
The first and second laser diode enable signals.

The crystal oscillator 832 serves as a reference clock for the image clock pulse and has an oscillation frequency of about 32 MHz. 834 and 835 are J-
The KF / F constitutes a quaternary counter, and the crystal oscillator 83
The output of 2 is divided by 4, and the first video clock VCKX21 (about 8MHz) corresponding to 1 dot of the minimum modulation unit of the laser beam
Generate.

The 837 and 838 compose a quaternary counter with the same J-KF / F as the above-mentioned 834 and 835, but the JK input of the J-KF / F837 has n
Carry out output of binary counter 845 of bits C ₀
Is input via the inverter 846. J-KF / F83
4,835,837,838 Q when JK input is high level
The output toggles in synchronization with the clock input CK,
When the JK input becomes low level, its Q output interrupts the toggle operation. As a result, the subsequent J-KF / F838
Q output of the second video cloak signal VCKY21 is "5 /" when the pulse interval during the normal operation is "1" and the carry-out output CO of the n-bit binary counter 845 occurs.
4 ”, which means that only 1/4 clock is extended.
Preset input D ₀ of the n-bit binary counter 845
.. to Dn are connected to the main forces Q _{0 to} Qn of the n-bit latch 847, and the set values thereof can be set by the CPU 501 according to Dip-sw or the like. The above set value sets the carry-out number of the n-bit binary counter 845 for one line (while LST1 is HIGH level), and as a result, sets the clock generation number of "5/4". is there. Inverter 839, shift register 840, 2 NOR gate 84
Reference numeral 1842 is a circuit that gives the n-bit binary counter 845 a predetermined operation.

The second video clock signal VCKY21 is used to correct the difference between the scanning lengths l ₁ and l ₂ of the _two laser beams. In this case, the first video clock signal VCKX21 may be designated for the laser beam having the long scanning length l ₁ and the second video clock signal VCKY21 may be designated for the laser beam having the short scanning length l ₂ .
848 is a selector for specifying the output C of I / O port 830
Performed by HGCK.

Next, a correction method will be described with an example. For example, if the laser beam l ₁ having a long scanning length is 200 mm and the laser beam l ₂ having a short scanning length is 199 mm, the difference in scanning length is 1 mm. When the resolution is 12 lines / mm, a laser beam l _{2 with} a short scanning length of 12 dot clocks per 2400 dot clock (200 × 12)
It is sufficient to extend the video clock signal VCKY21 of. Since 1/4 dot clock is stretched in one correction here, 240
Correction of 1/4 dot clock between 0 dot clocks is 12 ×
4 = 48 times.

Therefore, in the n-dot binary counter 845, since the clock input CP of the n-bit binary counter is 1/4 dot clock, its carry-out is 9600.
It is enough to output 48 while counting (2400 × 4) clocks. That is, the preset value may be set so that one carry is generated every 200 counts.

836 is a binary counter, and its Q ₂ output HCT31 is an 8-dot clock (about 1M) that is the first video clock VCKX21 divided by 8.
Hz) is output. A left margin counter 863 sets the data writing start point from the beam scanning start point.
A write margin counter 864 sets a data writing end point from a beam scanning start point. The line start signal L is applied to the gate input G4 of the left margin counter 863 and the gate input G5 of the right margin counter 864.
ST1, Clock input CK4 of the left margin counter 863
The 8-dot clock HCT31 is input to the clock input CK5 of the write margin counter. Both counters can simultaneously correct the fluctuations of the two laser beams at the data writing start point and the data writing end point due to the mechanical mounting error of the beam detector 518. The error correction can be adjusted in 8-dot clock units by changing the settings of both counters according to the DIP-SW or the like. The 8 dot clock unit is set because the data writing start position and the data writing end position on the paper are within an allowable range even if they are offset by 8 dots.
This is because the error can be adjusted more easily than that. The set value of the write margin counter changes depending on the paper size.

875 is a 2AND gate, one input of which is the output LMCTO of the left margin counter 863, and the other input of which is the output RMCTO of the right margin counter 864 through the inverter 874, and therefore the output of the 2AND gate 875 is Represents a horizontal print area.

The output of the 2AND gate 875 is shifted by 4 dot clocks by the shift register 868, and the horizontal print area signal HPEN1 is output from the Q output.

The horizontal print area signal HPEN1 is input to the CE input of the n-bit binary counter 850 and the shift register 854.
The n-bit binary counter 850 and the 2NAND gate 849,
n bit latch 851, J-KF / F852 sets the data writing start point to 1
It has a circuit configuration that allows right shifting in dot units.
-The KF / F852 outputs the first horizontal print area signal HPENB1. The preset inputs D _{0 to} Dn of the n-bit binary counter 850 are used to set the shift number for right shift.
The output of the bit latch 851 is connected, and the set value can be set by the CPU 501 according to Dip-sw or the like. The shift register 854, the shift register 855, and the inverter 853 have a circuit configuration that shifts the horizontal print area signal HPENA1 to the right by two dot clocks, and the output of the shift register 855 outputs the second horizontal print area signal HPENA1. . This is because even if the first horizontal print area signal HPENB1 is set to the minimum value, it is right-shifted by 2 dot clocks.

The output of the AND gate 857 is the first video clock signal VCLKB1 indicating the video clock signal for the first horizontal print area.
One of the inputs of the AND gate 857 is the first horizontal print area signal HPENB1 and the other is the Y1 output of the selector 848. The output of the AND gate 856 is the second video clock signal VCLKA1 indicating the video clock signal for the second print area,
One of the inputs to the D gate 856 is the second horizontal print area signal HP.
ENA1, the other is the Y2 output of the selector 848.

As described above, the signal for adjusting the data writing start point in units of one dot, the first horizontal print area signal HPENB1 and the first video clock signal VCLKB1 are used to correct the error between the scanning start points of the two laser beams. used. In this case, the second horizontal print area signal is sent to the S ₂ laser beam with a fast scanning start point.
HPENA1, The second video clock signal VCLKA1 is specified, and the first horizontal print area signal is sent to the S ₁ laser beam with a slow scanning start point.
The error d may be adjusted by specifying HPENB1 and the first video clock signal VCLKB1. The selector 858 is a selector that performs the designation, and is performed by the output CHG12 of the I / O port 830. The first video clock signal VCLKA1, which has been described so far,
The second video clock signal VCLKB1 becomes a video clock signal that is subsequently supplied to the host system 500 as the video clock signals IVCLK10 and IVCLK20, and is a crystal oscillator 832, J-KF / F834, 835, 837, 838. , AND gate
856 and 857 are means for forming the above video clock signal.

859 to 862 are counters for setting a data writing start point and a data writing end point in the vertical direction (paper advancing direction).
9 is the first page top counter that sets the first color data writing start point, 860 is the first page end counter that sets the first color data writing end point, and 861 is the second color data writing start Second page top counter for setting points
862 is a second page end counter for setting the end point of writing the second color data.

The page top signal PTOP1, which is the output of the I / O port 830, is connected to the gate inputs G _{0 to} G ₃ of the counters 859 to 862. It is activated by the VSYNC command.

The line start signal LST1 is connected to the clock inputs CK _{0 to} CK ₃ of the counters 859 to 862, and as a result, the scan 1
It is possible to count in line units (one dot unit). The setting method of each counter will be described later.

Reference numeral 871 denotes a 2AND gate, one input of which is the output PTCT10 of the first page top counter 859, and the other input of which is input from the output PECT10 of the first page end counter 860 through an inverter 870. Therefore, the 2AND gate 871 is provided. Is the first color vertical print area signal VPEN11.

Reference numeral 873 denotes a 2AND gate, one input of which is the output PTCT20 of the second page top counter 861 and the other input of which is the output PECT20 of the second page end counter 862 via the inverter 872. Is the second color vertical print area signal VPEN21.

The output PECT10 of the first page end counter and the output PECT20 of the second page end counter are input to the I / O port 830, and after the counting operation is completed respectively, the first color page end signal IPEND10 and the second color page end signal IPEND20.
To the host system 500.

878 is the horizontal sync signal IHSYN10 of the first color, 879 is the second
It is a 2NAND gate (first output means) for sending the horizontal synchronization signal IHSYN20 of the color to the host system 500.

880 is the first color video clock signal IVCLK10, 881
Is a 2NAND gate (first output means) for sending the video clock signal IVCLK20 of the second color to the host system 500.

882 is a horizontal sync signal I output from the 2NAND gate 878.
This is an inverter that receives the video data signal IVDT10 of the first color from the host system 500 in synchronization with the video clock signal IVCLK10 of the first color output from the HSYN10 and the 2NAND gate 880.

883 is a horizontal sync signal 1 output from the 2NAND gate 879.
This is an inverter that receives the video data signal IVDT20 of the second color from the host system 500 in synchronization with the video clock signal IVCLK20 of the second color output from the HSYN20 and the 2NAND gate 881.

Reference numeral 884 denotes a 3NA that sends the video data signal IVDT10 of the first color from the host system 500 via the inverter 882 to the first laser modulation circuit 514 as the first video data signal VDAT10.
It is an ND gate (second output means).

Reference numeral 885 denotes a 3NAND gate (second output means) for sending the video data signal IVDT20 of the second color supplied from the host system 500 via the inverter 883 to the second laser modulation circuit 521 as the second video data signal VDAT20. .

888 is an inverter that sends the first laser diode enable signal LDON10 to the first laser modulation circuit 514. Reference numeral 889 is an inverter for sending the second laser diode enable signal LDON20 to the second laser modulation circuit 521.

A timing chart of main signals for one page in the two-color printing mode is shown in FIG. 13, and a timing chart of main signals for one line is shown in FIG.

Next, the operation of each part that operates in response to the control command issued from the control part of the two-color LBP199 will be described in detail according to the flowcharts shown in FIGS.

15 to 19 are flowcharts showing the operation of the entire two-color LBP.

FIG. 15 shows each process of self-diagnosis and warm-up of the two-color LBP199.

In FIG. 15, when the operator turns on the power supply device 520, the system program stored in the ROM 502 starts, first, the self-diagnosis processing of steps A101 to A104 is executed, and the door switch is OFF (Yes in step A101). ,
The door open process (step A105) is performed, and the paper discharge switch is turned on, the manual stop switch is turned on, and the pass sensor is turned on, the jam process is performed (step A106).

If neither the test print mode nor the maintenance mode (No at step 107, No at step 108), the heater lamp for heating the fixing device 221 which requires a relatively long time to reach the ready state is turned on (step 111), and the warm-up process is performed. After the start, the motor of the fixing device 221 and the scan motor 512 are turned on (step A112). In the test print mode (Yes at step 107),
The test print process is executed (step A109), and if it is in the maintenance mode, the maintenance process is executed (step A110).

When the scan motor 512 is turned on and becomes ready (Yes at step A113), the blade solenoid is turned on (step A114). The scan motor 512 is ON
If the ready state is not reached even after 30 seconds have passed (step A113 negative, step A115 affirmative), failure processing of the scan motor 512 is performed (step 116).

After the subsequent delay process (step 117), the drum motor of the photoconductor 200, the developing device motor 425, the clutch of the first developing device 203,
Each of the clutch of the second developing device 206 and the lamp of the static eliminator 211 is turned on (step 118), and after a delay process (step 119), the first laser diode 302, the second laser diode 303, a laser test, pre-transfer charging. Each of the vessels 208 is ON
(Step A120).

After the subsequent delay processing (step A121), the monitor judges the failure of the first laser diode 302 and the second laser diode 303 (step A122, A123), and if normal (step A122 affirmative, step A123 affirmative), beam detection signal
Look at those beam detection ready in HSYO (Step A12
8). If the first laser diode 302 has failed (No at step 122), the first laser failure process (step A).
If the second laser diode 303 has failed (No in step 123), the second laser failure processing (step A125) is executed. Also, the beam detection signal HSYO
If the beam is not detected at (No at step 126), the beam detection failure process (step A127) is executed.

After the subsequent delay process (step A129), the peeling charger 209 turns off.
After N (step A130) and delay processing (step A131), potential control during warm-up as shown in FIG. 22 is executed (step A132). Note that step A1
32 is a process for enabling printing as fast as possible at the first printing.

After the subsequent delay process (step A133), steps A134-
Proceed to each processing of A140. That is, in step A134, each of the pre-transfer charger 207, the transfer charger 208, and the peeling charger 209 is turned off. In step A136, the developing device motor 425, the first developing device
203 clutch, 2nd developing device 206 clutch, 1st charger
Each of 201 and the second charger 204 is turned off. At step A138, the drum motor of the photoconductor 200, the static eliminator 211, the first laser diode 302, the second laser diode 303, and the motor of the fixing device 222 are turned off. In step A140, the blade solenoid is turned off.

Thereafter, the fixing device 221 waits for the ready state (Yes at step 141), and the routine proceeds to the routine shown in FIG.

FIG. 16 shows a process of reporting the status of each part of the two-color LBP 199 to the host system 500, and issuing a print request when the host system 500 determines that each part status is normal.

In FIG. 16, first, the contents of status 5 are judged from the host system (steps A142 to A145).
That is, in step A142, it is determined whether or not the toner bag should be replaced. If it needs to be replaced (step A142
Affirmative) and wait for the toner bag to be replaced (step
A146) and the exchange is completed (Yes at Step A146, A147), the process proceeds to Step A143. In step A143, it is determined whether or not there is no toner of the first color by turning on / off the empty switch of the first developing device 203. If the first color toner is absent (Yes at Step A143), it is confirmed by the status 1 whether the second color mode is set (Step A148). If the first color mode and the two-color printing mode are set (No at Step A148), First developing device
Completion of supply of the first color toner to 203 (Yes at Step A149), A
At 150, proceed to step A144. If it is the second color mode (Yes at Step A148), Step A149, Step A15
Skip 0 and proceed to step A144. In step A144, it is determined whether or not there is no toner of the second color by turning on / off the empty switch of the second developing device 206. If the second color toner is absent (Yes at step A144), it is confirmed by the status 1 whether or not the first color mode is set (step A15).
1) If the second color mode and the two-color printing mode are selected (No at step A151), the supply of the second color toner to the second developing device 206 is completed (Yes at step A152, A153), and the process proceeds to step 145. If it is the first color mode (Yes at Step A151), Steps A152 and A153 are skipped and Step 145 is performed.
Proceed to.

In this way, if there is no abnormality in the toner status of the first developing device 203 and the second developing device 206, the command reception from the host system 500 is permitted. (Step A145).

If there is a command to specify the first color print mode (Yes at Step A154), the first color mode is set in status 1 (Step A157), and if there is a command to specify the second color print mode (Yes at Step A155). ), The second color mode is set to status 1 (step A158).

If there is a command to specify the two-color printing mode (Yes at step A156), the two-color mode is set in status 1 (step A159).

Then, in the subsequent step A160, turn on IPRDY and set IPREQ
When the process of turning ON is executed, in the following step A161
If the IPRNT is turned on, a determination process is performed, and if it remains off (No at step A161), the process returns to step A142, and if it is on (affirmation at step A161), the print request is turned off (step A161). A162), and proceeds to the print processing after the routine shown in FIG.

In FIG. 17, steps A163 to A174 are the same as the warming-up routine.

In a succeeding step A177, it is confirmed by the status 1 whether or not the second color mode is set. If it is not the second color mode (No at step A177), the clutch of the first developing device 203 is turned on.
Then, the first developing device 203 is driven (step A178), and the process proceeds to step A179. If it is the second color mode (step A1
77), skip step A178 and proceed to step A179.

In step A179, it is confirmed by status 1 whether or not the first color mode is set. If the mode is not the first color mode (No at step A179), the clutch of the second developing device 206 is turned on to drive the second developing device 206 (step A180), and step A
Proceed to 181. If it is the second color mode, step A180 is skipped and the process proceeds to step A181.

In step A181, the bias table data for the toner color of the first developing device 203 is read, and the subsequent step A1
In 82, the read bias table data is set in the D / A converter 578, in the subsequent step A183, the bias table data for the toner color of the second developing device 206 is read, and in the following step A184, the read bias table data is D The process of setting in the / A converter 584 is executed.

After the subsequent delay process (step A185), the potential control before first printing as shown in FIG. 22 is executed (step A186).

In a succeeding step A187, it is confirmed by the status 1 whether or not the second color mode is set. If it is not the second color mode (No at step A187), the developing bias 4 of the first developing device 203
Turns 09 on (step A188) and proceeds to step A190. Second
If it is the color mode (Yes at Step A187), Step A188
Skipping to step A190 and proceeding to step A190, the second charging potential control is performed as shown in FIG. 22 (step A189).

In step A191 following the delay process of step 190, it is confirmed from status 1 whether or not the first color mode is set. If it is not the first color mode (No at step A191), the developing bias 409 of the second developing device 206 is turned on (step A19).
2) Go to step A194. If it is the first color mode (Yes at Step A191), Step A192 is skipped and the process proceeds to Step A194, and the first charging potential control is performed as shown in FIG. 22 (Step A193).

At step A194, it is judged from the status 1 whether the paper feed cassette is at the upper stage or the lower stage, and when it is decided at the upper stage, the paper feed motor is driven in the normal direction to carry out the upper stage paper feed (step A195). ), The process proceeds to step A199, and the feed motor is turned off after the delay process of step A208.
F (step A209). When it is determined that the paper is in the lower stage, step A195 is skipped, and after the delay process (step A196), the paper feed motor is rotated in reverse to perform the lower stage paper feeding (step A197), and the process proceeds to step A199 and step A208. After the delay process of (1), the paper feed motor is turned off (step A209).

In step 199, it is confirmed by status 1 whether or not the second color mode is set. If the second color mode is not set (step
(No in A199), step A202 after delay processing in step A200
Proceed to. If it is the second color mode (Yes at Step A199),
After the delay process of step A201, the process proceeds to step A202.

In step A202, the beam detection signal HSYO is used to check the beam detection ready, and the flow advances to step A204. If beam detection ready is not possible (No at Step A202), beam detection failure processing is executed.

In step A204, as shown in FIGS. 20 and 21,
A page top counter, a page end counter, a left margin counter, a right margin counter and a 2 beam scanning length correction value are set.

In the following step A205, the VSYNC request of status 1 is set and the VSYNC command waits (step A20).
6) When the VSYNC command is sent from the host system 500, the VSYNC request is reset (step A207).

At the subsequent step A210 in FIG. 18, the counting of the top / bottom counter is started and the image writing is started. After that, it is confirmed by the status 1 whether or not the two-color printing mode is set (step A211). If it is the first color mode and the second color mode (No at step A211), the process proceeds to step A213, and if it is the two-color mode (step A211 is Yes), the process proceeds to step A213 and the first charging position control is performed at the same time. Repeat (step A212). The details of the first charging potential control are described in the 23rd section.
It is described in the flowchart of FIG. 24 and FIG.

In the following step 213, the status 1 is used again for the second
Check if it is in color mode. If it is not the second color mode (No at step 213), the process proceeds to step 216 after the delay process at step A214, and if it is the second color mode (step 2).
13), the process proceeds to step 216 after the delay process of step A215.

When the registration motor is turned on and the total counter is turned on in step 216, the total counter is turned off after the delay process (A217) and the process proceeds to step A221.
F (step A220).

In step A221, it is confirmed again whether the second color mode is set. If it is not the second color mode (No at step A221), when the first page end is detected (step A221).
A222: Yes), the writing of the first color image is completed, and IPEND1 is output as a pulse (step A223), and the process proceeds to step A224. At step A224, it is confirmed whether the first color mode is set.

If status 1 is the first color mode (step A224
If the first developing unit 203 has the first color toner (No in step A231), the second developing unit 206 does not have the second color toner (Yes in step A238) and prints as shown in FIG. Request IPREQ is turned on (step A24)
8).

At this time, when there is no first color toner in the first developing device 203 (Yes at step A231) and no second color toner in the second developing device 206 (Yes at step A232), as shown in FIG. Is turned off (step A252).

Even if the first developing device 203 does not have the first color toner (Yes at Step A231), the second developing device 206 has the second color toner (No at Step A232), and any one of the first color and the second color. If the same color is obtained (Yes at Step A233), when the command for designating the second color print mode is issued (Step A234
(Yes), the developing bias 409 of the first developing device 203 and its clutch are turned off (step A235), the charge potential control of the first charger 201 is stopped, and the first charger 201 is turned off (step A236). , Status 1 second color mode is set (step A237), and print request IPREQ is turned ON.
(Step A248).

On the other hand, when the first developing device 203 has the first color toner (step A231 negative) and the second developing device 206 has the second color toner (step A238 negative), the second print mode designation command is issued. If there is (step A239 affirmative), the developing bias 409 of the first developing device 203 and its clutch are turned off (step A235), the charging potential control of the first charging device 201 is stopped, and the first charging device 201 is turned off ( (Step A236), the second color mode setting of status 1 is executed (step A236).
A237), and the print request IPREQ is turned on (step A248).

On the other hand, when it is determined in step A221 that the mode is the second color mode and when it is determined in step A224 that the mode is not the first color mode, the second color image writing is performed when the second page end is detected (step A225 affirmative). When completed, IPEND2 is output as a pulse (step A226) and the process proceeds to step A227. If the status 1 is the second color mode (Yes at step A227), the second developing device 206 does not have the second color toner (step A240).
If the first color is present in the first developing device 203 (No in step A241) and both the first and second colors are the same color (Yes in step A242), the first color printing mode is selected. When the designated command is issued (Yes at Step A243), the developing bias 409 of the second developing device 206 and its clutch are turned off.
Then, the control of the charging potential of the second charger 204 is stopped (step 244), and the second charger 204 is turned off (step A2).
45a), the first color mode of status 1 is set (step A245b), and then the print request IPREQ is turned on as shown in FIG. 19 (step A248).

If the status 1 is other than the second color mode in step A227, it is determined in step A228 based on the status 5 whether or not the first color toner is absent.
At 29, it is determined from status 5 whether or not the second color toner is absent. If no toner is present in steps A228 and A229, print ready IPRD is performed as shown in FIG.
Turn Y off (step A252).

If there is toner of the first color and the second color (step
A228 negative, 229 negative), at the same time as proceeding to step A248,
The second charging potential control is performed twice (step A230). still,
Details of the second charging potential control are described in the flowcharts of FIGS. 23 and 24.

In the routines of Steps A221 to A248, by deleting the determinations of Steps A242 and 242, even if the toners of the first developing device 203 and the second developing device 206 are not the same color, the developing device is switched. Continuous development is possible.

In Figure 19, print request in step A248
After the process of turning on IPREQ, the judgment process (steps A249 and A250) of waiting for IPRNT ON for 5 seconds is executed. If IPRNT is turned on (Yes at step A249), the print request IPREQ is turned off.
Then, (step F251), it is determined whether or not the print mode is changed (step A266).

If the print mode has been changed (Yes at step A266), the process returns to step A177 and steps A177 to A1.
During the period 94, the first developing device 203 or the second developing device 206 is set to the developable state while observing the status 1.

If the print mode has not been changed (step A266
(No), return to step A194, step A177 ~ step
Processing during A193 is omitted.

However, no matter which print mode is used, the step
Since the processing is repeated without performing the processing of A163 to A174, the recording operation is continued without temporarily stopping the two-color LBP199.

On the other hand, when 5 seconds elapses when the determination process (steps A249, A250) of waiting for IPRNT ON for 5 seconds is executed (step A250 affirmative), steps A253 to A2
After the stop processing of 65, the process returns to step A142, and the host system
It will be in a standby state waiting for a command from 500.

If the print ready IPRDY is OFF (step A252), the print operation is not required, so step A253
~ After the stop processing in step A265, the process returns to step A142 and waits for a command from the host system 500. 20 and 21 are flowcharts showing the process of step A204 of FIG.

In the subroutine shown in FIG. 20 and FIG. 21, in the steps B101 to B107, the top margin is roughly adjusted and set, and in the steps B108 to B112, the bottom margin is roughly adjusted and set, and the steps B114 to B119.
And step to fine-tune and set the top margin of
B120 to step B123 bottom margin fine adjustment setting process, step B124 to step B128 left margin coarse adjustment setting process, step B129 to step
The process is roughly divided into a process of roughly adjusting the line margin of B131, a process of finely adjusting the write margin of steps B132 to B136, and a process of two-beam scanning adjustment correction of steps B137 to B141. The details of are as illustrated.

That is, in the processing for coarsely adjusting and setting the top margin in steps B101 to 107, after reading the first color top margin table data D1 (step B101), the top margin coarse adjustment switch is read (step B102), and the corresponding switch is used. Top margin coarse adjustment table data D ₂
Is read (step B103).

In the subsequent step B104, the top margin rough adjustment table data D2 is set to the value of the top margin table data D1 for the first color.
Is added or subtracted to obtain the operation result D3.

In the subsequent step B105, if the status 1 is not the two-color mode (No in step B105), the calculation result D3 is set in the first page top counter 859 (step B106), and the bottom margin in steps B108 to B113 is roughly adjusted and set. Go to routine. If the status 1 is the two-color mode (Yes at step B105), the calculation result D3 is set in the second page top counter 861 (step B107), and the routine similarly proceeds to steps B108 to B113.

When the bottom margin table data D4 of the designated paper size is read in step B108, in the subsequent step B109, the first color top margin table data D1 is added to the bottom margin table data D4 to obtain the calculation result D5.

In the following step B110, the rough margin adjustment table data D2 is added to the value of the calculation result D5 to obtain the calculation result D6.

In the subsequent step B111, if step 1 is not the second color mode (step B111 negative), the calculation result D6 is set in the first page end counter 860 (step B113), and the top margin of steps B114 to B119 is finely adjusted and set. Proceed to the routine. If the status 1 is the second color mode (Yes in step B111), the calculation result D6 is set in the second page end counter 862 (step B112), and the routine similarly proceeds to steps B114 to B119.

When the second color top margin table data D7 is read in step B114, the top margin fine adjustment switch is read in the following step B115, and the top margin fine adjustment table data D8 corresponding to the switch is read in the following step B116.
Read.

In the following step B117, the rough margin adjustment table data D2 and the fine adjustment table data D8 are added to or subtracted from the value of the second color top margin table data D7 to obtain a calculation result D9.

If the status 1 is not the two-color mode in the subsequent step B118 (No in step B118), the process proceeds to the bottom margin fine adjustment setting routine in steps 120 to B123. If the status 1 is the two-color mode (Yes at Step B118),
The calculation result D9 is set in the second page top counter 861 (step B119), and the routine similarly proceeds to steps B120 to B123.

In step B120, the second color top margin table data D7 is added to the bottom margin table data D4 to obtain the calculation result D10, and then in step B121, the coarse margin adjustment table D8 is added to or subtracted from the value of the calculation result D10. Calculation result
Get D11.

If the status 1 is not the two-color mode in the subsequent step B122 (No in step B122), the routine proceeds to the left margin coarse adjustment setting routine in steps B124 to B128. If the status 1 is the two-color mode (Yes at Step B122), the calculation result D11 is set in the second page end counter (Step B123), and the routine similarly proceeds to Steps B124 to B128.

In step B124, the left margin table data D12 is read, in step B125, the left margin coarse adjustment switch is read, and then in step B126, the left margin rough adjustment table data D13 corresponding to the switch is read.

In the following step B127, the rough margin adjustment table D13 is added to or subtracted from the value of the left margin table data D12 to obtain the calculation result D14.

When the calculation result D14 is set in the left margin counter 863 in the following step B128, the routine proceeds to the routine for coarse adjustment of the right margin in steps B129 to B131.

In step B129, the write margin table data D15 of the designated paper size is read, and in the following step B130, the rough margin adjustment table data D13 is added to or subtracted from the value of the write margin table data D15 to obtain the calculation result D16.

When the calculation result D16 is set in the right margin counter 864 in the following step B131, the routine proceeds to steps B132 to B136 for fine adjustment and setting of the left margin.

In step B132, the left margin fine adjustment switch is read, in step B133, the left margin fine adjustment table data D17 corresponding to the switch is read, and then in step B134, the value of the table data D17 is set in the n-bit latch 851.

In the following step B135, read the print area changeover switch,
In the following step B136, I / O according to the print area changeover switch
After setting the port 830, the process proceeds to the two-beam scanning length correction routine in steps B137 to B141.

After the 2-beam scanning length correction switch is read in step B137, the scanning length correction table data D18 corresponding to the switch is read in subsequent step B138, and this table data D18 is set in the n-bit latch 847 in subsequent step B139.

In the following step B140, the dot clock changeover switch is read, and in accordance with this dot clock changeover switch, in the following step B141, the I / O port 830 is set, and the processing of step A204 shown in FIG. 17 ends.

Incidentally, steps B101, B106, B107, B108, B112, B113,
The first page top counters 859 and 860, the second page top counters 861 and 862, the left margin counter 863, and B114, B119, B123, B124, B128, B129, B131, etc.
Each set content of the write margin counter 864 is changed according to the designated paper size. Then, as the set contents are changed, the number of pulses of the video clock signal is changed corresponding to the size of the paper.

FIG. 22 is a flowchart showing potential control during warm-up and potential control before first printing.

For the potential control during warming up, the value CH _DT1 of the first charge initial control output is read from the table data (step C101), and the read value is set in the D / A converter 576 (step C102). Also, the value CH of the second charging initial control output
_{The DT2} is read from the table data (step C103), and the read value is set in the D / A converter 582 (step C1).
04).

When the first charger 201 is turned on in the subsequent step C105, the second charger
The first charging potential control is executed as shown in FIGS. 3 and 24 (step C106). Subsequent delay processing (step C107)
After that, when the second charger 204 is turned on in step C108,
The second charging potential control is executed as shown in FIGS. 3 and 24 (step C109).

Then, the potential control number n is incremented (step C110),
Until the potential control number n reaches three times, step C1
Repeat step 05 to step C111) three times and the first
The charger 201 and the second charger 204 are turned off (step C11
2), the potential control during this warm-up ends.

In the potential control before the first printing, if the status 1 is not the second color mode (No at step D101), the first charger 201 is turned on (step D102), and the potential control shown in FIGS.
As shown in the figure, the first charging potential control is executed (step
D103), if it is only the first color mode (Yes at step D104), the potential control before the first printing is completed.

If it is the two-color mode (No at step D104), after the delay process (step D105), the second charger 204 is turned on and the second charging potential control is executed as shown in FIGS. 23 and 24. (Step D107), the potential control before the first printing ends.

If the status 1 is the second color mode in the first step D101, only the second color mode is executed.
When the charging device 204 is turned on (step D106), FIG. 23 and FIG.
As shown in FIG. 4, the second charging potential control is executed (step D107), and the potential control before the first printing ends.

23 and 24 are flowcharts showing the details of the charging potential control process.

In the subroutines shown in FIGS. 23 and 24, the drum temperature detector 570 is first selected by the A / D converter 593 (step E101), and the temperature of the photoconductor 200 is measured (step E102). Then, either the first charging potential control or the second charging potential control is selected, and (step E10
3) Based on the data table of the ROM 503, in the case of the first charging potential control, each processing of step E104 to step E109 is executed, and in the case of the second charging potential control, the processing of step E113 to step E118. Each process is executed.

Then, in steps E110 and E119, the first target surface potential data (VOS1) and the second target surface potential data (VOS2) are respectively set so as to correspond to the actual temperature of the photoconductor 200.
To correct the corresponding correction data VOS1 ′ and VOS2 ′.
Get.

In the following step E111 and step E120, step E1
04-Each value obtained in step E110 and step E113-E1
Since the respective values obtained in 19 are both stored in the common register, the arithmetic processing as shown in step E111 and step E120 is executed.

At the following step E112 and step E121, the A / D converter 593 causes the first potential sensor 202 and the second potential sensor 20 respectively.
5 is selected.

Next, in any of the first charging potential control and the second charging potential control, each process after step E122 is executed.

First, a delay process is executed for a time corresponding to a stroke distance between the first and second chargers 201 and 204 and the first and second surface potential sensors 202 and 205, and the surface potentials are measured by the first and second surface sensors 202 and 205. Vs is measured (steps E122 and E123).

After the following steps, step E111 and step E120
Processing is performed based on each data shown in.

That is, in step E124, whether or not the read value is V _OS + V _OMAX or more is self-diagnosed according to the arithmetic expression V _S ≧ V _OS + V _OMAX . If it is above (Yes at Step E124), the potential control error process is executed. (Step E125). If it is less than (No at step E124), the process proceeds to step E126.

In step E126, it is determined whether or not the read value is within the control range of the target value and the error table according to the V _S = V _OS ± V _OZ arithmetic expression. If it does not enter (No at step E126), see how much it deviates from the target, for example, 200V, 100V, 50V stepwise (steps E127, E128, E129), and the control amount is the same as ΔX ₁ or ΔX _2. Alternatively, the processing of setting the sizes of 2 times, 4 times, and 6 times is executed (steps E130, E131, E132, E133).

After this setting, the process proceeds to step E134, where the charging output is set, and in the following step E135 it is checked whether or not the charging output is larger than the maximum value, and in the following step E136 whether the charging output is smaller than the minimum value or not. Is checked, and if it is too large or too small (Yes at step E135), potential control error processing is executed (step E137).

If the charging output is within the control range (No at Step E135, No at Step E136), the process proceeds to Step E138, and which of the first charger 201 and the second charger 204 is the actual potential control target. To be judged.

If this determination result is the first charger 201, after setting CH _DT1 = CH _DT (step E139), change CH _DT1 to D / A converter 576.
The process of setting to is executed, and the process proceeds to step E145.

If the determination result is the second charger 204, after setting CH _DT2 = CH _DT (step E141), CH _{DT2 is changed} to the D / A converter 582.
The process of setting to is executed, and the process proceeds to step E145.

In step E145, the charging potential control count is incremented to the 24th
The routine proceeds to step E146 and thereafter.

That is, if the potential control is before the first printing (Yes at Step E146), the potential control number m is three times (Step E146).
Affirmative in E151), the non-convergence ends due to the potential control, and the process returns to step E122 up to twice.

If the potential control is performed during warm-up (Yes at Step E147), the number of potential control times is 10 (see Step E147).
E152 affirmative), potential control error processing is executed (step
E153), and returns to step E122 up to 9 times.

If the status 1 is not the two-color mode (No at step E148), the process returns to step E122, but if the status 1 is the two-color mode (Yes at step E148), the potential control targets are the first charger 201 and the second charger. If it is the charger 204, the potential control is completed when the potential control is performed 5 times for the first charger 201 (Yes at step 150), and the potential control is performed for the second charger 204. When the operation is performed twice (Yes at step 154), the potential control ends.

As described above, in the embodiment of the present invention, as described in particular with reference to FIG. 4, the horizontal synchronizing signal (IHSY) is transmitted from the interface circuit 519 of the two-color LBP199 to the host system 500.
N1, IHSYN2) request to send 1 line of print data, and video clock signals (1VCLK1, 1VCLK2) to send 1 dot of print data.
The 500 is adapted to send out video data signals (1VDAT1, 1VDAT2) of dot image data to the interface circuit 519 based on the video clock signal or the like.

Therefore, even if the host system 500 does not perform arithmetic processing for transmitting the video data signal, the two-color LBP199
2 color LBP1 with horizontal sync signal from
The video data signal is sent from the host system 500 to the two-color LBP 199 in synchronization with the video clock signal from 99. Therefore, in the two-color LBP199, there is no cause of delay in the electrostatic latent image forming operation by the laser beam, and it is possible to suppress the variation in the recording position of the paper.

[Effects of the Invention] As described above, the image forming apparatus to which the present invention is applied has a system configuration in which the video data signal is sent from the host side to the printing side based on the video clock signal output from the printing side. Therefore, it is possible to eliminate the influence of the processing time on the host side, which is the cause of the error in the image forming operation. Further, it is possible to easily correct the recording start position of the sheet due to variations in the beam detector of the printing apparatus, the image carrier, the sheet cassette for storing the sheet, and the like.
Therefore, it is possible to provide the image forming apparatus that has been adjusted at the time of purchase without forcing the user to perform a troublesome operation such as changing the setting condition so that the print area becomes a desired area.

[Brief description of drawings]

FIG. 1 is a block diagram showing the outline of an embodiment of an image forming apparatus to which the present invention is applied, and FIG.
FIG. 3 is a block diagram showing the system configuration of color LBP, FIG. 3 is a diagram showing the contents of a ROM data table, FIG. 4 is a diagram showing details of interface signals between the interface circuit and the host system, and FIG. 5 is an interface signal and data. FIG. 6 is a detailed explanatory view of the command used in the two-color LBP, FIG. 7 is a detailed explanatory view of each status used in the two-color LBP, and FIG. 8 is a laser modulation circuit. FIG. 9 is a block diagram showing details of a semiconductor laser, FIG. 9 is a circuit diagram showing details of a beam detection circuit and a beam detector, and FIG. 10 is a scanning range of a laser beam, a beam detection position, and data writing. Fig. 11 is a diagram showing the relationship between the positions and each position, Fig. 11 is a diagram showing the positional relationship of the data writing positions on the entire sheet, Fig. 12 is a circuit diagram showing the details of the print data writing control circuit, and Fig. 13 is Mark in 2-color printing mode Timing charts of the data write control signal, the timing chart of FIG. 14 is one line of the data write control signal, FIG. 15-FIG. 19 is two-color LBP
20 and 21 are flowcharts showing the entire operation, a flowchart showing a page top counter, a page end counter, a left margin counter, a right margin counter, and a subroutine for setting a two-beam scanning length correction value, and FIG. 22 is a warm. 23 is a flowchart showing a subroutine of potential control at the time of up and potential control before first printing, FIGS. 23 and 24 are flowcharts showing a subroutine of charging potential control, and FIG. 25 is an explanatory diagram of a conventional image forming apparatus. 199 …… 2-color LBP 500 …… Host system 519 …… Interface circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Moriya Nagasawa 70 Yanagi-cho, Sachi-ku, Kawasaki-shi, Kanagawa Stock company Toshiba Yanagimachi plant (72) Inventor Yoshida, 70 Yanagi-cho, Sachi-ku, Kawasaki-shi, Kanagawa Stock company Toshiba Yanagimachi Plant (72) Inventor Toshihiro Kasai 70 Yanagimachi, Saiwai-ku, Kawasaki City, Kanagawa Stock Company Toshiba Yanagimachi Plant (72) Inventor Hironobu Machida 70, Yanagicho, Sachi-ku, Kawasaki City, Kanagawa Stock Company Toshiba Yanagimachi Plant ( 72) Inventor Naorou Ide 70 Yanagicho, Sachi-ku, Kawasaki-shi, Kanagawa Within Toshiba Intelligent Technology Co., Ltd. (56) Reference JP-A-60-174571 (JP, A) JP-A-52-108142 (JP, A)

Claims (2)

(57) [Claims] 1. A photosensitive member that moves in a first direction is printed on the photosensitive member from a predetermined print start point to a print end point along a second direction that is substantially orthogonal to the first direction. In an image forming apparatus having a laser light source that forms an electrostatic latent image on the photoconductor by performing exposure scanning with the light intensity modulated by the modulation means based on the data, on the upstream side in the scanning direction of the printing start point. Beam light detecting means for outputting a synchronizing signal by receiving a laser beam from the laser light source, and video clock signal forming means for forming a corresponding video clock signal from the print start point to the print end point. A first output means for outputting the video clock signal formed by the video clock signal forming means and the synchronization signal to an external device; and an output from the first output means. And a receiving means for receiving print data transmitted from the external device in synchronization with the video clock signal and the synchronizing signal, and between the print start point and the print end point received by the receiving means. An image forming apparatus, comprising: second output means for outputting print data to the modulating means. 2. A photosensitive member moving in a first direction is printed on the photosensitive member from a predetermined print start point to a print end point along a second direction substantially orthogonal to the first direction. A laser light source for forming an electrostatic latent image on the photoconductor by exposing and scanning with the light intensity modulated by the modulation means based on the data; and a developing means for developing the electrostatic latent image on the photoconductor. An image forming apparatus having a transfer means for transferring a developed image developed by the developing means onto a sheet of a predetermined size, and receiving a laser beam from the laser light source on the upstream side of the printing start point in the scanning direction. Corresponding between the light beam detection means for outputting the synchronization signal by the, and from the print start point to the print end point,
Video clock signal forming means for forming a video clock signal in which the number of output pulses changes according to the size of the paper, and the video clock signal formed by the video clock signal forming means and the synchronizing signal to an external device. First output means for outputting, receiving means for receiving print data transmitted from the external device in synchronization with the video clock signal output from the first output means and the synchronizing signal, and the receiving means An image forming apparatus comprising: second output means for outputting print data corresponding to the received print start point to the print end point to the modulation means.