JPH09163142A - Gradation data compressed transfer system for printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gradation data compressed transfer system by which the number of gradation data transferred to a printer is decreased. SOLUTION: In this system, n-Bits in one byte are used for gradation data and the remaining bits are used for number of times data respectively. A comparison control section 10a compares gradation data in series of gradation data with the preceding gradation data to detect the presence of matching. A data transfer control section 10b transfers the gradation data without any modification when matching is not detected as the result of comparison, and transfers the gradation data by adding frequency data indicating the number of times of matching to the gradation data whose matching is detected after succeeding nonmatching is detected when the matching is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gradation data compression transfer system for a color printer capable of gradation printing.

[0002]

2. Description of the Related Art As a printing method of a color printer, which is one of the peripheral devices of a personal computer (hereinafter referred to as a personal computer), a color gradation printing method is adopted. The gradation printing method is a printing method with good color reproducibility such as an intermediate color because one pixel, which is the minimum unit that can be reproduced by a printer, has a plurality of gradation values. In addition, the personal computer and the printer are connected by a Centronics interface cable, and eight data lines and control / status signal 1 are connected.
It consists of 0 pieces.

By the way, in this type of printer, it is desirable to reduce the number of data transfers as much as possible when transferring data. As a technology related to such requests,
Japanese Patent Laid-Open No. 4-262448 (hereinafter referred to as a first example),
JP-A-62-103154 (hereinafter referred to as the second example)
Is raised.

The first example is a data transfer device of an information processing system which transfers data between a communication processing device and an input / output management device via a bus. When data of the same content continues, one data Is stored and the number of consecutive times is stored, and only the content and the number of consecutive times for one data are transmitted at the time of transfer to the bus. Therefore, the first example is divided into two parts, a data sending part from the processor to the bus and a data input part from the bus to the processor. The data transmission unit includes a comparison control unit that compares data, a counter that counts continuous data, a selector that selects data and a counter value when transmitting data, and the like. The data input unit includes a register for storing data, a counter for counting the number of continuous times, and the like.

On the other hand, the second example relates to a character pattern storage circuit, which stores a character pattern storage circuit in which character data of n bits and count data are stored, and the count data when reading from this storage circuit. The character pattern data generator repeatedly outputs n-bit data according to the above. In this second example, the character pattern formed by the m × n dot matrix is stored in the character pattern storage circuit. When reading data from the memory circuit, the character data is stored in the data register,
The count data is supplied to the counter. As the count data supplied to the counter, the same data is transmitted for the continuous count.

[0006]

However, in the first example, since the data and the count value are transmitted to the bus in two steps, the transmission amount may be doubled if there is no continuous number. There is.

In the second example, since the character pattern already exists in the memory circuit and the same data is continuously transmitted from the memory circuit by the number of times of data, the number of data transfers is the same as before.

An object of the present invention is to provide a gradation data compression transfer system capable of reducing the number of gradation data transferred to a printer without causing the above problems.

[0009]

A gradation data compression transfer system according to the present invention is a transfer system for transferring printer gradation data from an external storage device to a printer output port. Comparison control means for detecting whether there is a match by comparing the gradation data of a series of gradation data with the gradation data before the gradation data using the gradation data and the remaining bits as count data, respectively. As a result, if no match is detected, the gradation data is transferred as it is, and if a match is detected, the next mismatch is detected, and then the number of times that the match is detected is indicated in the gradation data. And a data transfer control means for adding and transferring data.

The comparison control means includes register means for temporarily storing the previous grayscale data.

Further, the data transfer control means increments the number of times data when the match is detected, and when the match is repeated, whether the number of repetitions exceeds a predetermined maximum value or not. Detecting step is executed, and if it does not exceed the predetermined maximum value, the operation returns to the operation of detecting whether there is a match with the next gradation data, and when it exceeds the predetermined maximum value, the count data is decremented. The value is added to the gradation data and transferred.

[0012]

The width of the data of the cable connecting the personal computer and the printer is usually 8 bits. On the other hand, the grayscale data is determined by the number of grayscales per pixel, but there are cases where the entire 8-bit data width is not used. At this time, the number of data to be transferred is reduced by compressing the data by using the unused bits.

That is, assuming that the gradation data has 6 bits, the data width is 8 bits, which is an extra 2 bits. By utilizing the extra 2 bits, data is compressed and transferred. When there is continuous grayscale data, the number of times of data transfer is reduced by allocating the number of continuous times to extra 2 bits.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. Referring to FIG. 1, here, the gradation data 1 is described as 6 bits and the number data is 2 bits, but is described as a 1-byte (8 bits) configuration, but the invention is not limited to this.

The gradation data 1 is stored in the external storage device 13 of FIG.
Stored in. The data compression unit 10 according to the present invention has a function of adding the frequency data 2 to the gradation data 1.
It is. The data compression unit 10 includes a comparison control unit 10a that compares the current grayscale data 1 with the previous grayscale data 1 and the count data 2 to the current grayscale data 1 to add the printer output port 1
The data transfer control unit 10b for transferring the data to the No. 4 is provided. Further, in order to perform the comparison operation of the gradation data 1, the comparison control unit 10a uses the internal storage device 12 as a register for temporarily storing the gradation data of the previous time. Therefore, the comparison control unit 10a and the internal storage device 12 may be collectively referred to as comparison control means. Note that this register is also used for temporarily storing the count data.

A method of counting gradation data will be described. When the gradation data is the same data continuously, the number obtained by subtracting 1 from the continuous number is put in the number-of-times data. The maximum value is the binary number "11" when four consecutive times occur, "10" when three consecutive times, "01" when two consecutive times, and "00" when not consecutive.

Next, the detailed operation will be described with reference to FIG. First, the gradation data handled here is defined as follows.

Gradation data (hexadecimal number) 3A, 2A, 1
5,15,15,25,25,25,25,25,25,2
5, 30 Start from the start step 100 of data compression transfer processing. In step 101 of clearing data, the data transferred to the register or the printer output port 14 is cleared. In step 103, the presence / absence of gradation data is determined. Since there is gradation data “3A” here, the flow B
In step 120, the data temporarily stored in the register is compared with the gradation data. In the register
Since no data has been entered yet, the comparison result is "NO", and the routine proceeds to step 127. Here, it is determined whether the gradation data is the head of all the gradation data. Since the gradation data “3A” is the head of all gradation data, step 1
Go to 25. Here, the gradation data is transferred to the register. After that, the number data is cleared in step 126, and the process returns to step 103 again.

Next is the gradation data "2A". As in the previous case, since there is gradation data, comparison is made with the previous gradation data stored in the register in step 120. The data stored in the register is “3A” which is the previous gradation data, and the comparison result is “NO”, so the flow proceeds to step 127. Then, since the gradation data “2A” is not the head data, the process proceeds to step 124. here,
The data transfer control unit 10b transfers the data to the printer output port by adding the number of times data to the register value "3A". The count data at this time is "00". Then, in step 125, the gradation data “2A” is stored in the register.
Is transferred, the count data is cleared in step 126, and the process returns to step 103.

Since the next gradation data is "15", which is different from the previous gradation data, the same processing as the previous processing is performed. Therefore, description of this operation is omitted, and description will be made starting with the second gradation data “15”. When the data in the register and the grayscale data are compared in step 120 through step 103, the result is "YES", so the flow proceeds to step 121. Here, the count data is incremented by one. Next, at step 122, it is judged whether the number of times data exceeds the maximum value. Since the count data incremented in step 121 does not exceed the maximum value, the process proceeds to NO and returns to step 103. Since the next gradation data is also “15”, step 1
03, 120, 121, 122, step 122
Then, since the count data has not exceeded the maximum value yet, the process returns to step 103.

The next gradation data is "25". The process moves from step 103 to step 120, and the register data and the gradation data are compared. Since the register value is “15”, the process proceeds to step 124 via step 127. At step 124, the count value data 2, that is, "10" is added to the register value "15" and the data is transferred to the printer output port. After that, in step 125, the gradation data “25” is transferred to the register, in step 126 the count data is cleared, and the process returns to step 103.

The next gradation data is also "25", which is 6 continuous data. The description up to the point where the count data exceeds the maximum value is omitted. The maximum value of the number of times data is 3, that is, "11", indicating that the same data is continuous 4 times. Therefore, the description will be given from step 122 when the fifth gradation data is received. Since the count data exceeds the maximum value 3, the count data is decremented by 1 in step 123 and the count data is returned to 3 (“11”). In step 124, the count value data 3 (“1
1 ") is added and the data is transferred to the printer output port. After that, the gradation data" 25 "is transferred to the register in step 125, the number of times data is cleared in step 126, and the process returns to step 103.

Since the next gradation data is "25", which is the same data as the previous one, the description will be omitted and the description will be started from the next gradation data "30". In step 120, the register value is “NO” compared with the register value “25”.
Then, in step 124, the count value 1 (“01”) is added to the register value “25” and the data is transferred. In step 125, the gradation data “30” is transferred to the register, the count data is cleared (step 126), and step 103
Return to If there is no gradation data, the process proceeds from step 103 to step 104, and the register value is "30".
The number data “00” is added to the data, the data is transferred to the printer output port, and the process ends in step 104.

[0024]

As described above, according to the present invention, the data transfer is performed by adding the count data to the remaining bits which are not used for the gradation data in the 1-byte data width transferred to the printer. The number can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between gradation data and frequency data in a data compression transfer system according to the present invention.

FIG. 2 is a block diagram showing a configuration necessary for performing a data compression transfer system according to the present invention.

FIG. 3 is a flow chart diagram for explaining data compression transfer according to the present invention.

[Explanation of symbols]

 1 gradation data 2 number data 10 data compression unit 10a comparison control unit 10b data transfer control unit 12 internal storage device 13 external storage device 14 printer output port

Claims (3)

[Claims] 1. A transfer system for transferring gradation data of a printer from an external storage device to a printer output port,
The n bits of 1 byte are used as gradation data and the remaining bits are used as count data, respectively, and a certain gradation data of a series of gradation data is compared with the previous gradation data to detect whether there is a match. And the comparison control means for transferring the gradation data as it is if no match is detected as a result of the comparison, and if the match is detected, the next mismatch is detected and then the level at which the match is detected. A gradation data compression transfer system for a printer, comprising: a data transfer control means for adding the number data indicating the number of coincidences to the key data and transferring the data. 2. The gradation data compression transfer system according to claim 1, wherein the comparison control means includes a register means for temporarily storing the previous gradation data. Transfer method. 3. The gradation data compression transfer method according to claim 1, wherein the data transfer control means increments the number of times data when the match is detected, and when the match is repeated. And the step of detecting whether or not the number of repetitions exceeds a predetermined maximum value, and if it does not exceed the predetermined maximum value, return to the operation of detecting the presence or absence of a match with the next gradation data. A gradation data compression transfer method for a printer, characterized in that when a predetermined maximum value is exceeded, the number of times data is decremented and the value is added to the gradation data for transfer.