JP2658158B2 - Image recording device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic image recording apparatus that performs plain paper recording, and more particularly to an electrophotographic image recording apparatus that can reduce the cost of a page memory.

2. Description of the Related Art As shown in FIG. 2, for example, a plain paper facsimile apparatus using an electrophotographic method includes a communication control device 21, a storage device 22, a reproduction device 23, a page memory 24, a laser recording device 25, a system control device 26, and a signal line. 211,221,231,241,161.

In such a facsimile machine, a laser recording device
In the case of executing the constant speed recording by 25, the document information obtained through the communication control device 21 is stored in the storage device 22, and after being reproduced by the reproducing device 23, one page of data is further converted into raw data, that is, uncompressed data. In this state, it was necessary to temporarily store the data in the high-speed page memory 24.

The memory size of the page memory 24 is 4.1 bits at a line density of 8 × 8 dots / mm and 16.4 Mbits at a line density of 16 × 16 dots / mm when an A4 document is recorded as binary data. I need. The access time of the page memory 24 is, for example, 6 seconds / A4
Recording speed of 300 x 16 dots / mm density
Since a speed that can withstand the transfer of K bytes / s is required, only a semiconductor memory having a high unit price per bit can be used.

As a result, there are problems in terms of cost, size of the apparatus, and power consumption as compared with the thermal recording method capable of variable speed recording.

As for the conventional facsimile apparatus, for example, “Terminal characteristics of G4 facsimile, Yasuhiro Yamazaki,
13, No. 3, pp. 187-195 (1984) "and" Basics and Application of New Facsimile, edited by Yasuhiko Yasuda, IEICE (1982) ".

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic image recording apparatus which can solve the above problems and can be constructed at a low cost by reducing the cost of a page memory.

The image recording apparatus according to the present invention comprises a compressed data storage unit (storage device 22) for storing at least one page of recorded data in a data compressed state, and a reproducing device (reproducing device 23) for decoding the recorded data into raw data. ) And recording means (laser recording device 25) for recording the raw data at a constant speed, wherein the recording means has a plurality of different recording speeds, and the compression sent to the image recording apparatus. Means for measuring the compression ratio of the data in the state (signal line, reproducing device); and means for selecting the recording speed of the recording device based on the compression ratio (system control device 26). It is characterized in that the speed of the recording means is switched according to the ratio.

Further, the recording speed selecting means of the recording apparatus selects the recording speed for each page.

Further, the image recording apparatus according to the present invention comprises a compressed data storage means (storage device 22) for storing at least one page of recorded data in a data compressed state, and a reproducing means (reproducing device) for decoding the recorded data into raw data. 23) and a recording unit (laser recording device 25) for recording the raw data at a constant speed. The image recording device has a transfer speed corresponding to the constant speed recording of the recording unit and 1 / N (N > 0) raw data accumulating means having a size enough to store raw data equivalent to a page, and measuring means (signal line, reproducing device) for measuring the compression ratio of the compressed data, wherein the compression ratio is predetermined If the compression ratio has not reached the predetermined value, the decoded raw data is transferred to the recording unit via the compressed data storage unit. Via the serial raw data storing means is characterized by transferring to the recording means.

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an electrophotographic facsimile apparatus in an image recording apparatus according to a first embodiment of the present invention, and FIG. FIG. 4 is an explanatory diagram of a compression ratio N when coding by a lead (hereinafter, referred to as M ² R) compression method. FIG. 4 is a flowchart showing an operation of the facsimile apparatus in the first embodiment of the present invention.

In general, the data transfer speed from a storage device (store and forward memory (hereinafter referred to as SAF memory)) to a playback device is V _n , the data transfer speed from the playback device to a laser recording device is V _D , and the storage device is Assuming that the compression ratio of the stored data is M (M> 0), the relationship of V _D = V _n × M must be satisfied in order to perform normal recording.

For example, when a fixed magnetic storage device is used as a storage device, the read speed in actual use can only be about 75 Kbytes / s. When V _D = 300 Kbytes / s, M ≧
If it is 4, the relationship of V _D ≦ V _n × M is satisfied.

In other words, unless the data compression ratio M is document information of 4 or more, a fixed magnetic disk device cannot be used as a storage device.

For example, the compression ratio when a CCITT text document is coded by the M ² R compression method is shown in FIG. The number of pixels of each document is 1728 x 2376 PEL
(Pictureelement).

These documents give M> 7, so
Even if a fixed magnetic disk device is used as a storage device, a system can be configured to continuously transfer data at a constant speed to a laser recording device having a recording speed of 6 seconds / page. However, in the case of a more complicated information document, the compression ratio M may be 4 or less or near 1, and it is not possible to continuously supply raw data at a speed of 300 Kbytes / s to the laser recording device with such document information. .

Therefore, in this embodiment, the page memory (high-speed memory) according to the conventional method is changed to the SAF memory (low-speed memory) by changing the recording speed per page in the laser recording apparatus based on the compression ratio N measured in advance. Also used as

As shown in FIG. 1, the facsimile apparatus of this embodiment includes a communication control device 11, a storage device 12, a reproducing device 13, a laser recording device 14, a system control device 15, and signal lines 111, 112, 121,
It is composed of 131,151.

This storage device 12 is a fixed magnetic disk storage device, has a capacity of 0.5 to 20 Mbytes, and is used as a SAF memory. Further, the document information received via the communication line and the communication control device 12 is converted into a coding method using a modified Huffman code (MH),
In the state of being compressed by the encoding method by the read (MR) or the M ² R coding method, the data is temporarily recorded in page units, and then sent to the reproducing device 13.

The data to be stored in the storage device 12 is simultaneously input to the playback device 13 via the signal line 112, and the playback device 13
Measures the compression ratio M of this data and sends it to the system controller 15 via the signal line 151. The data sent from the storage device 12 is decoded into raw data and sent to the laser recording device 14 via the signal line 131.

The laser recording device 14 has a high-speed (6 seconds / A4) and a low-speed (12 seconds / A4, 24 seconds / A4) recording speed, and these recording speeds are variable.

Further, the system control device 15 sends a laser recording device for each document in accordance with the compression ratio M sent from the reproducing device 13.
Select and indicate the recording speed per page in 14. For example, if the compression ratio M of the data stored in the storage device 12 is M ≧
If it is, the recording speed is 6 seconds / A4, and if 4> M ≧ 2, it is 1
If the recording speed is 2 seconds / A4, and if 2> M ≧ 1, the recording speed per page of the laser recording device 14 is selected based on the compression ratio N measured in advance, such as the recording speed of 24 seconds / A4. I do.

As shown in FIG. 4, when the communication control device 11 receives document data via a communication network (401), the document data is stored in the storage device 12 in page units in the facsimile apparatus having such a configuration. It is temporarily stored (402). At the same time, the data is input to the reproducing device 13 via the signal line 112, the compression ratio M of the data is measured (403), and sent to the system control device 15.

Further, the reproduction device 13 decodes the data into raw data (404) and sends it to the laser recording device 14.

If the data compression ratio M is 4 or more (405), the system controller 15 selects high speed (6 seconds / A4) as the recording speed of the laser recording device 14 (406).

If the compression ratio M is smaller than 4 (405), the low speed (1
2 seconds / A4, 24 seconds / A4) is selected (407).

In the present embodiment, the recording speed of the laser recording device 14 is made variable, the page memory required for high-speed reading is removed,
The conventional page memory is replaced with the SAF memory (storage device 1
By combining this with 2), a fixed magnetic disk storage device with a unit price per bit of 1/6 or less of semiconductor memory can be
Can be used as AF memory.

FIG. 5 is a block diagram of an electrophotographic facsimile apparatus according to a second embodiment of the image recording apparatus of the present invention, and FIG. 6 is a coding efficiency when a CCITT text document is compressed by the G3 and G4 compression methods. FIG. 7 is a flowchart showing the operation of the facsimile apparatus according to the second embodiment of the present invention.

In a facsimile apparatus, for example, when a CCITT text document is compressed by the compression method in G3 and G4, the encoding efficiency is shown as in FIG. In addition,
In FIG. 6, the number of pixels of each document is 1728 × 2376 PEL. Also, the G4 encoding includes an end of fill bit (EOFB). In G3 encoding, 13
It includes a line synchronization signal of bits, a fill bit (FILL BIT) for a minimum transmission time of 20 ms, and a control return signal (RTC) of 6 × 13 bits.

Thus, the use of the M ² R a G4 compression method, any document it can be seen that to obtain more than 7 times the compression ratio.

Further, in order to perform normal recording, when the transfer speed of the laser recording device is V _p and the reading speed from the storage device is V _H , the following expression must be satisfied.

V _P ≦ M × V _H where M indicates the compression ratio.

For example, if V _P = 300 Kbytes / s and V _H = 75 bytes / s, M ≧ is required.

In this case, according to the compression method using M ² R, M ≧ 7 is satisfied.

Therefore, in laser recording of a standard document, a SAF memory having a slow access speed can be used also as a page memory for compressed data.

Accordingly, in this embodiment, M ^{2 is} used as the data compression method.
Using the R compression method, for documents with a compression ratio less than the expected compression ratio, a 1 / N size page memory for the raw data is provided, and the abnormal processing of dividing the page and recording is performed. Do.

As shown in FIG. 5, the facsimile apparatus according to the present embodiment includes a communication control device 51, a storage device (SAF memory) 52, and playback devices 53 and 1.
/ N page memory 54, laser recording device 55, system control device 56, and signal lines 511, 512, 521, 531, 541, 561. The laser recording device 55 records the raw data sent from the reproducing device 53 at a constant speed. The transfer speed is, for example, 300 Kbytes / s.

The storage device (SAF memory) 52 is composed of a fixed disk magnetic storage device, and stores document information obtained via the communication control device 51. Under the control of the system controller 56, the access speed is 75 Kbytes / s. This speed is the recording speed of the laser recorder 55 (16 × 16 dots / mm,
6 seconds / A4) is not enough for the required data transfer rate (300 Kbytes / s), but the modem rate in the PSTN (9.6 to 14.4 KBPS) or the data transfer rate in the digital data network (48 ~ 64KBPS), which is enough speed.

Also, the 1 / N page memory 54 is one of the conventional page memories.
/ N, and is composed of semiconductor RAM capable of high-speed transfer (300 Kbytes / s). Since this corresponds to the case of M <4, it is used as a page memory for raw data.

The system controller 56 controls the entire apparatus. Particularly, when the compression ratio of the sent document information is 4 or less, the timing of each apparatus is divided so that one page is divided into N pages. I support. In this case, the raw playback data
After being stored in the 1 / N page memory 54, the storage device 52, the reproducing device 53, the 1 / N page memory 5
4, and control the laser recorder 55.

Further, in the control of the 1 / N page memory 54, recording starts when the 1 / N page memory 54 is FULL, and when the 1 / N page memory 54 becomes empty, reads out from the storage device 52 and temporarily stops decoding of the playback device 53. After recording the data already read,
Data transfer to the 1 / N page memory 54 starts again, and FULL
By repeating the start of recording in the state, the number of times of divisional recording with a larger value of N can be reduced.

In this case, the operation of the facsimile apparatus of this embodiment is shown in FIG.

That is, when the communication control device 51 receives the document data via the communication network (701), the document data is stored in the storage device 52 in page units (703), and at the same time, the reproduction device via the signal line 512. 53,
The compression ratio M per page of the document data is calculated and notified to the system controller 56 (702).

Further, the raw data of the document data is reproduced (704).

Next, if the compression ratio M is 4 or more (705), the reproduced raw data is temporarily stored in the storage device 52 and then transferred to the laser recording device 55 for recording (706, 707).

If the compression ratio M is smaller than 4 (705), 1 / N
The data is temporarily stored in the page memory 54 (708).

Further, when the 1 / N page memory 54 enters the FULL state (70
9), the data is transferred to the laser recording device 55 and recorded (710).

Thus, when the 1 / N page memory 54 becomes empty (711),
Confirm the end of the page (712).

In this embodiment, for the worst condition M <4, only a page memory of 1 / N size is prepared as the page memory of the compressed data, and a low access speed for the normal document is prepared.
By using the SAF memory, an electrophotographic facsimile apparatus with high cost performance can be realized.

Effects According to the present invention, the cost of the page memory can be reduced by making the recording speed of the laser recording device variable and eliminating expensive semiconductor memories or reducing the size of the page memory to 1 / N.

This makes it possible to inexpensively configure an electrophotographic image recording apparatus that requires constant-speed recording.

[Brief description of the drawings]

Block diagram of a facsimile apparatus of an electrophotographic system in the first embodiment of Figure 1 the present invention, configuration diagram of FIG. 2 facsimile apparatus of a conventional electrophotographic system, a third figure CCITT text document M ² R FIG. 4 is an explanatory view of a compression ratio N when coding by a compression method, FIG. 4 is a flowchart showing an operation of the facsimile apparatus in the first embodiment of the present invention, and FIG. 5 is an electrophotograph in the second embodiment of the present invention. FIG. 6 is a diagram illustrating the coding efficiency when a CCITT text document is compressed by the G3 and G4 compression methods, and FIG. 7 is a diagram illustrating a facsimile device according to a second embodiment of the present invention. It is a flowchart which shows an operation. 11,21,51: Communication control device, 12, 22, 52: Storage device, 13, 23, 53:
Reproduction device, 14, 25, 55: Laser recording device, 15, 26, 56: System control device, 24: Page memory, 54: 1 / N page memory 111, 1
12,121,131,151,211,221,231,241,261,511,512,521,53
1,541,561: Signal line.

Claims (3)

(57) [Claims] A compressed data accumulating means for accumulating at least one page of recorded data in a data compressed state; a reproducing means for decoding the recorded data into raw data; and a recording means for recording the raw data at a constant speed. In the image recording device provided with, the recording means has a plurality of different recording speed, means for measuring the compression ratio of the compressed data sent to the image recording device, based on the compression ratio, Means for selecting the recording speed of the recording means, wherein the speed of the recording means is switched according to the compression ratio. 2. An image recording apparatus according to claim 1, wherein said means for selecting a recording speed of said recording apparatus selects a recording speed for each page. 3. A compressed data storage means for storing at least one page of recorded data in a data compressed state, a reproducing means for decoding the recorded data into raw data, and a recording means for recording the raw data at a constant speed. A raw data storage means having a transfer speed corresponding to the constant speed recording of the recording means and having a size sufficient to store raw data equivalent to 1 / N (N> 0) pages; Comprising a measuring means for measuring a compression ratio of the data in the compressed state,
If the compression ratio has reached a predetermined value, the decoded raw data is transferred to the recording means via the compressed data storage means, and if the compression ratio has not reached the predetermined value, decoding is performed. An image recording apparatus, wherein the raw data obtained is transferred to the recording means via the raw data storage means.