JP2001094712A - Image forming device using ieee 1394 image transfer and paper transport method for printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper transport method and an image forming device that can eliminate dispersion in the print start position of a printer and decrease the capacity of a reception buffer. SOLUTION: A scanner and the printer are connected via an IEEE 1394 interface. A printer paper transport means moves paper from a paper cassette to a position L of feeding rollers, feeds the paper from the position L of the feeding rollers to a paper start point M and starts transporting the paper from the paper start point M to a transfer position N on a photoreceptor drum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image transfer system and a paper feed system in an image forming apparatus in which a scanner for reading a document image or a page memory unit for holding image data is connected to a printer by IEEE1394.

[0002]

2. Description of the Related Art Conventionally, scanners and printers are IEEE1
When the copy function is realized by connecting at 394, the sub-scanning speed of the scanner and the sub-transport speed of the printer are the same, and the distance from the paper feed roller of the printer to the transfer position is the printing on the photosensitive drum by the laser of the printer. If the distance is longer than the distance from the position to the transfer position, the paper transport starts a fixed time after the transfer of the scan start command (hereinafter, simply referred to as a start command) from the printer to the scanner.
Further, the start of image data transfer and the start of paper conveyance are also predetermined.

Conventionally, when a page memory unit (hereinafter abbreviated as PM) and a printer are connected by IEEE 1394 to perform print output, the printer uses one page or 1/2 to 1
A large number of reception buffers, such as 1/4 pages, were prepared to transfer data.

A color scanner and a color printer are IEEE
When performing color copying by connecting at E1394, RGB data simultaneously transferred from a color scanner is temporarily stored in a receiving buffer, and is converted to YMCK data when printing.

[0005]

In IEEE 1394, the time from transmission of a start command to reception of the start command varies depending on the usage status of IEEE 1394.

For example, when a device other than a scanner or a printer is connected to the system or another scanner or a printer is connected, the usage rate of IEEE 1394 is increased. The time required for the scan start command to be transferred to the scanner varies.

If there is a variation in the time when the start command is transferred to the scanner, a variation occurs in the time from the start command transmission to the start of the image data transfer.

When the printer conveys the paper to the transfer position for a fixed time, if the time from the start command issuance to the start of the image data transfer varies, the print position changes due to the variation.

When a PM and a printer are connected by IEEE 1394 to perform print output, the PM transfers image data at a speed higher than the printing speed of the printer as long as the memory access time in the PM and the image data transfer (IEEE 1394 ISO transfer) speed permit. can do. This is IEEE1
As long as the 394 ISO transfer can get the transfer bandwidth,
This is because there is no control signal for restricting the data transfer from the printer side, and the transfer is performed in the flowing direction.

The fact that image data can be transferred at a speed higher than the printing speed of the printer requires a large amount of a receiving buffer in the printer to prevent data from being missed.

[0011] The color scanner and the color printer are IEEE
When performing color copying by connecting at E1394, the data transferred from the color scanner to the color printer is RGB data, and the data used by the color printer for printing is YMCK. Therefore, it was necessary to once store the RBG data from the scanner.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus with high printing accuracy which eliminates variations in the printing start position of a printer that receives image data by IEEE 1394 transfer.

Another object of the present invention is to provide a paper transport method capable of reducing the receiving buffer capacity of a printer in a system in which a scanner and a printer are connected, and an image forming apparatus using the paper transport method. Aim.

[0014]

In order to achieve the above object, an image forming apparatus according to the present invention reads an original image by scanning in a main scanning direction and a sub-scanning direction, and reads image data corresponding to the original image through an IEEE 1394 interface. And a printer that receives the image data from the scanner via an IEEE 1394 interface and forms an image corresponding to the image data on a conveyed sheet.

The printer moves the paper from a paper cassette to a paper feed roller position, feeds the paper from the paper feed roller position to a paper start point, and starts receiving the image data from the scanner. A paper transport unit for starting transport from a paper start point to a transfer position on the photosensitive drum is provided.

The sub-scanning speed of the scanner and the paper transport speed of the printer are the same. The printer sends a start command to the scanner, and the scanner sends a start command ACK signal to the printer after receiving the start command. The scanner transfers the image data after transmitting the start command ACK signal. The transfer of the start command and the start command ACK signal is performed by ASYNC transfer according to the IEEE 1394 transfer method, and the transfer of image data is performed by ISO transfer.

The paper is moved to the start point before the start command is transmitted, and the image data is set in a standby state until reception of the image data is started. The paper conveyance starts at the same time as the start of the image data reception. The transfer of the start command from the printer to the scanner has a transfer delay due to the IEEE 1394 ASYNC transfer, and even if the image data reception timing from the scanner varies, the paper transport is started together with the image data reception. Is not affected.

Further, the image forming system of the present invention comprises: a page memory unit for storing original image data and providing the image via an IEEE 1394 interface;
A printer that receives the image data from the page memory unit via an IEEE 1394 interface and forms an image corresponding to the image data on a conveyed sheet.

The page memory unit has a generating circuit for generating a main scanning synchronization signal of the original image, and reads out the image data in synchronization with the main scanning synchronization signal.

In the case of copying by a color scanner and a color printer, the data transferred from the scanner is RGB / Y
Convert MCK, scan 4 times for each color of YMCK, 4
One page is copied by multiple printing. This allows RGB
There is no need for a large-capacity memory for storing data at one time.

[0021]

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

FIG. 1 is a diagram showing a reading start position of the scanner 1. The scanner 1 scans a document placed on a platen glass 2 with reflected light from a light source 3 through a mirror M1 and a mirror M1.
2. The light is reflected by the mirror M3 and condensed on the CCD line sensor 4 through the reduction optical system lens 3. Light source 3 and mirror M
Reference numeral 1 moves in the vertical scanning direction together with the carriage 5 to read image data of a document.

The white reference plate 6 is used to adjust the white reference of the CCD line sensor 4. The position of the white reference plate is the carriage start position. At this position, the white reference data of the white reference plate is input to the CCD line sensor 4, and the white reference value is adjusted. The position moved by the distance E from the carriage start position is the reading start position. The difference D between the leading edge position of the document and the reading start position is the top margin. By adjusting the distance E, the top margin can be adjusted.

FIG. 2 is a diagram showing the relationship between the scanner carriage start position and the scanner reading start position.

Reading of image data for one line is performed by SHS
Data of the horizontal synchronizing signal SH = “L” period is read in the SHSYNC cycle based on the YNC-0 signal. SHSYN
The reciprocal of the SHSYNC cycle of the C-0 signal indicates the reading speed in the vertical scanning direction. That is, the shorter the SHSYN cycle, the higher the reading speed. The vertical synchronization signal SV is SHSY
The value ('L' or 'H') is changed in synchronization with the NC-0 signal to determine the vertical reading width within one page of the document.

As described above, the position moved by the distance E from the carriage start position is the reading start position in the vertical direction. The difference D between the document leading edge position and the reading start position is the top margin. By adjusting the distance E, the top margin can be adjusted.

The bottom margin is from the rising of the vertical synchronizing signal SV from 'L' to 'H' to the trailing edge of the paper, the left margin is the difference between the left edge of the original and the reading start position, and the horizontal synchronizing signal PH.
The difference from the rising edge to the right end is the write margin.

The distance from the rising edge of SHSYNC-0 to the reading start position has a fixed value depending on the document size.
The value is obtained by adding the value of the left end position of the document and the left margin.
At this position, the horizontal synchronization signal PH changes from 'H' to 'L'. The image data in the reading area inside the document size is output from the scanner to the printer.

FIG. 3 is a diagram showing the relationship between the PHSYNC-0 signal of the printer and the image data printing position.

The printer 7 forms image data as a latent image on the photosensitive drum 9 by laser scanning reflected by the polygon mirror 8. The polygon mirror 8 is driven to rotate by a polygon motor (not shown). The photosensitive drum 9 is rotating at the same peripheral speed as the reciprocal of the PHSYNC-0 signal cycle.

The laser scanning by the rotation of the polygon motor and the rotation of the photosensitive drum 9 cause the rotation of the photosensitive drum 9 to correspond to the image data.
A two-dimensional latent image is formed on the photosensitive drum. PHSYNC
The −0 signal is generated by irradiating a photodetector for PHSYNC-0 signal generation with a laser beam scanned by the rotation of the polygon motor.

As shown, the image data write start position on the photosensitive drum 9 has a value fixed by the paper size from the rise of the PHSYNC-0 signal, and is a value obtained by adding the paper size position and the left margin. At this position, the horizontal synchronization signal PH changes from 'H' to 'L'.

FIG. 4 shows the structure of the transport unit of the printer 7 and the IE.
FIG. 6 is a diagram showing a paper start point M when a scanner (or PM) / printer is connected by EE1394.

The paper moves from the paper cassette to the paper feed roller, and the leading edge of the paper is aligned (position L). Next, the paper moves to a paper start point M, which is a position close to the transfer roller by a distance C from the paper feed roller, and stops. When the latent image formation of the image data by the laser is started on the photosensitive drum 9, the paper starts to be conveyed from the paper start point M toward the transfer position N.

The latent image formed by the laser is developed before the photosensitive drum 9 rotates and reaches the transfer position. The developed image on the photosensitive drum 9 is transferred to paper at a transfer position. At this time, since the peripheral speed of the photosensitive drum 9 and the paper conveyance speed are transferred at the same rate, an image having a size of 1: 1 is formed on the paper. The image transferred to the paper is fixed on the paper by a fixing machine (not shown) and then discharged.

The distance A on the photosensitive drum from the laser writing position P to the transfer position N is substantially the same as the distance B from the paper start point M to the transfer position N (A = B).

FIG. 5 is a diagram showing the relationship between the paper start point M and the print start position N.

Printing of one line of image data is performed by PHSY
Data is printed during the horizontal synchronizing signal PH = 'L' period in the PHSYNC cycle based on the NC-0 signal.

The position moved by a distance B from the paper start point M is the print position (ie, transfer position) N. The difference D between the paper leading end position Q and the printing position N is the top margin. By adjusting the distance B, the top margin D can be adjusted. The position returned by the distance C from the paper start point M is the position L of the paper feed roller. The bottom margin is from the rising of the vertical synchronizing signal PV from 'L' to 'H' to the trailing edge P, the left margin is the difference between the left edge of the paper and the printing start position, and the difference from the rising to the right end of the horizontal synchronizing signal PH is the right. Margin.

The distance from the rising edge of PHSYNC-0 to the printing start position has a value fixed by the paper size, and is a value obtained by adding the value of the left end position of the paper and the left margin. At this position, the horizontal synchronization signal PH changes from 'H' to 'L'. Image data from the scanner is output to paper in a print area inside the paper size.

FIG. 6 is a block diagram showing the configuration and connection relationship of the scanner and the printer according to the first embodiment.
The CPU S10 of the scanner 1 controls each block of the scanner 1. The CPU P15 of the printer 7 controls each block in the printer 7.

The scanner 1 reads the image data of the original by the CCD line sensor 4 driven by the CCD drive circuit 11 from the reflected light of the light source 3, and transfers it to the image processing circuit 12. The image processing circuit 12 performs image processing on the image data read by the CCD line sensor 4 and
Transfer to 3. When a certain amount of image data transferred to the transmission buffer 13 is accumulated, the image data is transferred to the IEEE 1394 I / F 14. IEEE1394 I / F14 is IEEE1394
The image data is transferred to the printer through the cable 26. Another device such as a personal computer is connected to the IEEE1394 cable 26.

From the CCD line sensor 4 to the transmission buffer 1
The image data up to the input of 3 is processed in units of image data for one line in the HSYNC cycle, whereas the IEEE 1394 I / F1 after the output of the transmission buffer 13 is processed.
The transfer of image data according to No. 4 is fixed at a period of 125 μs. If the HSYNC cycle is 100 μs and the 1-line image data is 1 Kbyte during the 125 μs cycle, 1.25 Kbyte data is transmitted serially.

The transmission buffer 13 checks whether transmission data is available in the transmission buffer every 125 μs.
IEEE 1394 I / F when transmission data is available
The image data is transferred to the printer 7 through. The data input rate and the data output rate of the transmission buffer 13 are the same. The transmission buffer 13 has an HSYNC cycle and 1
The timing conversion of image data transfer with a period of 25 μs is performed.

The image data transferred to the printer 7 is IE
The data is transferred to the reception buffer 17 through the EE1394 I / F 16 and stored. When one line of the image data stored in the reception buffer 17 is completed, the image data is transferred to the laser drive circuit 18 for each HSYNC. The laser drive circuit 18 drives the laser LD 19 according to the image data. Laser L
The laser emitted from D19 is reflected by the polygon mirror 8 to form a latent image on the photosensitive drum 9.

125 μs until input to the reception buffer 17
While the image data transfer is performed in a cycle, the transfer after the output of the reception buffer 17 is performed in units of image data of one line in the HSYNC cycle. Receive buffer 17
Are the same in data input rate and data output rate.
In this case, the data storage capacity of the reception buffer 17 needs at least one line of image data. IEEE1
HSYNC is used for the 125 μs cycle used in the 394 I / F.
HSYN whose cycle is different from the cycle of 125 μs used in IEEE 1394 I / F asynchronously
When the C period is used, a storage capacity of several lines to about 10 lines of image data is required, but this capacity is much smaller than that of the conventional reception buffer. Conventionally, data storage capacity for one page or half a page of document image data was required. The receiving buffer has a cycle of 125 μs and HSYNC.
The timing conversion of the periodic image data transfer is performed.

The transfer of image data according to IEEE 1394 uses Isochronus. FIG. 7 shows the IEEE1394
1 shows an example of a data transfer format according to. 125μ
One unit of data is transferred in S. The maximum period of 80% (100 μS) in this unit is Isochronus.
, Image data is transferred, and the remaining minimum is 20% (25 μm).
During the period of S), the command / status is transferred by Asynchronus. In this embodiment, 1.25 per unit
K bytes of image data are transferred during the Isochronus transfer period. For details of IEEE 1394, see “IEEE S
td. 1394-1995 IEEE Standard
d fora High Performance Se
real Bus: ISBN 1-55937-583
-3 ".

FIG. 8 shows commands / commands between the printer and the scanner.
FIG. 14 is a diagram illustrating an example of a status transfer process (one-page copy). In this embodiment, the printer moves the paper to the paper start point M before sending the start command.

First, the printer prepares for printing (moving paper from the cassette to the paper feed roller, starting rotation of the photosensitive drum, etc.).
Is performed, and a scan request is transferred to the scanner (step S1). The scanner 1 receives the scan request from the printer 7 and prepares for scanning (lamp on,
Then, the scan ready is transferred to the printer 7 (step S2).

The printer 7 receives the scan ready of the scanner 1 and feeds the paper (the paper is moved to the paper start point M by a distance C).
(See FIG. 4), the start command is transferred to the scanner 1 (step S).
3). The scanner 1 receives the start command of the printer 7, starts scanning, and transfers image data to the printer 7 (step S4).

The printer 7 receives the image data from the scanner 1 and starts printing (laser printing, paper conveyance (moving the paper to the transfer position by distance B)) (step S5).
S6). At this time, the scanner 1 and the printer 7 operate in synchronization, and the printer 7 prints the image data scanned by the scanner 1. After the end of scanning, the scanner 1 performs processes such as back carriage and lamp off, and ends the scanning operation of the scanner 1 (step S7).

After the laser printing, the printer 7 completes the paper conveyance,
The rotation of the photosensitive drum is stopped, and the printing operation of the printer 7 ends (step S8).

As described above, command / status transfer is Asynchronous by IEEE1394, and image data transfer is by IEEE1394 Isochronous.

FIG. 9 shows commands / commands between the printer and the scanner.
FIG. 11 is a diagram illustrating an embodiment of a status transfer process (two-page copy). Also in this embodiment, the printer moves the paper to the paper start point M before transmitting the start command.

First, the printer 7 prepares for printing (moving the paper from the cassette to the paper feeding tray, starting rotation of the photosensitive drum, etc.) and transfers a scan request (first page) to the scanner 1 (step S21). The scanner 1 receives the scan request (first page) from the printer 7, prepares for scanning (lamp on, white / black reference correction, etc.), and transfers scan ready (first page) to the printer 7 (step S22).

The printer 7 receives the scan ready (first page) of the scanner 1 and performs a paper feeding operation (moves the paper to the paper start point M by the distance C (see FIG. 4) and stops), and then starts. The command is transferred to the scanner 1 (Step S23). The scanner 1 receives the start command (first page) of the printer 7, starts scanning, and performs image data transfer (first page) to the printer 7 (step S24).

The printer 7 receives the image data from the scanner 1 and starts printing (laser printing, paper conveyance (movement of the paper to the transfer position by distance B)) (step S2).
5, S26). At this time, the scanner 1 and the printer 7 operate in synchronization, and the printer 7 prints the image data scanned by the scanner 1. During this printing, the printer 7 further prepares for printing (page 2) (moves the paper from the cassette to the paper feed roller, etc.) and transfers a scan request (page 2) to the scanner 1 (step S27). .
After the end of scanning, the scanner 1 performs processes such as back carriage and lamp off, and ends the scanning operation of the scanner 1 (step S28).

After the laser printing is completed, the printer 7 finishes the paper conveyance and the like, and ends the printing operation of the printer 7 (first page).
(Step S29). After completion of the scan, the scanner 1 performs a scan preparation (lamp on or the like), and transmits a scan ready (second page) to the printer 7 (step S30).

The printer 7 receives the scan ready (second page) from the scanner 1 and performs a paper feeding operation (moves the paper to the paper start point M by the distance C (see FIG. 4) and stops). The start command (second page) is transferred to the scanner 1 (step S31). The scanner 1 is a printer 7
, The scanning is started and the image data is transferred to the printer 7 (page 2) (step S32).

The printer 7 receives the image data from the scanner 1 and starts printing (laser printing, paper conveyance (movement of the paper to the transfer position by distance B)) (steps S33, S3).
4). The scanner 1 and the printer 7 operate in synchronization, and the printer 7 prints image data scanned by the scanner 1. After the end of scanning, the scanner 1 performs processes such as back carriage and lamp off, and ends the scanning operation of the scanner 1 (step S35).

After completion of printing, the printer 7 terminates laser printing, paper conveyance, rotation of the photosensitive drum, etc., and terminates the printing operation of the printer 7 (step S36).

FIG. 10 shows commands / commands between the printer and the scanner.
FIG. 14 is a diagram illustrating an example of a status transfer process (one-page copy). In this embodiment, the printer moves the paper to the paper start point M between the transmission of the start command and the start of image data reception.

First, the printer 7 prepares for printing (moving paper from the cassette to the paper feed roller, starting rotation of the photosensitive drum, etc.), and transfers a scan request to the scanner 1 (step S41). The scanner 1 receives a scan request from the printer 7 and prepares for scanning (lamp on,
Scan / ready correction for white / black)
(Step S42).

The printer 7 receives the scan ready state of the scanner 1 and transfers a start command to the scanner 1.
At the same time, a paper feeding operation (moving the paper to the paper start point M by the distance C (see FIG. 4) and stopping) is performed (step S4).
3). The paper feeding operation of the printer 7 is completed before the image data transfer of the scanner 1 starts. This is when the minimum value (min) of the time from when the printer 7 transfers the start command to the scanner 1 to when the image data transfer of the scanner 1 starts is known. It is effective when it can be terminated.

The scanner 1 receives the start command of the printer 7 and starts scanning. Simultaneously with the start of scanning, image data is transferred to the printer 7 (step S).
44).

The printer 7 receives the image data from the scanner 1 and starts printing (laser printing, paper conveyance (movement of the paper to the transfer position by distance B)) (steps S45 and S4).
6). The scanner 1 and the printer 7 operate in synchronization, and the printer 7 prints image data scanned by the scanner 1.

The delay time from when the printer 7 transmits the start command in step S43 to when the scanner 1 receives the command in step S55 differs depending on the configuration of each system or the usage rate of the IEEE1394 signal transmission cable 26. ing. This is because the command is transferred by ASYNC transfer as shown in FIG. For example, an IEEE1394 signal transmission cable 26
The delay time is large when the usage rate is high. Therefore, the time from when the printer 7 transmits the start command to when the image data is received from the scanner to the printer 7 also varies. As a result, in the conventional method, the print start position on the paper varies. However, according to the present invention, the laser printing and the paper transport from the paper start point are started while the image data is received, so that the printing start position does not shift. This is because, as shown in FIG. 4, the paper conveying speed and the peripheral speed of the photosensitive drum are the same, and the laser irradiation position P
This is because the distance A from the paper surface to the transfer position N is the same as the distance B from the paper start point M to the transfer position N.

In step S47, the scanner 1 performs processing such as back carriage and lamp off after scanning is completed.
The scanning operation of the scanner 1 ends. After completion of printing, the printer 7 ends laser printing, paper conveyance, rotation of the photosensitive drum, and the like, and ends the printing operation of the printer 7 (step S48).

FIG. 11 is a diagram showing an embodiment of the command / status transfer process between the pudding / scanner (two-page copy). Also in this embodiment, the printer moves the paper to the paper start point M between the transmission of the start command and the start of image data reception.

First, the printer 7 prepares for printing (moving paper from the cassette to the paper feed roller, starting rotation of the photosensitive drum, etc.), and transmits a scan request (first page) to the scanner 1 (step S51). The scanner 1 receives the scan request (first page) from the printer 7, performs scan preparation (lamp on, white / black preparation correction, etc.), and transfers scan ready (first page) to the printer 7 (step S52).

The printer 7 receives the scan ready state of the scanner 1 and transfers a start command (first page) to the scanner 1. Simultaneous paper feeding (paper is moved to paper start point M by distance C (see FIG. 4) and stopped) (step S5)
3). The paper feeding operation of the printer 7 is completed before the image data transfer of the scanner 1 starts. As described above, this is a case where the minimum value (min) of the time from the transfer of the start command of the printer 7 to the scanner 1 to the start of the image data transfer of the scanner 1 is known. 7 is effective when the paper feeding can be completed.

The scanner 1 receives the start command (first page) of the printer 7 and starts scanning. At the same time as the start of scanning, image data transfer (first page) is performed to the printer 7 (step S54).

The printer 7 receives the image data from the scanner 1 and starts printing (laser printing, paper conveyance (moving the paper to the transfer position by distance B)) (steps S55 and S5).
6). The scanner 1 and the printer 7 operate in synchronization, and the printer 7 prints image data scanned by the scanner 1.

While the image data scanned by the scanner 1 is being printed by the printer 7, the printer 7 further prepares for printing (page 2) (moves the paper from the cassette to the paper feed roller, etc.). Then, a scan request (second page) is transferred (step S57). Scanner 1
After the scanning is completed, processing such as back carriage and lamp off is performed, and the scanning operation of the scanner 1 is completed (step S58).

The printer 7 finishes laser printing after printing is completed,
The printing operation of the printer 7 is completed by terminating the paper conveyance or the like (step S59). The scanner 1 performs scan preparation (lamp on or the like) after the scan is completed, and transfers a scan ready (second page) to the printer 7 (step S60).

The printer 7 receives the scan ready state of the scanner 1 and transfers a start command (second page) to the scanner 1. At the same time, a paper feeding operation (moving the paper to the paper start point M by the distance C (see FIG. 4) and stopping) is performed (step S61). The paper feeding operation of the printer 7 is completed before the image data transfer of the scanner 1 starts. The scanner 1 receives the start command (page 2) of the printer 7, starts scanning, and transfers image data (page 2) to the printer 7 (step S62).

The printer 7 receives the image data from the scanner 1 and starts printing (laser printing, paper conveyance (movement of the paper to the transfer position by distance B)) (steps S63, S6).
4). The scanner 1 and the printer 7 operate in synchronization, and the printer 7 prints image data scanned by the scanner 1. After the end of scanning, the scanner 1 performs processes such as back carriage and lamp off, and ends the scanning operation of the scanner 1 (step S65). After completion of printing, the printer 7 ends laser printing, paper conveyance, rotation of the photosensitive drum, etc., and ends the printing operation of the printer 7 (step S).
66).

FIG. 12 is a diagram showing a P according to the second embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of an M (Page Memory) and a printer. In the second embodiment, a PM 20 is connected to the printer 7 instead of the scanner 1 shown in FIG.

The CPU M21 in the PM 20 controls each block in the PM, and the CPU P15 in the printer 7 controls each block in the printer 7 block.

H of the HSYNC generation circuit 22 according to the present invention
The SYNC signal is set by the CPUM upon receiving data of the printer HSYNC cycle from the printer 7. The printer HSYNC cycle data from the printer 7 is transmitted to the PMP by the CPUP using the IEEE1394 I / F16.
Transfer to 1394 I / F14. IEEE1 of PM20
The printer HSYNC cycle transferred to the 394 I / F 14 is read by the CPU M21, and the same HSYNC cycle as that of the printer 7 is used.
To generate the C period, the HSYNC generation circuit 22 counts and generates a reference clock (not shown).

Synchronization signal 1 from HSYNC generation circuit 22
The memory control unit 23 reads one line of image data from the memory with respect to the cycle. The memory control unit 23 transfers the read image data to the transmission buffer 25.

The image data transferred to the transmission buffer 25 is transferred to the IEEE 1394 I / F 14 when a certain amount is stored. IEEE1394 I / F14 is IEEE139
4 The image data is transferred to the printer 7 through the cable 26.

The image data up to the input of the transmission buffer 25 is processed for each line of image data in the HSYNC cycle, while the IEs after the output of the transmission buffer 25 are processed.
The transfer of image data by EE1394 I / F14 is 12
The period is fixed at 5 μs. During this 125 μs cycle,
For example, if the HSYNC cycle is 100 μs and 1-line image data is 1 Kbyte, 1.25 Kbyte data is transmitted serially. The transmission buffer 25 is 125 μ
It is checked whether transmission data is available in the transmission buffer in units of s.
The image data is transferred to the printer 7 through the 394 I / F 14. The transmission buffer 25 has the HSYNC cycle and 125
The timing conversion of image data transfer with a period of μs is performed.

The image data transferred to the printer 7 is IE
The data is transferred to the reception buffer 17 through the EE1394 I / F 16 and stored. When one line of the image data stored in the reception buffer 17 is completed, the image data is transferred to the laser drive circuit 18 for each HSYNC of the printer.

The laser drive circuit 18 drives the laser LD according to the image data. The laser emitted from the laser LD is reflected by the polygon mirror 8 to form a latent image on the photosensitive drum 9.

125 μm before input to the receiving buffer 17
Image data transfer is performed for s cycles. Receive buffer 1
After the output of 7, the transfer for each line of image data is performed in the HSYNC cycle. The reception buffer 17 is 125
The timing conversion of the image data transfer between the μs cycle and the HSYNC cycle is performed.

FIG. 13 shows the HSYNC generation circuit 22 of HSY.
FIG. 4 is a diagram showing generation of an NC signal and memory read timing.

HSYNC generation circuit 22 in PM shown in FIG.
A reference clock generation circuit (not shown), a counter (not shown) for counting the reference clock, and a circuit (not shown) for generating an HSYNC signal from the count value are provided therein.

The CPU M21 sets a set value for counting the reference clock in the HSYNC generation circuit 22. The counter repeats the operation of counting down from the set value to '0' and returning to the set value. In FIG. 13, the CPU
The value set to M is '625', and the value of the counter is decremented by '1' in one clock cycle. The counter value repeats a value from '625' to '0', and can generate an HSYNC signal having a cycle 626 times the reference clock cycle. The HSYNC generation circuit 22 outputs “L” when the counter value is “0”, and outputs “H” when the counter value is other than “0”. The HSYNC signal generated by the HSYNC generation circuit 22 does not include signal jitter, that is, fluctuation, unlike the HSYNC signal generated by the printer.

H output from HSYNC generation circuit 22
The SYNC signal is input to the memory control unit 23. H
The memory control unit 23 starts the operation of reading image data from the memory 24 from the enable state under the control of the memory read enable (EN) by the SYNC signal. HSY
From the rising edge of the NC signal, the one-line data memory read enable signal EN becomes 'L' enabled. When one line of image data is read from the memory 24,
Line data memory read enable signal EN is 'H'
And the memory read operation is stopped. At the next rise of the HSYNC signal, the one-line data memory read enable signal EN is again set to the enable state of "L", and starts reading image data. By this repetition, one page of image data is read from the memory 24.

FIG. 14 is a block diagram showing a configuration of a color scanner 30 and a color printer 40 according to the third embodiment of the present invention.

The CPUCS in the scanner 30 is the scanner 1
Each block in the block is controlled, and the CPUCP in the printer 40 controls each block in the printer 7 block.

The color scanner 30 reads the image data 'RGB' of the original from the reflected light of the light source 32 by the RGB integrated color CCD line sensor 33 driven by the CCD drive circuit 34 and transfers it to the image processing circuit 35.

The image processing circuit 35 converts the input RGB signals into YM
The transmission buffer 36 converts the signal into a CK signal, performs image processing, and
Transfer to 4 scans, 4 prints and 1 original
To perform color copying of a page, the image processing circuit 35 transfers the image data of “Y” from the image data of “RGB” to the transmission buffer 36 in the first page scan. In the second page scan, the image processing circuit 35 transfers the image data “M” from the image data “RGB” to the transmission buffer 36. In the third page scan, the image processing circuit 35 sets the 'RG
The image data “C” is transferred from the image data “B” to the transmission buffer 36. In the fourth page scan, the image processing circuit 35 transfers the image data of “K” from the image data of “RGB” to the transmission buffer 36.

When a certain amount of image data is transferred to the transmission buffer 36, the image data is transferred to the IEEE 1394 I / F 14. IEEE1394 I / F14 is IEEE1394
The image data is transferred to the printer 40 via the cable 26.

While the image data up to the input of the transmission buffer 36 is processed for each line of image data in the HSYNC cycle, the transfer of the image data by the IEEE 1394 I / F 14 after the output of the transmission buffer 36 is 125 μs. Period and fixed. The transmission buffer 36 is 12
It is checked whether the transmission buffer has all the transmission data in units of 5 μs.
Image data is transferred to the printer 4 through the E1394 I / F14.
Transfer to 0. The transmission buffer 36 converts the timing of image data transfer in the HSYNC cycle and the 125 μs cycle.

The image data transferred to the printer 40 is I
The data is transferred to and stored in the reception buffer 42 through the IEEE 1394 I / F 16. When the image data stored in the reception buffer 42 is completed for one line, the image data is transferred to the laser drive circuit 43 for each HSYNC.

The laser drive circuit 43 drives the laser LD according to the image data. The laser emitted from the laser LD is reflected by the polygon mirror 45 and is
A latent image is formed thereon.

The image data “Y” transferred by page scanning from the scanner 30 for the first time is developed by the printer 40 using the “Y” developing unit of the color developing unit 46. The image data 'M' transferred by page scanning from the scanner 30 for the second time is transmitted to the color developing unit 4 by the printer 40.
6. Develop using the 'M' developing unit. The image data 'C' which has been page-transferred from the scanner 30 for the third time is developed by the printer 40 using the 'C' developing unit of the color developing unit. Scanner 3 for the fourth time
The image data 'K' which has been page-transferred from 0 is developed by the printer 40 using the 'K' developing unit of the color developing unit 46.

The color image (YMCK composite image) formed on the photosensitive drum 47 in the fourth development starts moving from the paper start point when the fourth image data 'K' is transferred to the color printer 40. Is transferred to the paper.

In the color printer 40, image data is transferred at a period of 125 μs until input to the receiving buffer 42. HSYNC after the output of the reception buffer 42
One line of image data is transferred periodically.
The reception buffer 42 performs the timing conversion of the image data transfer of the 125 μs cycle and the HSYNC cycle.

FIG. 15 is a diagram showing a data transfer procedure between the color scanner 30 and the color printer 40.

The CCD drive circuit 34 of the color scanner 30 always outputs the “R” G ”B” image data from the RGB integrated color CCD line sensor 33 to the image processing circuit 35 from one scan to four scans. ing.

The image processing circuit 35 outputs “Y” to the transmission buffer 36 at the first scan. The image processing circuit 35 outputs “M” to the transmission buffer 36 at the second scan. The image processing circuit 35 outputs “C” to the transmission buffer 36 at the third scan.
The image processing circuit 35 outputs “K” to the transmission buffer 36 at the fourth scan.

The IEEE 1394 cable 26 transfers the image data 'Y' to the color printer 40 in the first scan, transfers the image data 'M' in the second scan, and transfers the image data 'C' in the third scan. The image data 'K' is transferred at the fourth scan.

The receiving buffer 42 of the color printer 40 stores the image data “Y” at the first scan of the color scanner 30.
Is output to the laser drive circuit 43, the image data 'M' is output in the second scan, the image data 'C' is output in the third scan, and the image data 'K' is output in the fourth scan.

The color scanner 30 can read the image data of “R”, “G”, and “B” in one scan, but the printer 40 performs the development of “Y”, “M”, “C”, and “K” four times. To print a color image. When the image data from the scanner 30 is transferred to the color printer 40 in one scan, the image data from the scanner 30 must be stored in the color printer 40 until three developments, so that a large amount of data is received. You need a buffer. However, in this embodiment, the capacity of the receiving buffer is reduced by the printer 40 receiving image data necessary for development in four times.

[0108]

The method of moving to the start point M before transmitting the start command and the method of moving to the start point M between the time when the start command is transmitted and the start of image data reception are both performed by the image data from the scanner 1. To start the paper transport of the printer 7 after receiving the
Since the print position accuracy due to the time variation between the start command transmission using IEEE1394 and the paper transport start timing is reduced, the print position accuracy in the sub-transport direction is improved.

Further, since the data transferred from the PM to the printer 7 becomes the same as the print data transfer speed (that is, the print speed) of the printer 7 by the HSYNC signal, the amount of the reception buffer of the printer 7 is reduced.

Further, since the data transferred from the color scanner is of the same color as that used in the color printer, a large amount of reception buffer required when simultaneously transferring multiple colors is not required.

[Brief description of the drawings]

FIG. 1 is a diagram showing a scanner reading start position.

FIG. 2 is a diagram illustrating a relationship between a scanner carriage start position and a scanner reading start position.

FIG. 3 is a diagram showing a relationship between a PHDSYNC-0 signal of a printer and an image data printing position.

FIG. 4 is a diagram showing a paper start point M in the printer when a scanner / printer is connected according to IEEE1394.

FIG. 5 is a diagram illustrating a relationship between a paper start point M and a print start position.

FIG. 6 is a connection block diagram of the scanner / printer 7;

FIG. 7 is a diagram showing an example of a data transfer format according to IEEE1394.

FIG. 8 is a diagram showing a command / status (one-page copy) transferred between a printer and a scanner by a method of moving to a paper start point before transmitting a start command.

FIG. 9 is a diagram showing a command / status (continuous copy: two pages) transferred between a printer and a scanner by a method of moving to a paper start point before transmitting a start command.

FIG. 10 is a diagram illustrating a command / status (one-page copy) transferred between a printer and a scanner by a method in which paper is started during the time from the transmission of a start command to the start of image data reception.

FIG. 11 is a diagram showing a command / status (continuous copy: two pages) transferred between a printer and a scanner by a method of starting a paper at a time from transmission of a start command to start of reception of image data.

FIG. 12 is a PM / printer connection block diagram.

FIG. 13 is a diagram showing generation of an HSYNC signal and memory read timing.

FIG. 14 is a connection block diagram of a color scanner / color printer.

FIG. 15 is a diagram showing a data transfer procedure between a color scanner and a color printer.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koichi Watanabe 70, Yanagimachi, Yuki-ku, Kawasaki-shi, Kanagawa Toshiba Tec Co., Ltd. (72) Masahiko Taniguchi 70, Yanagimachi, Yuki-ku, Kawasaki-shi, Kanagawa F-term (reference) in Yanagimachi Office of Co., Ltd. 5C062 AA05 AB08 AB16 AB17 AB22 AB42 AB47 AC12 AC13 AC14 BA00

Claims (11)

[Claims] An image of an original is scanned and read in a main scanning direction and a sub-scanning direction, and image data corresponding to the original image is read by IEEE.
And a printer that receives the image data from the scanner via an IEEE 1394 interface and forms an image corresponding to the image data on a conveyed sheet. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the sub-scanning speed of the scanner is the same as the paper conveyance speed of the printer. 3. The image forming apparatus according to claim 1, wherein an original image reading speed of said scanner and an image forming speed of said printer are substantially the same. 4. The printer moves paper from a paper cassette to a paper feed roller position, feeds the paper from the paper feed roller position to a paper start point, and starts receiving the image data from the scanner. Further comprising a paper conveying means for starting conveyance from the paper start point to a transfer position on the photosensitive drum, wherein a distance from the paper feed roller position to the transfer position is from a laser printing position on the photosensitive drum to the transfer position. The image forming apparatus according to claim 1, wherein the sheet is longer than the distance to and the sheet temporarily stops at the sheet start point. 5. The printer moves paper from a paper cassette to a paper feed roller position, feeds the paper from the paper feed roller position to a paper start point, and starts receiving the image data from the scanner. Further comprising a paper conveying means for starting to convey the paper from the paper start point to a transfer position on the photosensitive drum, and after the paper feeding operation from the paper feed roller position to the paper start point is completed, a scan start command from the printer to the scanner. Is transmitted.
The image forming apparatus according to claim 1. 6. The printer moves paper from a paper cassette to a paper feed roller position, feeds the paper from the paper feed roller position to a paper start point, and starts receiving the image data from the scanner. Further comprising a paper conveying means for starting conveyance from the paper start point to a transfer position on the photosensitive drum, wherein a distance from the paper feed roller position to the transfer position is from a laser printing position on the photosensitive drum to the transfer position. The image forming apparatus according to any one of claims 1 to 3, wherein the distance is longer than a distance to the image forming apparatus. 7. The printer moves paper from a paper cassette to a paper feed roller position, feeds the paper from the paper feed roller position to a paper start point, and starts receiving the image data from the scanner. Further comprising a paper transport means for starting transport from the paper start point to a transfer position on the photosensitive drum, after the scan start command is transferred from the printer to the scanner, from the paper feed roller position to the paper start point. The image forming apparatus according to claim 1, wherein a sheet feeding operation is started. 8. An image forming apparatus comprising:
A printer for receiving the image data from the page memory unit via an IEEE 1394 interface and forming an image corresponding to the image data on a conveyed sheet; An image forming system comprising: 9. The apparatus according to claim 8, wherein said page memory unit has a generating circuit for generating a main scanning synchronization signal of said original image, and reads out said image data in synchronization with said main scanning synchronization signal. Image forming system. 10. The image forming system according to claim 9, wherein a sub-scanning speed synchronized with a main-scanning synchronization signal of said page memory unit and a transport speed of a printer are the same. 11. A printer for receiving image data via an IEEE 1394 interface and forming an image corresponding to the image data on a conveyed sheet, wherein the printer starts conveying the sheet together with the start of reception of the image data. A sheet conveying method characterized by the above-mentioned.