JPH04354465A - Picture forming device - Google Patents

Abstract

PURPOSE:To transfer a picture signal from a scanner 1 to a printer 2 at a high speed without increasing number of data lines. CONSTITUTION:A scanner 1 transfers a read picture signal to a scanner I/F control circuit 103 of a printer 2 via an interface line S by using a synchronizing clock signal (VCLK signal). The scanner I/F control circuit 103 uses one of two line buffers 130, 131 provided therein to store the picture signal. Then a horizontal synchronizing signal generating section 105 uses a switching signal synchronously with the horizontal synchronizing signal generated for each scanning line to select the other of two line buffers 130, 131 one of which has received the input of the picture signal and the scanner I/F control circuit 103 outputs a picture signal of the line buffer stored before the changeover.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, such as a digital copying machine, in which a scanner and a printer are separated.

0002

[Prior Art] In data transfer such as image signals between the scanner and the printer in a digital copying machine where the scanner and printer are separated, in a conventional slow printer or a printer with a small number of recording gradations, the image signal A clock signal was supplied from the printer side, and the scanner transferred the image signal in accordance with the clock signal. Depending on the image signal, slow printers print directly, and printers with a small number of recording gradations further develop the image information into serial data and print.

0003

However, in recent years, high-speed printers with a high number of gradations and a large amount of data per pixel have been used, and in order to fully utilize this function using the conventional method, it is necessary to The problem was that it had to be increased.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming apparatus that can transfer an image signal from a reading means to an image forming means at high speed without increasing the number of data lines.

[0005]

[Means for Solving the Problems] The image forming apparatus of the present invention includes a reading means for reading an image, a first output means for outputting an image signal read by the reading means, and an output by the first output means. a first device comprising a clock signal generating means for generating a synchronous clock signal for transferring an image signal to be transferred; a second output means for outputting a clock signal generated by the clock signal generating means; the second device of
receiving means for receiving an image signal outputted from the first outputting means and transferred in synchronization with a clock signal supplied from the outputting means; and a storage means for storing the image signal received by the receiving means; For each predetermined scanning line, the first
processing means for storing in the storage means an image signal transferred in synchronization with a clock signal supplied from the second output means of the apparatus, and outputting the image signal stored in the storage means; and a second device comprising an image forming means for forming an image on the image carrier according to the image signal outputted by the processing means.

[0006]

[Operation] The present invention is a first device that reads an image by a reading means, generates a synchronous clock signal for transmitting the read image signal, and reads the image by the reading means in synchronization with this synchronous clock signal. The second device receives the transferred image signal in synchronization with the synchronized clock signal, stores the received image signal in the storage means for each predetermined scanning line, and stores the received image signal in the storage means for each predetermined scanning line. The processing means outputs an image signal, and the image forming means forms an image on the image carrier in accordance with the output image signal.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 and 4 show an image forming apparatus of the present invention,
A scanner 1 as a reading means that outputs image information of each color read from a color original, and a printer as an image forming means that forms a color image based on the image information of each color supplied from the scanner 1. 2 and
It consists of an interface line S interposed between a scanner 1 and a printer 2. FIG. 2 shows the configuration of the scanner 1.

That is, on the top surface of the scanner 1, there is a document mounting table (platen glass) made of transparent glass.
3 is fixed. For example, A3
It is possible to place originals G up to this size. Further, on the upper surface of the scanner 1, a document cover 4 that can cover the document G on the document table 3 is rotatably provided.

The scanner 1 includes a first carriage 5, an exposure lamp 6 in the first carriage 5, a first mirror 7, a second carriage 8, and a second carriage 5 as a document scanning section below the document table 3. 8, a second mirror 9, a third mirror 10, an optical system (light focusing lens) 11, and a line sensor 12 are provided.

The original G placed on the original placing table 3 by an operator or the like is moved between the first carriage 5 and the second carriage 8.
is exposed and scanned by moving along the lower surface of the document table 3. In this case, the second carriage 8 moves at half the speed of the first carriage 5 so as to keep the optical path length constant.

The light reflected from the original G by the scanning of the optical system, that is, the light reflected from the original G by the light irradiation of the exposure lamp 6 is reflected by the first mirror 7, the second mirror 9, and the third mirror 1.
After being reflected by 0, the optical system (light focusing lens) 1
1 and is received by the line sensor 12.

The line sensor 12 detects the original G by photoelectrically converting reflected light or transmitted light from the original G.
It outputs the image as an electrical signal, for example CC
It is mainly composed of a D-type line image sensor.

A shading correction plate 13 is also provided for shading correction. This is performed at startup before the start of the reading operation. First, a black shading operation is performed with the exposure lamp 6 turned off, and then the first carriage 5
When the position is below , the exposure lamp 6 is turned on, the shading correction plate 13 is read, and white shading is executed. After this shading correction is completed, the original G on the original placing table 3 is read. FIG. 3 shows the configuration of the printer 2. As shown in FIG.

That is, the printer 2 sequentially transmits image information of each color supplied from the scanner 1 to a laser beam 21.
The photoreceptor drum 23, which has been charged in advance, is irradiated with the light through the mirrors, lenses, etc. of the exposure optical system 22, thereby forming an electrostatic latent image. The photoreceptor drum 23 has an organic photoreceptor coated on its surface, and is rotated by a pulse motor 24 in the direction of arrow E. The photosensitive drum 23 is
By adsorbing the first color toner from the developing device 25A, the electrostatic latent image formed by the laser beam 21 is visualized to form a toner image.

A transfer drum 26 as a rotating body is provided below the photosensitive drum 23 and is connected to the photosensitive drum 23, and is configured to rotate in the direction of arrow F. This transfer drum 26 is provided with a flat portion 26a, and a gripper 28 as a support member is provided on this flat portion 26a. This gripper 28 is
The transfer paper (image forming medium) P stored in the paper feed cassette 29 is sandwiched, and the sandwiched transfer paper P is attached to the outer peripheral surface of the transfer drum 26. In addition, this transfer drum 2
A vertical synchronization signal generating section 26b that detects the position of the transfer drum 26 and generates a vertical synchronization signal is provided near the transfer drum 6.

The photosensitive drum 23 and the transfer drum 26 are located at a point 3 at a portion other than the flat portion 26a of the transfer drum 26.
Rotate facing each other while maintaining contact at the 0C position,
The first color toner image formed on the photosensitive drum 23 is transferred onto the transfer paper P. When the transfer of the first color to the transfer paper P is completed, the transfer drum 26 is rotated so that the flat portion 26a of the transfer drum 26 faces the position 30C of the photosensitive drum 23, and they are separated from the contact state.

As a result, the transfer paper P on the transfer drum 26
The initial position is opposite to the photoreceptor drum 23 at the point 30C. Further, while rotating the photosensitive drum 23 in the E direction, it is similarly set to a position where transfer can be resumed when the initial position reaches the point 30C. In this way, the second, third, and fourth color toner images are sequentially transferred onto the transfer paper P. When the transfer is completed, the transfer paper P is peeled off from the transfer drum 26 and sent to a fixing device 31, where it is fixed and discharged onto a collection tray 32.

The exposure optical system 22 is provided at the top of the printer 2, and includes a high-speed rotation motor 33, a polyhedral rotating mirror 34, and an fθ
Lens 35, reflective mirrors 36, 37, aspherical lens 38
, and a protective glass 39. A laser beam 21 according to image information oscillated from a semiconductor laser oscillator (not shown) is input to the exposure optical system 22 after being shaped by a beam shaping optical system (not shown) comprising, for example, a collimator lens. be done.

Further, the laser beam 21 is transmitted to a drive controller 41 adjacent to the exposure optical system 22 in the upper part of the printer 2.
The beam is deflected by a polyhedral rotating mirror 34 that is rotationally driven by a high-speed rotating motor 33 using an air bearing that is drive-controlled. Then, the deflected laser beam 21 passes through the fθ lens 35, is reflected by the mirror 36 and the mirror 37, passes through the aspherical lens 38 and the protective glass 39, and passes through the exposure position 30A on the photoreceptor drum 23.
A spot image is formed at the required resolution and scanned and exposed.

Around the photosensitive drum 23, a charger 43 is arranged along the rotational direction E to charge the drum surface.
, a developing device support 44 equipped with developing devices for each color, a transfer drum 26 that rotates with transfer paper P attached to the drum surface, a cleaner 45, and an erasing and discharging lamp 46 are provided. The photosensitive drum 23 is rotationally driven by a pulse motor 24, which will be described later, and the drum surface is charged by a charger 43 having a grid electrode 47 and provided facing the drum surface.

A spot image of the laser beam 21 is formed at the exposure position 30A on the drum surface of the charged photosensitive drum 23 via the aspherical lens 38 and the protective glass 39.
As a result, the electrostatic charge is removed in response to the laser beam 21, thereby forming an electrostatic latent image. When the photosensitive drum 23 on which the electrostatic latent image is formed is rotated at an outer circumferential speed V in the direction of arrow E to the developing position 30B, it comes into contact with the developing device 25A of the developing device support 44 and is released from the developing sleeve 49A. Yellow toner is supplied to the photoreceptor drum 23 and adsorbed.

A cylindrical developing device support 44 housing the developing device 25A includes a developing device 2 having a developing sleeve 49B storing magenta toner in addition to the developing device 25A.
5B, a developing device 25C having a developing sleeve 49C containing cyan toner, and a developing device 25D having a developing sleeve 49D containing black toner are provided adjacent to each other. This developing device support 44 is connected to the center shaft 5.
The developing units 25A to 25D are rotated in the direction of the arrow H by a mechanism (not shown) around the center of the photosensitive drum 23, and each time the transfer of each color to the transfer paper P attached to the transfer drum 26 is completed, the developing units 25A to 25D are rotated in the direction of the arrow H by a mechanism (not shown). It is moved to the development position 30B.

For example, the toner image formed with the first yellow toner is transferred to the transfer position 30 of the photosensitive drum 23.
The image is transferred to the transfer paper P attached to the transfer drum 26 at point C, but between the end of the transfer and the start of the second color transfer, the developer support 44 moves in the direction of arrow H. It rotates and moves the second color magenta developing device 30B to the developing position 30B of the photosensitive drum 23.

The photosensitive drum 23, on which a toner image is formed by adsorbing toner of one color in the developing device 25B, continues to rotate, and the photosensitive drum 23 is transferred to the transfer drum 2 at the transfer position 30C.
The toner image is transferred to the transfer paper P attached to the paper 6. After the transfer at the transfer position 30C, the photosensitive drum 23 moves in the direction of arrow E.
The photoreceptor drum 23 continues to rotate further in the direction, and the photoreceptor drum 23 is
The residual toner adhering to the surface of the photosensitive drum 23 is removed, and the residual potential on the surface of the photoreceptor drum 23 is further removed by the erasing and neutralizing lamp 46.

The rotating shaft of the photosensitive drum 23 is connected to the photosensitive drum 23 through a pulley 51 that is connected to the drive shaft of the pulse motor 24 and a timing belt 52. The signal is transmitted to the pulley 53 which is connected to the pulley 53.

The transfer drum 26 is configured such that the rotational force from the pulse motor 24 is transmitted to a pulley 56 to which a rotating shaft of the transfer drum 26 is connected via a timing belt or a gear (not shown). There is. Further, in addition to the photoreceptor drum 23, a paper feed roller 57, a corona charger 58 for removing electricity from the transfer paper, and a movable guide plate 59 are arranged around the transfer drum 26.

When the transfer paper P stored in the paper feed cassette 29 is fed one by one by the rotational drive of the paper feed roller 57, the gripper 28 provided on the flat part 26a of the transfer drum 26 grips the transfer paper P stored in the paper feed cassette 29 one by one. Hold the tip of P. Subsequently, by applying a bias voltage to the transfer drum 26, the transfer paper P is attached to the transfer drum 26. The transfer drum 26 to which the transfer paper P is attached rotates in the direction of arrow F at the same speed as the photosensitive drum 23.

Then, at the transfer position 30C, the leading edge position of the toner image on the photosensitive drum 23 and the leading edge position of the transfer paper P match, so that the toner image formed on the photosensitive drum 23 is transferred to the transfer drum. The image is transferred to the transfer paper P on 26. Then, the toner image formed on the photosensitive drum 23 for the next image information is also transferred to the transfer paper P on the transfer drum 26. Thereafter, it operates in the same manner as above. This series of operations is repeated until full-color transfer, in which four colors are superimposed and transferred, is completed.

When the transfer of toner images of all colors is completed, a movable guide plate 59 whose one end is rotatably supported and whose other end is movable toward and away from the surface of the transfer drum 26 moves toward the surface of the transfer drum 26. For example, from a position (59a) several cm away from 5
By being moved in the direction 9b, it comes into contact with the transfer drum 26.

As a result, the transfer paper P adhering to the transfer drum 26 is peeled off by the movable guide plate 59 and guided to the fixing device 31 provided near the movable guide plate 59.
The toner is conveyed between a heat roller 60 and a pressure roller 61 in the fixing device 31 . The conveyed transfer paper P has a toner image heated and fixed onto the transfer paper P by a heat roller 60 and a pressure roller 61, and then is further conveyed by paper discharge rollers 62 and 63 and discharged onto a collection tray 32.

FIG. 1 schematically shows the overall control system of the scanner 1 and printer 2. That is, the CPU 70 as a control unit that controls the entire scanner 1 has a program ROM 72 via an internal bus 71, a RAM 73 in which various data are stored, a lamp regulator 74 that adjusts the light amount of the exposure lamp 6, and the 1. A motor control circuit 76 that rotationally controls the carriage motor 75 that moves the second carriages 5 and 8, a read signal control circuit 77 that controls the read signal (image information) supplied from the line sensor 12, and a read signal control circuit. a color signal processing circuit 78 that performs image processing on the read signal (image information) supplied from 77; a printer I/F control circuit that outputs the image information processed by the color signal processing circuit 78 as a read result to the printer 2; 79, an operation panel 80 for inputting various instructions such as erasing binding margins and document size, or displaying various states; various sensors 81; and an interrupt signal for generating an interrupt signal in response to interface signals of the printer 2, etc. They are respectively connected to a generating section 82 and a horizontal synchronizing signal supply section 83 that supplies an internal or external horizontal synchronizing signal.

The CPU 90 as a control unit that controls the entire printer 2 also has a program ROM 92 via an internal bus 91, a RAM 93 in which various data are stored,
A paper feed motor 94 that rotationally drives the paper feed roller 57, a first motor control circuit 95 that rotationally controls the paper feed motor 94 and the pulse motors 24, 27, and a developer switching motor 9.
6, a second motor control circuit 99 that controls the rotation of the fuser motor 97 and the cleaner motor 98, a third motor control circuit 101 that controls the rotation of the high-speed rotation motor 33 and the wire cleaning motor 100, the developer 25A, ~25
A high-voltage power supply 102 that applies a developing bias to D, a charging charger 43, a transfer bias to the transfer drum 26, a scanner I/F control circuit 103 that inputs an image signal from the scanner 1, a laser diode 104, and a horizontal synchronization signal generator. a laser drive control circuit 106 that controls 105;
and are connected to various sensors 107, respectively. Next, the transfer state of the interface signal on the interface line S between the scanner 1 and the printer 2 will be explained using FIG. 4.

In FIG. 4, a power-on signal (POWR signal) is a signal indicating that the printer 2 is powered on. The print ready signal (READY signal) is a signal indicating that the printer 2 is in a print ready state. The initialization signal (PRIM signal) is a signal used when the scanner 1 wants to initialize the printer 2. The image formation request signal (PREPR signal) is a signal for causing the printer 2 to perform a print standby operation and prepare to start a print operation at any time, and is sent from the scanner 1 to the printer 2 via the standby signal line Sg.

[0035] Print request signal (PREQ signal;
The image signal output request signal) is a request signal for a print operation from the printer 2, and is sent from the printer 2 to the scanner 1 via the request signal line Sh. This is the print signal (PR) that the printer 2 sends to the scanner 1.
This signal indicates that the INT signal can be received. In other words, this indicates that the printer 2 is in a state where it can immediately start a printing operation upon receiving the PRINT signal from the scanner 1. PRINT like this
The signal is sent from the scanner 1 to the printer 2 via the print signal line S.
Emitted via i.

Command/Status Data Line (CSDT)
line; second transmission means) Sa is the scanner 1 and printer 2
This is a bidirectional data line used for communicating (transferring) command data or status data between serial data.

The clock signal (CSCK signal) is a signal used for transmitting and receiving the command data and status data, and is transmitted from the scanner 1 to the printer 2 via the clock signal line (first transmitting means) Sb.

The busy signal (PBSY signal; processing information) is a signal indicating that the printer 2 has received command data from the scanner 1 and is performing an operation corresponding to the command data. (transmission means) Sd from the printer 2 to the scanner 1. The printer 2 performs an operation corresponding to the command data from the scanner 1, and turns off the busy signal when it is ready to respond with the corresponding status data.

The discrimination signal (STAT signal; identification data) is a signal emitted from the scanner 1 to distinguish whether the CSDT line is transmitting command data or receiving status data. 3 transmission means)
Sc is sent from the scanner 1 to the printer 2.

The vertical synchronization signal (VSYN signal) is a signal for synchronizing the printing operations of the scanner 1 and the printer 2, and is emitted from the printer 2. Similarly, the horizontal synchronization signal (HS
YN signal) is also a signal for synchronizing the printing operations of the scanner 1 and the printer 2. Page printing operation end signal (PG
The END signal) is a signal for notifying the scanner 1 that the printing operation for one page has been completed.

The transmission start signal (VDEN signal) is a signal emitted from the scanner 1 when the signal for transmitting image information from the scanner 1 is started in response to the vertical synchronization signal from the printer 2. During transfer, it remains on, indicating that input is in progress. Then, it is reset to off by the PGEND signal from the printer 2.

The data lines (VDAT7-0) are data lines for transferring image information from the scanner 1 to the printer 2, and are transmitted from the scanner 1 to the printer 2 via the data line Se.

The synchronous clock signal (VCLK signal) is a synchronous signal for transferring image information, and is sent from the scanner 1 to the printer 2 via the synchronous clock signal line Sf.

Next, the operation of the above configuration will be described with reference to timing charts of the interface signal printing operation by the scanner 1 and printer 2 shown in FIGS. 5(a) to 5(m).

First, when power is turned on to the scanner 1 and the printer 2, a warming-up operation is started, and communication of command data and status data is started. What is communicated at this time is the size of the transfer paper P, the total number of copies used by the developer of each developing device (25A, 25B, 25C, 25D), the total number of copies used by the photoreceptor drum 23, and the total number of copies used by the fixing device 31. This is information about consumables such as the number of copies used, the total number of copies used in the main body of the machine, or information inside the machine of the printer 2. Based on this information, the printer 2 is also displayed on the operation panel 80 of the scanner 1.
Information about can be displayed.

When the warm-up of the printer 2 is completed and the printer 2 becomes ready for printing, the READY
The signal is turned on and the printer 2 notifies the scanner 1.

In this state, when the copy start button on the operation panel 80 of the scanner 1 is pressed and communication of command data and status data between the scanner 1 and the printer 2 is started, the process shown in FIG. 5(f) occurs. Like PREP
The R signal turns on. When the printer 2 determines that the PREPR signal is on, it rotates the developer holder 44 according to the pre-designated color designation, and prints Y (yellow), M
(magenta), C (cyan), K (black)
Three developing devices (25A, 25B, 25C, 25D) are set so as to be in contact with the photoreceptor drum 23, and a pulse motor 24 and a polyhedral rotating mirror 34 rotate the photoreceptor drum 23, which rotates in conjunction with the transfer drum 26. a high-speed rotation motor 33 that rotationally drives the cleaner motor 9 of the cleaner 45;
8 and the fixing device motor 97 of the fixing device 31 and the charger 43 are turned on to perform standby for printing operation.

[0048] The printer 2 is on standby for printing operation,
When the high-speed rotation motor 33 of the polygonal rotating mirror 34 reaches a constant speed, the laser diode controlled by the laser drive control circuit 106 is turned on, and the light beam causes the horizontal synchronization signal generation optical beam sensor 105 to move as shown in FIG. ) generates the horizontal synchronization signal (HSYN signal) shown in
Start sending signals to scanner 1. This HSYN signal is used by both the printer 2 and the scanner 1, and is very important for commonizing horizontal synchronization. Also, this H
The SYN signal continues to be sent while the PREPR signal is on.

Unless this HSYN signal is supplied from the printer 2 to the scanner 1, the printer 2 and scanner 1 cannot be synchronized. Therefore, scanner 1 is P
After turning on the REPR signal, the H shown in FIG. 5(c)
The status of the printer 2 is checked to see if the SYN signal is being output.

After this standby operation is completed, the printer 2 sends a PREQ signal to the scanner 1 when the transfer drum 26 reaches a predetermined position (not shown). The transfer drum 26 rotates in conjunction with the photoreceptor drum 23, and is configured such that it cannot be stopped. Furthermore, the transfer drum 26 is provided with a gripper 28 that grips the transfer paper P, and the position at which the transfer paper P is gripped is determined in advance. Therefore, the transfer paper P
The transfer drum 26 determines not only the timing at which paper feeding starts but also all timings related to printing. Therefore, the position of the transfer drum 26 is constantly monitored by the vertical synchronization signal generating section 26b, and the paper feeding start timing, printing start timing, and peeling claw timing are determined based on the output thereof.

Now, when a PRINT signal is sent from the scanner 1 in response to this PREQ signal, the printer 2 rotates the paper feed roller 57 and grips the transfer paper P between the gripper 28 attached to the transfer drum 26. wear. continue,
When the transfer drum 26 comes to a predetermined synchronization position with the scanner 1, the printer 2 performs a process (see FIG. 5) with respect to the scanner 1.
Send the VSYN signal shown in d). Since this VSYN signal requires time for the carriage motor 75 of the scanner 1 to start up, it is output earlier than the start of actual image information transfer.

Upon receiving the VSYN signal, the scanner 1 moves the first carriage 5 to perform a black shading operation, and then, when the first carriage 5 comes under the shading correction plate 13, the exposure lamp 6 is turned on. , reads the shading correction plate 13 and executes white shading. Thereafter, the scanner 1 performs exposure scanning on the original G on the original platen 3 to read image information, processes the read image information, and outputs the data to the printer 2 together with the VDEN signal shown in FIG. 5(j).

The printer 2 checks the VDEN signal before and after the rise of the VSYN signal, and detects the VDE within a specified time.
Check whether the N signal has been sent. This is also confirmed by the scanner 1 at the same time, and is used to check whether synchronization has been achieved successfully. If synchronization cannot be achieved, after the printing operation is completed and the transfer paper P is discharged outside, the operator is informed of the malfunction of the machine without starting the next printing operation.

The printer 2 modulates the laser beam 21 according to the image information sent from the scanner 1, forms a latent image on the photosensitive drum 23, and uses a developing device (25A) of a designated color.
, 25B, 25C, and 25D), and the image is transferred to the transfer paper P on the transfer drum 26.

When the printing operation is completed with only a single color, the transfer paper P is peeled off by a peeling claw at the peeling position and sent to the fixing device 31. However, when printing is performed in the next color, such as in color, it is designed not to peel off. In this way, when the transfer of image information for one page is completed, the PGEND signal shown in FIG. 5(e) is sent from the printer 2 to the scanner 1.
The image transfer is completed and the VDE
The N signal is also reset. Further, the scanner 1 returns the first carriage 5 and the second carriage 8 to the reading start position to prepare for the next scan.

The printer 2 rotates the developer holder 44 upon completion of printing, and removes the developer (25) to be used for the next development.
A, 25B, 25C, 25D) is set on the photosensitive drum 23. Next, when the transfer drum 26 comes to a predetermined synchronization position with the scanner 1, the printer 2 transmits a VSYN signal to the scanner 1. In this way, the printing sequence is repeated between the scanner 1 and the printer 2. The transfer paper P that has been printed a specified number of times is peeled off by a peeling claw, fixed by a fixing device 31, and then discharged to a paper discharge tray 32.

[0057] During this peeling process, if printing is to be performed on a second sheet subsequently, the PREPR signal sent from the scanner 1 to the printer 2 is kept on. This PREPR signal is an image formation request signal as described above, and is a signal for causing the printer 2 to perform a print standby operation. In this case, the PREPR signal is a signal for maintaining a state (standby) in which the printing operation can be started at any time. When the position of the transfer drum 26 reaches the paper feeding timing, the printer 2 turns on the PREQ signal shown in FIG. 5(b) to the scanner 1, and starts the next printing sequence. In this way, the scanner 1 continues to turn on the PREPR signal to the printer 2 as long as there is a continuous printing operation.

Furthermore, even if the scanner 1 cannot output the PRINT signal shown in FIG. PRI for PREQ signal
If the NT signal can be output, PR to printer 2.
Keep the EPR signal on. This is because if the standby state is continuously requested, the printing operation can be performed quickly. In other words, once the termination sequence is entered, it takes a very long time to return to the standby state.

The operation of the timing chart in FIG. 5 describes the printing sequence for two sheets (two pages) of monochrome printing, but the same applies to multicolor printing as described above.

A horizontal synchronizing signal (HSYN signal) during normal copying operation in this embodiment is supplied from the printer 2 to the scanner 1. This is the polyhedral rotating mirror 3 of the printer 2.
This is because the HSYN signal is generated depending on the scanning position of the laser beam scanned by the rotation of 4, and the timing cannot be changed freely from the outside. Also, horizontal synchronization is necessary because a line buffer, which will be described later, is used to transfer image information between scanner 1 and printer 2, and the number of line buffers required is only two lines. This is because if the same clock is used to read and write image information, no errors will occur.

Next, image information is transferred in the image forming apparatus of this embodiment by two line buffers 130 and 131 provided in the printer 2, as shown in FIG. That is, for example, when the scanner 1 is writing data to the line buffer 130, the printer 2 reads data written one line before from the line buffer 131. line buffer 13
0,131 writing (memory)/reading switching is HSY
A switching signal is outputted by a signal switching unit (not shown) based on the N signal (horizontal synchronization signal), and this switching signal is input to the changeover switches 132 and 133 to perform the switching every time.

Conventionally, as shown in FIG. 7, a synchronous clock signal (VCL) for image transfer supplied from the printer 2
K signal), the printer 2 sends image information (VDAT7~
It would not have been necessary if it had been done by receiving a 0 signal). However, in this method, the scanner 1 receives the image information (VDA) shown in FIG. 8(b) in response to the synchronized clock signal (VCLK signal) shown in FIG.
T signal), there is a limit to the transfer speed.
The problem is that it is not suitable for high-speed data transfer.

On the other hand, as shown in FIG.
In the method of sending the synchronous clock signal (VCLK signal) for transfer with the DAT7-0 signal from the same direction, the method shown in Figure 10
As shown in (a), the clock signal (VCLK signal)
and image information (b) (both VDAT signals have almost the same delay, so even faster transfer is possible. However, in this case, the line buffers 130 and 131 are However, this is necessary for high-speed data transfer.

As explained above, according to the above embodiment,
It becomes possible to transfer image information from the scanner to the printer at high speed, and it is possible to support digital image forming apparatuses that are high-speed and have a large number of recording gradations.

[0065]

As described in detail above, according to the present invention, it is possible to provide an image forming apparatus that can transfer image signals from the reading means to the image forming means at high speed without increasing the number of data lines. .

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall schematic configuration of a scanner and a printer in an embodiment of the present invention.

FIG. 2 is a configuration diagram showing the configuration of a scanner.

FIG. 3 is a cross-sectional view schematically showing the internal structure of the printer.

FIG. 4 is a diagram for explaining the transfer state of interface signals between a scanner and a printer.

FIG. 5 is a timing chart showing the operation of each interface signal in an image transfer sequence.

FIG. 6 is a circuit diagram showing the configuration of a line buffer.

FIG. 7 is a diagram for explaining a conventional example regarding transfer of a VCLK signal and a VDATA signal.

FIG. 8 is a diagram for explaining a conventional example regarding transfer of a VCLK signal and a VDATA signal.

FIG. 9 is a diagram for explaining an embodiment regarding transfer of a VCLK signal and a VDATA signal.

FIG. 10 is a diagram for explaining an embodiment regarding transfer of a VCLK signal and a VDATA signal.

[Explanation of symbols]

1...Scanner, 2...Printer, 5...First carriage, 8
...Second carriage, 12...Sensor, 21...Laser light, 2
3... Photosensitive drum, 26... Transfer drum, 25A, 25B
, 25C, 25D...Developer, 31...Fixer, 70,90
...CPU, 76...Motor control circuit, 79...Printer I/
F control circuit, 82... Interrupt signal generation section, 83... Horizontal synchronization signal supply section, 103... Scanner interface control circuit, 130, 131... Line buffer, 132, 133
...Choice switch.

Claims (1)

[Claims] 1. A reading means for reading an image, a first output means for outputting an image signal read by the reading means, and a synchronous clock signal for transferring the image signal output by the first output means. a clock signal generating means for generating;
A first device comprising a second output means for outputting the clock signal generated by the clock signal generation means, and a clock signal that is transferred in synchronization with the clock signal supplied from the second output means of the first device. a receiving means for receiving an image signal outputted from the first outputting means; a storage means for storing the image signal received by the receiving means; A processing means for storing an image signal transferred in synchronization with a clock signal supplied from an output means in the storage means and outputting the image signal stored in the storage means; and a second device comprising an image forming means for forming an image on an image carrier in response to an image signal.