JPH08180179A - Image controller - Google Patents

Abstract

PURPOSE: To provide an image controller which can attain large capacity at high speed and has an advantage in cost by constituting the controller so that an SDRAM operating at high speed may be used as the storage part of image information and only a part of storage element area may be refreshed. CONSTITUTION: In an image controller controlling the storage and read out of image information, the controller is provided with an image storage means 1 composed of plural SDRAMs stored with image information and an image control means 2 which can refresh only part of SDRAMs when the SDRAM of the image storage means 1 is refreshed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to storage control means for image information required for image formation in printers, electrophotographic copying machines, fax machines and the like.

[0002]

2. Description of the Related Art Conventionally, a dynamic RAM (hereinafter referred to as DRAM) has been mainly used in an image control device for controlling storage and reading of image information because the storage of image information has a large capacity. With the increase in speed of CPUs, printers, etc., storage of image information is required at high speed and has a large capacity. For this reason, in recent years, a static RAM (hereinafter referred to as SRAM) has been used for a storage unit for high-speed storage of image information. However, as the image quality is improved, the storage capacity of the storage unit tends to increase more and more. There has been a problem that the power consumption increases and the cost becomes high.

[0003]

As described above, a large capacity DRAM or a high speed SRAM for storing image information is provided.
However, there is a problem in that the maximum power consumption at the time of refreshing the DRAM is increased, an extra power system is required, the cost of the power supply unit is increased, and the size of the entire device is increased.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the conventional image control apparatus described above, and uses an SDRAM operating at a high speed as a storage unit for image information.
An object of the present invention is to provide an image control device that reduces the maximum power consumption, achieves high-speed and large-capacity, and is advantageous in terms of cost by refreshing only a part of SDRAM when refreshing. .

[0005]

In order to achieve the above object, the present invention provides, as a first means, an image control device for controlling storage and reading of image information, which comprises a plurality of SDRAMs storing image information. The most main feature is that the image control device includes the image storage means and the image control means capable of refreshing only a part of the SDRAM when refreshing the SDRAM of the image storage means. As a second means, in the image control device described in the item 1, the image control means refreshes only a part of SDRAMs necessary for image storage of the image storage means, and refreshes the remaining SDRAMs. The main feature is that it is not configured.

[0006]

As described above, the present invention is provided with the image storage means composed of a plurality of SDRAMs for storing image information and the image control means capable of refreshing only a part of the SDRAMs of the image storage means. Some SDR at time
Since the AM can be refreshed and the remaining part or all of the SDRAM can be refreshed at another time, it is not necessary to refresh all the SDRAM at once, and the instantaneous maximum power consumption can be reduced. . Furthermore, some SDRAMs used for image storage
Only by refreshing only the SDRAM and not refreshing the rest of the SDRAM not used for image storage, it is possible to reduce the overall power consumption.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings. FIG. 1 is a configuration diagram of essential parts showing an embodiment of an image forming apparatus adopting an image control apparatus of the present invention. In the figure, reference numeral 1 is an image storage means, 2 is an image control means, and an apparatus including the above two blocks is an image control apparatus 8 according to the present invention. Further, 3 is a CPU for performing overall control, and 4 to 7 are the image control device 8 and the upper C.
The PU 3 is a scanner interface (4), a host interface (5), a printer interface (6) and a ROM / RAM (7) which are connected by a bus line.

The operation of this configuration will be described below.
In response to a command from U3, image information read by an external device such as a scanner is taken in via the scanner interface 4 and stored in a specific pre-allocated location in the image storage means 1 via the bus line. It In addition to this, image information fetched from a host device such as a personal computer through the host interface 5 is also stored in a specific location of the same image storage means 1. In addition, the image storage means 1 includes a plurality of synchronous dynamic RAMs (S in the text).
It is composed of a DRAM) and is suitable for storing image information that needs to be processed at a high speed and in a large capacity. SR
The SDRAM, unlike the AM, needs to be refreshed within a predetermined time in order to retain the memory, and the control is performed by the image control means 2.

Further, when the image control means 2 receives the image formation command from the CPU 3, the image stored in the image storage means 1 is timed so that the image formation information of the external forming apparatus can be received. The information is read and output to an external forming device such as a printer via the printer interface 6. ROM / RAM7 ROM has CP
The program executed by U3 and various parameters used for overall control are stored, and the RAM of ROM / RAM7
Is used for temporary storage of the execution result of the CPU 3. The range including the image storage means 1 and the image control means 2 surrounded by the chain line is the image control device 8 of the present invention.

FIG. 2 is a block diagram showing a detailed configuration example of the image control means 2 described above. The CPU information control section 23 receives a refresh request command from the CPU 3 via the bus line, and the adjustment control section 22. Tell. The adjustment control unit 22 monitors the bus line usage state of each input / output device through the I / O control unit 25, confirms that the image storage unit 1 is not in the writing state through the SDRAM control unit 24, and then the refresh control unit 21 It receives a refresh signal and responds to the refresh operation of the image storage means 1 via the SDRAM control unit 24. In addition, this SDRAM
The control section 24 has a refresh position control register so that the refresh operation can be performed only in a specific area of the image storage means 1 according to the judgment of the adjustment control section 22. The image control means 2 is generally contained in one ASIC chip.

FIGS. 3 to 5 show timing examples of the refresh operation. The refresh control section 21 is a clock signal to which the information of the image storage location and the storage time from the CPU 3 to the SDRAM is given in advance. A REFREQ signal requesting refresh is output at the 0th position of the CLK signal. The adjustment control unit 22 receives the REFREQ signal, and the SDRAM control unit 24 constantly monitors the state of the SDRAM so that the refresh request can be accepted and there is another request having a higher priority. If you confirm that there is no CLK signal 1
Secondly, REFAC indicating that the refresh request is allowed
Output K signal.

When the refresh control unit 21 confirms that the refresh request is permitted at the second CLK signal, it stops outputting the REFREQ signal, and outputs the RAS signal, which is a column (row) address strobe, and the row (column). ) Output the CAS signal which is the address strobe. In addition, a CS signal that determines whether the RAS signal and the CAS signal are valid or invalid is also output at the same time. If the CS1 signal and the CS2 signal are output in accordance with the RAS signal and the CAS signal as shown in FIG. 4, the memory 1 shown in FIG.
The refresh operation can be performed on the SDRAMs on both the side (M1 side) and the memory 2 side (M2 side).

As shown in FIG. 5, when the CS1 signal is output and the CS2 signal is not output, the memory 1 side (M1 side) in FIG. 3 performs the refresh operation, but the memory 2 side (M2 side). Does not perform a refresh operation. In this way, the SDR of the partial area where the image is stored
It is possible to refresh only the AM, but it is also possible to refresh the remaining SDRAM at another timing if necessary. Therefore, unlike the conventional case, it is not necessary to refresh all SDRAMs at once, and the instantaneous maximum current consumption can be greatly reduced.

Further, as an example of refreshing only a necessary portion, for example, when a memory capable of storing A3 size image information is provided and the size of the image information actually used is A4 size, After the image information is stored, the memory is retained by refreshing only the A4 size memory that is actually used for storage, and the rest of the memory is not refreshed. It is possible to realize an image control device that not only reduces the power consumption, but also reduces the overall power consumption. Although the storage contents of the SDRAM in the area which is not refreshed for a specified time or longer are not guaranteed, there is no inconvenience if the SDRAM is cleared before use.

Although not shown in the above drawing, SD
There is a method of reducing power consumption by using a CKE signal that invalidates the CLK signal of the RAM. This is a method of keeping the power consumption low by changing the CKE signal of the unused SDRAM at high speed while keeping a certain timing with the CLK signal. However, the SDRAM to be enabled and the SDRAM to be disabled It is troublesome to control the CKE signal of the SDRAM for distinguishing and invalidating it at high speed, and since many signal lines are drawn out, the stray capacitance increases, and a countermeasure against the waveform blunting is required. The same effect as the present invention cannot be expected. Moreover, unlike the RAS signal and the CAS signal, the CKE signal is always strictly defined in terms of setup time and hold time with respect to the rising edge of the CLK signal.
An external high-speed buffer and a circuit for synchronizing synchronization are required. On the other hand, the method by controlling the refresh operation of the SDRAM as in the present invention can be a system with a simple configuration and surely reducing the maximum power consumption.

[0016]

As described above, the present invention comprises the image storage means composed of a plurality of SDRAMs for storing image information, and the image control means capable of refreshing only a part of the SDRAMs of the image storage means. Therefore, some SDRAMs can be sequentially refreshed at different times so that some SDRAMs are refreshed at one time and the rest or all of the SDRAMs are refreshed at another time. Therefore, all SDRAMs can be refreshed at once. It is not necessary to refresh, and therefore, the instantaneous maximum power consumption can be reduced, and the cost increase of the power supply device and the size increase of the device can be prevented. In addition, the SR
It is possible to realize an image control device which has a smaller number of elements, a smaller size, and a lower price than those configured by AM.

Further, a part of the SDRAM effective for image storage
In the method in which only the SDRAM used for image information is refreshed by the method in which only the SDRAM used for image storage is not refreshed by refreshing only the SDRAM that is not used for image storage, the instantaneous maximum power consumption can be reduced. In addition to the effect, it is possible to obtain the effect of significantly reducing the overall power consumption.

[Brief description of drawings]

FIG. 1 is a principal block diagram showing an embodiment of an image forming apparatus using an image control apparatus according to the present invention.

FIG. 2 is a block diagram of a main part of image control means showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating a refresh operation of the image control apparatus according to the embodiment of the present invention.

FIG. 4 is a timing diagram illustrating a refresh operation of the image control device according to the embodiment of the present invention.

FIG. 5 is a timing diagram illustrating another refresh operation of the image control apparatus according to the embodiment of the present invention.

[Explanation of symbols]

1 ... Image storage means, 2 ... Image control means, 3 ...
・ CPU, 4 ... Scanner interface, 5 ...
Host interface, 6 ... printer interface, 7 ... ROM / RAM, 8 ... image control device, 21 ... refresh control unit, 22 ... adjustment control unit, 23 ... CPU Information control unit, 24 ... SD
RAM control unit, 25 ... I / O control unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomoki Ishii 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (2)

[Claims] 1. An image control device for controlling storage and reading of image information, wherein a plurality of SDRs storing image information
Image storage means composed of AM and SD of the image storage means
An image control device comprising image control means capable of refreshing only a part of SDRAM when refreshing RAM. 2. The image control device according to claim 1, wherein
An image characterized in that the image control means refreshes only the SDRAM storing the image among the image storing means and does not refresh the remaining SDRAMs not storing the image. Control device.