JP4308680B2 - Image forming apparatus - Google Patents

Description

The present invention relates to an image forming apparatus such as a full-color multifunction peripheral (MFP) that handles various image data and performs various processes.

  In general, an image forming system (image forming apparatus) such as a digital copying machine or MFP that handles image data and other data may handle various types of image data having different data amounts. In particular, in a full-color digital copying machine, a full-color MFP, and the like, for example, a color scanner handles 8-bit image data for each RGB color, while a color printer handles 2-bit image data for each YMCK color. In this case, in order to temporarily store the image data in a form suitable for each image data, a separate memory is assigned to the input system and the output system, and a separate memory controller is assigned to each memory, thereby handling the image data. There is something that made it easier.

  In this type of image forming system (image forming apparatus), the use of a high-speed serial interface such as IEEE1394 or USB is considered as an interface between devices. For example, according to Patent Document 1, it is proposed to use a high-speed serial interface such as IEEE1394 or USB as an internal interface.

  As another high-speed serial interface, an interface called PCI Express (registered trademark), which is a successor to the PCI bus system, has been proposed and has been put to practical use (for example, see Non-Patent Document 1).

JP 2001-16382 A “Outline of PCI Express Standard” Interface, July’2003 Naoshi Satomi

  However, in the case of Patent Document 1 using a high-speed serial interface such as IEEE1394 or USB, it is difficult to secure a scalable bus width. For example, in a configuration including a plurality of memory controllers as described above, it is attempted to operate in parallel. In this case, a configuration with the maximum standard is required as a high-speed serial interface, which increases costs.

  An object of the present invention is to effectively utilize a PCI Express standard high-speed serial bus having features such as high scalability in a system configuration including, for example, a memory controller function unit, so that various types of image data having different data amounts can be obtained. In handling, the parallel operation by the memory controller function unit is to be maximized at low cost.

An image forming apparatus of the present invention executes an image processing unit that performs image processing on image data, a first memory control unit that executes control on a first memory, and controls on a second memory A second memory control unit, a connection unit that connects the image processing unit and the first memory control unit and the second memory control unit, and a connection between the image processing unit and the connection unit. A first bus having a variable number of lanes and conforming to the PCI Express standard, and the first bus is connected to the image processing unit from the first memory control unit via the connection unit. The number of lanes having a first value corresponding to the size of the image data to be transferred is set, and the image transferred from the image processing unit to the second memory control unit via the connection unit Was assumed is a bus lane number is set to have a different second value and the first value corresponding to the size of the generated image data by the processing section.

The image forming apparatus of the present invention, the input unit is a full-color scanner that handles RGB image data for each color 8-bit, the output unit is a full-color printer to handle YMCK image data for each color 2 bits, storage compression This is an HDD for storing data.

The image forming apparatus of the present invention, the number of lanes of the high-speed serial bus that form a data transfer path between the input section and the image-picture processing unit and one memory controller is x12, images processing unit and output unit and a number of lanes of high-speed serial bus that form a data transfer path between the other one of the memory controllers x4, fast to connect between the storage and the switch The number of serial bus lanes is x1.

  According to the present invention, attention is paid to the fact that the type of image data is specified by the data transfer path when handling various types of image data having different data amounts, and a system configuration including a plurality of memory controller function units is provided. In addition, each data transfer path is formed using a PCI Express standard high-speed serial bus with high scalability, and the number of lanes is set according to the image data size. The configuration is based on the optimal number of lanes, and the parallel operation by the memory controller function unit can be maximized at low cost.

  The best mode for carrying out the present invention will be described with reference to the drawings.

[Outline of PCI Express standard]
First, this embodiment uses PCI Express (registered trademark), which is one of high-speed serial buses. As an assumption of this embodiment, an outline of the PCI Express standard is a part of Non-Patent Document 1. Explained with excerpts. Here, the high-speed serial bus means an interface capable of exchanging data at high speed (about 100 Mbps or more) by serial (serial) transmission using a single transmission line.

  PCI Express is a standardized expansion bus that can be used for all computers as a successor to PCI. In general, low-voltage differential signal transmission, point-to-point independent communication channels, and packetization Split transactions and high scalability due to differences in link configuration.

  FIG. 1 shows a configuration example of an existing PCI system, and FIG. 2 shows a configuration example of a PCI Express system. In the existing PCI system, PCI-X (PCI upward compatible standard) devices 104a and 104b connect the PCI-X bridge 105a to the host bridge 103 to which the CPU 100, the AGP graphics 101, and the memory 102 are connected. A tree structure in which a PCI-X bridge 105b to which PCI-X devices 104c and 104d are connected and a PCI bridge 107 to which a PCI bus slot 106 is connected are connected via a PCI-X bridge 105c ( Tree structure).

  On the other hand, in the PCI Express system, the PCI Express graphics 113 is connected by the PCI Express 114a to the root complex 112 to which the CPU 110 and the memory 111 are connected, and the endpoint 115a and the legacy endpoint 116a. The switch 117a connected by the PCI Express 114b is connected by the PCI Express 114c, and the PCI bridge 119 to which the switch 117b to which the end point 115b and the legacy end point 116b are connected by the PCI Express 114d and the PCI bus slot 118 are connected is a PCI. The switch 117c connected by the Express 114e has a tree structure (tree structure) connected by the PCI Express 114f.

  An example of an actually assumed PCI Express platform is shown in FIG. The illustrated example shows an application example to a desktop / mobile. For example, graphics 125 is connected to a memory hub 124 (corresponding to a root complex) to which a CPU 121 is connected by a CPU host bus 122 and a memory 123 is connected. An x16 PCI Express 126a and an I / O hub 127 having a conversion function are connected by a PCI Express 126b. For example, a memory 129 is connected to the I / O hub 127 by a Serial ATA 128, a local I / O 131 is connected by an LPC 130, and a USB 2.0 132 and a PCI bus slot 133 are connected. Furthermore, a switch 134 is connected to the I / O hub 127 by a PCI Express 126c, and a mobile dock 135, a Gigabit Ethernet 136, and an add-in card 137 are connected to the switch 134 by PCI Express 126d, 126e, and 126f, respectively. Yes.

  That is, in the PCI Express system, the conventional PCI, PCI-X, AGP bus is replaced with PCI Express, and a bridge is used to connect an existing PCI / PCI-X device. Connection between chipsets is also PCI Express connection, and existing buses such as IEEE1394, Serial ATA, and USB 2.0 are connected to PCI Express by an I / O hub.

[Components of PCI Express]
A. Port / Lane / Link
FIG. 4 shows the structure of the physical layer. A port is a set of transmitters / receivers that are physically in the same semiconductor and form a link, and logically means an interface that connects components one-to-one (point-to-point). The transfer rate is, for example, one-way 2.5 Gbps (in the future, 5 Gbps or 10 Gbps is assumed). The lane is, for example, a set of 0.8 V differential signal pairs, and includes a transmission-side signal pair (two) and a reception-side signal pair (two). A link is a collection of lanes connecting two ports and the two ports, and is a dual simplex communication bus between components. The “xN link” is composed of N lanes, and N = 1, 2, 4, 8, 16, 32 are defined in the current standard. The illustrated example is an x4 link example. For example, as shown in FIG. 5, by changing the lane width N connecting the devices A and B, a scalable bandwidth can be configured.

B. Root Complex
The root complex 112 is located at the highest level of the I / O structure, and connects the CPU and the memory subsystem to the I / O. In a block diagram or the like, as shown in FIG. 3, it is often described as “memory hub”. The root complex 112 (or 124) has one or more PCI Express ports (root ports) (indicated by squares in the root complex 112 in FIG. 2), and each port is an independent I / O hierarchical domain. Form. The I / O hierarchical domain is a simple endpoint (for example, the example of the endpoint 115a side in FIG. 2), or is formed from a large number of switches and endpoints (for example, the endpoint in FIG. 2). 115b and switches 117b and 115c side).

C. End point
The endpoint 115 is a device having a configuration space header of type 00h (specifically, a device other than a bridge), and is divided into a legacy endpoint and a PCI Express endpoint. The major difference between the two is that the PCI Express endpoint basically does not request I / O port resources in the BAR (base address register), and therefore does not request an I / O request. PCI Express endpoints also do not support lock requests.

D. Switch
The switch 117 (or 134) couples two or more ports and performs packet routing between the ports. From the configuration software, the switch is recognized as a collection of virtual PCI-PCI bridges 141 as shown in FIG. In the figure, double-headed arrows indicate PCI Express links 114 (or 126), and 142a to 142d indicate ports. Of these, the port 142a is an upstream port closer to the root complex, and the ports 142b to 142d are downstream ports farther from the root complex.

E. PCI Express 114e-PCI bridge 117
Provides connection from PCI Express to PCI / PCI-X. Thereby, an existing PCI / PCI-X device can be used on the PCI Express system.

[Hierarchical architecture]
As shown in FIG. 7A, the conventional PCI architecture has a structure in which protocols and signaling are closely related and has no concept of hierarchy. In PCI Express, as shown in FIG. 7B, Like general communication protocols and InfiniBand, it has an independent hierarchical structure, and specifications are defined for each layer. In other words, a transaction layer 153, a data link layer 154, and a physical layer 155 are provided between the uppermost software 151 and the lowermost mechanism (mechanical) unit 152. Thereby, the modularity of each layer is ensured, and it becomes possible to provide scalability and reuse the module. For example, when adopting a new signal coding method or transmission medium, it is possible to cope with only changing the physical layer without changing the data link layer or the transaction layer.

  The core of the PCI Express architecture is a transaction layer 153, a data link layer 154, and a physical layer 155, each having the following roles described with reference to FIG.

A. Transaction layer 153
The transaction layer 153 is located at the highest level and has a function of assembling and disassembling a transaction layer packet (TLP). The transaction layer packet (TLP) is used for transmission of transactions such as read / write and various events. The transaction layer 153 performs flow control using credits for transaction layer packets (TLP). An outline of a transaction layer packet (TLP) in each of the layers 153 to 155 is shown in FIG. 9 (details will be described later).

B. Data link layer 154
The main role of the data link layer 154 is to guarantee data integrity of the transaction layer packet (TLP) by error detection / correction (retransmission) and link management. Packets for link management and flow control are exchanged between the data link layers 154. This packet is called a data link layer packet (DLLP) to distinguish it from a transaction layer packet (TLP).

C. Physical layer 155
The physical layer 155 includes circuits necessary for interface operations such as a driver, an input buffer, a parallel-serial / serial-parallel converter, a PLL, and an impedance matching circuit. It also has interface initialization / maintenance functions as logical functions. The physical layer 155 also serves to make the data link layer 154 / transaction layer 153 independent of the signaling technology used in the actual link.

  The PCI Express hardware configuration uses a technology called embedded clock, there is no clock signal, the clock timing is embedded in the data signal, and the receiving side is based on the crosspoint of the data signal. The clock is extracted.

[Configuration space]
PCI Express has a configuration space like conventional PCI, but its size is expanded to 4096 bytes as shown in FIG. 10, whereas conventional PCI has 256 bytes. As a result, sufficient space is secured in the future even for devices (such as host bridges) that require a large number of device-specific register sets. In PCI Express, the configuration space is accessed by accessing a flat memory space (configuration read / write), and the bus / device / function / register number is mapped to a memory address.

  The first 256 bytes of the space can be accessed as a PCI configuration space by a method using an I / O port from a BIOS or a conventional OS. The function of converting conventional access to PCI Express access is implemented on the host bridge. From 00h to 3Fh, it is a PCI2.3 compatible configuration header. As a result, a conventional OS and software can be used as they are except for functions extended by PCI Express. That is, the software layer in PCI Express inherits a load / store architecture (a method in which a processor directly accesses an I / O register) that is compatible with the existing PCI. However, in order to use functions expanded by PCI Express (for example, functions such as synchronous transfer and RAS (Reliability, Availability and Serviceability)), it is necessary to make it possible to access a 4 Kbyte PCI Express expansion space.

  Various form factors (shapes) are conceivable as PCI Express. Examples of specific examples include add-in cards, plug-in cards (NEWCARD), and Mini PCI Express.

[PCI Express architecture details]
The transaction layer 153, data link layer 154, and physical layer 155, which are the core of the PCI Express architecture, will be described in detail.

A. Transaction layer 153
The main role of the transaction layer 153 is to assemble and disassemble transaction layer packets (TLP) between the upper software layer 151 and the lower data link layer 154 as described above.

a. Address space and transaction type
In PCI Express, memory space (for data transfer with memory space), I / O space (for data transfer with I / O space), and configuration space (device configuration and setup) supported by conventional PCI In addition to message space (in-band event notification between PCI Express devices and general message transmission (exchange) ... Interrupt requests and confirmations are communicated by using the message as a "virtual wire" And four address spaces are defined. Transaction types are defined for each space (memory space, I / O space, configuration space is read / write, and message space is basic (including vendor definition)).

b. Transaction layer packet (TLP)
PCI Express performs communication in units of packets. In the transaction layer packet (TLP) format shown in FIG. 9, the header length of the header is 3DW (DW is an abbreviation of double word; total 12 bytes) or 4DW (16 bytes), and the transaction layer packet (TLP) format ( Information such as header length and presence / absence of payload), transaction type, traffic class (TC), attribute, and payload length are included. The maximum payload length in the packet is 1024 DW (4096 bytes).

  ECRC is an end-to-end data integrity guarantee and is a 32-bit CRC of the transaction layer packet (TLP) portion. This is because when an error occurs in the transaction layer packet (TLP) inside the switch or the like, the LCRC (link CRC) cannot detect the error (because the LCRC is recalculated with the TLP in error).

  Some requests do not require a completion packet, and some requests.

c. Traffic class (TC) and virtual channel (VC)
Upper software can differentiate (prioritize) traffic by using a traffic class (TC). For example, video data can be transferred with priority over network data. There are eight traffic classes (TC) from TC0 to TC7.

  A virtual channel (VC) is an independent virtual communication bus (a mechanism that uses a plurality of independent data flow buffers sharing the same link), each having resources (buffers and queues) As shown in FIG. 11, independent flow control is performed. Thereby, even if the buffer of one virtual channel becomes full (full), the transfer of another virtual channel can be performed. In other words, it can be used effectively by physically dividing one link into a plurality of virtual channels. For example, as shown in FIG. 11, when a route link is divided into a plurality of devices via a switch, the priority of traffic of each device can be controlled. VC0 is indispensable, and other virtual channels (VC1 to VC7) are mounted in accordance with the cost performance trade-off. The solid line arrow in FIG. 11 indicates the default virtual channel (VC0), and the broken line arrow indicates the other virtual channels (VC1 to VC7).

  Within the transaction layer, a traffic class (TC) is mapped to a virtual channel (VC). One or more traffic classes (TC) can be mapped to one virtual channel (VC) (when the number of virtual channels (VC) is small). In a simple example, it can be considered that each traffic class (TC) is mapped to each virtual channel (VC) on a one-to-one basis, and all traffic classes (TC) are mapped to the virtual channel VC0. The mapping of TC0-VC0 is essential / fixed, and the other mappings are controlled from the upper software. The software can control the priority of the transaction by using the traffic class (TC).

d. Flow control Flow control (FC) is performed in order to avoid overflow of the reception buffer and establish the transmission order. Flow control is done point-to-point between links, not end-to-end. Therefore, it cannot be confirmed that the packet has reached the final partner (completer) by flow control.

  PCI Express flow control is performed on a credit basis (a mechanism that confirms the buffer availability on the receiving side before starting data transfer and prevents overflow and underflow). That is, the receiving side notifies the transmitting side of the buffer capacity (credit value) at the time of link initialization, and the transmitting side compares the credit value with the length of the packet to be transmitted, and transmits the packet only when there is a certain remaining. There are six types of credits.

  Flow control information exchange is performed using data link layer packets (DLLP) in the data link layer. The flow control is applied only to the transaction layer packet (TLP) and not to the data link layer packet (DLLP) (DLLP can always be transmitted / received).

B. Data link layer 154
The main role of the data link layer 154 is to provide a reliable transaction layer packet (TLP) exchange function between two components on the link, as described above.

a. Handling of transaction layer packet (TLP) For the transaction layer packet (TLP) received from the transaction layer 153, a 2-byte sequence number at the beginning and a 4-byte link CRC (LCRC) at the end are added to the physical layer. To 155 (see FIG. 9). The transaction layer packet (TLP) is stored in the retry buffer and retransmitted until a reception confirmation (ACK) is received from the partner. When the transmission of the transaction layer packet (TLP) continues to fail, it is determined that the link is abnormal, and the physical layer 155 is requested to retrain the link. If link training fails, the state of the data link layer 154 transitions to inactive.

  The transaction layer packet (TLP) received from the physical layer 155 is inspected for the sequence number and the link CRC (LCRC). If normal, the transaction layer packet (TLP) is passed to the transaction layer 153. If there is an error, a retransmission is requested.

b. Data link layer packet (DLLP)
A packet generated by the data link layer 154 is called a data link layer packet (DLLP), and is exchanged between the data link layers 154. Data link layer packet (DLLP)
-Ack / Nak: TLP reception confirmation, retry (retransmission)
-InitFC1 / InitFC2 / UpdateFC: Flow control initialization and update-DLLLP for power management
There are different types.

  As shown in FIG. 12, the length of the data link layer packet (DLLP) is 6 bytes. From the DLLP type (1 byte) indicating the type, the information specific to the type of DLLP (3 bytes), and CRC (2 bytes) Composed.

C. Physical layer-logical sub-block 156
The main role of the physical layer 155 in the logical sub-block 156 shown in FIG. 8 is to convert the packet received from the data link layer 154 into a format that can be transmitted by the electrical sub-block 157. It also has a function of controlling / managing the physical layer 155.

a. Data encoding and parallel-serial conversion
PCI Express uses 8B / 10B conversion for data encoding so that consecutive “0” s and “1” s do not continue (in order not to maintain a state where there is no cross point for a long period of time). The converted data is serial-converted and transmitted from the LSB onto the lane as shown in FIG. Here, when there are a plurality of lanes (FIG. 13 illustrates the case of x4 link), data is allocated to each lane in units of bytes before encoding. In this case, it looks like a parallel bus at first glance, but since the transfer is performed independently for each lane, the skew which is a problem with the parallel bus is greatly reduced.

b. Power management and link state As shown in Table 1, a link state of L0 / L0s / L1 / L2 is defined in order to keep the power consumption of the link low.

  L0 is a normal mode, and power consumption is reduced from L0s to L2, but it takes time to return to L0. As shown in FIG. 14, by actively performing active state power management in addition to software power management, it is possible to reduce power consumption as much as possible.

D. Physical layer—Electric sub-block 157
The main role of the physical layer 155 in the electrical sub-block 157 is to transmit the data serialized in the logical sub-block 156 onto the lane, and to receive the data on the lane and pass it to the logical sub-block 156. is there.

a. AC coupling On the transmission side of the link, a capacitor for AC coupling is mounted. This eliminates the need for the DC common mode voltage on the transmission side and the reception side to be the same. For this reason, it is possible to use different designs, semiconductor processes, and power supply voltages on the transmission side and the reception side.

b. De-emphasis
In PCI Express, as described above, processing is performed so that continuous “0” and “1” do not continue as much as possible by 8B / 10B encoding, but continuous “0” and “1” may continue (maximum). 5 times). In this case, it is specified that the transmission side must perform de-emphasis transfer. When bits of the same polarity are consecutive, it is necessary to increase the noise margin of the signal received on the receiving side by dropping the differential voltage level (amplitude) from the second bit by 3.5 ± 0.5 dB. . This is called de-emphasis. Due to the frequency-dependent attenuation of the transmission line, there are many high-frequency components in the case of changing bits, and the waveform on the receiving side becomes small due to attenuation. Becomes larger. For this reason, de-emphasis is performed in order to make the waveform on the receiving side constant.

[Image forming system]
The image forming system such as a full-color digital copying machine or a full-color MFP according to the present embodiment uses a PCI Express standard high-speed serial bus as described above for its internal interface.

  First, a basic and principle configuration example of the present embodiment will be described with reference to FIGS. FIG. 15 is a schematic block diagram showing an example of a basic and principle configuration example of the image forming system of the present embodiment. The image forming system 1 of the present embodiment is configured to include a control unit 2, an input unit 3, an output unit 4, and a memory 7 as the minimum components.

  Here, the control unit 2 includes a CPU that controls the entire system according to an installed control program (software), and means a device portion that performs processing such as path control and path determination. The input unit 3 refers to a device or a unit for capturing image data based on a document image or the like into the system. In this case, for example, the input unit 3 is a full-color scanner that photoelectrically reads a document image and acquires image data. ing. The output unit 4 is a device or unit that prints out image data on paper or the like. In the present embodiment, the output unit 4 is, for example, an electrophotographic full-color laser printer.

  With respect to such components, in the present embodiment, the connection unit as a PCI Express standard switch so that the input unit 3 and the output unit 4 each form a data transfer path with the PCI Express standard end point as described above. 11 and PCI Express standard high-speed serial buses 12a and 12b. The number of lanes of each of these high-speed serial buses 12a and 12b is set according to the image data size handled by the data transfer path. In the illustrated example, the number of lanes of the high-speed serial bus 12a is set to x12, and the number of lanes of the high-speed serial bus 12b is set to x4 (refer to the description of FIG. 18 for details).

  FIG. 16 illustrates an application example to an image forming system in which a processing unit (image processing unit) 5 that performs image processing on image data is added to the configuration illustrated in FIG. The processing unit 5 indicates a device or a unit that performs image processing such as enlargement / reduction, rotation, and compression / decompression processing on image data, and includes, for example, a magnification changer, a rotator, and a compression / decompression unit. It is said that.

  With respect to such components, in the present embodiment, the PCI Express standard is formed so that each of the input unit 3, the output unit 4, and the image processing unit 5 forms a data transfer path as an endpoint of the PCI Express standard as described above. The connection unit 11 as a switch and the PCI Express standard high-speed serial buses 12a to 12d are connected. The number of lanes of each of these high-speed serial buses 12a to 12d is set according to the image data size handled by the data transfer path. In the illustrated example, the number of lanes of the high-speed serial bus 12a is x12, the number of lanes of the high-speed serial bus 12b is x4, the number of lanes of the high-speed serial bus 12c is x12, and the high-speed serial bus 12d The number of lanes is set to x4 (refer to the description of FIG. 18 for details).

  FIG. 17 shows an application example to the image forming system in which the storage unit 6 by the HDD as a storage for storing image data is added to the configuration shown in FIG.

  With respect to such components, in the present embodiment, the input unit 3, the output unit 4, the image processing unit 5, and the storage unit 6 are used as endpoints of the PCI Express standard as described above to form data transfer paths, respectively. The connection unit 11 as a PCI Express standard switch and the PCI Express standard high-speed serial buses 12a to 12e are connected. The number of lanes of each of these high-speed serial buses 12a to 12e is set according to the image data size handled by the data transfer path. In the illustrated example, in addition to the number of lanes of the high-speed serial buses 12a to 12d, the number of lanes of the high-speed serial bus 12e is set to x1 (refer to the description of FIG. 18 for details).

  FIG. 18 shows a more specific configuration example of the present embodiment based on an example of such a basic and principle configuration example. FIG. 18 is a schematic block diagram illustrating a configuration example of the image forming system according to the present embodiment. The image forming system 1 according to the present embodiment is applied to a device such as a full-color MFP, for example, and includes a control unit 2, an input unit 3, an output unit 4, an image processing unit 5, and an HDD as storage. And a plurality of memory controllers 9 and 10 for individually controlling the memories 7 and 8 as the memory units, here, the memory controllers 9 and 10 as the two memory controller units.

  Here, the control unit 2 includes a CPU that controls the entire system according to an installed control program (software), and means a device portion that performs processing such as path control and path determination. The input unit 3 is a device or unit for capturing image data based on a document image or the like into the system. In this embodiment, for example, a document image is photoelectrically read to acquire image data. It is a full color scanner. The output unit 4 is a device or unit that prints out image data on paper or the like. In the present embodiment, the output unit 4 is, for example, an electrophotographic full-color laser printer. The processing unit 5 indicates a device or a unit that performs image processing such as enlargement / reduction, rotation, and compression / decompression processing on image data, and includes, for example, a magnification changer, a rotator, and a compression / decompression unit. It is said that.

  With regard to the components of such a full-color image forming system (MFP), in this embodiment, the input unit 3, the output unit 4, the image processing unit 5 and the storage unit 6 are provided with a plurality of PCI Express standard end points as described above. As a point, it is connected by a connection unit 11 as a PCI Express standard switch and a PCI Express standard high-speed serial bus 12a to 12j so as to form a data transfer path between the memory controller (memory controller function unit) 9 and 10, respectively. ing. The number of lanes of each of these high-speed serial buses 12a to 12j is set according to the image data size handled by the data transfer path.

  Specifically, 8-bit data for each RGB color = 24-bit data is handled from the input unit 3 by the full-color scanner to the memory 7 of the memory controller 9, and therefore, between the input unit 3 and the processing unit 5 and the memory controller 9. High-speed serial bus 12a connecting the input unit 3 and the connection unit 11 for forming a transmission / reception data transfer path, high-speed serial buses 12g and 12h connecting the connection unit 11 and the memory controller 9, and the connection unit 11 The high-speed serial bus 12c connecting the image processing units 5 has the number of lanes (bus width) set to x12 corresponding to the image data size. In addition, since the memory 8 of the memory controller 10 outputs 2 bits of data for each color of YMCK = 8 bits from the memory 8 to the output unit 4 of the full-color printer, data transmitted / received between the processing unit 5 / output unit 4 and the memory controller 10 is transmitted. High-speed serial bus 12c for connecting the image processing unit 5 and the connection unit 11 to form a transfer path, high-speed serial buses 12i and 12j for connecting the connection unit 11 and the memory controller 10, and the connection unit 11 and the output unit The high-speed serial bus 12d connecting the four has a lane number (bus width) set to x4 corresponding to the image data size. Furthermore, since the storage unit 6 stores the image data compressed by the image processing unit 5, the high-speed serial bus 12e connecting the connection unit 11 and the storage unit 6 has a number of lanes (buses) corresponding to the image data size. (Width) is set to x1.

  In such a configuration, for example, when considering an operation at the time of a full-color copy operation, 8-bit RGB color data captured from an original image by the input unit 3 is an x12 high-speed serial bus 12a, a connection unit 11, and a high-speed serial bus 12g. The data is transferred to the memory 7 by the memory controller 9 through the data transfer path (set by the control of the connection unit 11 by the control unit 2) and temporarily stored, and the 8-bit data of each RGB color stored in the memory 7 is The data is transferred to the image processing unit 5 through the data transfer path of the x12 high-speed serial bus 12h, the connection unit 11, and the high-speed serial bus 12b, and used for necessary image processing, in this case, RGB → YMCK conversion processing and the like. Further, the YMCK color 2-bit image data converted by the image processing unit 5 is a data transfer path of the x4 high-speed serial bus 12c, the connection unit 11, and the high-speed serial bus 12i (by the control of the connection unit 11 by the control unit 2). The data is transferred to the memory 8 by the memory controller 10 and stored once, and the YMCK 2-bit data of each color stored in the memory 8 is the x4 high-speed serial bus 12j, the connection unit 11, and the high-speed serial bus 12d. The data is transferred to the output unit 4 through the data transfer path and is used for full-color printing. The image processing unit 5 also generates compressed data in parallel by compression processing, and the compressed data is transferred to the storage unit 6 via the data transfer path of the connection unit 11 and the high-speed serial bus 12e of x1, and is used for backup or the like. Saved for.

  These processes are executed simultaneously and at high speed as input / output parallel processes by the memory controllers 9 and 10.

  As described above, according to the present embodiment, the PCI Express standard switch (connection unit) 11 and the PCI 11 can be configured with scalable bus widths such as x1, x2, x4, x8, x12, x16, x16, and x32 lanes. By using the Express standard high-speed serial buses 12a to 12j to form data transfer paths for the two memory controllers 9 and 10, the optimum bus width is selected and set according to the data transfer rate (image data size). The parallel processing of input / output by the two memory controllers 9 and 10 can be exhibited to the maximum with a cost-effective configuration.

  In particular, when handling various types of image data having different data amounts, paying attention to the fact that the type of the image data is specified by the data transfer path, the scalability of the system configuration including a plurality of memory controllers 9 and 10 is provided. By using the PCI Express standard high-speed serial bus 12 having high characteristics, each data transfer path is formed, and the number of lanes is set according to the image data size. The configuration is based on the number of lanes, and the parallel operation by the memory controllers 9 and 10 can be maximized at low cost.

  Note that the memory controller and the memory are not necessarily configured as separate devices, as shown in FIG. 18, for example. In short, it is only necessary to have a plurality of these functions, depending on the allocation within the same device. It may be divided. For example, in the image forming systems shown in FIGS. 19 and 20 showing different configuration examples depending on the model, the ASIC-1 indicated by reference numeral 21 is configured as a device having functions of two memory controller function units and a connection unit, for example. Show. Further, in the examples shown in these drawings, the image processing unit 5 is configured to be separated into a normal image processing unit 5a, a compression unit 5b, and an expansion unit 5c. Further, FIG. 20 shows an example in which a memory control hub 22 corresponding to the root complex in the tree structure of the PCI Express system is provided on the upstream side of ASIC-1 indicated by reference numeral 21. The CPU 23 corresponds to the control unit 2.

It is a block diagram which shows the structural example of the existing PCI system. FIG. 2 is a block diagram illustrating a configuration example of a PCI Express system. It is a block diagram which shows the structural example of the PCI Express platform in desktop / mobile. It is a schematic diagram which shows the structural example of the physical layer in the case of x4. It is a schematic diagram which shows the example of lane connection between devices. It is a block diagram which shows the logical structural example of a switch. (A) is a block diagram showing an existing PCI architecture, and (b) is a block diagram showing a PCI Express architecture. It is a block diagram which shows the hierarchical structure of PCI Express. It is explanatory drawing which shows the format example of a transaction layer packet. It is explanatory drawing which shows the configuration space of PCI Express. It is a schematic diagram for demonstrating the concept of a virtual channel. It is explanatory drawing which shows the format example of a data link layer packet. It is a schematic diagram which shows the byte striping example in x4 link. It is a time chart which shows the example of control of active state power management. 1 is a block diagram schematically illustrating an example of a basic and principle configuration example of an image forming system according to an embodiment. FIG. 3 is a block diagram schematically showing another example of the basic and principle configuration example of the image forming system of the present embodiment. FIG. 10 is a block diagram schematically showing still another example of the basic and principle configuration example of the image forming system of the present embodiment. 1 is a block diagram schematically showing a configuration example of an image forming system of an embodiment. It is a block diagram which shows the modification structural example schematically. It is a block diagram which shows the modification structural example schematically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming system 3 Input part, full color scanner 4 Output part, full color printer 5 Image processing part 6 Storage 7, 8 Memory part 9, 10 Memory controller function part 11 Switch 12 PCI Express standard high-speed serial bus

Claims (5)

An image processing unit for performing image processing on the image data ;
A first memory control unit for executing control on the first memory;
A second memory control unit for executing control on the second memory;
A connection unit that connects the image processing unit to the first memory control unit and the second memory control unit;
A first bus that connects the image processing unit and the connection unit and has a variable number of lanes and conforms to the PCI Express standard;
Comprising
In the first bus, the number of lanes having a first value corresponding to the size of the image data transferred from the first memory control unit to the image processing unit via the connection unit is set. A second value different from the first value according to the size of the image data generated by the image processing unit transferred from the image processing unit to the second memory control unit via the connection unit An image forming apparatus comprising a bus having a set number of lanes . The image forming apparatus according to claim 1, wherein the first value is larger than the second value . An input unit for inputting the image data;
A second bus connecting the input unit and the connection unit and having a variable number of lanes and conforming to the PCI Express standard;
Further comprising
The second bus corresponds to the size of the image data transferred from the input unit to the image processing unit via the connection unit, the first memory control unit, and the connection unit. 2. The image forming apparatus according to claim 1, wherein the number of lanes having a third value which is the same value as the first value of the number of lanes of the bus is set . An output unit for outputting image data generated by the image processing unit;
A third bus connecting the output unit and the connection unit and having a variable number of lanes and conforming to the PCI Express standard;
Further comprising
The third bus has a size of image data generated by the image processing unit transferred from the image processing unit to the output unit via the connection unit, the second memory control unit, and the connection unit. The image forming apparatus according to claim 1 , wherein the bus is set with a corresponding number of lanes having a fourth value that is the same as a second value of the number of lanes of the first bus. . The image forming apparatus according to claim 1 , wherein the image processing unit is an image processing unit that generates YMCK image data by performing image processing on the RGB image data .

Images