JPS63108864A - Printer device - Google Patents

Abstract

PURPOSE:To simplify signal processing for modifying a picture element density by completing exposure if the exposure for a previous printout is not finished when a request to modify a picture element density is accepted and modifying the picture element density. CONSTITUTION:When a data control part requests the modification of the printing density, a CPU 202 decides whether the requested printing density is the same as a current printing density or not. If not, a switch in a sensor 210 is switched so that the requested printing density is attained. However, if a printer device is exposing, that is, in case of expossure of the previous printout is not end, the printing density is not modified, and when printing the printout(exposure) is detected to end, the printing density is modified. Thus a drop in a processing speed can be prevented, which does not cause a host computer to process signals more complicatedly in order to modify the picture element density.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a printer device that forms images using pixels, such as a laser printer, and provides a printer that can appropriately respond to requests for changing pixel density. It is related to the device.

(Prior Art and its Problems) A laser printer is a printer device that forms an image using a large number of pixels arranged in a matrix, and scans light onto a photoreceptor drum using modulated scanning light that turns on and off according to information. A latent image is formed by pixels, and a visible image is obtained by toner development, which is transferred to plain paper and then fixed. Laser printers can achieve high-speed, high-quality (high-density) printing and graphic recording because the laser beam is modulated at high speed in the rotating part, and for this reason, the output of various data processing systems and image creation systems using combinators is possible. It has a wide range of uses as a device.

By the way, the image signal output from the host combinator! There are various image densities, and in order to receive these outputs and print normal images, it is necessary to vary the pixel density of the laser printer in accordance with these outputs. Furthermore, in order to change the print size using character generators having the same pixel configuration, it is necessary to make the pixel density of the laser printer variable. In order to meet these demands, laser printers with variable pixel density have been proposed (for example, Japanese Patent Laid-Open No. 59-1
98076).

By the way, when the pixel density is changed from a new page of images that are being sequentially processed by a host computer, control data for requesting a pixel density change is sent from the host computer to the laser printer along with the image data of those images. output for In this case, if the laser printer still has exposure for the print request received before the time it receives the pixel density change request, or if it is in the process of exposure, the laser printer will change the pixel density until the exposure is completed. Therefore, the host combinator had to constantly be aware of the state of the laser printer and wait until all the exposures for the requested print were completed before making a request to change the pixel density. . For this reason, there have been problems in that the signal processing for changing the pixel density in the host combinator is complicated and the processing speed is reduced.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides that, if a request to change the pixel density is sent from a host computer or the like, the printer device side can send a request to change the pixel density. The purpose of the present invention is to provide a printer that can send a message at any timing regardless of the state, and the technical means for this purpose is a printer device that forms an image with a large number of pixels on a photoreceptor using scanning light. , means for receiving a print request, means for receiving a pixel density change request, and means for changing the pixel density, and the print request is received before the time when the image density change request is received. This is characterized in that the pixel density is not changed until the exposure is completed.

(Example) The present invention will be explained below based on illustrated embodiments.

FIG. 1 is a sectional view of the laser printer 1. FIG. In the figure, 2 is a photoreceptor on which a latent image is formed by a laser beam;
3 is a charging device for uniformly charging the photoreceptor 2; 14 is a developing device for developing a latent image formed by a laser beam; 5 is a transfer charger for transferring the developed toner onto paper; 6 is a separation belt to separate the paper from the photoconductor 2; 7 is a cleaner blade that collects excess toner after transfer; 8 is an irradiation device to remove excess charge to make the charging uniform at step 3 during charging. 9 is a density reader that reads the density of toner, 10 is a paper cassette that stores paper, 11 is a half-moon-shaped paper feed roller that guides the paper to the conveyance path, 12 is a conveyance roller, and 13 is a manual paper feed roller. A conveyance roller 14 that also serves as a paper feed roller determines the recording position with respect to the paper in the sub-scanning direction (the direction in which the laser beam scans the paper is the main scanning direction, and the direction perpendicular thereto is the sub-scanning direction). A registration roller 15 is a fixing roller that fixes the toner transferred by the transfer charger 5 onto the paper, 16 is a main body discharge roller, and 17 is a reversing unit for discharging the paper from the back side. Reference numeral 18 denotes a paper guiding claw for switching between back side and front side ejection, which can be operated manually. Reference numeral 19 represents a conveyance path for back side ejection, and 20 represents an ejection roller. 21 is a group of magnets for identifying the paper size in the paper cassette 10, and the sensor 22 detects and identifies whether or not there is a magnet in the 3-focus storage frame; 23 indicates the presence of paper in the cassette; Paper empty sensor to detect, PSL, PS
2. Each PS3 has a paper sensor.

FIG. 2 schematically shows the optical system of the laser printer 1. As shown in FIG. Referring to FIGS. 1 and 2, 31 is a laser diode (hereinafter referred to as LD), which will be described later.
It is modulated and driven by the D drive section. 32 and 33 are so-called collimator lenses and cylindrical lenses for correcting the spread of the laser beam. Reference numeral 34 denotes a polygon mirror, which is configured so that when it rotates, a laser beam scans the photoreceptor 2 and scan light 39 is obtained.

35 is an fθ lens for scanning the laser beam on the photoconductor at a uniform speed, 36.37 is a folding mirror for guiding the laser beam to the photoconductor 2, and 3B is for determining the printing position in the main scanning direction. This is a beam detector, and the scanning light 39 is configured to scan the photoreceptor 2 after passing through the beam detector.

FIG. 3 is a system block diagram when the laser printer 1 is actually used, and 400 is a general-purpose data processing device (
300 is a data control unit, and 200 is a print Ws control unit of the laser printer 1 that controls the printing operation of the laser printer 1.

Generally, when a print request occurs in the data processing device 400, printer control data that determines the printing operation mode of the laser printer l and print data that determines the actual print content are sent to the data control unit through the interface 301 using code data. 300. The purpose of transmitting the code is to shorten the transmission time as much as possible.

The data control unit 300 receives the data based on the code data, and if the data is printer control data, it is transmitted as is to the printing +W control unit 200 of the laser printer 1 through the interface 201 that follows.

On the other hand, if the data is print data, the code data is converted into bit image data and then developed into a memory called bitmap memory that can store l page's worth of bit image data, and /page's worth of data is developed. At this point, the interface 201 issues a print start request to the print control unit 200 of the laser printer l. The laser printer 1 prints s
When the ai section 20G receives and receives the print start request, it starts the printing operation, and at the time of exposure when image data is actually required, data is read from the bitmap memory through the interface 201, and the data is read out from the bitmap memory using the data.
The protocol of the 0-order interface 201 that modulates D31 to create a latent image on the photoreceptor 2 and the printing vi control of the laser printer 1 will be explained.

The interface 201 is for exchanging data between the data control section 300 and the print control section 200 in the laser printer 1, and consists of the following two interfaces.

Referring to FIG. 5, the control interface 201a:
This is used for exchanging data related to the operation control of the laser printer l, and the data control unit 300 sends data for specifying print formats such as the paper feed port and ejection port, and data for determining the timing of print start requests, etc. On the other hand, the print control unit 200 sends data for the internal status of the laser printer, such as paper size information and error information, and data for determining the timing of printing completion, paper ejection, etc. . The interface 201 is made up of commands and statuses, and the commands are used to exchange data related to the timing, and the statuses are used to exchange other data. These commands and status are shown in Tables 1 and 2.

Table 1 Command Table 2 Status Next, the image interface 201b controls the data control unit 30 during so-called exposure when a latent image is being formed on the photoreceptor 2.
It is used to read image data from the bitmap memory 0.

Figure 4 shows the configuration of the signal line, slo.

3101 is a light rasp (WR3T) signal indicating that exposure is in progress, and 3101 is a laser beam scanning light 39 (
A sensor scan (hereinafter referred to as 5ScAN) signal indicating that the beam (see FIG. 2) has passed the beam detection 1138;
3102 is a data request (hereinafter referred to as DREQ) signal for requesting g-focus image data, and S103 is a g-bit image data signal output by the DREQ signal.

At the time of exposure, the WR3T signal S100 becomes "L", and thereby the data control section 300 enters the system for transmitting image data. Furthermore, the start of the 7947th minute is recognized by the fall of the 5SCAN signal S101, and the DREQ signal 5102
The g-bit parallel data is transmitted to the laser printer 1 in synchronization with the rising edge of .

FIG. 5 is a block diagram of the print control section 200 of the laser printer 1. As shown in FIG. The configuration is a so-called multi-chip configuration centered around the CPU 2O5, and data can be exchanged with each chip via a bus 310.In the figure, 205 is a system ROM that stores the control program.

206 is a system R serving as a work area for the control program.
AM, 203 is an oscillator that creates a clock that synchronizes the operation of the CPU, 204 is a reset circuit that resets the entire circuit when the power is turned on, 208 is various driving parts such as motors, solenoids, heaters, etc., 207 is Drive section 20
8, 210 is various sensors such as a paper sensor and concentration sensor, 209 is an input port that receives and receives signals from sensor 210, and 212 is an operation having a display element such as an LED or an input element such as a switch. It is a panel.

A scanner driving unit 215 controls the rotation of the polygon mirror 34, and determines the rotation speed of the polygon mirror 34 in accordance with the clock 512 transmitted from the timer 213, and drives the polygon mirror 34. The setting value of timer 213 is CPU U2O5
It can be set by command from CP 020.
2 allows the rotation speed to be arbitrarily changed and set. This is the polygon mirror 3 when changing the printing density.
This is because it is necessary to change the rotation speed of No. 4. Also,
The scanner driver 215 sends a polygon lock signal 311 to the input port 209 indicating whether the polygon mirror 34 is rotating at a constant speed.

218 is an LD drive unit that controls the drive of the LD 31;
A print data write circuit 2 that modulates the LD 31 based on a signal sent from the print data write control circuit 217.
Reference numeral 17 designates scanning light 39 at a predetermined position on the photoreceptor 2 from the image data sent from the data control unit 300.
LDIII to the LD drive unit 218 so that it turns on and off.
Create data. Note that image data is exchanged using the image interface 201b.
is an interface control circuit that controls the control interface 201a.

FIG. 6 shows the contents of the output signal from the output port 207. Here, only the details of the objects to be driven are shown, and the circuits and specific connections for actually driving these drive parts are omitted. Also, the mechanical drive part (each roller or toner supply) in this example is omitted. 224) are all driven by a chain from the main motor 224, and are turned on and off by a clutch using a solenoid.

220 is a solenoid that determines whether or not to transmit the drive of the chain to the paper feed roller 11; 221 is a solenoid for the registration roller 14; and 222 is a solenoid that determines whether or not to drive a portion that replenishes toner to the developing unit 4. Solenoid, 22
3 is an ED attached to the density reader 9, 224 is a main motor, and 227 is a motor relative to the photoreceptor 2 so that the toner in the developer 4 adheres only to the latent image formed on the photoreceptor 2. The potential (hereinafter referred to as developing bias) is applied to the developing device 4.
229 is a heater section of the fixing roller 15. Print data writing control circuit 2
The output signal to 17 will be described later.

FIG. 7 shows the contents of the input signal to the input port 209. Here, like the output signal, only the contents to be detected are shown, and specific connections, comparators, etc. are omitted.

230 is Y7 that separates the inside and outside of the laser printer 1
231 is the main motor 22
4 defect detection I! , 232 and 233 are defective detectors during charging -3 and during transfer charging -5, respectively.
4 is a toner embossing 4 that detects the amount of toner in the developer 14;
- Detection sensor number, 235 is the density detection sensor number for density reading a9, 236 is a face up/down switch that detects which state the paper guiding claw 18 is in;
37 is 2 for setting the initial value of printing density (pixel density)
This is an initial setting switch consisting of a sliding inch, which allows you to set the settings. In addition, 238 has a heat roller salinity IIIg6″t″, and input port 209
Informs the salinity status of the heater.

FIG. 8 is a detailed circuit diagram of the print data write control circuit 21f.

This IIa 217 determines the image printing position in the main scanning direction,
Deciding the printing position of the mark for automatic image density control (hereinafter referred to as AI()C) in the main scanning direction, forcing the LD31 to emit light outside the image area to generate a synchronization signal (SSCAN) to determine the printing position, This is used to determine the sample tie for automatic power control (hereinafter referred to as PC) of the LD 31, and to control the light emission of the LD 31 and the rotation of the polygon mirror 34. Table 3 shows the contents of the input/output signals to this 1111217.

Margin 3J In Figure 8, 250 indicates the clock 3115 (hereinafter referred to as basic clock) which is the basis of the modulation synchronization clock 3119 (hereinafter referred to as image clock) of LD31.
There is a clock selector to select from self-oscillation 11251 252.253, and DPESt from CPυ202.
! Selection is made by LECT signal 3113.

The image clock 5119 is activated by a command from the CPυ202.
The reason why the frequency can be selected is to make the printing density (Illi density) of the laser printer l variable.

To change the printing density, if no changes are made to the mechanical structure of the optical system shown in FIG. 2, the rotation speed of the polygon mirror 34, the modulation frequency of the LD 31, or the acid delivery rate of the paper It is necessary to change at least two of the rotational speed of the cWs light body 2), but in the embodiment, a method of changing the rotational speed of the polygon mirror 34 and the modulation frequency of the LD 31 is adopted as the changing means, and when the power is turned on. The initial setting of time is done by the above-mentioned initial setting switch, and subsequent changes are made by setting the value corresponding to the change request to the DP I RQ flag as described later. You can now choose. Below is that JN! The printing densities of llll are set as printing density 1, printing density 2, and printing density 3 in descending order of density.

Next, Figures 9, 10, and 11 + al ~ (0)
The image position determination '#4111 will be explained with reference also to .

First, during printing, the 5SCAN signal 5112 is periodically generated as shown in the upper row of FIGS. The operation will begin. Figure 11 (5SCAN signal 311 as in al.
2 rises, the output Q (CTGATEO) S116 of the flip-flop 254m becomes 'H', which causes the output Q (CTGATEO) of the flip-flop 254b to become 'H'.
ATEI) 3117 is the basic clock (1/I CLK)
CTGA becomes 'H' in synchronization with the rise of 3115.
When TBl 3117 becomes 'H', flip-flop 2
The clear (CLR) of 55 is released, and the output Q S 11
8 to 1/2 divided clock of basic clock 5115 (1
/2 (, LK) starts to be output. Furthermore, the load (LD) of the 4-bit counter (CTI) 256 is released, and 1/2CLKS11B starts counting down by inputting 1/2CLK to 1/2.1 from the outputs QA, QB, QC, and QD, respectively. A clock whose frequency is divided into /4.1/8.1/16 is output.

A start counter (C70) 257 and an end counter (C70) are used to determine the start and end of printing in the main scanning direction.
) 258 has its gate opened by the rise of the 5SCAN signal 5112, and then starts counting by the inverted clock from the output QD of the 4-bit counter 256. Output S of start counter 257 and end counter 258 122. S123 is " while counting continues.
When the countdown from the set value reaches zero, it becomes @H°, so this output is used to determine the image area in the main scanning direction. When the end counter 258 finishes counting, the Figure 11 (As shown in 01, the output 5123 rises and an "L" pulse is output from the output 5124 of the monostable multivibrator 259,
As a result of this rise, the output Q of the flip-flop 261 becomes 6L''.As a result, the LD DATES 104 is forced to become ``H@'', and the LD 31 emits light.

By forcing the LD 31 to emit light, the beam detection sensor 38 is scanned again, and an "H" pulse of the 5SCAN signal S112 is generated. Monostable multibiprerator 259
The output pulse from the 4-bit count 256 further sends a pulse from the borrow (BR) 5138 to the clear (CLR) S140 of the flip-flop 254-, and outputs Q S 1 of the flip-flops 254a and 254b.
16. S 117 is set to "L2". This stops the output of the clock from the output Q S 118 of the flip-flop 255.

The image area in the main scanning direction is the start counter (C
70) 257 and the end counter (C70) 25B (see Figure 19), that is, 5SCAN
An appropriate value (determined by the paper size) is set from the CPU 2 O 5 to the start counter 257, which determines the start of the image from the rising edge of the signal, and the end counter 258, which determines the end of the image from the rising edge of the 5SCAN signal 5112, before exposure. Set in advance and its output S122. An image area is determined from S123. FIG. 11 (bl, (C1) is a detailed time chart near the end of each counter. Between the image areas, the DREQ signal 5102 and the LOAD signal S 131 are issued as shown in FIG. 10. The data control unit 300 outputs 8-bit parallel data (L DATE
) to the laser printer. Furthermore, the parallel-to-serial converter 264 takes in the data 5103 due to the “L” level of the LOAD signal 5131, and the image clock (IMCLK) S1
LD drive data (LD DATA) S synchronized with 19
104 to the LDII moving unit 218.

The image area in the sub-scanning direction is CP as shown in FIG.
It is determined by the WR3T signal 5100, which is a signal obtained by latching the 5TARTS 114 from U2O5 with the 5SCANS signal. In other words, the DREQ signal S102 is
Data control unit 300 only when signal S 100 is “H”
sent to.

Next, the method of generating the AIDC mark will be explained.

AIDC is created by exposing and developing a solid black mark at a certain position and size on the photoconductor 2.The density of the mark is read by a reader 9, and if the density is below a certain level, the developing device 4 This control replenishes toner.

The AIDC mark is a mark for reading. The position of this AIDC mark is naturally created outside the image area, but in this embodiment, in the main scanning direction, it is within the range where printing is actually performed, and in the sub-scanning direction, it is located within the actual printing area. Therefore, the mark for AIDC is formed on the part of the photoreceptor 2 that is actually used for printing (see Fig. 19). , photoreceptor 2
Appropriate concentration control can be performed without being affected by changes in sensitivity due to the use of .

Positioning of the AIDC mark in the main scanning direction is performed by a start counter 257 that determines the image start and a monostable multi-by-break 260, that is, as shown in FIG. When the output 5122 rises due to the end of the start counter 257 whose value has been set, an H'' pulse is output from the output QS125 of the monostable multivibrator 260, and the area between these 1H1 pulses is defined as a mark area. Positioning is done using monostable multivibrator 2
The pulse time from the monostable multi-by-break 260 output by the AIDC signal 3108 from the CPU 202 is constant, so printing The mark width in the main scanning direction changes depending on the density.

Next, the generation of the 5SCANOυT signal will be explained.

In the monostable multivibrator 262, when the input signal to the input B rises, an "L" pulse with a value slightly longer than the pulse period of the 5SCAN signal 8112, that is, the beam scan period of the beam detector 38, is emitted from the output Q S 136. . Since the 5SCAN signal S112 is connected to the input B, as long as the polygon mirror 34 rotates at a normal rotation speed and LDB1 continues to generate normally, the output "L" pulses overlap and become "L". Continue the condition. However, since LDB1 does not emit light while the LDB IAs signal 5109 is "L", the AND gate 263 forces it to "L" during that time. This 5SCANOUT
Signal 5107 is input to the interrupt terminal of CPU2O5.

Next, while referring to the flowcharts in FIGS. 12 to 17 and the time chart in FIG.
The details of control by 2O5 will be explained. First, the flag and internal timer used here will be explained.

PREJT indicates a state in which print commands are not accepted.

PRRT indicates that this flag is “1” indicating that printing is in progress.
If a print command is accepted at the time of ', printing can be performed immediately from paper feed without starting up the main motor or photoreceptor 2.

DP I RQ indicates a request to switch (change) the print density and the print density after switching; O indicates no request, and 1°2.3 indicates a request to switch to print density 1.2.3, respectively.

PLYC)I indicates that it is necessary to judge whether the polygon Bunko-34 has reached a constant speed.

EXPEND indicates the end of exposure.

BFEXP indicates that a print command has been accepted, but exposure for printing has not yet started.

1.2.3 DPIAC indicates acceptance of print density command and print density content, O indicates not accepted.
indicates that a print density command with a request to switch (change) print density 1, 2, or 3 has been received.

TIM O~14. TMMEO~E2. TIMSO~S
L, TIMNX indicates an internal timer that determines the on/off timing of each element during printing.

4. Enjoy t1~. tEo~tE2. tso〜ts1゜tN
X is a timer value, the details of which are shown in the column of Figure 18. [O] will time out immediately when this value is set as a timer.

Figure 1112 shows the main flow of control. When the power is turned on, first the RAM 206 and the interface 201a are loaded.

Initial settings of input/output ports 207, 209, timer 213, start counter (C70) 257, and end counter (C70) 25111 are performed.
A clock 312 with a period determined by the cell value is output from the timer 213, and a start counter (C7
0) 257 and the end counter (C70) 258 are 1L° while counting the clock input from the outside.
maintain the state of Furthermore, the flag and internal timer are cleared (step Nl).

Next, initial startup control (step N2) is performed.

FIG. 13 is a flow showing the details. First, turn on the heater 229 of the fixing roller 15 in step N9.
), then read the value of the print density initial value setting switch 237 (step NIG).Since the switch 237 has two sets, it can take the following states: 0, 1, and 2.3, and each Print density 1, print density 1, print density 2
, print density 3, and in order to obtain the rotation speed of the polygon mirror 34 and the frequency of the basic clock that match each print density, the timer 213 and DPISELC are used.
Set an appropriate value to the T signal 3113 (step Ni1
．． N12. N15), Therefore, the initial setting switch 2 should be set to match the printing density that the user always uses.
37, the value of the initial setting switch 237 is read in step N2 when the power is turned on, and the printing density is initialized in accordance with this value. Note that the print density is subsequently changed by a command from the data control unit 300 as described later (steps N27 to N35), tel, tc2.
tc3 is a value set in the timer 213, and is the period of a synchronization pulse that synchronizes the rotation speed of the polygon mirror 34 at a printing density of 1.2.3.

By the way, the heater 229 and the polygon mirror 34 are
It is not possible to become ready for printing (hereinafter referred to as READY state) immediately; in other words, the heater 229 requires a transition time to reach the set temperature, and the polygon mirror 34 requires a transition time to reach a constant speed. be.

Therefore, in step N14, it is determined whether the heater 229 and the polygon mirror 34 are both in the READY state, and if YES, the status is set to READY @1''.
(Step N15).

When the initial startup control (step N2) is completed, that is, R
When the EADY state is reached, the main loop is entered. In the main loop, status transmission and reception control is first performed (step N
3), here the data control unit 300 shown in Table 2
The status of the laser printer l is read and the status of the laser printer l is sent out.

Next, command control is performed (step N4), in which processing at the time of receiving or transmitting each command shown in Table 1 is performed.

FIG. 14 is a flowchart showing details of command control. Steps N16 to N27 of these represent processing when a print command is received. When a print command is received (step N16), is there an error? (step N17)
, or the PRRJT flag indicating whether the print command cannot be accepted is determined (Step N18). If the printer is not in an error state and is in the acceptable state, the print command is accepted. If the print command is not accepted, send NAK to the data control unit 300 (step N27).If the print command is accepted (step N9), if the PRNT flag indicating the print status is 101, that is, if it is not in the print status, the NAK is sent to the data control unit 300 (step N27). Step N
20), and further TIMEI, Tr! Clear LE2 (step N21), while the PRNT flag is “1”.
If @, set to in 71M5, step N2
0), further clear TIMEO (step N2
5) Printing is activated by either step N20 or N22. When printing is started, PR
The RJT flag is set to 1 to prohibit acceptance of print commands (step N24), and the BFEXP flag indicating that exposure has not yet started is set to 1 (step N25).

An ACK is transmitted to the data control unit 300 (step N2B).

Next, steps N28 to N35 show processing when a print density command is received.

When the print density command is received (step N28), it is determined whether an error other than a recoverable error such as vapor empty or toner empty is occurring (step N29). If an error is occurring, the data control unit 30
Send NAK to 0 (step N35), accept the command if there is no error, and send NAK to 1 according to the print density request.
, 2.3 to the DPIA flag in step N.
31. N32. N33), A to the data control unit 300
CK is transmitted (step N34).

Next, steps N36 to N3B show processing when sending an exposure end command. If the EXPEND flag indicating the end of exposure is 61" (step N36), an n light end command is sent to the data control unit 300 (step N37),
Then clear the EXPEND flag (step N3
8) The data control unit 300 uses this command to prepare for sending the next print data.

When the command control (step N4) is completed, the process moves to sequence control (step N5).

FIG. 15 is a flow showing details of sequence control.

Here, the on/off flow of each element during printing is controlled by connecting internal timers in a chain. The start of this control is command control (step N4)
This is done by accepting a print command at the TI.
It is activated by setting the timer value to to MO or 71M5. The detailed timing is shown in the time chart of FIG.

In the command system m (step N4), to TIMO
When is set, the time-up immediately occurs in step N39, and thereafter the on/off timing of each element as shown in FIG. When to is set in step N51, a time-up immediately occurs, and then N517! Steps N39 to N504 are the start-up operation for starting the actual printing operation, which controls steps from 1 to N101. Main motor 224, eraser 8 turned on, charging charger 3 turned on, developing bias of developer 4 227 on and followed by LDON on the other hand
When the signal is turned on and the LDB IAS signal is turned on, LD31
is forced.

emits light, thereby sending scanning light 39 to the beam detector 38.
light enters, and a series of controls within the print data write control circuit 217 starts. The LDON signal is turned off after a period of time sufficient to initiate the control.

The PRNT flag indicating the print status becomes 1'' immediately when TMMO times up (step N39).

This becomes "V" at the time when the series of printing operations ends (step N96).

Steps N51 to N55 are paper feeding control. After the leading edge of the fed paper passes PSL (steps N56 and N57), exposure is started after a certain period of time (step N58). However, if the polygon mirror 34 is not at a constant speed, that is, the PCYCH flag is "l". ”, the exposure is not started and a check is repeated to see if the PCYCH flag becomes 'O' (step N59), the polygon mirror 34 becomes constant speed, and the PCYCH flag becomes 1.
If it becomes 0'', start counter (CT 2) 257
, and set a timer value according to the print density and paper size to the end counter (CT3) 258, and turn on the 5TART signal 3114 to start exposure (Step N60). This starts exposure, so BFEXP
Set the flag to 10''.

Therefore, for example, if the rotation speed of the polygon mirror is changed in response to a request to change the print density before exposure, the exposure will be stopped until it is determined that the polygon mirror has reached a constant speed after the change in rotation speed. , exposure is performed as soon as the polygon mirror reaches a constant speed.

5TAR at the end of exposure (steps N67 to N70)
EXPEN turns off the T signal 3114 and indicates the end of exposure
Set the D flag to 11.

Steps N64 to N66 and N71 to N72 are controls related to the registration roller 14, and the timing (after exposure and when transfer to paper is performed at a predetermined position) is performed.
Here, it is turned on at time t111 (Uk) and turned off when the paper finishes encountering the registration rollers 14.

Steps N72 to N86 are controls related to AIDC. After the tfi time has elapsed after the end of exposure, first, a count value for determining the starting position of the AIDC mark in the main scanning direction is set in the start counter (CTC) 257 (step NT3), and then the AIDC signal is immediately turned on (step NT4). t1! After the time elapses, it is turned off (step 87B). As a result, a mark is formed at the position in the main scanning direction determined by the print data write 1#IrB circuit 217 during the time t2. This mark is formed at a position where the density reading 119 can be read based on the count value, but in order to determine the starting position in the main scanning direction, the start counter ( C70) 257, and no dedicated counter or timer for this mark is used. Further mark formation t & t +a
After the elapse of time (this is the time when the exposed mark is developed and just reaches the density reading section 129), the density detection tB D223 is turned on (step N81).
, determine the density of the mark (step N82), and if the density is below a certain value, turn on the solenoid 222 for toner replenishment (step N83)
, turns off after L+4 hours (steps N8B, N87
>.

Steps N88 to N889 perform control to determine the timing for accepting the next print command.

In this embodiment, after TNX has elapsed after the start of exposure, the PRRJT flag that prohibits reception of print commands is cleared at that time.

Steps N9G to N94 are for controlling the timing of turning on the transfer charging mode -5, and are turned on only when the paper passes through the transfer charging mode -5. This is because if the mark for AIDC is on when it passes the transfer charger 5, there is a risk that the toner will separate from the photoreceptor 2 and pollute the inside of the machine.

Steps N95 to N102 are controls for stopping the printing operation when the printing operation is completed and there is no next print request. When sequence v4gA (step N5) is completed, image forming unit control rB (step N6) is completed.
)to go into.

FIG. 16 is a flowchart showing details of image forming section control.

Here, matting is performed on image-related portions such as the polygon mirror 34 or the LD 31.

Steps N103 to N10B determine the timing to actually change the print density in response to the reception of the print density command. In other words, even if a print density command is accepted, if the print density command is before the start of exposure for the previously accepted print command, the DPIRQ flag indicating a change request is not set (steps 8103 to 8106. However, if exposure is in progress (START signal O
(N time), the request to change the print density based on the DPIRQ flag is not accepted (step N107, 810B).Therefore, the actual start of the print density change operation is
This is the time when all print exposures based on print commands received before the time when the print density command related to the change was received have been completed.

When a request to change the printing density is accepted, interrupts of 5SCANOUT are prohibited (step N109), and an appropriate timer value tel is set to the timer 213 in order to obtain the rotation speed of the polygon mirror 34 and the frequency of the basic clock according to the requested printing density. DPISEL for setting tc2 or tc3 and selecting an appropriate oscillator clock
Send ECT signal (steps N110 to N113)
.

After that, the DPIRQ flag is cleared and the FLYCH flag, which indicates that the polygon mirror 34 is not at a constant speed, is set to "1".
(Step N114), while the PLYCH flag is ``1'' (Step N115), it is determined whether the polygon mirror 34 has reached a constant speed or not.Step N116
), when the speed becomes constant, the FLYCH flag is cleared and the interrupt prohibition of the 5SCANOUT signal is canceled.

Here, the reason why interrupts are prohibited while the polygon mirror 34 is not at a constant speed is because the frequency of the polygon mirror 34 and the basic clock are not matched during this period, so even though there is no abnormality, the interrupt of the 5ScANOUT signal is prohibited. This is because there is a possibility that there will be interference.

Figure 17 is a flowchart showing the processing at the time of an interrupt of the 5SCANOUT signal.When a 0 interrupt occurs, further interrupts are prohibited (step N119), the power to the LDIlih is turned off (step N12G), and the LD31 is prevented from emitting light. Make it.

When the image forming unit control (step N6) is completed, error control (step N7) is performed. Here, errors such as paper empty, toner empty, jam, eraser lamp burnout, or high voltage unit failure are detected.

Finally, in step N8, display control, temperature control 11II
I11 Perform other controls related to print control such as paper size detection, and then return to step N3 again.
This is repeated below.

In the above embodiment, a presettable down counter is used as a timer means, and the timer function is achieved by inputting pulses of a fixed period to this, but other counters and timers may also be used. often,
In short, it is sufficient that substantially two types of time setting, one for the image area and one for the mark, or on the hour hand side are performed.

(Effects of the Invention) According to the present invention, a request to change the pixel density from the host combinator side can be made at any timing regardless of the state of the printer device, as long as the request to change the pixel density is sent before the print request for the desired print is sent. Can be sent. Therefore, a request to change the pixel density from the host combinator side is a print request for the amount to be printed using the pixel density before the change (that is, the current one), and a print request for the amount to be printed using the pixel density after the change. It is only necessary to send the signals between requests, and the creation or processing of these signals can be done very naturally and easily.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a front sectional view of a laser printer, FIG. 2 is a perspective view schematically showing the optical system of the laser printer, and FIG. System block diagram when using Iz-Saflinter - Figure 4 is a diagram showing the configuration of the signal line of the interface 201, Figure 5 is a circuit showing an example of the print data writing circuit of the print control printing section 1111m of the laser printer Figures 9 to 11 (a)) (C) are time charts showing the status and timing of each signal, Figures 12 to 17 are flow charts showing the control details of the laser printer, and Figure 18 is a flow chart showing the control details of the laser printer. A time chart showing the operation timing of each part of the laser printer, Figure 19 shows the image area on the photoreceptor and the AI
FIG. 3 is a developed view for explaining the position of a DC mark. 1... Laser printer (printer device), 2... Photoreceptor, 38... Beam detector (detection sensor), 39.
...Scan light, 200...Print control section, 21? −
...Print data writing control circuit. ! 82 flash @ 3E No. 41!1 Fig. 14 C Fig. 14 C Filling 15 Group h No. f51! lc Figure 17 Figure 19 Procedural Dispute Manual (Method) % Formula % 2. Name of the invention Printer device 3. Person making the amendment Relationship to the case Applicant address: 2-30 Azuchi-cho, Higashi-ku, Osaka-shi, Osaka Prefecture Osaka Kokusai Building Name: Minolta Camera Co., Ltd. 4. Agent (i=-:: iη21g) 6. Subject to correction

Claims (1)

[Claims] A printer device that forms an image using a large number of pixels on a photoreceptor using scanning light, the printer device comprising means for receiving a print request, means for receiving a request to change pixel density, and means for changing pixel density. 1. A printer device characterized in that the pixel density is not changed until the exposure of the print request is completed before the time when the image density change request is received.