JPH07168106A - Image copying device - Google Patents

Abstract

PURPOSE:To provide an image copying device constituted so that the preliminary action of a leader part can be started regardless of a standby time required for stabilizing a printer part. CONSTITUTION:By a control part 121, a signal iHSYNC generated by a false synchronizing signal part 116 is selected by using a selector 117 and a main scanning synchronizing signal HSYNC synchronized with the signal iHSYNC is supplied to the respective constitution of the leader part 101 from a synchronous control part 120 while a BD ready signal BDRDY is '0'. When the signal BDRDY becomes '1' and the preliminary action of the leader part 101 is finished, a main scanning synchronizing signal PBD synchronized with an image forming process generated by the printer part 103 is selected by using the selector 117 and the main scanning synchronizing signal HSYNC synchronized with the signal PBD is supplied to the respective constitution of the leader part 101 from the control part 120 by the control part 121.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image copying apparatus, for example, a digital copying machine which switches a main scanning synchronizing signal between an image reading preliminary operation and subsequent operations.

[0002]

2. Description of the Related Art In a conventional digital copying machine, when a copy button is pressed, a document image is read by an image sensor in synchronism with a beam detection signal BD from a printer section, and the image signal of the read document is read by MCYK. It is sent to the latent image forming means in a frame sequential manner to form a latent image on one photoconductor. Further, the developing means for each MCYK color independently develops the latent image on the photoconductor in the MCYK frame-sequential manner, and sequentially transfers the toner image for each MCYK onto the recording paper held by the recording paper holding means to obtain a color image. Had formed.

The operation of such a conventional digital copying machine will be described. FIG. 1 is a block diagram showing the configuration of a conventional digital copying machine, and FIG. 2 is a timing chart showing the copy sequence. When a copy button provided on an operation unit (not shown) is pressed, the CPU unit (not shown) turns on a polygon mirror motor (not shown) provided in the laser scanning system of the printer unit, and the rotation of the polygon mirror 401 is stabilized. After waiting for a certain period of time, a laser blinking signal is sent to the laser driving unit 402 to scan the photosensitive drum 405 with a laser beam. When the laser beam scans the BD detection position, the BD detection sensor 404 causes the printer controller 4 to move.
The signal BD is sent to 15 and used as a main scanning synchronizing signal of the image signal.

The image processing section 414 of the reader section uses the signal BD as a main scanning synchronization signal to perform shading correction and white balance adjustment of the CCD image sensor 413 constituting the reading system, and then prescans the reading optical system. Then, the document detection operation is performed. When the preliminary operation of the reader unit is completed, the reader ready signal sent from the reader unit to the printer unit becomes "1".

While the reader section is performing the preliminary operation,
The printer unit conveys the recording paper to a predetermined position and makes it stand by, and performs optimization control of process conditions such as control of the surface position of the photosensitive drum 405. When the optimization control in the printer unit is completed and the reader ready signal is “1”, the printer unit starts feeding the recording paper. The reader unit starts scanning in the sub-scanning direction in synchronization with the paper leading edge signal ITOP from the paper leading edge detecting sensor 406 located on the recording paper conveyance path. Then, the original 411 placed on the original table glass 412 is scanned in the MCYK frame sequential manner.

The CCD image sensor 4 is synchronized with the signal BD.
The image of the document 411 is read by 13, and the image signal of the read document is subjected to predetermined processing by the image processing unit 414, and then the image signal subjected to the image processing is sent to the printer controller 415. The printer controller 415 PWM-modulates the input image signal and sends it to the laser drive unit 402, and the photosensitive drum 405 is irradiated with the PWM-modulated laser light.
Form a latent image on top. Further, the latent image on the photosensitive drum 405 is developed by MCYK independent developing units 407 to 410 in the surface sequence of MCYK, and the toner image for each MCYK is sequentially transferred onto the recording paper held on the transfer drum 418. A color image is formed.

The recording paper on which the color image is formed is separated and conveyed from the transfer drum 418, and the toner image is thermally fixed by the fixing device 416. When the discharge sensor 417 monitors the discharge of the recording paper, the copy operation ends. That is, in the above digital copying machine, the signal BD is used as a main scanning synchronization signal by both the printer unit and the reader unit after the laser beam scanning is started in the printer unit by pressing the copy button. Was there.

On the other hand, in recent years, since the price of the memory has become low, a memory having a sufficient storage capacity has become available, and when the copy button is pressed, the image signal from the image sensor is temporarily stored in the page memory, There is also an image forming apparatus that sends the image signal stored in the page memory to the printer unit to form a latent image on the photoconductor. Furthermore, the latent image formation and the photoconductor are performed corresponding to the four MCYK toner colors. Dyes and transfer drums are provided for each color independently, and a color image forming device aiming to greatly improve the copying speed by sequentially transferring the MCYK toner images onto the recording paper held by the belt-shaped recording paper holding means is also available. is there.

In such a color image forming apparatus, the MCYK image forming units are arranged in parallel and the four color toner images are sequentially transferred onto the recording paper conveyed by the recording and holding means. In this case, according to the arrangement of the image forming unit for each color,
The image forming timing in the sub-scanning direction is determined. For example, while the M image forming unit is forming an M image, the C image forming unit
The timing of image formation for each color may overlap, such as the start of image formation. Therefore, the image data for one page is stored in the page memory, the memory reading timing in the sub-scanning direction is determined according to the arrangement of the image forming portions for each color, and the memory reading timing in the main scanning direction is set to the signal BD for each color. Do it synchronously.

In the image forming apparatus having such a page memory, the image data is stored in the page memory irrespective of the preliminary operation of the printer unit such as the rotation of the polygon mirror motor and the optimization control of the process condition of the printer unit. There is an advantage that can be done.

[0011]

However, the above-mentioned conventional example has the following problems. That is, in the above-mentioned conventional example, when the signal BD is used as the main scanning synchronization signal in the reader unit, the signal BD is generated after a waiting time sufficient for the rotation of the polygon mirror motor to be stable and the amount of laser light after lighting to be stable. To be done. Such waiting time,
There is a problem that the start of preliminary operation of the reader unit such as shading correction and preliminary scanning is delayed.

In order to avoid this delay, there is a method of constantly scanning the laser beam to generate the signal BD, but since the lighting time of the laser element becomes long, there is a drawback that the deterioration of the laser element is accelerated. there were.

[0013]

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems, and has the following structure as one means for solving the above problems. That is, a reading unit that reads a document image and outputs image data, a forming unit that forms an image from the image data output by the reading unit, and a first synchronization signal that synchronizes with the image forming process of the forming unit. The reading means includes a first generating means for generating, a second generating means for generating a second synchronizing signal, and a judging means for judging the timing of the first synchronizing signal. It is characterized in that it synchronizes with the second synchronization signal until the normal timing is determined by the means, and when the normal timing is determined, it synchronizes with the first synchronization signal at a predetermined timing.

[0014]

According to the above construction, the operation of the reading means is the second operation until the judging means judges the normal timing.
It is possible to provide an image copying apparatus which is synchronized with the first synchronizing signal which is synchronized with the image forming process at a predetermined timing when the normal timing is determined.
The preliminary operation of the reading unit can be started regardless of the waiting time of the forming unit until the rotation of the polygon mirror motor is stabilized and the amount of laser light after lighting is stabilized. Also, for example,
In order to avoid this delay, it is not necessary to lengthen the laser element lighting time, and the deterioration of the laser element is not accelerated.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image copying apparatus according to an embodiment of the present invention will be described in detail below with reference to the drawings.

[0016]

[First Embodiment] FIG. 3 is a schematic view of an image copying apparatus according to a first embodiment of the present invention. This embodiment is roughly divided into a reader unit 101 and a printer unit 103, and the document feeder 102 is
This is a well-known optional device that automatically conveys a document to the document reading area of the reader unit 101.

[Structure of Reader Unit] FIG. 4 shows the reader unit 101.
3 is a block diagram showing a configuration example of FIG. In the figure, 12
Reference numeral 1 denotes a control unit, which is composed of a CPU, a RAM, a ROM, etc., and according to a program stored in the ROM, etc., controls each component shown in FIG. To do.

Reference numeral 100 denotes an image sensor composed of a CCD or the like, which converts read image information into an electric signal and outputs it. Reference numeral 101 denotes an A / D & S / H unit, which converts an analog RGB image signal input from the image sensor 100 into, for example, 8-bit digital RGB image signals. A / D & S / H section 101
The shading correction unit 102 corrects the light distribution distribution of the document illumination lamp to the digital image signal output from
The input masking unit 103 is RGB of the image sensor 100.
Perform filter characteristic correction. The digital image signal G output from the shading correction unit 102 is also sent to the document detection unit 114 to discriminate between the document image and the document pressure plate.

A scaling unit 104 processes the image signal input from the input masking unit 103 to enlarge or reduce the image. A logarithmic conversion unit 105 converts the image signal input from the scaling processing unit 104 from an RGB luminance signal to an MCY density signal. Reference numeral 106 denotes an output masking unit, and 107 denotes a lower color removal (UCR) unit, which removes the gray component of the MCY image signal input from the logarithmic conversion unit 105 and generates a K image signal of a black component.

A page memory 108 stores the MCYK image signal output from the UCR unit 107 for each color component. Details of the operation of the page memory 108 will be described later. A tone correction unit 109 performs various tone processes (γ correction, brightness, contrast, density conversion, etc.) on the image signal input from the page memory 108. An edge enhancement unit 110 subjects the image signal input from the gradation correction unit 109 to a process of increasing the density of the edge portion in order to clearly reproduce the edge portion of the image.

Reference numeral 111 denotes an image signal I / I with the printer unit 103.
It is F. In addition, the printer unit 103 and the reader unit 101 communicate with each other via a serial I / F (not shown). In addition, sub-scanning synchronization signals MVRE, CVRE, YVRE, K of each color
VRE, main scanning synchronization signals MBD, CBD, YBD, KBD of each color, a printer ready signal sent from the printer unit 103 to the reader unit 101, and a reader ready signal sent from the reader unit 101 to the printer unit 103 are a reader / printer not shown. I / F
Are being exchanged through.

Reference numeral 112 is a video selector, and 113 is an external I / F, which transmits the image signal output from the input masking unit 103 to an external device or outputs the image signal received from the external device to the logarithmic conversion circuit 105. Control the flow of the video signal. A pseudo sync signal unit 116 generates a pseudo main scanning sync signal iHSYNC which is not necessarily synchronized with the BD signal of the printer.

Reference numeral 118 denotes a selector which controls the control unit 12 to output any one of the M, C, Y and K signals BD sent from the printer unit 103.
It is selected by the instruction 1 and is output as the signal PBD.
A selector 117 is a signal iHSYNC generated by the pseudo synchronization signal unit 116 and a signal selectively output by the selector 118.
One of the PBDs is selected and output according to an instruction from the control unit 121.

Reference numeral 120 denotes a synchronization controller which generates an image clock CLK synchronized with either the signal PBD or iHSYNC selected by the selector 117 and supplies it to each block. Further, the memory read / write clock RWCLK having a frequency more than twice the image clock CLK is generated and supplied to the address counter 115 and the page memory 108, and the input signal PBD or iHSYNC is supplied by the image clock CLK. Waveform is shaped and output as signal HSYNC.
Further, the page memory 108 and the address counter 1
15 control signals are generated.

An address counter 115 generates a write address WR and a read address RD of the page memory 108 in synchronization with the clock RWCLK and the signal HSYNC according to the control signal of the page memory 108 sent from the synchronization controller 120. To do. [Page Memory] FIG. 5 is a block diagram showing a configuration example of the address counter 115, FIG. 6 is a block diagram showing a configuration example of the page memory 108, and FIG. 7 is a timing chart showing a main timing example. In the following description, only magenta color will be described for simplification of description.

In FIG. 6, 705 is a RAM, and 70
1 to 704 are first-in first-out memory FI
In the FO, when the signal HSYNC is "1", the write address counter (not shown) in the FIFO is cleared, and the synchronization control unit 120
Memory write enable signals MWE1 and MWE sent from
When 2 is '1', the write address counter counts up in synchronization with the image clock CLK. Similarly, the signal HSY
When NC is "1", the read address counter (not shown) in the FIFO is cleared, and when the memory read enable signals MRE1 and MRE2 sent from the synchronization control unit 120 are "1", the read address counter becomes the clock RWCLK. Count up synchronously.

The image signal MDI from the UCR unit 107 is sent to the FIFO 7
01 and 702, and are written in the FIFOs 701 and 702 in synchronization with the clock CLK in accordance with the sequentially increasing write address. As shown in FIG. 7, the signals MWE1 and MWE2 are alternately set to "1" for each line for the image width.
Is written to the FIFO 701 at W1 shown in FIG. 7, and then to the FIFO 702 at W2 of the next line.

The stored image signal is stored in the FIFO 7 in synchronization with the clock RWCLK in accordance with the read address which is sequentially increased.
01 and 702. As shown in Figure 7, the signal
MRE1 and MRE2 are alternately set to "1" for each line by the image width, and the image signal MDT is read from the FIFO 702 at R2 shown in FIG. 7 and then from the FIFO 701 at R1 of the next line.

In FIG. 5, signals MRE1, MRE2, MWE1 and
When all of MWE2 are "0", the output of the OR gate 605 becomes "0" and the main scanning address counter 604 is cleared. When the signal MRE1 or MRE2 is '1', OR
The output of the gate 605 becomes "1", and the main scanning address counter 604 starts the count-up operation in synchronization with the clock CLK from the clear state.

When the sub-scanning write enable signal VWE is "1", the sub-scanning write address counter 601 starts the count-up operation in synchronization with the signal HSYNC from the clear state. Similarly, the sub-scanning read enable signal VRE is "1".
At this time, the sub-scanning read address counter 602 starts the count-up operation in synchronization with the signal HSYNC from the clear state.

When the memory read enable signal MWE3 or MWE4 of the FIFO memories 703 and 704 of FIG. 6 is "1",
The output of the OR gate 606 in FIG. 5 becomes "1", and the selector 603 selects the count value of the sub-scanning read address counter 602 and outputs it as the address signal MAD.
When the signals MWE3 and MWE4 are both "0", the output of the OR gate 606 is "0", and the selector 603 selects the count value of the sub-scan write address counter 601, and the count value and the main scan. The count value of the address counter 604 is combined with the RAM as the address signal MAD.
It is sent to 705. That is, the main scanning address counter 6
The count value of 04 becomes the lower address of the RAM 705, and the count value selected by the selector 603 becomes the upper address of the RAM 705.

Now, the signal VWE is "1" and the signal MWE2 is "1".
When the signal MRE1 is '1', the OR gate 7
The 06 output becomes "1" and the RAM 705 is in the write mode.
Then, the image signal written in the FIFO memory 701 when MWE1 is "1" in the previous line is read in synchronization with the clock RWCLK at R1 shown in FIG. At this time, the signal MWE3, MW
Both E4 are “0”, and the selector 603 selects the count value of the sub-scanning write address counter 601 and
The image signal MDT read from the FO 701 is written in the RAM 705.

When the signal VRE indicating the start of image formation of the printer section 103 becomes "1" and the signal MWE4 becomes "1", the output of the OR gate 706 becomes "0" and the RAM 705 enters the read mode. At this time, the selector 603 selects the count value of the sub-scanning read address counter 602, and the upper address of the signal MAD is counted up for each line. In W4 shown in FIG. 7, the image signal MDT is read from the RAM 705 in synchronization with the clock RWCLK and written in the FIFO 704. The image signal written in the FIFO 704 is the next line.
When MRE4 is “1”, that is, at R4 shown in FIG. 7, it is read in synchronization with the image clock CLK and sent to the gradation correction unit 109 as an image signal MDO. At this time, if the signal VWE is "1", the image signal MDI is FIFO when the signal MWE1 is "1".
701 is written.

Therefore, after the copy button is pressed, the sub-scanning write enable signal VWE becomes '1' at a predetermined timing, the image reading operation is started, and the read image signal MD is read.
I is written alternately in FIFO 701 and 702, and one FIFO
Is in the write operation in synchronization with the image clock CLK, the other FIFO is in the read operation in synchronization with the high-speed clock RWCLK, and the read image signal MDI is in the RAM.
Written in 705. Then, when the printer unit 103 starts image formation, the sub-scanning read enable signal VRE becomes “1”, and the image signal MDI read from the RAM 705.
Are written alternately in the FIFOs 703 and 704 in synchronization with the clock RWCLK. When one FIFO is in the write state in synchronization with the clock RWCLK, the other FIFO is in the read operation state in synchronization with the low-speed image clock CLK. FIFO 7
The image signals alternately read from 03 and 704 are sent to the gradation control unit 109.

[Printer Unit] The printer unit 10 shown in FIG.
3, a polygon scanner 301 scans a laser beam output from a laser control unit (not shown) to expose a predetermined position of a photosensitive drum of image forming units 302 to 305, which will be described later. As shown in FIG. 8, the polygon scanner 3
01 is on the photosensitive drum of the image forming unit corresponding to each color,
Laser element 5 driven independently by MCYK by the laser controller
Scan the laser beam from 01-504. 505-
508 are beam detection sensors (hereinafter referred to as “BD sensor”)
That is, the scanned laser beam is detected to generate a main scanning synchronization signal.

As shown in FIG. 8, when two polygon mirrors are arranged on the same axis and are rotated by one motor, for example, the laser beams of M, C and Y, K are scanned in the main scanning direction. They are opposite each other. Therefore, normally, the image data of one of the M and C images and the other of the Y and K images is a mirror image in the main scanning direction. Again in FIG. 3, 302 is M
An image forming unit, a C image forming unit 303, a Y image forming unit 304, and a K image forming unit 305 form images of corresponding colors. Since the configurations of the image forming units 302 to 305 are substantially the same, the details of the M image forming unit 302 will be described below, and the description of the other image forming units will be omitted.

In the M image forming unit 302, 318 is a photosensitive drum, on which a latent image is formed by the laser beam from the polygon scanner 301. A primary charger 315 charges the surface of the photosensitive drum 318 to a predetermined potential to prepare for latent image formation. A developing device 313 develops the latent image on the photosensitive drum 318 to form a toner image. The developing device 313 includes a sleeve 314 for developing by applying a developing bias.

Reference numeral 319 denotes a transfer charger, which is the transfer belt 306.
Then, the toner image on the photosensitive drum 318 is transferred to a recording sheet or the like on the transfer belt 306. After the transfer, the surface of the photosensitive drum 318 is cleaned by the cleaner 317, the charge is removed by the auxiliary charging device 316, the residual charge is erased by the pre-exposure lamp 330, and the primary charging device 315 again performs good charging. Get it.

Next, a procedure for forming an image on a recording paper or the like will be described. Reference numeral 308 denotes a paper feeding unit, which is a cassette 309, 3
The recording paper stored in 10 is supplied to the transfer belt 306. The recording paper supplied from the paper supply unit 308 is charged by the adsorption charger 311. A transfer belt roller 312 rotates the transfer belt 306 and is paired with the suction charging device 311 to suction-charge the recording paper or the like.

Reference numeral 329 is a paper edge sensor, which is a transfer belt 30.
The leading edge of the recording paper on 6 is detected. Paper edge sensor 32
The detection signal 9 is sent from the printer unit 103 to the reader unit 101.
And is used by the reader unit 101 as a sub-scanning synchronization signal. After that, the recording paper or the like is conveyed by the transfer belt 306, and toner images are formed in the order of MCYK in the image forming units 302 to 305.

The recording paper or the like that has passed through the K image forming unit 305 is separated from the transfer belt 306 after being discharged by the discharging charger 324 in order to facilitate separation from the transfer belt 306. A peeling charger 325 prevents image disturbance due to peeling discharge when the recording paper or the like is separated from the transfer belt 306.

For the separated recording paper or the like, the pre-fixing charger 32 is provided in order to supplement the toner suction force and prevent image disturbance.
After being charged by 6, 327, the toner image is thermally fixed by the fixing device 307 and discharged. A paper discharge sensor 340 detects that the recording paper is discharged. On the other hand, the transfer belt 306 from which the recording paper and the like have been separated is destaticized by the transfer belt decharging chargers 322 and 323, is electrostatically initialized, and the dirt is removed by the belt cleaner 328. Preparations for adsorbing etc. are made.

[Switching of Main Scan Synchronization Signal] FIG. 9 is a timing chart showing an example of the copy sequence of this embodiment. In the same figure (b), when the copy button is pressed, the signal iHSYNC is immediately output regardless of the waiting time of the printer unit 103.
Using, the preparatory operation of the reader unit 101 and the document image data are stored in the page memory 108. However, even if the generation of the signal BD is started during shading correction or image data storage in the page memory 108, the signal iHSYNC
Signal iHSY because signal BD is not always synchronized.
NC cannot be switched to signal BD. Therefore, the signal iHSYNC is used as the main scanning synchronizing signal of the reader unit 101 until the image data is completely stored in the page memory 108, and the signal iHSYNC is switched to the signal BD when the image data is completely stored. According to this method, after the copy button is pressed, the preliminary operation of the reader unit 101 and the page memory 10 are performed.
It is possible to shorten the time until the start of storing the image data in # 8.

However, in the method of FIG. 7B, the signal iHSYNC is kept until the storage of the image data for the original size is completed.
Since it is not possible to switch to BD, printing cannot be started even if the printer unit 103 is in the ready state during data storage, that is, the printer ready signal becomes '1'. Next, in FIG. 9A, when the copy button is pressed, the printer unit 1
Pseudo main scanning synchronization signal regardless of the standby time in 03.
The preliminary operation of the reader unit 101 is started using iHSYNC.

The selector 117 shown in FIG. 4 selects the signal iHSYNC by a selection signal from a control unit (not shown),
Since the signal is output to the synchronization control unit 120, the clocks CLK, RWCLK and the signal HSYNC synchronized with the signal iHSYNC are generated. The reader unit 101 preliminarily scans the document reading optical system,
Preparatory operations such as document detection and shading correction are performed, and when the preliminary operations are completed, the reader ready signal becomes "1".

While the reader unit 101 is performing the above-described preliminary operation, the printer unit 103 conveys the recording paper to a predetermined position and puts it on standby, and also turns on the polygon mirror motor to a predetermined position until the rotation is stabilized. Wait time. After the rotation of the polygon mirror motor reaches a predetermined number of rotations, the laser is turned on by a laser driving unit (not shown), and a predetermined time is waited until the laser light amount is stabilized. And the signal BD
Is generated at regular timing, which will be described later.
It is determined by the BD ready circuit 820. When each color is provided with a laser beam independently, four BD ready circuits 820 need to be provided independently.

When the laser light amount or the polygon motor rotation speed reaches a predetermined value, the BD ready signal BDRDY output from the BD ready circuit for each color becomes "1", and the printer unit 103 controls the surface potential of the photosensitive drum 318. Start optimization control of process conditions. When the optimization control of the printer unit 103 is completed, the printer ready signal becomes "1". Also,
When the signal BDRDY becomes '1', the control unit 121 selects and selects one of the beam detection signals MBD, CBD, YBD, KBD sent from the printer unit 103 by the selector 118. The signal is sent to the selector 117 as the signal PBD.

Before the optimization control of the printer unit 103 is completed,
That is, even if the printer ready signal is "0", the reader unit 10
In No. 1, when the preparatory operations such as the shading correction and the prescan for detecting the original are not performed and the signal BDRDY is “1”, the control unit 121 causes the selector 117 to change the signal iHSYNC to the signal PBD. Switch. Therefore, the reader unit 101 and the printer unit 103 both receive signals.
The PBD will be used as the main scanning synchronization signal.

For example, as shown in FIG. 10A, the signal BDRD is generated during the shading correction of the reader unit 101.
When Y becomes '1', the main scan sync signal is sent after the shading correction and before the preliminary scan is started.
Switch to PBD. After that, the reader unit 101 performs a main scan of the document image and stores the image data of the document in the page memory 108. 10A and 10B are also timing charts showing an example of the copy sequence of the present embodiment, and FIGS. 10A and 10B correspond to FIGS. 9A and 9B, respectively. 10B shows a method of switching the main scanning synchronization signal before the image data is stored in the page memory 108 and FIG. 10B shows a method of switching the main scanning synchronization signal after the image data is stored in the page memory 108.

Even while the reader unit 101 is storing image data, the optimization control of the printer unit 103 is completed,
Both printer ready and reader ready signals are '1'
Then, the printer unit 103 supplies the recording paper onto the transfer belt 306 by the paper feeding unit 308. Transfer belt 30
The leading edge of the recording paper fed onto the paper 6 is the paper leading edge sensor 329.
The laser scanning section (not shown) of the printer section 103 sends the sub-scanning synchronization signals MVRE, CVRE, YVRE, and KVRE of the respective colors to the reader section 101 in synchronization with the signal ITOP indicating that the detection is performed in step S1. The reader unit 101 reads image data from the page memory 108 independently for each color of MCYK in synchronization with the sub-scanning synchronization signal and sends it to the printer unit 103.

The printer unit 103 causes a laser control unit (not shown) to blink the laser according to the image data of each color sent from the reader unit 101, and the latent image formation and the toner are formed by the image forming units 302 to 305 of MCYK. Develop. The toner images formed on the respective photosensitive drums are sequentially transferred onto the recording paper conveyed by the transfer belt 306, and thermally fixed by the fixing device 307 to form a color image. When the paper discharge sensor 340 detects the passage of the recording paper after fixing, the printer ready signal becomes "0", and the reader unit 101 is notified of the end of the copy operation. When the control unit 121 detects the fall of the sub-scanning synchronization signal KVRE, that is, the end of reading the K image data from the page memory 108, the reader ready signal from the reader unit 101 also becomes “0”.

In the case of the continuous copy operation, the image formation of the first sheet is performed while the image data is stored in the page memory 108 by the main scan, but the image formation of the second and subsequent sheets is stored in the page memory 108. This is done by reading the image data. Further, in the case of the continuous copy operation, the printer ready signal becomes “0” after the discharge of the last sheet of recording paper is detected by the paper discharge sensor 340, and the reader unit 101 is notified of the end of the copy operation. In addition, the control unit 1
When 21 detects the trailing edge of the sub-scanning synchronization signal KVRE for the final sheet, the reader ready signal from the reader unit 101 becomes "0".

As described above, the method shown in FIG. 9A is different from the method shown in FIG. 9B in which the main scan synchronizing signal is switched after waiting for the image data to be stored in the page memory 108. There is an advantage that the image forming start in the printer unit 103 can be advanced by the time T1 shown in the figure and the time required for the first copy output can be shortened. [BD ready circuit] In the following, for simplification of explanation, M
Only the color BD ready circuit 820 will be described.

FIG. 11 is a block diagram showing a configuration example of the BD ready circuit 820, and FIGS. 12 to 14 are timing charts for explaining the operation thereof. When the laser beam for forming the magenta image is detected, the BD sensor 505 outputs the signal MB.
D is set to "1", and the signal is sent to the BD ready circuit 820. The BD ready circuit 820 is a flip-flop F / F80.
1, 802 and the AND gate 803 detect the rising edge of the signal MBD and generate the signal BDEG. When the rising edge is detected, the signal BDEG becomes “1” during one cycle of the clock MPCLK of the printer unit 103 corresponding to M color.

When the signal BDEG is "1", for example, the 14-bit counter 804 and the F / F 809 are cleared, and then the counter 804 starts counting up the clock MPCLK. For example, one main scanning cycle is 400dpi and 8,000
Equivalent to pixels, the effective image area is a count value of 1 to 4,677
, The 0th pixel and the 4,678-8,000th pixel are non-image areas. Now, in consideration of variations in the signal BD obtained from each surface of the polygon mirror 301 due to uneven rotation of the polygon mirror motor and angular accuracy of the adjacent reflection surface of the polygon mirror 301, for example, an area of 8,000 ± 200 pixels is BD The detection period is valid.

That is, the control unit registers the register 807 in advance.
7,800 to the register 808 and to the register 808 to set 8,200 respectively, and the comparator 805 and 806 sets the counter 804.
And the value set in the register,
As shown in FIG. 12, the signal BD output from the F / F 809
Set GATE to '1' only between 7,800 and 8,200 pixels. Further, the signal BDGATE is sent to the AND gate 810 and the NOT gate 812, and the outputs of both gates are AND gate 81.
It is logically ANDed with the signal BDEG at 0 and 811. That is, the signal BD
During the BD detection period when GATE is '1', the BD ready signal MBDRDY is set to '1' when the rising edge of the signal MBD is detected, and when the rising edge of the signal MBD is detected outside the BD detection period. Signal MBDRDY is reset to '0'. Even if the rising edge of the signal MBD is not detected, the signal MBDRDY is reset to "0" when the counter 804 counts up to 8,200.

The number of revolutions of the polygon mirror motor and the amount of laser light have not yet reached the predetermined values, and the period at which the signal MBD is detected is
When it is longer than 8,200 pixels, or when the laser is not turned on at the detection position of the BD sensor 505, as shown in FIG. 12, the rising edge of the signal BD is not detected during the BD detection period, and the F / F 813 Output remains reset and signal M
BDRDY remains '0'. Then, when the number of revolutions of the polygon mirror motor and the amount of laser light reach a predetermined value,
As shown in, the rising edge of the signal MBD is detected during the BD detection period, the output of the F / F 813 is set, and the signal MBDRDY becomes "1".
Maintained at. Furthermore, even once, the signal is detected within the BD detection period.
When the rising edge of BD cannot be detected, the output of the F / F 813 is reset and the signal MBDRDY is reset to "0" as shown in FIG.

As described above, according to this embodiment,
During the preparation period of the printer unit, such as the time until the rotation of the polygon mirror motor stabilizes, the time until the amount of laser light after lighting turns on, the heat-up period of the fixing device, etc.
The reader unit does not need to be on standby, and preliminary operations of the reader unit such as shading correction and preliminary scanning can be executed during this period.

Further, since it is not necessary to lengthen the lighting time of the laser element, deterioration of the laser element is not accelerated.
In the above description, a digital color copying machine having four color independent image forming means has been described as an example. However, the present embodiment is not limited to this, and one image forming means sequentially forms MCYK toner images. It is needless to say that the present invention can be applied to an apparatus that transfers and forms a color image and an apparatus that forms an image with only a single color.

In the description of this embodiment, as shown in the timing chart of FIG. 9, the shading correction and the prescan are described as an example of the preparatory operation after the copy button is turned on. However, other preparatory operations may be included. I'm sorry. For example, home position search of the document reading optical system may be included.

[0061]

Second Embodiment It is also useful to apply the present invention to the preliminary operation of various external devices and units. Hereinafter, a digital color copying machine linked with the original feeder 102 will be described.
This will be described as an example. In FIG. 10, when the copy button is pressed, the printer unit 103 is activated as in the first embodiment.
Immediately without waiting for the waiting time at the signal iHSYNC
Is used to start the preliminary operation of the reader unit 101. That is, the selector 117 selects the signal iHSYNC, and the signal iHSY
Clocks CLK, RWCLK, and HSYNC synchronized with NC are generated, and preliminary operations such as shading correction, document feeding, and preliminary scanning are executed.

When the copy button is pressed, the control section 121 activates the document feeder 102 and the document is conveyed to a predetermined position. That is, when the feeder ready signal sent from the feeder control unit (not shown) of the document feeder 102 to the control unit 121 is “0”, the document feeder 10
2 is a standby state. When the control section 121 detects that the document feeder 102 is in the standby state and the copy button is pressed, the feeder control section 102.
The feed start signal sent to is set to "1" and the document feeder 102 is started. According to this, the document feeder 1
02 starts the handling of the document, and the feeder control unit sets the feeder ready signal to "1".

The originals stacked on the original feeder 102 are
When the feeding to the predetermined position in the document reading area of the reader unit 101 is completed, the feeder control unit sets the feeder ready signal to “0”. When the feeder ready signal changes from "1" to "0", the control unit 121 detects the end of the operation of the document feeder 102. When the preliminary operations such as shading correction and document feeding are completed, the reader ready signal becomes "1".

In this embodiment, when the copy button is pressed,
While the reader unit 101 is performing a series of preliminary operations, the printer unit 103 conveys the recording paper to a predetermined position and makes it stand by, performs polygon mirror motor and laser lighting control, and waits until each becomes stable. When the signal BD from the BD detection sensor 404 has a normal cycle, the BD ready signal BDRDY becomes “1”. The signal is sent to the reader unit 101 via a reader / printer I / F (not shown), and optimization control of process conditions is performed.

In the reader section 101, the printer section 1
One of the signals BD sent from 03 is the signal PBD
Is input to the selector 117. In the reader unit 101, at the time when any one of the preliminary operations such as the preliminary scan and the shading correction is completed, or during the operation of the external device such as the document feeder 102 which does not depend on the main scanning synchronization signal, the BD from the printer unit 103 is operated. If the ready signal BDRDY is “1”, the control unit 121 causes the sector 117 to switch the main scanning synchronization signal from the signal iHSYNC to the signal PBD.

When all the preliminary operations are completed, the main scan of the original reading system is performed, and the image data of the original is stored in the page memory 108. Therefore, as the main scanning synchronization signal, the signal PBD is used in both the reader unit 101 and the printer unit 103. When the optimization control in the printer section is completed, the printer ready signal becomes "1". Main scanning sync signal is signal P
Since the mode is switched to BD, when the optimization control of the printer unit 103 is completed, the printer unit 103 immediately determines the paper feeding unit even if the reader unit 101 is storing image data in the page memory 108 by the main scan. Recording paper is supplied onto the transfer belt 306 by 308, and formation of a color image is started. Hereinafter, a color image is formed by the same procedure as in the first embodiment.

As described above, according to this embodiment,
In addition to the same effects as those of the first embodiment, the document can be fed to the reader section during the preparation period of the printer section. It should be noted that during this preparation period, it is also possible to perform a preliminary operation of other external equipment, for example, a preliminary operation such as an autofocus operation that is required when the slide film projector is linked to a color copying machine. Good. Further, it may be a preliminary operation of a sorter connected to the printer unit.

[0068]

[Modifications] In each of the above-described embodiments, an example in which the main scan synchronization signal is switched according to the BD ready signal BDRDY indicating that the signal BD has become normal has been described, but the main scan is performed according to the printer ready signal. It is also possible to switch the synchronization signal. FIG. 15 is a timing chart showing the operation of the modified example of the present invention, which is an example in which the main scanning synchronization signal is switched according to the printer ready signal. 9A and 9B respectively correspond to FIGS. 9A and 9B. FIG. 15A shows before image data is stored in the page memory 108, and FIG. The method of switching the main scanning synchronization signal after the image data is stored in the page memory 108 is shown.

That is, when a predetermined waiting time elapses until the laser light amount or the polygon motor rotation speed reaches a predetermined value, the printer unit 103 starts optimization control of process conditions such as surface potential control of the photosensitive drum 318. When the optimization control of the printer unit 103 is completed, the printer ready signal becomes "1". Further, when the printer ready signal becomes “1”, the control unit 121 causes the selector 118 to
Selects one of the beam detection signals MBD, CBD, YBD, and KBD sent from the printer unit 103, and sends the selected signal to the selector 117 as the signal PBD. When a preliminary operation such as a shading correction or a preliminary scan for detecting an original is not performed, the control unit 121
The selector 117 switches the signal iHSYNC to the signal PBD. Therefore, the reader unit 101 and the printer unit 103 both use the signal PBD as the main scanning synchronization signal.

In this way, the main scan synchronizing signal cannot be switched until the printer ready signal becomes "1", that is, until the optimization control of the process conditions is completed, but the BD ready circuit becomes unnecessary. Cost can be reduced. The present invention may be applied to a system including a plurality of devices or an apparatus including a single device.

It goes without saying that the present invention can also be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0072]

As described above, according to the present invention, the operation of the reading means is synchronized with the second synchronizing signal until the determining means determines the normal timing, and the predetermined timing is determined when the normal timing is determined. It is possible to provide an image copying apparatus that is synchronized with a first synchronization signal that is synchronized with an image forming process at a timing,
For example, the preliminary operation of the reading unit can be started irrespective of the waiting time of the forming unit until the rotation of the polygon mirror motor is stable and the amount of laser light after lighting is stable. Further, for example, in order to avoid this delay, it is not necessary to lengthen the lighting time of the laser element, and deterioration of the laser element is not accelerated. Further, for example, even before the image data corresponding to the document size is stored, the main scanning synchronization signal is switched according to the operation of the reading unit and the determination result of the determination unit, so that the timing problem in the switching does not occur. The simple circuit configuration has the effect of shortening the time until the first copy output.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a conventional digital copying machine.

FIG. 2 is a timing chart showing a copy sequence of the copying machine shown in FIG.

FIG. 3 is a schematic view of an image copying apparatus according to an embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration example of a reader unit in FIG.

5 is a block diagram showing a configuration example of an address counter of FIG.

6 is a block diagram showing a configuration example of a page memory in FIG.

FIG. 7 is a timing chart showing a main timing example of the present embodiment.

FIG. 8 is a diagram illustrating a relationship between a polygon mirror and a scanning direction of a laser beam.

FIG. 9 is a timing chart showing an example of a copy sequence of this embodiment.

FIG. 10 is a timing chart showing an example of a copy sequence of this embodiment.

FIG. 11 is a block diagram showing a configuration example of a BD ready circuit of the present embodiment.

FIG. 12 is a timing chart illustrating the operation of the BD ready circuit in FIG.

FIG. 13 is a timing chart explaining the operation of the BD ready circuit in FIG. 11.

FIG. 14 is a timing chart illustrating the operation of the BD ready circuit in FIG.

FIG. 15 is a timing chart showing an operation of a modified example of the present invention.

[Explanation of symbols]

 100 image sensor 101 reader section 102 document feeder 103 printer section 108 page memory 115 address counter 116 pseudo sync signal section 117 selector 118 selector 120 sync control section 121 control section

Claims (4)

[Claims] 1. A reading unit that reads a document image and outputs image data, a forming unit that forms an image from the image data output by the reading unit, and a first unit that is synchronized with an image forming process of the forming unit. The operation of the reading unit includes a first generating unit that generates a synchronization signal, a second generating unit that generates a second synchronization signal, and a determination unit that determines the timing of the first synchronization signal. It is characterized in that it synchronizes with the second synchronization signal until the determination unit determines a normal timing, and synchronizes with the first synchronization signal at a predetermined timing when the normal timing is determined. Image copier. 2. A reading unit that reads a document image and outputs image data, a forming unit that forms an image from the image data output by the reading unit, and a first unit that is synchronized with an image forming process of the forming unit. It comprises a first generating means for generating a synchronizing signal and a second generating means for generating a second synchronizing signal, and the operation of the reading means is such that when the forming means is in a ready state, An image copying apparatus, wherein the image copying apparatus is synchronized with a synchronization signal, and is synchronized with the first synchronization signal at a predetermined timing when the preparation state ends. 3. The image copying apparatus according to claim 1, wherein the first synchronizing signal is a main scanning synchronizing signal. 4. The predetermined timing is set after completion of a preliminary operation executed by the reading means in synchronization with the synchronization signal.
The image copying apparatus according to claim 1 or 2, wherein the image forming image data is not read yet.