KR0132883B1 - Video printer - Google Patents

Abstract

A video printer is disclosed for printing high resolution, high quality image printing by compensating the deviation of the resistances of the thermal transfer head. A frame memory (100) has memories (101-103) storing the image signals (R,G,B) by frame; a switch (110) selects one of the image signals (R,G,B) stored in frame memory (100); a memory controller (120) controls the data recording and reading timing of the frame memory (100); a color converter (130) converts the image data selected by the switch (110) to additive complementary colors of C,M,Y color signals; a resistance compensator (140) corrects the resistance; a gamma compensator (150) corrects the signal from the resistance compensator (140); a line memory (160) stores the data by lines; and the thermal transfer head (180) prints the data tone-compared by a TPH controller (170).

Description

Video printer device

1 is a block diagram of a conventional video printer apparatus.

2 is a diagram for explaining a screen printed by a thermal transfer head.

3 is a block diagram according to an embodiment of a video printer apparatus according to the present invention.

4 is a detailed block diagram of the resistance correction shown in FIG.

5 is an operating waveform diagram of the resistance correction of FIG.

* Explanation of symbols for main parts of the drawings

100: frame memory 110: memory controller

120: switching unit 130: color converter

140: resistance government 150: gamma government

160: line memory 170: TPH controller

180: thermal transfer head (TPH)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video printer apparatus, and more particularly, to a video printer apparatus for compensating for image quality deterioration due to variation of heating elements constituting a thermal transfer head in a sublimation thermal transfer printer apparatus using a thermal transfer head. In general, a video printer device uses a thermal transfer head to apply energy to the thermal transfer head to sublimate the dye on the film coated with the dye with energy generated by the thermal print head (also called TPH). It is a device for printing a desired image or picture by the amount of dye transfer. The video printer apparatus using the conventional thermal transfer head is as shown in FIG.

Referring to FIG. 1, the first to third frame memories are configured according to the write and read control signals CON of the frame memory outputting the red, green, and blue signals output from the signal input source from the memory controller 20. Fill in (11-13) and read. In addition, the switching unit 30 switches the image data stored in the frame memory 10 in one signal type frame unit among red, green, and blue signals according to the selection signal SEL output from the memory controller 20. The color converter 40 converts R, G, and B light data sequentially transmitted from the switching unit 30 for each color into data of Y, M, and C colors having a complementary color relationship. Here, the signal input source may be a video camera, a television, a personal computer, or a graphic computer.

The gamma correction unit 50 transmits the gamma correction to the TPH controller 70 via the line memory 60, and the TPH controller 70 converts the gamma corrected image data into data for heat generation. The converted data is transmitted to the yarn head 80, and the thermal transfer head 80 generates heat by generating heat energy corresponding to the converted data to represent an image. On the other hand, the TPH controller 70 inputs a line synchronization myth and a data synchronization signal output from the memory controller 20 to read out image data stored in the line memory 60 in line units and through a gradation comparator (not shown). Compared with the gradation data generated from the gradation counter (not shown), the image data larger than the output of the gradation counter is 1, otherwise 0 data is transmitted to the thermal transfer head 80, so that the resistance of the thermal transfer head 80 is reduced. They express heat by generating heat.

Although not shown in the drawing, the thermal transfer head 80 includes a shift register that stores the output of the gradation comparator as a line, a latch that temporarily latches the output of the shift register, and a resistor that generates the output of the latch. It is. However, such a conventional printer apparatus has a problem in that the heating energy is changed according to the resistance deviation of the thermal transfer head, so that the density is not the same for the same gray level in the main scanning direction as shown in FIG. SUMMARY OF THE INVENTION In order to overcome the above problems, it is an object of the present invention to provide a video printer apparatus having a compensation circuit for compensating for variations in resistance of a thermal transfer head to print with high resolution and high image quality.

Another object of the present invention is to provide a video printer apparatus which realizes correction due to resistance deviation of a thermal transfer head with a small memory capacity. In order to achieve the above objects, the video printer apparatus according to the present invention introduces the energization factor by the thermal transfer head composed of a plurality of heating elements after the image signal is input from the signal input source and the tone value is preset in line units. A video printer apparatus comprising: a quantization value for a deviation of an address generator which generates an address corresponding to a heating element position of the thermal transfer head in synchronism with an incoming image data, and a heating element corresponding to a heating element position address generated by the address generator; And a resistance compensator including the stored sub-memory and a main memory in which the output of the sub-memory and the incoming image data are inputted as addresses, and the data compensated for the resistance deviation and the gradation are stored at corresponding addresses. I am doing it. Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of a video printer device according to the present invention.

2 is a block diagram according to an embodiment of a video printer apparatus according to the present invention. 2 shows a frame memory 100 having first to third frame memories 101-103 for storing image signals flowing from a signal input source in units of frames for each of R, G, and B signals; A switching unit 110 for signal type switching among R, G, and B image data stored in the frame memory 100, a memory controller 120 for controlling timing of data write / read of the frame memory 100; The R, G, and B data selected by the switching unit 110 may convert the color converter 130 into a C, M, Y color signal having a complementary color relationship, and a resistor to output an output of the color converter 130 by resistance correction. A gamma correction unit 150 for gamma-correcting the output of the resistance correction unit 140, a line memory (160) for storing the output of the gamma correction unit 150 in units of lines, and a line memory The TPH controller 170 compares the gray scale from the output of 160 and the TPH controller 170 Heating the comparison to the data consists of a thermal print head (180) representing parameter.

Here, the resistance correction unit 140 inputs the line synchronization signal and the data synchronization signal generated from the memory controller 120 as shown in FIG. 3 to obtain an address corresponding to the positions of the resistors of the thermal transfer head 180. Image data and second output from the second memory 143 and the color converter 130 in which the generated address generator 142 and the resistance deviation corresponding to the resistance position address generated in the address generator 142 are stored. In order to input the quantized signal of the resistance deviation for each resistance position generated from the memory 142 as an address signal and output the resistance compensated data stored at this address, the resistance compensation is performed for each gray level according to the deviation value of each resistance in advance. The first memory 141 stores data.

Next, the operation of FIG. 3 will be described with reference to FIGS. 4 and 5.

Referring to FIG. 3, the configuration of the frame memory 100, the switching unit 110, the memory controller 120, and the color converter 130 may include the switching unit 10, the memory controller 20, Since the configuration and operation of the color converter 30 are the same, a detailed description thereof will be omitted. The resistance correction unit 140 converts the image data output from the color converter 130 for converting the image data of the R, G, and B forms into the image data of the Y, M, and C forms from the memory controller 120 to the TPH controller 170. The line synchronous signal and the data synchronous signal are transmitted to the gamma correction unit 150 to compensate for the resistance deviation.

In addition, the gamma correction unit 150, the line memory 160, the TPH controller 170, the thermal transfer head 180 is the gamma correction unit 50, line memory 60, TPH controller (shown in FIG. 70), the same as the thermal transfer head 80, detailed description thereof will be omitted. Here, the resistance correction unit 140 shown in FIG. 4 will be described in detail.

Referring to FIG. 4, in the first ROM 141 of the resistance correcting unit 140, 8-bit Y, M, and C type 1-byte data from the color converter 130 are lower 8-bit addresses of the first ROM 141. It is input as a signal. The output of the first ROM 141 is transmitted to the gamma correction unit 150. On the other hand, the line synchronization signal transmitted from the memory controller 120 is input as a clear signal CLR of the address generator 142, and the synchronization signal of the Y, M, and C input data transmitted from the memory controller 120, that is, the data. The synchronization signal is input to operate as the clock signal CLK, which is an address increase signal of the address generator 141.

Here, the line synchronizing signal is as shown in FIG. 4A, the period of the line synchronizing signal is 5 mseo, and in the row section of the line synchronizing signal is a period for transmitting Y, M, C data to the line memory 160, In the high section of the line synchronization signal, the signal stored in the line memory 160 is transferred to the TPH 180 via the TPH controller 170 to express the factor.

The signal shown in FIG. 4B is a signal waveform in which the line synchronization signal shown in FIG. 4A is enlarged.

The signal shown in FIG. 4C is a data synchronization signal, and 1 to 4096 clock pulses are generated during the low period of the line synchronization signal shown in FIG. 4B. In this case, 1 to 4096 heating elements as shown in FIG. 4D are generated. Corresponding to 4096 heating data are transmitted. Here, in the present invention, the number of resistances of the TPH 180 required for printing one line is set to 4096.

The address generator 142 generates a 12-bit address signal corresponding to 1 to 4096 based on the line synchronization signal and the data synchronization signal and inputs the address signal of the second ROM 143. In the period in which the line synchronization signal shown in FIG. 4B is high, the address of the address generator 142 is initialized to zero (0). If the line synchronization signal is low, the address synchronization unit 142 is canceled and the data synchronization signal is reset. Whenever one is displayed, the address of the address generator 142 is increased one by one starting from the initialization address 0.

Thus, in the second ROM 143, the 6-bit data stored at the corresponding address is input as the upper 6-bit address signal of the first ROM 14 by the address signal generated by the address generator 142. When the first ROM 141 is inputted with 8 bits of Y, M, and C data, which are lower address signals, and the upper 6 bits of the second ROM 143, the 14 bits of address signal are input. It designates one address and outputs one byte of resistance-compensated data stored at that address. Here, the first ROM 141 may be referred to as a main memory, and the second ROM 142 may be referred to as a sub memory.

The resistance correction process is described in more detail as follows.

The energy or factor concentration applied to the thermal transfer head 180 is proportional to the multiplier and the application time of the applied voltage and inversely proportional to the resistance of the heating element as shown in Equation 1 below.

E = (V ² / R) T ---- (1)

In the present invention, the factor of change in the factor concentration is directly related to the resistance value of the heating element, and thus, two elements of the remaining variables, the applied voltage and the applied time, are fixed elements. Therefore, since the factor concentration is inversely proportional to the resistance value of the heating element, the heating data corresponding to the heating element with the small resistance value should be converted to lower than the input data and transmitted as the heating data.

The 12-bit address generated by the address generator 141 is initialized using the line synchronization signal as an initialization signal, and the data synchronization signal is incremented one by one from the initialized address of the address generator 143 (not shown). The clock signal). Here, the 8-bit Y, M, C input data input to the first ROM 141 is sequentially inputted from the first heating element of the thermal transfer head 180 having 4096 heating elements to the last heating element. It is a form. Therefore, the data synchronization signal shown in FIG. 4C serving as the clock signal of the address generator 141 becomes 4096 pulses, and the number thereof corresponds to a power of 12 in terms of a power of 2, so the address generator 141 generates 12 bits. Thus, the value acting as the address of the second ROM 142 is 0 to 4095.

The second ROM 143 is quantized data of corresponding resistance values for each of 4096 heating elements (resistances) of the thermal transfer head 180, that is, a quantized value of 64 steps in which the maximum value of the resistance value is 63 and the minimum value is 0. It is stored. Specifying any one address of the second ROM 143 containing the quantized value is a 12-bit address generated from the address generator 141. In other words, the resistance value of the heat transfer head heating element is such that the fluctuation of the print concentration does not exceed 25% of the maximum value when the same energy is applied to all the heat generating elements by the heat transfer head.

Of course, the smaller the variation is, the better the thermal transfer head 180 becomes, but it is impossible in the semiconductor manufacturing process, so the maximum variation is allowed and the maximum value of the input data in FIG. 3 is 255 (8 bits). ), The maximum variation is 64. Therefore, the output value of the resistance value of the quantized heating element of the second ROM 143 acts as 6 bits. In the first ROM 141, 256 8-bit data forms one block and is generally composed of 64 blocks. 256 pieces of data corresponding to one block are outputted as 256 bits of 8-bit Y, M, and C input data in the first ROM 141 by 6-bit output data of the second ROM 143 that designates a block. Values corresponding to the case constitute one block. The number of gray scales that can be represented by 8-bit data is 256 steps, and the tolerance of the resistance variation is 25%. Therefore, the first ROM 141 stores data having resistance compensation of 256 8-bit data in 64 blocks.

Therefore, 8-bit Y, M, and C input data that are sequentially input are simultaneously generated and act as an address of the first ROM 141 by forming one address bus with 6-bit data that designates one quantized block to be input. One data is generated from the address and transmitted to the gamma correction unit 150 of FIG. 2 to perform normal thermal transfer head data transmission and control. The memory capacity required for implementing the resistance correction using two ROMs proposed in the present invention is 23 Kbytes. If the resistance compensation unit 140 is implemented in the form of a ROM, a storage place for storing 256 heating data for one heating element resistance of the thermal transfer head 180 is required. Therefore, if all data is stored for all 4096 heating elements, a capacity of 4096 × 256, that is, a large capacity of 1 Mbyte is required.

However, in the present invention, since the capacity of the first ROM 141 is 64 × 256 bytes, that is, 20 Kbytes, and the capacity of the second ROM 142 requires 4096 × 6 bytes, that is, 3 Kbytes, the capacity of 23 Kbytes is required. The memory capacity can be reduced. As described above, the video printer apparatus according to the present invention compensates the resistance deviation of the thermal transfer head by using two memories in which the compensation data is stored, thereby achieving a high image quality and high definition image and having a small memory capacity. There is an effect that can be implemented.

Claims (4)

A video printer apparatus in which an image signal is input from a signal input source and expresses an energization factor by a thermal transfer head made up of a plurality of heating elements after comparing a gray level value preset in line units with a gray level, corresponding to the position of the heating element of the thermal transfer head. An address generator which generates one address in synchronization with the incoming image data, a sub-memory in which a quantization value of the deviation of the heating element corresponding to the heating element position address generated in the address generator is stored, and the output of the sub-memory and the incoming image And resistance correction means for inputting data as an address, and having a main memory in which data for each of the resistance deviation and the gray level are compensated at an address corresponding thereto. The video printer apparatus according to claim 1, further comprising control means for outputting a line synchronization signal as a clear signal and a data synchronization signal as a clock signal to the address generator. The video printer apparatus according to claim 1, wherein the sub-memory stores a quantized value within 25% of the number of gray scales that can be represented by the image data input of the tolerance of the resistance deviation. The video printer apparatus as claimed in claim 1, wherein the main memory stores data compensated for each gray level corresponding to the quantization step generated in the sub memory.