JPH04156766A - Optical printer - Google Patents

Abstract

PURPOSE:To perform high-speed printing without using an expensive page memory by controlling driving speed based on the maximum decoding time in a page. CONSTITUTION:A bit-compressed signal from a communication line 1 is stored in an input memory 2, and a decoding part 3 detects the decoding time for each line by a decoding time detection part 6 while decoding the data of the input memory 2 by each line to a bit image signal. Further, the printing speed in the page is decided based on the maximum decoding time detected by the dimension when the decoding for all lines in one page is completed, and the driving speed of a printer part 5 is controlled by a driving control part 7. Thus, the optical printer practically enabling the high-speed printing while performing the decoding for each line can be obtained without using an expensive page image memory.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical printer that can be used in facsimile machines and the like.

(Prior art) In facsimile communication, bit image information read from an image is processed using MH and M, which have high bit compression efficiency.
It is converted into R code etc. and transmitted. Conventionally, when decoding and printing out a bit-compressed signal in this way, when printing with an optical printer that writes using light, such as an electronic copying printer that can print at high speed, it is difficult to print. Since decoding could not keep up with the speed, page memory had to be interposed as a buffer memory.

FIG. 2 is a block diagram for explaining the outline of a printing system in a conventional facsimile machine having an optical printer. In the figure, 1 is a communication line, 2 is an input memory, 3 is a decoding section, 5 is a print section, and 8 is a page memory.

The bit-compressed signal from the communication line 1 is stored in the manual memory 2, and the stored data is sequentially read out and decoded into a bit image signal in the decoding section 3. The decoded signals are stored line by line in the page memory 8, and after one page is stored in the page memory 8, they are transferred to the print section 5 and printed.

The reason for using the page memory 8 is that while the printing time for one line in the print section 5 is constant, the opening time when decoding one line of encoded data in the decoding section 3 is not constant. It is.

That is, the print section of the optical printer stores print data for each line as a latent image on a photosensitive drum charged in a charging process, and prints on recording paper through development, transfer, and fixing processes. For this reason, the photosensitive drum is driven at a constant speed, and the printing time per line is
That is, the driving speed is, for example, about 2 msec, and high-speed printing is possible.

On the other hand, the decoding time opening per line in the decoding unit 3 varies stochastically, and the shortest value is close to O, but in the case of fine patterns, even when high-speed processing is performed, the maximum Approximately 5 msec is also required. −
In boat fishing, there are many lines that can be decoded within 2 milliseconds. Therefore, the printing speed of one line in the print section 5 is
For example, if it is set to 2 msec, data for which the decoding time for one line takes longer than that cannot keep up with the printing speed and cannot be printed.

If the printing speed of one line in the printing section 5 is set to a slow value that takes sufficient account of the decoding time, printing failure can be avoided, but the advantages of high-speed printing cannot be achieved. Therefore, if you store the decoded data and print it when all the data for one page has been decoded, the problem of opening during decoding can be avoided even if the drive speed is increased. This does not occur, and high-speed printing can be performed. However, this requires the use of an expensive page memory that can store one page of decoded data.

(Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned circumstances, and it is possible to decode line by line without using expensive page image memory, and to print at substantially high speed. The purpose is to realize a possible optical printer.

(Means for Solving the Problems) The present invention provides an optical printer that decodes encoded signals such as MR and MH codes into bit signals and sequentially records the bit signals by line scanning. 1
The present invention is characterized in that the line printing speed for each page is controlled based on the maximum value of the decoding time required for each line in each page.

(Embodiment) FIG. 1 is a schematic configuration diagram for explaining an embodiment of a recording section in a facsimile machine using an optical printer according to the present invention. In the figure, 1 is a communication line, 2 is an input memory,
3 is a decoding section, 4 is a line memory, 5 is a print section, 6 is a decoding time detection section, and 7 is a drive control section.

The bit-compressed signal from the communication line 1 is stored in the input memory 2. First, the maximum decoding time is detected. The decoding unit 3 decodes the data in the input memory 2 line by line into a bit image signal, while the decoding time detection unit 6 detects the decoding time for each line, and detects and holds the maximum value of the decoding time. At this stage, the decoded data is not led to the line memory 4. When decoding of all lines of one page is completed, the printing speed for that page is determined based on the detected maximum decoding time, and the drive control section 7 controls the driving speed of the printing section 5. The drive speed may be set to a speed that can accommodate the maximum decoding time, but the maximum printable speed may be selected from a plurality of speeds determined in stages.

Next, that page is printed at the set driving speed. Again, the decoding unit 3 decodes the information in the input memory 2 line by line, converts it into a bit image signal, and transfers it to the line memory 4 each time one line is decoded. The printing unit 5 prints the bit image signals from the line memory 8 one line at a time. Line memory 8 is
Since decoding data is stored and print data is read out alternately for one line at a time, two lines are provided, and while one line memory is reading print data, the other line memory is decoding data. It is preferable to store data and alternately switch between them.

In this way, the drive speed of the print unit 5 controlled by the drive control unit 7 is set to a drive speed that allows printing in the maximum decoding time for one line of the page, so some lines become unprintable. Never. Note that the driving speed means the time pitch from when printing of one line is started and when printing of that line is finished until moving to the next line in the printing unit.

FIG. 3 is a flowchart of an embodiment in which the driving speed is determined in the decoding time detection section of FIG. 1.

The flow starts every time one page of data is printed. In order to initialize in 5 steps, the maximum decoding time BT is set to 0 and stored in the RAM. At step 52, one line of data is read from the input memory 2, and the process advances to step 5, where it is decoded and the decoding time detection unit 4 detects the decoding time t of that line. Move to 5tep4, compare the decoding time t with the maximum decoding time T stored in the RAM, and if it is greater than or equal to T, proceed to 5tep4.
In step 5, the memory in the RAM is updated with t as the new maximum decoding time T, and if the data of one page is not completed in step 5, step 2 is repeated and the next line is read. In step 5, if the maximum decoding time T is less than or equal to T, the process moves to step 6 without updating the maximum decoding time T.

When detection of the decoding time of all lines for one page is completed, the drive speed of the print unit 5 is set by the drive control unit 7 according to the maximum decoding time T stored in the RAM. The driving speed may be selected from a plurality of predetermined speeds. Step 5 and subsequent steps are a flow for selecting the driving speed of the printing unit 5 from among three stages: 2 msec, 3 msec, and 5 msec. Driving speeds and stages are examples and are not limiting.

If the maximum decoding time of each line is divided into smaller sections and the corresponding driving speed is set in multiple stages, the decrease in the average printing speed will be further reduced.

Note that the maximum value of decoding time was not to exceed 5 msec.

At 5tep7, compare the maximum decoding time T stored in the RAM with 3ms, and if T is longer than 3ms, then 5tep
At IO, drive speed is set to 5 msec. If it is below, compare T with 2 ms in step 8, and if it is 2 ms or more, set the drive speed to 3 ms, and if it is below, set the drive speed to 2 ms and start the flow. After that, printing is performed at the set driving speed as described above.

As mentioned above, most of the ordinary facsimile documents have a decoding time of 2 milliseconds or less per line. Therefore, most of the original pages can be driven at a constant speed of 2 msec pitch, and the proportion of original pages that need to be driven at 5 msec pitch is small. That is, when viewed as an average of all original pages, the print speed decreases only slightly.

FIG. 4 is a flowchart of another embodiment in which the driving speed is determined in the decoding time detection section. In Figure 3, the decoding time was detected for all lines of one page of manuscript data, but if the driving speed can be determined, it is not necessary to detect the decoding time for all lines as shown in the flow of Figure 4. There isn't. Also, in this example,
The driving speed was set to two levels: 2 msec and 5 msec.

The flow is set as a star, and in the initial setting of 5tep21, the maximum decoding time T is set to 2 msec and is stored in the RAM.

Similarly to FIG. 3, the decoding time t for each line is detected at 5tep22 and 5tep23, and at 5tep24, as long as t does not exceed T, the decoding time t is detected from 5tep25 to 5tep25.
Repeat the loop to p22. If the decoding time t exceeds the maximum decoding time T of 2 msec, the process moves from 5tep24 to 5tep26, and the flow ends with the maximum decoding time T set to 5 msec.

Note that detecting the decoding time does not necessarily involve detecting the actual decoding time; for example, in the case of MH codes, it is also necessary to check the number of bits, so that the maximum decoding time T is clearly determined from the number of bits. For lines that can be recognized as not being exceeded, the next line may be moved to without being decoded.

In the embodiment described above, the capacity of the line memory 8 was set to be two lines, but by increasing this capacity, the average printing speed can be further effectively reduced.

When the capacity of the line memory 8 is set to several lines, for example, 8 lines, the decoding time detection unit 6 detects the decoding time for each line, and sequentially updates the data for 8 lines line by line. Calculate the average time of the line. The average time is calculated using a moving average of 8 lines, from the 1st line to the 8th line, then from the 2nd line to the 9th line, and so on, dropping the oldest line and adding one new line. Then, the maximum value of the average value for every 8 lines of the decoding time of each line is detected.

For example, if we take the decoding time of the previous 7 lines for the Pth line and take the average, the decoding time of the 8th line will be 0.3°, 0.5, 5.0, 4, respectively.
．． 6, 2.6, 0.3, 1°2.0.6 msec, the average is 1.9 msec, so even if some lines have long decoding times, the average The time is 2 msec or less.

In this way, even if there is a line with a long decoding time of 5 ms in one page as in the above example, if the maximum value of the moving average does not exceed 2 ms for the page, the decoding time will be 2 ms. It can be driven by 100 kHz, and high-speed printing can be performed without increasing the line memory.

(Effects of the Invention) As is clear from the above description, according to the present invention, by controlling the drive speed for each page based on the maximum decoding time for that page, it is possible to use expensive page memory. This has the effect of providing an optical printer that can perform high-speed printing.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram for explaining one embodiment of a recording unit in a facsimile device using an optical printer according to the present invention, FIG. 2 is a schematic configuration diagram of a facsimile device to which an optical printer is applied, and FIG. This figure is a flowchart of one embodiment in which the driving speed is determined in the decoding time detection section of FIG. 1, and FIG. 4 is a flowchart of another embodiment in which the driving speed is determined in the decoding time detection section. DESCRIPTION OF SYMBOLS 1... Communication line, 2... Input memory, 3... Decoding part, 4... Line memory, 5... Printing part, 6...
...Decoding time detection section, 7... Drive control section. Patent applicant Murata Machinery Co., Ltd.

Claims (1)

[Claims] In an optical printer that decodes encoded signals such as MR and MH codes into bit signals and sequentially records the bit signals by line scanning, the time required to decode the encoded signal for each line in one page unit. An optical printer characterized in that the line printing speed for each page is controlled based on the maximum value of .