JP4234860B2 - Image forming apparatus using IEEE1394 image transfer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image transfer method and a printer paper feeding method 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]
[Prior art]
Conventionally, when a copying function is realized by connecting a scanner and a printer with IEEE 1394, the scanner's sub-scanning speed and the printer's sub-transport speed are the same, and the distance from the printer's paper feed roller to the transfer position is the printer's laser. Is longer than the distance from the printing position on the photosensitive drum to the transfer position, the paper conveyance starts after a predetermined time from the transfer of the scan start command (hereinafter simply referred to as the start command) from the printer to the scanner. Furthermore, image data transfer start and paper transport start timing are also determined in advance.
[0003]
Conventionally, when a page memory unit (hereinafter abbreviated as PM) and a printer are connected via IEEE 1394 and printed out, the printer prepares a large amount of reception buffers such as one page or 1/2 to 1/4 page to store data. Had been transferred.
[0004]
When color copying is performed by connecting a color scanner and a color printer with IEEE 1394, RGB data simultaneously transferred from the color scanner is temporarily stored in a reception buffer and converted to YMCK data when printing. .
[0005]
[Problems to be solved by the invention]
In IEEE 1394, the time from the start command transmission to the start command reception varies depending on the use condition of IEEE 1394.
[0006]
For example, when a device other than a scanner or printer is connected to the system, or when another scanner or printer is connected, the usage rate of IEEE1394 increases, so a scan start command from a printer that is ASYNC (asynchronous) transfer Variation occurs in the time when the image is transferred to the scanner.
[0007]
When variations occur in the time when the start command is transferred to the scanner, variations occur in the time from the start command transmission to the start of image data transfer.
[0008]
When the printer transports the paper to the transfer position in a certain time, if there is a variation in the time from the start command transmission to the start of image data transfer, the printing position changes due to this variation.
[0009]
When printing is performed by connecting the PM and the printer with IEEE 1394, the PM may transfer the 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 allow. it can. This is because, as long as the IEEE 1394 ISO transfer can acquire the transfer bandwidth, the printer side performs the transfer without a control signal for limiting the data transfer.
[0010]
The fact that image data can be transferred at a speed higher than the printing speed of the printer necessitates a large amount of reception buffer for the printer so as not to miss data.
[0011]
When color copying is performed by connecting a color scanner and a color printer with IEEE1394, 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. The printer had to store RBG data from the scanner once with a large amount of reception buffers.
[0012]
Accordingly, it is an object of the present invention to provide an image forming apparatus with high printing accuracy by eliminating variations in the print start position of a printer that receives image data by IEEE1394 transfer.
[0013]
It is another object of the present invention to provide a paper transport method capable of reducing the capacity of a receiving buffer of a printer and an image forming apparatus using the paper transport method in a system in which a scanner and a printer are connected. .
[0014]
[Means for Solving the Problems]
In order to achieve the above object, an image forming apparatus of the present invention scans and reads a document image in the main scanning and sub-scanning directions and provides image data corresponding to the document image via the IEEE 1394 interface, and IEEE 1394. A printer that receives the image data from the scanner via an interface and forms an image corresponding to the image data on a sheet to be conveyed;
[0015]
The printer is configured to feed paper from a paper cassette to a paper feed roller. Through the photosensitive drum The paper is fed to the paper start point, and the conveyance of the paper from the paper start point to the transfer position on the photosensitive drum is started simultaneously with the start of image data reception from the scanner.
[0016]
The sub-scanning speed of the scanner and the paper transport speed of the printer are the same. The printer transmits a start command to the scanner, and the scanner transmits 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. Transfer of the start command and start command ACK signal is performed by IEEE 1394 transfer ASYNC transfer, and image data transfer is performed by ISO transfer.
[0017]
The paper is moved to the start point before transmission of the start command, and is in a standby state until image data reception starts. At the same time as the reception of image data, paper conveyance is started. Even if there is a transfer delay due to IEEE 1394 ASYNC transfer in the transfer of the start command from the printer to the scanner, and even if there is a variation in the timing of image data reception from the scanner, paper conveyance is started at the same time as the reception of the image data. Is not affected.
[0018]
The image forming system of the present invention stores document image data and provides the image data via the IEEE 1394 interface, and receives the image data from the page memory unit via the IEEE 1394 interface. And a printer for forming an image corresponding to the data on the conveyed paper.
[0019]
The page memory unit has a generation circuit for generating a main scanning synchronization signal of the document image, and reads the image data in synchronization with the main scanning synchronization signal.
[0020]
In the case of copying using a color scanner and a color printer, RGB / YMCK conversion is performed on data transferred from the scanner, and one page of YMCK is scanned four times, and one page is copied by four printing. This eliminates the need for a large-capacity memory for storing RGB data at a time.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0022]
FIG. 1 is a diagram showing a reading start position of the scanner 1. The scanner 1 condenses the original placed on the original table glass 2 on the CCD line sensor 4 through the reduction optical system lens 3 by reflecting the reflected light from the light source 3 with the mirror M1, the mirror M2, and the mirror M3. The light source 3 and the mirror M1 move in the vertical scanning direction together with the carriage 5 to read the image data of the document.
[0023]
The white reference plate 6 is used for adjusting 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. A difference D between the document leading edge position and the reading start position is a top margin. The top margin can be adjusted by adjusting the distance E.
[0024]
FIG. 2 is a diagram showing the relationship between the scanner carriage start position and the scanner reading start position.
[0025]
The image data for one line is read in the horizontal synchronization signal SH = 'L' period in the SHSYNC cycle with reference to the SHSYNC-0 signal. The reciprocal of the SHSYNC cycle of the SHSYNC-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 changes its value ('L' or 'H') in synchronization with the SHSYNC-0 signal to determine the vertical reading width in one page of the document.
[0026]
As described above, the position moved by the distance E from the carriage start position is the reading start position in the vertical direction. A difference D between the document leading edge position and the reading start position is a top margin. The top margin can be adjusted by adjusting the distance E.
[0027]
The bottom margin is from the rising edge of the vertical synchronizing signal SV from 'L' to 'H' to the trailing edge of the paper, the difference between the left edge of the document and the reading start position is the left margin, and the difference from the rising edge of the horizontal synchronizing signal PH to the right edge is the right margin. become.
[0028]
The distance from the rising edge of SHSYNC-0 to the reading start position has a value fixed according to the document size, and is a value obtained by adding the value of the document left end position and the left margin. At this position, the horizontal synchronizing signal PH changes from “H” to “L”. Image data in the reading area inside the document size is output from the scanner to the printer.
[0029]
FIG. 3 is a view showing the relationship between the PHSYNC-0 signal of the printer and the image data printing position.
[0030]
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 rotationally driven by a polygon motor (not shown). The photosensitive drum 9 rotates at the peripheral speed of the same speed as the reciprocal of the PHSYNC-0 signal period.
[0031]
A two-dimensional latent image corresponding to image data is formed on the photosensitive drum by laser scanning by rotation of the polygon motor and rotation of the photosensitive drum 9. The PHSYNC-0 signal is generated by irradiating the PHSYNC-0 signal generating photodetector with a laser beam scanned by the rotation of the polygon motor.
[0032]
The image data writing start position on the photosensitive drum 9 has a value fixed according to the paper size from the rise of the PHSYNC-0 signal as shown in the figure, and is a value obtained by adding the paper size position and the left margin. At this position, the horizontal synchronizing signal PH changes from “H” to “L”.
[0033]
FIG. 4 is a diagram showing the configuration of the conveyance unit of the printer 7 and the paper start point M when the scanner (or PM) / printer is connected according to IEEE1394.
[0034]
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 formation of a latent image of 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.
[0035]
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 the transfer position. At this time, since the peripheral speed of the photosensitive drum 9 and the paper conveyance speed are transferred at the same speed, 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 device (not shown) and then discharged.
[0036]
The distance A on the photosensitive drum from the laser writing position P to the transfer position N and the distance B from the paper start point M to the transfer position N are substantially the same (A = B).
[0037]
FIG. 5 shows the relationship between the paper start point M and the print start position N.
[0038]
The printing of the image data for one line is performed during the horizontal synchronization signal PH = 'L' with a PHSYNC cycle based on the PHSYNC-0 signal.
[0039]
A printing position (that is, a transfer position) N is a place moved by a distance B from the paper start point M. The difference D between the paper leading edge 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 from the paper start point M by the distance C is the position L of the paper feed roller. The bottom margin is from the rising edge of the vertical synchronizing signal PV from “L” to “H” to the trailing edge P of the paper, the difference between the left edge of the paper and the printing start position is the left margin, and the difference from the rising edge of the horizontal synchronizing signal PH to the right edge is the writing. It becomes a margin.
[0040]
The distance from the rise of PHSYNC-0 to the print start position has a value fixed depending on the paper size, and is a value obtained by adding the value of the left edge position of the paper and the left margin. At this position, the horizontal synchronizing signal PH changes from “H” to “L”. Image data from the scanner is output to paper in a print area inside the paper size.
[0041]
FIG. 6 is a block diagram showing the configuration and connection relationship according to the first embodiment of the scanner and printer. The CPUS 10 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.
[0042]
The scanner 1 reads the image data of the original from the reflected light of the light source 3 by the CCD line sensor 4 driven by the CCD drive circuit 11 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 transfers it to the transmission buffer 13. When a certain amount of image data transferred to the transmission buffer 13 is stored, it is transferred to the IEEE1394 I / F14. The IEEE 1394 I / F 14 transfers image data to the printer through the IEEE 1394 cable 26. Other devices such as a personal computer are connected to the IEEE 1394 cable 26.
[0043]
The image data from the CCD line sensor 4 to the input of the transmission buffer 13 is processed in units of image data for one line in the HSYNC cycle, whereas the image data is transferred by the IEEE1394 I / F 14 after the output of the transmission buffer 13. Is fixed at a period of 125 μs. For example, 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.
[0044]
The transmission buffer 13 checks whether the transmission data is ready in the transmission buffer in units of 125 μs. When the transmission data is ready, the image data is transferred to the printer 7 through the IEEE 1394 I / F 14. The data input rate and the data output rate of the transmission buffer 13 are the same. The transmission buffer 13 performs timing conversion of image data transfer in the HSYNC cycle and 125 μs cycle.
[0045]
The image data transferred to the printer 7 is transferred to and stored in the reception buffer 17 through the IEEE 1394 I / F 16. When the image data stored in the reception buffer 17 is prepared for one line, it is transferred to the laser drive circuit 18 for each HSYNC. A laser drive circuit 18 drives a laser LD 19 in accordance with image data. The laser emitted from the laser LD 19 is reflected by the polygon mirror 8 to form a latent image on the photosensitive drum 9.
[0046]
The image data is transferred in a 125 μs cycle until the input of the reception buffer 17, whereas the transfer is performed in units of image data for one line in the HSYNC cycle after the output of the reception buffer 17. The data input rate and the data output rate of the reception buffer 17 are the same. In this case, the data storage capacity of the reception buffer 17 is required to be at least one line of image data. When the 125 μs period used in the IEEE1394 I / F is used as the HSYNC period, or when the HSYNC period that is different from the 125 袖 s period used in the IEEE1394 I / F is used, the image data is about several lines to about 10 lines. Although a storage capacity is required, this capacity is very small compared to a conventional reception buffer. Conventionally, data storage capacity for one page or half page of document image data has been required. The reception buffer performs timing conversion of image data transfer in the 125 μs cycle and the HSYNC cycle.
[0047]
The transfer of image data by IEEE 1394 uses Isochronus. FIG. 7 shows an example of a data transfer format according to IEEE1394. One unit of data is transferred within 125 μS. Image data is transferred by Isochronus for a maximum period of 80% (100 μS) in one unit, and commands / statuses are transferred by Asynchronus for the remaining period of 20% (25 μS). In this embodiment, 1.25 Kbytes of image data is transferred per unit during the Isochronus transfer period. Details of IEEE 1394 are shown in “IEEE Std. 1394-1995 IEEE Standard for High Performance Serial Bus: ISBN 1-55937-583-3”.
[0048]
FIG. 8 is a diagram showing an embodiment of command / status transfer processing (one page copy) between the printer and the scanner. In this embodiment, the printer moves the paper to the paper start point M before sending the start command.
[0049]
First, the printer prepares for printing (moves paper from the cassette to the paper feed roller, starts rotating the photosensitive drum, etc.), and transfers a scan request to the scanner (step S1). The scanner 1 receives the scan request from the printer 7, prepares for scanning (lamp on, white / black reference correction, etc.), and transfers the scan ready to the printer 7 (step S2).
[0050]
The printer 7 receives the scan ready of the scanner 1 and performs paper feeding (moves the paper to the paper start point M by the distance C (see FIG. 4) and stops), and then transfers a start command to the scanner 1 ( Step S3). The scanner 1 receives the start command of the printer 7, starts scanning, and transfers image data to the printer 7 (step S4).
[0051]
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 the distance B)) (steps S5 and S6). At this time, the scanner 1 and the printer 7 operate in synchronization, and the printer 7 prints image data scanned by the scanner 1. After the scanning is completed, the scanner 1 performs processing such as back carriage, lamp off, and the scanning operation of the scanner 1 is finished (step S7).
[0052]
After the laser printing, the printer 7 terminates paper conveyance, stops the photosensitive drum rotation, etc., and ends the printing operation of the printer 7 (step S8).
[0053]
As described above, the command / status transfer uses Asynchronous according to IEEE 1394, and the image data transfer uses IEEE 1394 Isochronous.
[0054]
FIG. 9 is a diagram showing an embodiment of command / status transfer processing (two-page copying) between the printer and the scanner. Also in this embodiment, the printer moves the paper to the paper start point M before sending the start command.
[0055]
First, the printer 7 prepares for printing (moves the paper from the cassette to the paper feeding rose, starts rotating 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 the scan ready (first page) to the printer 7 (step S22).
[0056]
The printer 7 receives the scan ready (first page) of the scanner 1 and performs a paper feed operation (the paper is moved to the paper start point M by the distance C (see FIG. 4) and stopped), and then the start command is sent to the scanner 7. 1 (step S23). The scanner 1 receives the start command (first page) of the printer 7 and starts scanning, and also transfers image data (first page) to the printer 7 (step S24).
[0057]
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 the distance B)) (steps S25 and S26). At this time, the scanner 1 and the printer 7 operate in synchronization, and the printer 7 prints image data scanned by the scanner 1. During this printing, the printer 7 further prepares for printing (second page) (moves paper from the cassette to the paper feed roller, etc.), and transfers a scan request (second page) to the scanner 1 (step S27). . After the scanning is completed, the scanner 1 performs processing such as back carriage and lamp off, and the scanning operation of the scanner 1 is completed (step S28).
[0058]
After the laser printing is finished, the printer 7 finishes paper conveyance and the like, and finishes the printing operation of the printer 7 (first page) (step S29). After completing the scan, the scanner 1 prepares for scanning (lamp-on, etc.), and transfers the scan ready (second page) to the printer 7 (step S30).
[0059]
The printer 7 receives the scan ready (second page) from the scanner 1 and performs a paper feed operation (moves the paper to the paper start point M by the distance C (see FIG. 4) and stops), and then performs a start command ( (Second page) is transferred to the scanner 1 (step S31). The scanner 1 receives the start command (second page) of the printer 7 and starts scanning, and also transfers image data (second page) to the printer 7 (step S32).
[0060]
The printer 7 receives the image data from the scanner 1 and starts printing (laser printing, paper transport (moving the paper to the transfer position by the distance B)) (steps S33 and S34). The scanner 1 and the printer 7 operate in synchronization, and the printer 7 prints image data scanned by the scanner 1. After the scanning is completed, the scanner 1 performs processing such as back carriage and lamp off, and the scanning operation of the scanner 1 is completed (step S35).
[0061]
After completing the printing, the printer 7 ends the laser printing, the paper conveyance, the photosensitive drum rotation stop, and the like, and the printing operation of the printer 7 is ended (step S36).
[0062]
FIG. 10 is a diagram showing an embodiment of a printer / scanner command / status transfer process (one page copy). In this embodiment, the printer moves the paper to the paper start point M between the start command transmission and the start of image data reception.
[0063]
First, the printer 7 prepares for printing (moves the paper from the cassette to the paper supply roller, starts rotating the photosensitive drum, etc.), and transfers a scan request to the scanner 1 (step S41). The scanner 1 receives the scan request from the printer 7, performs scan preparation (lamp on, white / black preparation correction, etc.), and transfers the scan ready to the printer 7 (step S42).
[0064]
The printer 7 receives the scan ready of the scanner 1 and transfers a start command to the scanner 1. At the same time, a paper feed operation (the paper is moved to the paper start point M by a distance C (see FIG. 4) and stopped) is performed (step S43). The paper feeding operation of the printer 7 is completed before the image data transfer of the scanner 1 is started. This is when the minimum value (min) of the time from when the printer 7 transfers the start command to the scanner 1 until the start of image data transfer of the scanner 1 is known. It is effective when it can be terminated.
[0065]
The scanner 1 receives the start command from the printer 7 and starts scanning. When the scan starts, image data is transferred to the printer 7 (step S44).
[0066]
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 the distance B)) (steps S45 and S46). The scanner 1 and the printer 7 operate in synchronization, and the printer 7 prints image data scanned by the scanner 1.
[0067]
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 IEEE 1394 signal transmission cable 26. This is because the command is transferred by ASYNC transfer as shown in FIG. For example, when the usage rate of the IEEE 1394 signal transmission cable 26 is high, the delay time is large. Therefore, the time from when the printer 7 transmits the start command to when the printer 7 receives the image data from the scanner also varies. As a result, in the conventional method, the print start position on the paper varies. However, in the present invention, since the image data is received and the laser printing and the paper conveyance from the paper start point are started, the print start position is not shifted. This is because, as shown in FIG. 4, the paper conveyance speed and the peripheral speed of the photosensitive drum are the same, and the peripheral surface distance A from the laser irradiation position P to the transfer position N and the distance B from the paper start point M to the transfer position N are as follows. This is because they are identical.
[0068]
In step S47, the scanner 1 performs processing such as back carriage and lamp off after the scanning is completed, and the scanning operation of the scanner 1 is completed. After completing the printing, the printer 7 terminates the laser printing, the paper conveyance, the photosensitive drum rotation stop, etc., and the printing operation of the printer 7 is terminated (step S48).
[0069]
FIG. 11 is a diagram showing an embodiment of the command / status transfer process (two-page copy) between the pudding and the scanner. Also in this embodiment, the printer moves the paper to the paper start point M between the start command transmission and the start of image data reception.
[0070]
First, the printer 7 prepares for printing (moves the paper from the cassette to the paper feed roller, starts rotating the photosensitive drum, etc.), and transfers a scan request (first page) to the scanner 1 (step S51). The scanner 1 receives the scan request (first page) from the printer 7, prepares for scan (lamp on, white / black preparation correction, etc.), and transfers the scan ready (first page) to the printer 7 (step S52).
[0071]
The printer 7 receives the scan ready of the scanner 1 and transfers a start command (first page) to the scanner 1. At the same time, the paper is fed (the paper is moved to the paper start point M by a distance C (see FIG. 4) and stopped) (step S53). The paper feeding operation of the printer 7 is completed before the image data transfer of the scanner 1 is started. As described above, this is a case where the minimum value (min) from the transfer of the start command of the printer 7 to the scanner 1 until the start of the image data transfer of the scanner 1 is known. This is effective when the sheet 7 can be finished.
[0072]
The scanner 1 receives the start command (first page) from the printer 7 and starts scanning. Simultaneously with the start of scanning, image data transfer (first page) is performed to the printer 7 (step S54).
[0073]
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 the distance B)) (steps S55 and S56). The scanner 1 and the printer 7 operate in synchronization, and the printer 7 prints image data scanned by the scanner 1.
[0074]
While the printer 7 is printing the image data scanned by the scanner 1, the printer 7 further prepares for printing (second page) (such as moving the paper from the cassette to the paper feed roller), and scans the scanner 1. The request (second page) is transferred (step S57). After the scanning is completed, the scanner 1 performs processing such as back carriage and lamp off, and the scanning operation of the scanner 1 is completed (step S58).
[0075]
After the printing is completed, the printer 7 ends the laser printing, the paper conveyance, and the like, and ends the printing operation of the printer 7 (step S59). After completing the scan, the scanner 1 prepares for scanning (lamp-on, etc.), and transfers the scan ready (second page) to the printer 7 (step S60).
[0076]
The printer 7 receives the scan ready of the scanner 1 and transfers a start command (second page) to the scanner 1. At the same time, a paper feeding operation (the paper is moved to the paper start point M by a distance C (see FIG. 4) and stopped) is performed (step S61). The paper feeding operation of the printer 7 is completed before the image data transfer of the scanner 1 is started. The scanner 1 receives a start command (second page) from the printer 7 and starts scanning, and also transfers image data (second page) to the printer 7 (step S62).
[0077]
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 the distance B)) (steps S63 and S64). The scanner 1 and the printer 7 operate in synchronization, and the printer 7 prints image data scanned by the scanner 1. After the scanning is completed, the scanner 1 performs processing such as back carriage and lamp off, and the scanning operation of the scanner 1 is completed (step S65). After completing the printing, the printer 7 terminates the laser printing, the paper conveyance, the photosensitive drum rotation, and the like, and the printing operation of the printer 7 is terminated (step S66).
[0078]
FIG. 12 is a block diagram showing a configuration of a PM (Page Memory) and a printer according to the second embodiment of the present invention. In the second embodiment, a PM 20 is connected to the printer 7 instead of the scanner 1 of FIG.
[0079]
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.
[0080]
The HSYNC signal of the HSYNC generation circuit 22 according to the present invention is set by the CPU M upon receiving data of the printer HSYNC cycle from the printer 7. The printer HSYNC cycle data from the printer 7 is transferred to the IEEE 1394 I / F 14 of the PM by the CPUP using the IEEE 1394 I / F 16. The printer HSYNC cycle transferred to the IEEE 1394 I / F 14 of the PM 20 is read by the CPU M21 and is generated by counting a reference clock (not shown) in the HSYNC generation circuit 22 in order to generate the same HSYNC cycle as that of the printer 7.
[0081]
For one cycle of the synchronization signal from the HSYNC generation circuit 22, the memory control unit 23 reads image data for one line from the memory. The memory control unit 23 transfers the read image data to the transmission buffer 25.
[0082]
When a certain amount of image data transferred to the transmission buffer 25 is stored, it is transferred to the IEEE1394 I / F14. The IEEE 1394 I / F 14 transfers image data to the printer 7 through the IEEE 1394 cable 26.
[0083]
The image data up to the input of the transmission buffer 25 is processed for each line of image data in the HSYNC cycle, whereas the image data transfer by the IEEE1394 I / F 14 after the output of the transmission buffer 25 is fixed at a 125 μs cycle. is there. For example, 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 25 checks whether transmission data is prepared in the transmission buffer in units of 125 μs. When the transmission data is prepared, the image data is transferred to the printer 7 through the IEEE 1394 I / F 14. The transmission buffer 25 performs timing conversion of image data transfer in the HSYNC cycle and the 125 μs cycle.
[0084]
The image data transferred to the printer 7 is transferred to and stored in the reception buffer 17 through the IEEE 1394 I / F 16. When the image data stored in the reception buffer 17 is prepared for one line, it is transferred to the laser drive circuit 18 for each HSYNC of the printer.
[0085]
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.
[0086]
Until the input of the reception buffer 17, image data transfer with a period of 125 μs is performed. After the output of the reception buffer 17, transfer for each line of image data is performed in the HSYNC cycle. The reception buffer 17 performs timing conversion of image data transfer in the 125 μs cycle and the HSYNC cycle.
[0087]
FIG. 13 is a diagram showing the generation of the HSYNC signal of the HSYNC generation circuit 22 and the memory read timing.
[0088]
In the HSYNC generation circuit 22 in the PM of FIG. 12, 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. ing.
[0089]
The CPU M21 sets a setting 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 value set in CPUM is “625”, and the value of the counter is “−1” in one clock cycle. As the counter value, the value from “625” to “0” is repeated, and the HSYNC signal having a period 626 times the reference clock period can be generated. The HSYNC generation circuit 22 outputs “L” when the counter value is “0”, and outputs the “H” value other than “0”. Unlike the HSYNC signal generated by the printer, the HSYNC signal generated from the HSYNC generation circuit 22 does not include signal jitter, that is, fluctuation.
[0090]
The HSYNC signal output from the HSYNC generation circuit 22 is input to the memory control unit 23. The memory control unit 23 starts an image data read operation from the memory 24 from the enable state in the control of the memory read enable (EN) by the HSYNC signal. The one-line data memory read enable signal EN is set to the “L” enable state from the rise of the HSYNC signal. When one line of image data is read from the memory 24, the one-line data memory read enable signal EN is disabled to “H”, and the memory read operation is stopped. The one-line data memory read enable signal EN becomes “L” enabled again from the next rise of the HSYNC signal, and image data starts to be read. By repeating this, image data for one page is read from the memory 24.
[0091]
FIG. 14 is a block diagram showing the configuration of a color scanner 30 and a color printer 40 according to the third embodiment of the present invention.
[0092]
The CPUCS in the scanner 30 controls each block in the scanner 1 block, and the CPUCP in the printer 40 controls each block in the printer 7 block.
[0093]
The color scanner 30 reads the image data “RGB” of the original with the RGB integrated color CCD line sensor 33 driven by the CCD drive circuit 34 and transmits the reflected light of the light source 32 to the image processing circuit 35.
[0094]
The image processing circuit 35 converts the input RGB signal into a YMCK signal, performs image processing, and transfers it to the transmission buffer 36. In order to perform color copying of one page of the document by four times scanning and four times printing, 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 “M” image data from the “RGB” image data to the transmission buffer 36. In the third page scan, the image processing circuit 35 transfers the image data “C” from the image data “RGB” to the transmission buffer 36. In the fourth page scan, the image processing circuit 35 transfers the image data “K” from the image data “RGB” to the transmission buffer 36.
[0095]
When a certain amount of image data transferred to the transmission buffer 36 is stored, it is transferred to the IEEE 1394 I / F 14. The IEEE 1394 I / F 14 transfers image data to the printer 40 through the IEEE 1394 cable 26.
[0096]
The image data up to the input of the transmission buffer 36 is processed for each line of image data in the HSYNC cycle, whereas the transfer of image data by the IEEE1394 I / F 14 after the output of the transmission buffer 36 is fixed at a 125 μs cycle. It is. The transmission buffer 36 checks whether transmission data is prepared in the transmission buffer in units of 125 μs. When the transmission data is prepared, the image data is transferred to the printer 40 through the IEEE 1394 I / F 14. The transmission buffer 36 performs timing conversion of image data transfer in the HSYNC cycle and 125 μs cycle.
[0097]
The image data transferred to the printer 40 is transferred 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 prepared for one line, it is transferred to the laser drive circuit 43 for each HSYNC.
[0098]
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 to form a latent image on the photosensitive drum 47.
[0099]
The image data “Y” that has been page-scan transferred from the scanner 30 for the first time is developed by the printer 40 using the “Y” development unit of the color development unit 46. The image data 'M' transferred for page scan from the scanner 30 for the second time is developed by the printer 40 using the 'M' developing unit of the color developing unit 46. The image data 'C' that has been page-scan 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. The image data “K” that has been page-scan transferred from the scanner 30 for the fourth time is developed by the printer 40 using the “K” developing unit of the color developing unit 46.
[0100]
The color image (YMCK composite image) formed on the photosensitive drum 47 by the fourth development is transferred from the paper start point when the transfer of the fourth image data 'K' to the color printer 40 is started. Is transcribed.
[0101]
In the color printer 40, image data is transferred at a cycle of 125 μs until the input to the reception buffer 42. After the output of the reception buffer 42, image data for one line is transferred in the HSYNC cycle. The reception buffer 42 performs timing conversion of image data transfer in the 125 μs cycle and the HSYNC cycle.
[0102]
FIG. 15 is a diagram showing a data transfer procedure between the color scanner 30 and the color printer 40.
[0103]
The CCD drive circuit 34 of the color scanner 30 always outputs “R ″ G ″ B” image data from the RGB integrated color CCD line sensor 33 to the image processing circuit 35 from 1 scan to 4 scans.
[0104]
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 in 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.
[0105]
The IEEE 1394 cable 26 transfers the image data “Y” to the color printer 40 at the first scan, transfers the image data “M” at the second scan, transfers the image data “C” at the third scan, and performs four scans. The image data 'K' is transferred with the eyes.
[0106]
The reception buffer 42 of the color printer 40 outputs the image data “Y” to the laser drive circuit 43 at the first scan of the color scanner 30, outputs the image data “M” at the second scan, and the image data “at the third scan”. C 'is output, and image data' K 'is output at the fourth scan.
[0107]
The color scanner 30 can read the image data of “R” G ”B” by one scan, but the printer 40 can read the color image by “Y” M ”C” K ”four times of development. To print. 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 the development is performed three times. A buffer is required. However, in this embodiment, the capacity of the reception buffer is reduced by the printer 40 receiving image data necessary for development in four steps.
[0108]
【The invention's effect】
Both 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 transmission of the start command and the start of image data reception both receive the image data from the scanner 1 and then the printer. 7 is started, the print position accuracy due to the time variation of the start command transmission using IEEE 1394 and the paper transfer start timing is reduced, so the print position accuracy in the sub-transport direction is improved.
[0109]
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 reception buffer of the printer 7 is reduced.
[0110]
Furthermore, since the data transferred from the color scanner is the same color as that used in the color printer, a large amount of reception buffer required when simultaneously transferring multiple colors is not necessary.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a scanner reading start position.
FIG. 2 is a diagram showing a relationship between a scanner carriage start position and a scanner reading start position.
FIG. 3 is a diagram illustrating a relationship between a printer's PHDYNC-0 signal and an image data printing position.
FIG. 4 is a diagram showing a paper start point M in a 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 a scanner / printer 7;
FIG. 7 is a diagram showing an example of a data transfer format according to IEEE 1394.
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: 2 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 showing a command / status (one page copy) transferred between a printer and a scanner by a paper start method in a time from start command transmission to image data reception start.
FIG. 11 is a diagram showing commands / status (continuous copy: 2 pages) transferred between the printer and the scanner by a paper start method in the time from the start command transmission to the start of image data reception.
FIG. 12 is a PM / printer connection block diagram.
FIG. 13 is a diagram showing generation of a HSYNC signal and memory read timing.
FIG. 14 is a block diagram of a color scanner / color printer connection.
FIG. 15 is a diagram showing a data transfer procedure between a color scanner and a color printer.

Claims (5)

A scanner that scans and reads a document image in the main scanning and sub-scanning directions and provides image data corresponding to the document image via the IEEE 1394 interface;
A printer having a paper cassette, a paper feed roller, and a photosensitive drum, receiving the image data from the scanner via an IEEE 1394 interface, and forming an image corresponding to the image data on the conveyed paper;
The printer feeds paper from a paper cassette to a paper start point in front of the photosensitive drum via a paper feed roller, stops the laser, and when image data reception from the scanner starts, a laser corresponding to the image data. Means for irradiating the photosensitive drum with light and starting the paper conveyance from the paper start point to a transfer position on the photosensitive drum by the paper feed roller;
The peripheral speed of the photosensitive drum and the paper conveyance speed are the same, and the distance on the photosensitive drum from the laser writing position to the transfer position is also the same as the distance from the paper start point to the transfer position. apparatus. The image forming apparatus according to claim 1 , wherein the printer sends a scan start command to the scanner after feeding the paper to the paper start point . The printer front SL paper moves from a paper cassette to the paper feed roller, and sends a scan start command to the scanner, then claims, characterized in that stopping by the paper feed the paper until the paper start point Item 2. The image forming apparatus according to Item 1. 2. The image forming apparatus according to claim 1 , wherein a sub-scanning speed of the scanner and a paper transport speed of the printer are the same . 2. The image forming apparatus according to claim 1, wherein a document image reading speed of the scanner and an image forming speed of the printer are substantially the same .

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