JPS58150371A - Compensating circuit of coloring characteristics for color printer - Google Patents

Abstract

PURPOSE:To simplify the compensation of each color, by extracting a color code signal out of a color print signal and supplying each color signal as an address signal of a fixed memory which stores the compensating data of corresponding coloring characteristics. CONSTITUTION:The input signal is made pass through a color code signal circuit 21 to deliver a color code signal. This color code signal controls a color signal separating circuit 22 and a fixed memory 24. If the input signals have 4 colors of Y, M, C and B, the circuit 21 delivers 00, 01, 10 and 11 to Y, M, C and B respectively. The circuit 22 is controlled by a color code signal of 2 bits, and each color is selected. Each color signal is digitized by an A/D converter 23 and then read into a memory 18. On the other hand, the color code signal of 2 bits is supplied as an address signal of a fixed memory 24 which stores the compensating data of coloring characteristics corresponding to said 4 colors and then used as an upper bit of the output of a counter which designates the print gradation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit that can obtain a hard copy based on a print signal and corrects the coloring characteristics of a printer.
This invention relates to a correction circuit that can correct the color characteristics of [6] in color printing.

As is well known, in a thermal printer using a heat-sensitive head, a drive signal corresponding to the image or character to be printed is supplied to each of the heat-sensitive elements arranged in a row, and a hard copy is produced using colored ink heated by the heat-sensitive elements. This is what you get.

In the case of color printing, an ink ribbon containing disperse dyes such as yellow, magenta (M), cyan (C), and black (B1) is used, and each color is printed in sequence, resulting in a color print. can be obtained.

However, since the energization time of the drive signal supplied to the thermal head and the rate of color development by the ink ribbon are generally non-linear, the drive signal energized to the thermal head is proportional to the density of the screen to be printed. If the print image is supplied with a different density than the original image, the printed image will not be expressed in the same way as the original image. Therefore, generally a so-called coloring correction circuit is used to form the drive signal.

Therefore, regarding the correction circuit for coloring characteristics in a printer (application@56-123588) previously filed by Masu Motoyama, we will explain the block diagram in FIG. 1 and the waveform diagram in FIG. 2.

In FIG. 1, 11 is a clock pulse generator;
2 is a preset counter preset with data output from the fixed memory 1S, and 14 is a counter that counts the carry output CA of the preset counter 2 and specifies the address of the fixed memory 13 according to the count value. It is. The carry output CA is the address counter 15.
The input 8t1 is input to the reference level signal generator 16, and the address counter 1S is output to the oscillator 21 every time the carry output CA is input.
The number of output pulses starts from the address signal.

form. On the other hand, the reference level signal generator @1@ which receives the carry output CA also outputs a low comparison level signal every time the carry output CA is input. Reference numeral 17 denotes a magnetometer parator, which compares the comparison level signal Dr of the reference level signal generator 16 with the pixel data D read out from the memory 18, and outputs an H level comparison output when D v > Dr. is generated and sent to the latch circuit 11C.

Memory 18 mentioned above. The address of the latch circuit 11 is specified by the address signal of the address counter 15, and the pixel data D stored in the specified address in the memory 1$ is read out.
At 9, Magnitude Bum Valetator 1 is placed at the specified address.
7 comparison data D is written.

Note that 20 is a register for holding the comparison data Da stored in the latch circuit 19 as a carry output chvci, and the output of this register 20 is sent to a head (not shown) as a printer drive signal.

Next, the operation of the present invention will be explained with reference to FIG.

When a carry output CA is output as described later to the preset counter 12 which has the clock signal CK of the clock pulse generator 11 as the number of stitches, a different value is output from the reference level signal generator 16 each time the carry output CA is generated. Comparison level signals are sequentially outputted and sent to the i-doneitude converter 17.

On the other hand, the memory 111 stores A/D-converted pixel data (1 degree level) DY, which is an image signal, for one printer, and this pixel data D is sequentially addressable one time.
A comparison level signal is read out by the address signal of
compared to Figure 2 shows pixel data D for l blocks,
Data when there are 4 Dy+, Dyi * DYI
+ DY4 is shown in width, and the signal in the case of lO level is illustrated as a comparison level signal, and the pixel data DYl to DYI are shown as a constant level by the carry output CA. The address signal is sent during this period.

(l・2・3・4)K are read out sequentially and input into the magnitude comparator 17 in the 111st order. Therefore, it is not detected that the pixel data Dr is smaller than the comparison level signal at time A shown in FIG. 2, and at that time, the magnitude humerator 1T generates the comparison data I)at at the H level. Similarly, pixel data D
! , is detected to be smaller than the comparison level signal D1 at time B, so comparison data I) am is generated at that time, and similarly, comparison data I) cs is generated at time C for pixel data DYI, and pixel data Dy , the comparison data Dc as of point in time.

occurs. Comparison data Dcs obtained in this way
~DC4 is the latch circuit 1 located at the same location as the memory 18
It is stored and held by the address signal 9 and transferred to the register 20 by the next carry output CAK. Therefore, the signal transferred to the register 20 is a signal having a pulse width indicated by diagonal lines.

The comparison data DC transferred to this register 20 is the pixel data DY pulse width modulated, so when a printer (not shown) is driven with this signal, the pixel data D! A print image having shading corresponding to the amplitude/width values is formed.

From the above explanation, correction of coloring characteristics, that is, pixel data D
It can be seen that the problem of what pulse width to create the comparison data Dc with respect to the magnitude of Y can be determined by the step-like pattern of the comparison level signal p.

By the way, as mentioned above, this step-like pattern which is the output of the reference level signal generator 1B is determined by the appearance cycle of the carry output CA, so it can be made into any shape by the preset value of the preset power inputter 12. We meet.

Therefore, if preset values for correcting the coloring characteristics are recorded as data in the fixed memory 13, any coloring characteristics can be obtained.

However, in the case of color printing, the coloring quality of the coloring ink varies depending on the color used for printing, so for example, there are four colors (Y, C, M).

When printing in color with Bs), unless the coloring characteristics of each color are corrected independently, the hue of the hard copy will be different from that of the original.

The present invention has been made in view of this point, and is capable of correcting the coloring properties (r-correction) of each color to be printed.

Figure 3 is a block diagram of a correction circuit for the coloring characteristics of the color print (k) of the present invention. ! ,(!!
signal separation circuit 22. An A/D converter 23 is added, and a fixed memory 24 stores correction data of coloring characteristics corresponding to the color density to be printed.

A block diagram of the present invention will be explained below.

The main operation is similar to that shown in FIG.
The period of appearance of the carry output CA changes depending on the data of the colored bone, and is the same in that it determines the pattern of the comparison level signal Dr.

The color signal separation circuit 22 outputs a color-specific signal. and fixed notes! ll 24 Yll is to be controlled. For example, the color of the color print signal is Y (
yellow), M (magenta), C (cyan).

To explain the case of four colors of Bs (black), the color-specific signal circuit 21 outputs 00. 01° for M; 10° for CK. A 2-bit signal of 11 is output for B and B, and the color signal separation circuit 22 is controlled by this color-specific signal to separate each color. Next, the A/D converter 823 converts it into a digital signal, and the address No. 11 is sent to the memory 1.
8km included.

On the other hand, the 2-bit color signal is supplied as an address signal to the fixed memory 24 in which correction data for coloring characteristics corresponding to the four colors is stored, and is supplied as the upper bit of the output of the counter 14 that specifies the 1lllli tone of printing. used. In other words, the output of the counter 14 is 4 pins) (AO~A4
), the upper A1. The above-mentioned color signals are applied to AO, and the fixed memory 24 is read out using the 6-bit address signals A, to A-.

The data read out from the fixed memory 24 can be different for each color, so as explained in FIG. 1, different stepped comparison data DC are output for each color, and the γ-correction It can be performed.

Although the case of four color signals has been described, it goes without saying that the case of multiple colors can also be made possible by increasing the capacity of the fixed memory 24.

As explained above, the colored bone correction circuit in the color printer of the present invention is capable of individually correcting each color to be printed using a single circuit configuration. Osseousness has the advantage that it can be done arbitrarily by changing the fixed memory.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a coloring characteristic correction circuit for correcting the gradation of the printer, Fig. 2 is a waveform diagram for explaining the operation of Fig. 1, and Fig. 3 shows an embodiment of the present invention. FIG. 2 is a block diagram of a coloring characteristic correction circuit in a color printer. In the figure, 12 is a preset kakunta, 14 is a counter, 1
Reference numeral 5 indicates an address power output, 16 indicates a reference level, a signal generator, I7 indicates a magnitude controller (rake), 18 indicates a memory, 1s indicates a latch circuit, 22 indicates a color-specific signal circuit, and 24 indicates a fixed memory.

Claims (1)

[Claims] a preset card preset by the output of the first memory;
a reference level signal generator that generates a comparison level signal fk11 based on the carry output of the preset counter; a second memory that receives print signal data and can read it; and the comparison level signal. The data in the first memory is composed of a pulse generator that compares the data of the print signal and a latch circuit that latches the comparison output of the comparator. What is claimed is: 1. A circuit for correcting dark color excursions in a color printer, characterized in that the output is sequentially read out as an address signal, and the data is capable of correcting coloring characteristics for each color.