JPH044160A - Image recording device - Google Patents

Abstract

PURPOSE:To make it possible to change an image density by providing a device to add the number of image sheets inhibited by an image density change inhibition device when the formation of an image for each sheet is started by an image formation part and a device to subtract the number of image sheets inhibited. CONSTITUTION:An image density state designated by an argument in the first byte is compared with a current image density setting state after selecting the former from between two byte data fetch from a receiving buffer. Then if both coincide with each other, an image density change inhibition counter is incremented(+1) and a fetch address pointer is incremented)+2) to allow the program to return to a main routine. On the other hand, if both do not coincide, the image density change inhibition counter interprets whether the count is 0, and if the count is not 0, the program is permitted to return to a main routine. If the count is 0, the counter interprets whether the image density is represented by an 82 hex code. If the 82 hex code is true, an image density switching signal is set to a low level 'L', and if the code is of 81 hex, the signal is set to a high level 'H' and the image density change inhibition counter is incremented(+1).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to image recording devices such as various printers and digital copying machines that are used as computer terminals and can change image density (recording density).

[Conventional technology]

In an image recording device such as a laser printer, the image density (recording density) is changed according to an external image density change instruction.
Some devices are equipped with image density switching means for switching the image density.

However, if the image density is switched during image formation in such an image recording device, the rotation speed of the polygon mirror will change and the image will become distorted, so switching the image density is not recommended. When this is done, it is done after the image forming operation has been completed, resulting in a significant reduction in throughput.

In order to solve this problem, for example, as shown in Japanese Patent Application Laid-Open No. 1-285349, a recording density (image density) switching command is detected during image formation or during reception of a recording start command from an external source. An image recording apparatus has been proposed in which the recording density switching command is sometimes held, and the recording density switching control is performed in accordance with the held recording density switching command after image formation is completed and when a recording start command is not being received. There is.

However, as shown in FIG. 8, an image forming apparatus 1, such as a laser printer, equipped with such a function requires data (print start commands and image density information) from a host system (external device) 60 such as a computer or word processor. It is equipped with a control unit composed of an image information processing device 161 that processes commands such as change commands, character data, etc., and a sequence controller 62 that drives each image forming process device to print characters, etc. on paper. but,
A plurality of signals output from the image information processing device 61 are sent to the sequence controller 62 through independent signal lines.
Therefore, there is a possibility that the sequence controller 62 may switch to an incorrect image density due to the time difference between the detection processing of the image density switching signal DP ISEL and the print start signal PRINT.

In other words, if the print start signal becomes active after the image density switching signal changes, printing must be started after changing the image density, but depending on the sequence in which each signal is detected, one image Printing may start before the temperature is changed.

For example, in the case of the signal detection sequence shown in FIGS. 9(a) to 9(c), the section A that passes when transitioning from the DPI (image density) signal check to the print start signal check shown in FIG. , the image density switching signal DPISEL and the print start signal PRINT change as shown in the area surrounded by the broken line A in FIG. 10(A).

A completely different case is also possible. In the section B that is passed when returning from the print start signal check to the main routine shown in FIG. 9(a), the image density switching signal DP I
SEL and print start signal PRINT are shown in Figure 10 (
An example of this is the case where the change occurs as shown in the part surrounded by the broken line B in b).

Also, during image recording, processing such as print commands and image density change commands related to the next print is not performed.
If each signal is generated or changed during this time,
The order in which the signals occur (change) becomes unclear.

Therefore, in the past, image density change commands and print start commands were issued by the external device such as the host system that outputs them.
It was made to occur or change at a certain time with a certain amount of time difference.

[Problem to be solved by the invention]

However, as described above, managing the generation timing of each command on the external device side increases the burden on the external device, resulting in a decrease in processing speed.

Particularly in the case of an external device that creates image writing data, it takes time to create the data, so the increase in the burden of timing management as described above has a large impact on printing speed.

In addition to such a reduction in printing speed, there is also the problem that there is a large possibility of making a mistake in changing the image density.

This invention has been made in view of the above points, and it solves the above problems and makes it possible to change the image density at any timing without making a mistake without reducing the printing speed, thereby improving the image quality. The purpose is to stabilize the situation.

[Means for Solving the Problems] In order to achieve the above object, the present invention has an image forming section A that can change the image resolution by one, and an external device as shown in the functional block diagram in Figure 1. an instruction holding means B for storing and holding various instructions including an image density change instruction and an image formation start instruction in the order in which they occur; an instruction reading means C for reading out the instructions held in the means in the order in which they are stored; Image formation start instruction means instructs the image forming section A to start image formation for each sheet based on the issued image formation start command; In an image recording apparatus having an image density change instructing means E for instructing the forming section A to change the image density, an image density change inhibiting means F for prohibiting the image density change instructing means E from changing the image density while there is a prohibited number of sheets. and 1. Prohibited sheet number adding means G which adds the prohibited number of sheets of image density change prohibition means F when the image forming section A starts forming an image for each sheet, and image density changing when the image forming section A finishes forming an image for each sheet. A prohibited number of sheets subtracting means H for subtracting the number of sheets prohibited by the prohibiting means F is provided.

[For production]

According to the image recording apparatus configured in this way, each time the image forming section A starts forming one image, the prohibited number of sheets adding means G adds the number of sheets prohibited by the image density change prohibiting means F, and 1 Prohibited number of sheets subtraction means H every time image formation of one sheet is completed
subtracts the prohibited number of sheets, so during one image formation, the number of prohibited sheets of the image density change prohibition means F is always one or more, and the image density change instruction means E is prohibited from changing the image density, and image formation is stopped. When finished, it is released and the image density can be changed.

Therefore, no matter what time an image density change command and an image formation start command are issued from an external device, the image density will not be changed during image formation or an error in changing the image density will not occur.

〔Example〕

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 2 is a schematic diagram showing the mechanism of a laser printer according to an embodiment of the present invention.

This laser printer is equipped with two removable paper feed cassettes 1゜2, upper and lower, each of which can store multiple sheets of paper at the same time, with a first paper output tray 3 at the top and a second paper output tray 4 at the rear. There is.

Normally, the first output tray 3 is selected among the two output trays 3 and 4, but in special cases, such as when using paper that tends to curl, such as envelopes or postcards, the second output tray is selected. 4 is selected. Note that the paper output to these two paper output trays is as follows:
Switching is possible using a switching claw 5.

Further, inside this laser printer, a photosensitive drum 6, a charger 7, a laser writing unit 8, and a laser writing unit 8, which constitute the image forming section of the printer engine, are installed. Developing unit 9. Transfer charger 10. Fuser 11゜Cleaning unit 12
and two paper feed rollers 13 and 14 and registration roller 1.
5, etc., a conveyor belt 16, and a paper ejection roller 1.
7 and a paper ejecting conveyance section 18 consisting of a paper guide plate.

Note that boards for an image processing controller and a sequence controller, which will be described later, are also installed inside this laser printer.

FIG. 3 is a perspective view showing the configuration of the laser writing unit 8.

In the figure, a light beam emitted from a semiconductor laser 22 is collimated by a collimating lens 23 and shaped by an aperture 24 in which a slit is formed.

The parallel light beam shaped by the aperture 24 passes through the lens 25 and is focused onto the polygon mirror 26, is deflected and scanned by the rotation of the polygon mirror 26, and is further
The laser beam LB passing through the θ lens 27 is reflected by one reflection mirror 28. A spot image of a predetermined beam diameter is formed on the photoreceptor tram 6 via the cylindrical lens 29 .

Note that 30 is a synchronization detection sensor such as a phototransistor, which detects the laser beam LB just before scanning on the photoreceptor drum 6 by making it incident thereon via a mirror 31 and a lens 32 .

FIG. 4 is a block circuit diagram showing the configuration of the control section of this laser printer.

The control section of this laser printer includes an image processing controller 40. Sequence controller 41. and a polygon motor control circuit 42.

The image processing controller 40 is a computer.

Image data sent from a host system 60 such as a word processor is converted into laser modulation data WDATA, a paper feed selection command, a paper ejection selection command, a paper feed start command, etc., which will be described later. The sequence controller 41 sequentially sends various commands including each command at a predetermined timing through a serial communication path.
At the same time, one page of laser modulation data W
DATA is also sequentially sent to the sequence controller 41 at predetermined timings.

It also inputs instruction signals from the operation panel 44 and performs corresponding processing, and outputs various display data such as data indicating the status of this printer to the operation panel 44.

The sequence controller 41 includes a sequence control microcomputer 45, and a 240DPI clock generation circuit 4.
6,300DPI clock generation circuit 47. Optical write signal generation circuit 48. and an inverter 49, etc., and controls the printing operation according to each command from the image processing controller 40.

The microcomputer 45 for sequence control.

It is a microcomputer consisting of a CPU, ROM, RAM, IIJ counter, 10, etc., and sequentially processes each command sent through a serial communication path.Of this processing, the processing related to this invention will be described later. Explain in detail.

The 240DP I clock generation circuit 46 receives the image density switching signal D from the sequence control microcomputer 45.
Input PISEL as is, and the signal is high level i.
Generates a clock signal for 240DPI at the time of “iH”,
It is output to the optical write signal generation circuit 48 as an image clock signal.

The 300DPI clock generation circuit 46 inputs a signal obtained by inverting the image density switching signal DPI SEL by an inverter 49, and when the signal is at a high level "H", the 300DPI clock generation circuit 46
Generates a clock signal for DPI.

The optical write signal generation circuit 48 is connected to the image processing controller 40
The laser modulation data WDATA sent from the controller is synchronized with the image clock signal and output as a video signal VIDEO.

The polygon motor control circuit 42 includes an oscillation circuit 50° splitter 51. and a polygon motor drive circuit (hereinafter simply referred to as "drive circuit") 52, and the frequency divider 51 is connected to an oscillation circuit 50.
The frequency signal is divided according to the image density switching signal DPISEL, and one of two types of reference clock signals corresponding to 240 DPI or 300 DPI is output.

The drive circuit 52 drives a polygon motor 53 that rotates the polygon mirror 26 shown in FIG. 3 at a rotation speed according to the reference clock signal from the frequency divider 51.

Further, when the polygon motor 53 reaches the normal rotation speed corresponding to the reference clock signal, this drive circuit 52 sends a signal PMLOK indicating this to the sequence control microcomputer 4.
Output to 5. Microcomputer 45 for sequence control
detects that the image density switching is completed by the signal PMLOK.

Next, commands according to the present invention sent from the image processing controller 40 to the sequence control microcomputer 45 will be explained.

The print start command includes a paper feed start command and a print start command.

The print start command is used for image formation (charging, exposure).

This is an instruction to start development, transfer, fixing), and AS
CII code 'VT' has been assigned.

The paper feed start command starts feeding paper from the selected paper feed cassette and starts feeding the paper from the registration roller 15 (shown in FIG. 2).
It instructs transport to the image leading edge synchronization mechanism), and is assigned the ASCII coat 'P'.

The paper feed selection command is for paper feed cassette (paper feed path) 1.2.
ASCII code l I+ is assigned.

The paper discharge selection command instructs the selection of one of the paper discharge trays (paper discharge paths) 3 and 4, and is assigned the ASCII code 'o'.

The paper feed start command and each other selection command each consist of 2 bytes, the first byte indicates the selection content (hereinafter referred to as "argument"), and its most significant bit (MSB) is re 1 u. It has become.

The second byte indicates the type of instruction (hereinafter referred to as "operand"), and its most significant bit (MSB) is "0".
ASCII code numbers 40hex to 5Ahex can be defined.

Here, the sequence control microcomputer 45 is 1,
When a paper feed selection command or paper ejection selection command is received from the image processing controller 40, the receiver sends the most significant bit of the received argument to LL OI in response.
Returns the + value.

However, this is a case where the command and argument instructions are appropriate and valid. If a command or argument is undefined,
A code indicating refusal to accept the command is returned.

Furthermore, when receiving the FF command, the paper ID number is returned as a reception response. This ID number is counted up after being returned.

The configurations of the above-described paper feed selection command, paper discharge selection command, and paper feed start command are shown below.

1) Paper feed route specification command operand: ASCI I 'I' (49
hex) Argument: 81hex Overprint paper selection 82hex Underprint paper selection 2) Paper ejection route specification command operand: ASCII '0' (4Fhex
) Argument: 81hex Top paper selection 82hex Top paper selection 3) Paper feeding start command operand 2 ASCII 'P' (50h
ex) Argument: 81hex 240DPI selection 82hex 300DPI selection Next, the operation of this embodiment configured as described above will be specifically explained with reference to the flowcharts shown in FIG. 5 and subsequent figures.

FIG. 5 is a flowchart showing command reception processing by the sequence control microcomputer 45.

This routine is executed by the sequence control microcomputer 4.
5 is data (command) from the image processing controller 40
When it receives, it exits from the main routine and starts.
First, in step 1, it is determined whether the received data is an 8Qhex undropped code, and if it is not an 80hex undropped code, that is, if it is a code (argument) of 80hex or more, then in step 2, the argument reception flag (A
GFLAG) is set.

If the argument reception flag is not set (AGFLAG=○), the received data, that is, the argument, is transferred to the argument register (A
GREG), set the argument reception flag in step 4, and then return to the main routine.

Further, if the argument reception flag is set in step 2 (AGFLAG=1), an error code is returned to the image processing controller 40 in step 5, and after the argument reception flag is reset in step 6, the process returns to the main routine.

On the other hand, if the received data in step 1 is 80 hex and undropped coat, the received data is 40 hex in step 7.
~Determine whether the code is 5Ahex or not, and send 40 hex
If the code is -5Ahex, it is determined in step 8 whether or not the argument reception flag is set.

If the argument reception flag is set, the data (
Argument) is extracted and stored in the reception buffer, and in step 10, the data received following that data (coats of 40hex to 5Ahex, ie, operands) are also stored in the reception buffer.

After that, in step 11, the command reception counter CINP
UT is incremented (+1), a command acceptance code is sent to the image processing controller 40 in step 12, and the argument reception flag is reset in step 6, after which the process returns to the main routine.

In step 8, if the argument reception flag is not set, the process proceeds to step 5, where an error code is returned to the image processing controller 40, and after the argument reception flag is reset in step 6, the process returns to the main routine.

On the other hand, in step 7, the received data is 40hex to 5Ahe.
In the case of a code other than Process.

Note that the address for storing data (1 byte) in the reception buffer is R in the sequence control microcomputer 45.
It is indicated by a storage address pointer IN_PTR secured in a pointer area provided on AM.

The value in this storage address pointer IN_PTR is incremented by ``rl'' by the sequence control microcomputer 45 every time data is stored in the reception buffer, thereby making it possible to indicate the next storage address.

Furthermore, the sequence control microcomputer 45 performs not only command reception processing but also execution processing of commands stored in the reception buffer. Indicated by PTR.

The value of this extraction address pointer UT_PTR is incremented by I'1j by the sequence control microcomputer 45 every time data is extracted from the reception buffer, thereby making it possible to indicate the next extraction address.

FIG. 6 is a flowchart showing command execution processing by the sequence control microcomputer 45.

This routine starts when called by the main routine, first determines whether the receive buffer is empty, and then
If it is empty, it simply returns to the main routine, and if it is not empty, it extracts 1 byte of data from it and then determines whether it is an argument or not.

If it is not an argument, it is left as is; if it is an argument, it extracts one more byte of data from the reception buffer, then determines whether that data is a paper feed start command (2 bytes), and if it is a paper feed start command, the data is After processing the paper start command (details are shown in Figure 7),
Decrement the command reception counter CINPUT (
-1) and return to the main routine.

If the data retrieved from the reception buffer is not a paper feed start command but a print start command (1 byte), the print start command is processed, that is, the image write permission counter and the extraction address pointer ○UT PTR are sequentially incremented (+1)L. , and further command reception counter CI
Decrement (-1) NPUT and return to the main routine.

In the case of a paper feed selection command (2 bytes), the paper feed selection command processing, that is, the most significant bit (N
SB) to If Q If and paper feed selection register IN
In addition to setting SEL, the extraction address pointer ○
Increment the UT PTR (+2) L, and then decrement the command reception counter C and INPUT (
-1) and return to the main routine.

In the case of the paper ejection selection command (2 bytes), the paper ejection selection command processing, that is, the most significant bit (N
SB) to (r OIf) and output selection register○UT
In addition to setting SEL, the extraction address pointer ○
Increments (+2) the UT PTR and decrements (-) the command reception counter CINPUT.
1) and return to the main routine.

FIG. 7 is a flowchart showing a subroutine for processing the paper feed start command shown in FIG.

First, among the 2 bytes of data taken out from the reception buffer, the image density specification (CREGI) by the argument of the 1st byte and the current image density constant state (CURD)
PI) to determine whether they match or not, and if they match, the image density change prohibition counter is incremented (
+1) to start the paper feeding operation, then the take-out address pointer OUT_PTR is incremented (+2) and the process returns to the main routine.

On the other hand, if the above image density specification and the current image density setting state do not match, then the image density change prohibition counter is set to r.
It is determined whether or not it is QJ, and if it is not rQJ, it returns to the main routine as it is, and if it is "0", then the image density (C
REGI) is an 82hex code (a code for selecting 300DPI).

If the code is 82hex, the image density switching signal DP I SEL shown in FIG.
)-"L," and if it is not an 82hex code, that is, if it is an 81hex code, the image density switching signal DP
After setting I SEL to high level (high) II H11, increment the image density change prohibition counter (+
1) L, perform the above-mentioned processing thereafter.

In addition, the image density change prohibition counter is decremented (-1) if the count value is not "0" when writing of the image for one page is completed in the processing of another routine (not shown). It has become so.

Here, the printing operation of this laser printer will be briefly explained with reference to FIG.

The print sequence by the sequence control microcomputer 45 is performed at a predetermined timing based on the count value of the software counter.

When the paper feeding operation is started in the routine shown in FIG. 7, the paper feeding selection register IN of paper feeding trays 1 and 2 is
At a predetermined timing, paper is fed as a transfer member by either paper feed rollers 13 or 14 from the paper feed tray selected according to the data in SEL, and the paper is temporarily stopped when it hits the registration rollers 15.

On the other hand, if the photosensitive drum 6 rotates in the direction of the arrow and the count value of the image writing permission counter is not "○", the semiconductor laser 22 of the laser writing unit 8 shown in FIG. 3 emits light at a predetermined timing. After setting the light intensity of the laser beam, a laser beam modulated according to image data (video signal) by a laser writing unit 8 is applied to the surface charged by the charging charger 7 on the axis of the photoreceptor drum 6. It is irradiated and exposed while main scanning in the direction, and a latent image is formed on the surface.

Note that when this image writing is performed, the image writing permission counter is decremented (-1) L, and if the image density change prohibition counter is not "O" when the image writing for one page is completed, it is decremented. (-1).

Thereafter, the latent image formed on the photoreceptor drum 6 is developed with toner from the developing unit 9, and the registration roller 1
The transfer charger 6 transfers the image onto the paper fed to the image transfer section at a predetermined timing by the transfer charger 5.

Peel off the paper on which the image has been transferred from the photoreceptor drum 6,
After being conveyed to the fixing device 11 by the conveyor belt 16 and heated and fixed, the sheet output selection register OU of the sheet output trays 3 and 4 is
Depending on the state of the switching claw 43 that is set to eject paper to the paper ejection tray selected by the data in T SEL, the second paper ejection tray 4 or the paper ejection transport section 18
The paper is ejected to the first paper ejection tray via.

Although the embodiments in which the present invention is applied to a laser printer have been described above, the present invention can be widely applied to other optical printers such as LED printers and liquid crystal shutter printers, as well as image forming apparatuses such as digital copying machines and facsimile machines. It is applicable.

〔Effect of the invention〕

As explained above, according to the present invention, there is no need for the external device to manage the generation or transmission timing of image density change commands and image formation start, so the burden is reduced accordingly and image writing data can be created easily. etc., and the printing speed can be increased.

Furthermore, the image density can be reliably changed at any timing without mistakes.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing the basic configuration of an image recording apparatus according to the present invention, FIG. 2 is a schematic configuration diagram showing the mechanism of a laser printer according to an embodiment of the present invention, and FIG. FIG. 4 is a block circuit diagram showing the configuration of the control section of the laser printer shown in FIG. 2. FIGS. FIG. 8 is a block diagram explaining the conventional laser printer; FIG. 9 is a flow diagram of the signal detection sequence by the sequence controller; FIG. 10 is a flow diagram showing the changes in each signal. 5 is a timing chart showing a switching state of image density. 2. Paper feed cassette 3, 4 Paper output tray photoconductor tram
8. Laser writing unit semiconductor laser 26.
・Polygon mirror image processing controller Sequence controller Polygon motor control circuit Sequence control microcomputer 24 ODPI clock generation circuit 300DPI clock generation circuit ・Optical write signal generation circuit 50 ・Oscillation circuit frequency divider 5
2...Polygon motor movement circuit/polygon motor
60...Host system 1. 40.. 41.. 45. 46. 47.. 51.. Figure 2 Figure 3 Figure 4 Mark

Claims (1)

[Scope of Claims] 1. An image forming unit capable of changing image density, and a command holding unit that stores and holds various commands including an image density change command and an image formation start command from an external device in the order in which they occur; command reading means for reading out commands held in the means in the order in which they are stored; and image formation start for instructing the image forming section to start forming images for each sheet based on the image formation start command read by the means. An image recording apparatus comprising: an instruction means; and an image density change instruction means for instructing the image forming section to change the image density based on the image density change command read by the command reading means. an image density change prohibition means for prohibiting the change of image density by the instruction means while the prohibited number of sheets is present; and a prohibited number of sheets for adding the prohibited number of sheets set by the image density change prohibition means when the image forming section starts forming an image for each sheet. An image recording apparatus comprising: an adding means; and a prohibited number of sheets subtracting means for subtracting the number of sheets prohibited by the image density change prohibiting means when the image forming section finishes forming an image for each sheet.