JP2712414B2 - Image storage circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an image storage circuit, and more particularly to an image storage circuit used in a facsimile apparatus having an electrophotographic image recording unit.

[Conventional technology]

Conventionally, an image storage circuit of this type has been used as shown in FIG. In FIG. 2, reference numeral 11 denotes an image memory for temporarily storing image data, 12 denotes an image recording unit for forming an image on recording paper by an electrophotographic method, 13 denotes a refresh control circuit for controlling a refresh operation of the image memory 11, Reference numeral 15 denotes a decoder for decoding a facsimile signal received by a communication control unit (not shown) into image data. Reference numeral 14 denotes a bus control unit for arbitrating a read / write request from the image recording unit 12, the refresh control circuit 13, and the decoder 15 to the image memory 11, and outputting an image memory use permission signal.

Here, the image memory 11, the image recording unit 12, the refresh control circuit 13 and the decoder 15 are connected to a bus 16 and sled.The image memory 11 temporarily stores image data. You. For example, if the image resolution is 400 dots / inch x 400 dots / inch
In the case of the A4 size, the capacity of the image memory 11 is 16M bits. Since such a large capacity is required, the image memory 11 is usually realized using a dynamic RAM element. This dynamic RAM element is required to perform a refresh cycle within a predetermined time as a condition of the element itself. The refresh control circuit 13 controls the generation of this refresh cycle. Also,
The bus control unit 14 also receives the bus use request signal from the refresh control circuit 13 with the highest priority, performs bus arbitration, and outputs a bus use permission signal to the refresh control circuit 13.

Accordingly, the refresh control circuit 13 executes the refresh cycle for the image memory 11 at substantially constant time intervals by generating a bus use request signal at regular time intervals.

On the other hand, when the decoder 15 decodes the facsimile signal and writes the decoded image data to the image memory 11, the decoder 15 outputs a bus use request signal to the bus control unit 14. The image recording unit 12 outputs a bus use request signal to the bus control unit 14 because it is necessary to read image data from the image memory 11 when forming an image on recording paper. At this time,
The priority order of the bus arbitration in the bus control unit 14 is in the order of the refresh control circuit 13, the image recording unit 12, and the decoder 15.

[Problems to be solved by the invention]

In the conventional image storage circuit described above, the refresh control circuit 13 is assigned the highest priority for bus use, and always executes the refresh operation at a constant cycle. For this reason, during the period when the image recording unit 12 is recording an image, the addresses of the image memory 11 are read one after another due to the nature of the image data, and the refresh operation is substantially unnecessary. However, since the refresh operation is performed, there is a problem that there is a limit in improving the performance of the bus including the image memory.

[Means for solving the problem]

In order to solve such a problem, an image storage circuit according to the present invention includes an image memory having a capacity of at least one document, and an image memory connected to the image memory and reading or writing image data. An image recording unit of an electrophotographic system, which continuously executes the processing over all addresses corresponding to one original, and a refresh control circuit connected to the image memory and refresh-controlling the image memory. The control circuit stops the refresh operation for all addresses of the image memory while the image recording unit is reading image data from the image memory.

(Operation)

Therefore, in the present invention, when the image recording unit is recording, by stopping the refresh control on the image memory, it is possible to shorten the time from the bus use request to the bus use permission on the bus including the image memory. Will be possible.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an image storage circuit according to the present invention. In FIG. 1, 1 is an image memory for temporarily storing image data, 2 is an image recording unit for forming an image on a recording sheet by an electrophotographic method, 3 is a refresh control circuit for controlling a refresh operation of the image memory 1, Reference numeral 5 denotes a decoder for decoding a facsimile signal received by a communication control unit (not shown) into image data. Reference numeral 4 denotes a bus control unit for arbitrating read / write requests from the image recording unit 2, refresh control circuit 3 and decoder 5 to the image memory 1, and outputting an image memory use permission signal.

Here, the image memory 1 is connected to the bus 6. The image recording unit 2 is connected to the bus 6 and outputs a bus use request signal to the bus control unit 4 and outputs a signal during image recording to the refresh control circuit 3. The refresh control circuit 3 is connected to the bus 6 and outputs a bus use request signal to the bus control unit 4. The decoder 5 is connected to the bus 6 and outputs a bus use request signal to the bus control unit 4. Further, the bus control unit 4 is connected to the bus 6, receives a bus use request signal from the image recording unit 2, the refresh control circuit 3 and the decoder 5, and sends a bus use permission signal to the image recording unit 2, the refresh control circuit 3. And output to the decoder 5.

 Next, the operation will be described.

The bus control unit 4 receives a bus use request signal from the image recording unit 2, the refresh control circuit 3, and the decoder 5, and arbitrates the bus use right according to the priority of the bus use right. In the case of the present embodiment, the priorities are in the order of the image recording unit 2, the refresh control circuit 3, and the decoder 5. Then, the bus control unit 4 outputs a bus use permission signal to the image recording unit 2, the refresh control circuit 3, and the decoder 5 based on the arbitration of the bus use right. Then, the image recording unit 2 outputs a bus use request signal to the bus control unit 4, drives the bus 6 when the bus use permission signal is responded, and reads out image data from the image memory 1. Thus, an image is formed on recording paper by an electrophotographic method according to the read image data. Further, during the image recording, an image recording signal is output to the refresh control circuit 3.

On the other hand, the decoder 5 decodes the facsimile signal to generate image data, outputs a bus use request signal to the bus control unit 4, drives the bus 6 when the bus use permission signal is responded, and converts the image data. Write to image memory 1.

The refresh control circuit 3 outputs a bus use request signal to the bus control unit 4 at fixed time intervals, and drives the bus 6 when the bus use permission signal is responded, thereby executing a refresh cycle for the image memory 1. Then, the refresh control circuit 3 receives the image recording signal from the image recording unit 2 and
During image recording, the image recording unit 2 controls so as not to generate a bus use request signal to the bus control unit 4.

Therefore, the image recording unit 2 stops the operation of the refresh control circuit 3 during the image recording. The refresh operation of the image memory 1 can be performed by performing reading or writing with a predetermined address sequence within a certain time or a predetermined number of times. The reading operation of the image recording unit 2 from the image memory 1 reads out the image data in a continuous address sequence due to the nature of the image data, that is, continuously reads out the image data over all addresses corresponding to one original in the image memory 1. read out.
Similarly, at the time of writing, image data is written continuously over all addresses corresponding to one document in the image memory 1. Therefore, even if the image recording unit 2 stops the operation of the refresh control circuit 3 during image recording, the refresh operation for the image memory 1 is effectively performed.

〔The invention's effect〕

As described above, according to the present invention, when the image recording unit of the electrophotographic system is recording, the refresh control for the image memory is stopped, so that the time from the bus use request to the bus use permission on the bus including the image memory is reduced. Can be shortened. Thus, there is an effect that the performance of the bus can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram for explaining the prior art. 1 ... image sensor, 2 ... image recording unit, 3 ... refresh control circuit, 4 ... bus control unit, 5 ... decoder, 6 ... bus.

Claims (1)

(57) [Claims] 1. An image memory having a capacity of at least one original, connected to the image memory and reading or writing image data over all addresses of the image memory corresponding to the one original. An electrophotographic image recording unit that is continuously implemented, and a refresh control circuit that is connected to the image memory and refresh-controls the image memory, wherein the refresh control circuit is configured such that the image recording unit is more than the image memory. An image storage circuit wherein a refresh operation for all addresses of the image memory is stopped during a period in which image data is being read.