JP2011088390A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transmit reliable image data at a low price. <P>SOLUTION: The image forming apparatus includes a controller part 1 with FIFO 19 to 22 for holding image data, a serial data transfer part 2 for transmitting the image data of each color through time sharing for each color from the controller part 1, and a printer engine part 3 with FIFO 33 to 36 for holding the transmitted image data temporarily for each color. FIFO status detection part 49 detects the empty situation of FIFO 33 to 36 for each color and decides the color with the largest empty, and then notifies the color to the controller part 1 as a data request. The controller part 1 chooses the color of the image data transmitted according to the notified data request, and the image data of the chosen color are transmitted to the printer engine part 3 by the serial data transfer part 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to a technique suitable for use in an inline printer.

  As a conventional image printing apparatus, a page printer has a controller unit and an engine unit, and is connected to a host computer having a printer driver via a network, a USB interface, or the like as shown in FIG. The controller unit converts the intermediate output data generated from the printing source data by a device such as a host computer into output image data suitable for output, and the engine unit acquires the output image data output from the controller unit, such as paper Images to other media. Generation of intermediate output data suitable for the controller unit is generally performed by software called a printer driver. Further, the controller unit converts the intermediate output data into output image data suitable for the engine unit, and outputs it as a video signal to the engine unit in synchronization with an image transfer permission signal from the engine unit. The engine unit controls and drives the electrophotographic process, and outputs the input video signal as an image on a medium such as paper.

  On the other hand, for an electrophotographic process type color printer, a high-speed printing method based on parallel processing called an inline method has been proposed and put into practical use. In the in-line method, it is possible to shorten the printing time by arranging the photosensitive drums for four colors in a line and overlapping the printing processes of the respective colors.

  FIG. 4 shows the output data output timing of the inline system, a is a page synchronization signal, and b to e are transfer timings of the print data. As shown in FIG. 4, in the inline type electrophotographic printer, it is necessary to transfer the print data of each color almost simultaneously in synchronization with the page synchronization signal.

  In recent years, with an increase in resolution and speed of a printer engine, it is required to increase the transmission speed of the video signal. Therefore, with recent advances in serial data transfer technology, a technology for serially transferring image data at high speed using a high-speed serial transfer technology has been disclosed (for example, see Patent Documents 1 and 2).

JP 2002-321407 A JP 2005-301673 A

  As described above, in an in-line color image forming apparatus, it is necessary to transfer data by overlapping four colors of cyan, magenta, yellow, and black. However, when four-color image data is transmitted in a time-sharing manner using one-channel serial data transfer means, the transfer of the color data may not be in time for the speed required by the printer engine. In such a case, problems such as failure to perform normal printing occur.

  Therefore, it is possible to provide a high-speed serial data transfer means for each color to avoid this problem, but since a plurality of serial transfer means are required, the cost of the image forming apparatus is increased. It is also conceivable to provide a page memory in the second image processing means and transfer one page of data in advance, but even if this method is used, it is necessary to provide an expensive page memory. As a result, the cost of the image forming apparatus is increased.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to realize a reliable transfer of image data at a low cost.

  An image forming apparatus according to the present invention includes a first image processing unit including a first storage unit that holds image data, and serial data transfer for transferring image data of each color from the first image processing unit for each color. And a second image processing means having a second storage means for holding the image data transferred by the serial data transfer means for each color, and detecting an empty state for each color of the second storage means And a status detection means for determining a color having the largest vacancy, and a notification means for notifying the first image processing means of a result detected by the status detection means as a data request. The processing means selects the color of the image data to be transferred in response to the data request notified by the notification means, and the serial data transfer means selects the image data of the selected color from the second image. Characterized by transferring to the processing means.

  According to the present invention, since necessary image data is requested from the printer engine to the printer controller, it is not necessary to have a page memory in the printer engine. Therefore, an inexpensive image forming apparatus can be realized. Further, it is possible to realize highly reliable data transfer without using analog data transfer from the controller to the printer engine.

1 is a block diagram illustrating a configuration example of a color image forming apparatus according to a first embodiment. It is a block diagram which shows the example of a structure of a part of conventional inline system printer. It is a figure which shows the controller part and engine part of the conventional page printer. FIG. 6 is a diagram illustrating output data output timing of an inline method. It is a figure which shows an example of the transmission timing of a request signal, and the empty state of FIFO. It is a block diagram which shows the structural example of the color image forming apparatus of 2nd Embodiment. It is a figure which shows a mode that the signal of the transfer request | requirement of four image data is packetized.

  Embodiments according to the present invention will be described below in detail with reference to the accompanying drawings.

(First embodiment)
First, the configuration of a conventional general inline printer will be described.
FIG. 2 is a block diagram illustrating a configuration example of a controller of a conventional inline printer.
As shown in FIG. 2, the controller includes a CPU 201 connected to a system bus 207, a ROM 202, an external i / f unit 203, a 4-channel DMAC 204, a page memory 205, an image output unit 260, and the like. Further, the image output unit 260 is connected to the printer engine 280. The intermediate output data generated by the host computer is received by the external i / f unit 203, converted into compressed data that can be processed by hardware under the control of the CPU 201, and stored in the page memory 205. When the storage of compressed data necessary for output is completed, the DMAC 204 for four channels is activated by an instruction from the CPU 201, and the stored compressed data for four colors is transferred from the page memory 205 to the image output unit 260.

  Here, the image output unit 260 includes decoder units 261a to 261d, temporary storage buffer memories 262a to 262d, and an engine i / f unit 263. The decoder units 261a to 261d convert the compressed data into an output image data format suitable for the engine i / f unit 263. The engine i / f unit 263 is connected to the printer engine 280 and outputs the image data as a video signal.

Next, a configuration in the present embodiment will be described.
FIG. 1 is a block diagram showing a configuration example of a color image forming apparatus related to image data transfer of an inline laser beam printer in the present embodiment.
As shown in FIG. 1, the color image forming apparatus of this embodiment is divided into a controller unit 1 as a first image processing unit and a printer engine unit 3 as a second image processing unit. Further, image data is serially transferred between the controller unit 1 and the printer engine unit 3 by using a high-speed serial data transfer unit 2. In this embodiment, transfer of image data of four colors of cyan, yellow, magenta, and black is performed using the serial data transfer unit 2 of one channel.

  The CPU 11 controls the entire apparatus and generates image data that can be output to the printer engine unit 3 from print data received from the external interface 13. The ROM 12 stores processing procedure programs processed by the CPU 11, font data, and the like. The external interface 13 is a LAN interface such as Ethernet (registered trademark) or an I / O interface such as USB, IEEE1284, or IEEE1394, and receives image data from a host device (host computer). The image memory 14 is a memory for temporarily storing image data for one page or one band generated by the CPU 11. At this time, in order to save the memory capacity, the CPU 11 may compress the image data and store the compressed data. The printer engine unit 3 is an inline laser beam printer and requires simultaneous transfer of image data of a plurality of colors.

  Next, the internal configuration of the image data output unit 15 will be described. Reference numerals 19 to 22 denote FIFO (First In First Out) which are memories of cyan, yellow, magenta, and black, respectively, and image data for each color stored in the image memory 14 is transferred by the DMA access control unit 18. . The multiplexer unit 23 is for selecting the data of each color stored in the FIFOs 19 to 22 as the first storage means. The serializer 17 converts the parallel data input from the FIFOs 19 to 22 into serial data and performs high-speed serial data transfer of 600 Mbps to 1 Gbps.

  Next, the configuration of the printer engine unit 3 will be described. The deserializer 31 converts the serial data transferred by the serial data transfer unit 2 into parallel data. The demultiplexer 32 distributes and transfers the parallel data to the FIFOs 33 to 36 as the second storage means for the color. Each color FIFO 33 to 36 stores image data (parallel data) and transfers the image data to the respective image processing units 37 to 40. Each color image processing unit 37 to 40 performs image processing such as γ correction and halftone processing. Each of the image processing units 37 to 40 includes a look-up table, and can perform appropriate image processing according to the print image by changing the γ table and the halftone table. Furthermore, image processing according to the characteristics of the printer engine unit 3 can be performed by changing the lookup table based on feedback from various sensors of the engine (not shown).

  The video signal conversion units 41 to 44 convert the image data transferred from the corresponding image processing units 37 to 40 into video signals for controlling the lighting of the laser, respectively, and the corresponding scanner units 45 to 48 respectively. Control the laser. The video signal conversion units 41 to 44 control the exposure timing based on the horizontal synchronization signals from the scanner units 45 to 48. The scanner units 45 to 48 control the lighting of the laser according to the video signal to expose a photosensitive drum (not shown) and output a horizontal synchronization signal to the video signal conversion units 41 to 44. The FIFO status detection unit 49 monitors the availability of the FIFOs 33 to 36 for each color, and determines the color with the largest FIFO availability. Then, the resulting signals 50 to 53 are transferred to the controller unit 1.

  In the above configuration, the CPU 11 receives data sent from the host computer via the external interface 13, generates image data in a format that can be output to the printer engine unit 3, and stores the image data in the image memory 14. When image data of a predetermined amount (a page or a band of a predetermined size) is generated, the CPU 11 notifies the printer engine unit 3 of a print start instruction via an engine interface circuit (not shown). Receiving the print start instruction, the printer engine unit 3 starts the printing operation and outputs a vertical synchronization signal indicating the transfer timing of the image data. The engine interface circuit receives the vertical synchronization signal from the printer engine unit 3, and notifies the CPU 11 of the data transfer timing of each color from the vertical synchronization signal. As a result, the CPU 11 activates a DMA controller (not shown) in the DMA access control unit 18 for the color to be transferred to the printer engine unit 3 to transfer image data. The image data stored in the FIFOs 19 to 22 by the DMA controller is controlled by the multiplexer unit 23 to be transferred to the printer engine unit 3.

  On the other hand, the image data request signal is input from the FIFO status detection unit 49 to the multiplexer unit 23. The multiplexer unit 23 selects one FIFO from the four FIFOs 19 to 22 in accordance with the image data request signal, and permits input to the serializer 17. At this time, the image data request signal is given a certain amount of time width so that the multiplexer unit 23 can reliably capture the image data request signal. Hereinafter, this situation will be specifically described with reference to FIG.

FIG. 5 is a diagram illustrating an example of the transmission timings of the four image data request signals (signals 50 to 53) generated by the FIFO status detection unit 49 and the empty states of the FIFOs 33 to 36.
The numerical value shown in FIG. 5 is a numerical value from 0 to 100 indicating the free state of the FIFOs 33 to 36, and the higher the numerical value, the larger the free space of the FIFOs 33 to 36. Further, “-” in FIG. 5 represents a state where the FIFO status detection unit 49 has not yet read the states of the FIFOs 33 to 36. This signal is input to the multiplexer unit 23 and becomes “H” when the FIFO free space is the largest in CMYK, and becomes “L” otherwise.

  In FIG. 5, in the section (a), since the empty space is the largest in the C FIFO 33, the C signal is “H”. Similarly, since the vacant area is the largest in the FIFO of M in the section (c), Y in the section (e), and K in the section (g), the signal of M is' H in the section (c). In the section (e), the Y signal is “H”, and in the section (g), the K signal is “H”. In addition, as in the sections (b), (d), (f), and (h), when all of the CMYK signals are “L”, this indicates a state in which CMYK image data is not requested.

  Here, as shown in the section (i), when there are a plurality of FIFOs having the largest vacancy among the four CMYK signals, the plurality of signals are not simultaneously set to “H”. Therefore, priorities of CMYK are given to the FIFO status detection unit 49 in advance. For example, if the priority is given as C> M> Y> K, M becomes 'H' and K becomes 'L' in the section (i). The multiplexer unit 23 extracts the image data stored in the FIFO corresponding to the color being “H” from any of the FIFOs 19 to 22 from the four input signals 50 to 53, and supplies the image data to the serializer 17. Allow input. Specifically, the image data of FIFO 19 is C, FIFO 20 is M, FIFO 21 is Y, and FIFO 22 is K.

  Assuming that, when the four signals 50 to 53 shown in FIG. 5 are input to the multiplexer unit 23, the multiplexer unit 23 outputs the image from the FIFO 19 because the C signal is “H” in the section (a). Extract data. Similarly, in the section (c), the M signal is “H”, so from the FIFO 20, the Y signal is “H” in the section (e), and from the FIFO 21, the K signal is sent in the section (g). Since it is “H”, image data is extracted from the FIFO 22. In the sections (b), (d), (f), and (h), since all four signals are 'L', the multiplexer unit 23 does not extract image data from any of the FIFOs 19 to 22.

  As described above, according to the present embodiment, when the image data of each color is transferred, the FIFO status detection unit 49 monitors the empty state of the FIFOs 33 to 36 of the printer engine unit 3, and from among these FIFOs 33 to 36, Determine the color with the largest vacancy. Then, the signal corresponding to the color is set to “H”. At this time, if there are two or more FIFOs with the largest vacancy, the color signal having a higher priority is set to “H” in accordance with the CMYK priority determined in advance. These four signals 50 to 53 are input to the multiplexer unit 23. Therefore, the multiplexer unit 23 selects any one of the FIFOs 19 to 22 in accordance with “H” or “L” of the signal, passes the serializer 17, and transfers the image data to the engine unit. Therefore, data transfer can be performed for a specific color with a small remaining amount of data stored in the FIFO. As a result, the serial data transfer unit can be used according to the data required by the engine control unit, and data transfer can be performed efficiently.

  In this embodiment, the serial data transfer rate is set to 600 Mbps to 1 Gbps, but is not limited to these transfer rates. In addition, since the printer engine unit 3 includes a FIFO, it is possible to start the transfer of image data at the same time that the controller unit 1 issues a print start instruction without waiting for the vertical synchronization signal of the engine.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described.
FIG. 6 is a block diagram illustrating a configuration example of a color image processing apparatus according to the present embodiment. In addition, the same number is attached | subjected to the location which has the same function as the structure of 1st Embodiment. Therefore, the description of the overlapping part described in the first embodiment is omitted.

  Hereinafter, this embodiment will be described with reference to FIG. The present embodiment is characterized in that a packet signal 58 is generated and transferred using the four generated image data request signals. By transferring packets, in the first embodiment, four signals can be replaced with one packet signal 58, and cost, circuit area, and the like can be suppressed.

Next, the packet communication of this embodiment will be specifically described with reference to FIG. FIG. 7 is a diagram illustrating a state in which four image data transfer request signals are packetized.
As shown in FIG. 7, since the C signal is “H” and the MYK signal is “L” in the section (a), the packet signal 58 is “HLLL”. Similarly, the sections (b) to (i) can be packetized as shown in FIG. The multiplexer unit 23 selects one of the four FIFOs 19 to 22 based on the input packet signal 58 and extracts image data of a requested color. Here, if “H” is “1” and “L” is “0”, the packet signal 58 of “1000” is input to the multiplexer unit 23 in the section (a).

  Here, the multiplexer unit 23 is set to extract data from the K FIFO 22 when the first digit bit is “1”. Similarly, when the second digit bit is “1”, from the FIFO 21 of Y, when the third digit bit is “1”, from the FIFO 20 of M, when the fourth digit bit is “1”, Set to retrieve data from C FIFO 19. In this case, in the section (a), the multiplexer unit 23 extracts the image data from the C FIFO 19 and permits the serializer 17 to input the image data. Similarly, in the interval (c), the image data is extracted from the M FIFO 20, the image data is extracted from the Y FIFO 21 in the interval (e), and the image data is extracted from the K FIFO 22 in the interval (g). The image data is input to the serializer 17.

  As described above, according to the present embodiment, the FIFO status detection unit 49 packetizes the four generated image data request signals and transfers the packet signal 58, as in the first embodiment. It is not necessary to transmit four image data request signals. As a result, cost reduction and circuit area reduction can be expected.

(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

1 controller unit, 2 serial data transfer unit, 3 printer engine unit, 19-22, 33-36 FIFO, 49 FIFO status detection unit

Claims (3)

First image processing means comprising first storage means for holding image data;
Serial data transfer means for transferring image data of each color from the first image processing means for each color;
A second image processing means comprising a second storage means for holding the image data transferred by the serial data transfer means for each color;
Status detecting means for detecting a vacant state for each color in the second storage means and determining a color having the largest vacancy;
Notification means for notifying the first image processing means as a data request of the result detected by the status detection means,
The first image processing means selects a color of image data to be transferred in response to the data request notified by the notification means,
The image forming apparatus, wherein the serial data transfer unit transfers the image data of the selected color to the second image processing unit.   The image forming apparatus according to claim 1, wherein the notification unit notifies a signal for each color.   The image forming apparatus according to claim 1, wherein the notifying unit notifies the image data transfer request using packet communication.

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