KR0154761B1 - Sublimation type color printer with automatic density control apparatus - Google Patents

Abstract

The present invention relates to a device for automatically adjusting the density of a thermal sublimation type printer, and in particular, to detect the density of printing before printing the color image data to be actually printed, and to detect the optimum density in advance and to automatically adjust the density. A sublimation type color printer having a device. A halftone control unit for outputting a heat generation control signal corresponding to the input of density-adjusted image data, a TPH for generating heat corresponding to the heat generation control signal to adsorb ink on the ink ribbon onto the sublimation recording paper, and a preset density. A test image generating means for generating test image data, and a plurality of density adjustment data are stored at a plurality of addresses, the LUT for inputting image data and image density adjustment data as addresses and outputting image data corresponding to the input address. And density detection means for detecting and outputting the density of the color printed on the recording paper by the heat generation of the TPH, and printing the test image data by selecting and supplying the test image data to the LUT during initial printing. Supplying the image control data corresponding to the printing density to the LUT; It is the actual printing of the image data to be supplied from the outside at the time of configuration, including control means for controlling printing by supplying to the LUT

Description

Sublimation Color Printer with Automatic Density Control

1 is a block diagram of a general sublimation color printer.

2 is a view showing a coupling relationship between the heat generating head and the heat sensor shown in FIG.

3 is a view showing the state of the printing mechanism of a general sublimation color printer.

4 is a view for explaining the principle of the present invention, for explaining the state of the concentration test by printing test data.

5 is a diagram showing the configuration of a sublimation type color printer having an automatic density control apparatus according to the present invention.

FIG. 6 is a diagram showing an example of the test image data generator shown in FIG.

The present invention relates to an apparatus for automatically adjusting the density of a thermal sublimation type color printer, and in particular, before printing the color image data to be actually printed, the density of the printing is detected in advance by detecting the density of the printing in advance and automatically detecting the density. The apparatus which cuts into an is related with the sublimation type color printer which has.

The sublimation type color printer stores image data transmitted from a device such as a computer in a memory, accesses image data stored in the memory line by line, and transfers the image data to a thermal print head (TPH) for each line. Record the data on the recording sheet. TPH used in such a sublimation type color printer is a method of expressing an image on recording paper by sublimating ink on an ink ribbon by converting electrical energy into energy of heat and adsorbing the sublimed ink on the recording paper.

On the other hand, a sublimation thermal transfer color printer capable of expressing the color tone of an image is capable of expressing the color tone of an image using a color ink ribbon having a structure as shown in FIG. That is, in the case of expressing a color, various colors are expressed by sequentially printing yellow, magenta, cyan, and black inks according to the printing order.

A circuit of a general sublimation type color printer which prints on recording paper using the color ink ribbon as described above is shown in FIG.

FIG. 1 is a block diagram of a general sublimation type color printer. The heat generating head (hereinafter referred to as TPH) 12 which generates heat in response to the heat generation control signal input and sublimes the ink on the color ink ribbon, and FIG. A thermal sensor 14 for detecting a heat generation temperature, a CPU 16 for outputting address data for outputting data of a heat generation time corresponding to the detected temperature of the thermal sensor 14, an address data output from the CPU 16, and an external device; A look-up table (hereinafter referred to as LUT) 18 which inputs input image data as an address and outputs image data whose heat generation time of the corresponding table is adjusted, and the image data output from the LUT 18. And a halftone control unit 20 for supplying a heating control signal to the TPH 12 in response to the input.

2 is a view showing a coupling relationship between the heat generating head and the heat sensor shown in FIG. In FIG. 2, reference numeral 12 denotes a TPH in which a plurality of heat generating heads are arranged at regular equal intervals. A ceramic substrate 22 having good thermal conductivity is positioned above the heating element 12, and a heat sink 24 for dissipating heat generated by heat generation on the surface of the heating element 12 is positioned above the ceramic substrate 22. 24 is mutually bonded by an adhesive agent. At this time, the ceramyl substrate 22 is provided with a thermal sensor, for example, a thermistor 14 for sensing the temperature accumulated in the ceramic substrate 22 by the heat of the TPH 12.

First, the operation of a conventional sublimation color printer will be described with reference to FIGS. 1 and 2. FIG.

The sublimation type color printer configured as shown in FIG. 1 receives image data from a computer or a digital camera. This image data is transmitted to LUT 18 shown in FIG. 1 vertically, as is well known in the art. In such a state, the heat detector 14 detects heat transmitted to the ceramic substrate 22 by the heat of TPH 12 and transmits corresponding temperature data to the CPU 16.

At this time, the CPU 16 transmits address data for outputting data having a heat generation time corresponding to the temperature data as an address of the LUT 18. Therefore, the image data and the address data output from the CPU 16 are input to the address terminal of the LUT 18, and the LUT 18 outputs the image data corresponding to the address signal.

The reason for using the above-described LUT 18 is that, as is well known in the art, the printing (output) characteristics of the original image data and the sublimation type color printer are different, so that the data is manipulated in the middle so that the original density and the recording paper of the image data can be changed. This is to ensure that the concentrations expressed are nearly identical. In this case, as described above, the CPU 16 outputs the heat sensor 14 so that the heat generation time is decreased when the temperature of the TPH 12 is high, and when the temperature of TPH 12 is low, the heat generation time is long. Adjust the output.

Data output from the LUT 18 is transmitted to the halftone control unit 20 is converted into a signal capable of driving the TPH 12, which is then sent to the TPH 12 to control the heat generation. Referring to Fig. 3, the operation of printing image data on a recording sheet by the heat generation of TPH 12 as described above is as follows.

3 is a drawing showing the general configuration of the printing mechanism of a general sublimation type color printer, which includes a roller 30 for conveying a recording sheet 26 placed on an upper portion thereof, and an ink of a ribbon placed on the recording sheet 26 by TPH 12 heating. Is composed of an ink ribbon 28 for adsorbing on the recording paper 26 and a TPH 12 for subliming the ink of the ink ribbon 28.

A schematic operation of the printing mechanism of the sublimation type color printer configured as shown in FIG. 3 is as follows. When a current flows through the heat generating element TPH 12, heat is generated to generate heat. When the heat generating element TPH 12 generates heat, the ink on the ink ribbon 28 positioned below the substrate is sublimed and adsorbed onto the recording paper 26 placed below the ink ribbon 28. At this time, the density adjustment of the ink adsorbed on the recording paper 26 is performed by adjusting the heat generation time of the heat generating element TPH 12. For example, a concentration difference of about two times occurs between the concentration of exothermic heat for 5 ms and the concentration of exothermic heat for 10 ms. However, since the heating time of the heating element TPH 12 is not necessarily proportional to the concentration recorded on the recording sheet 26, it is a general technique to adjust the concentration using the correction data stored in the LUT 18 shown in FIG.

As described above, when the heat generating element TPH 12 generates heat corresponding to the image data, the ink of the ink ribbon 28 is sublimed to express the desired density on the recording paper 26, and printing of one line is completed. In the case of A4 size printing, printing about 3,000 lines completes one color printing. Therefore, when the sublimation color printer uses a three-color ink ribbon, printing proceeds in the order of yellow, magenta, cyan, and the like, and in the order of yellow, magenta, cyan, and black, when the four-color ink ribbon is used. When the three colors are printed in progress, the printing of one screen is completed.

At this time, whenever printing of one color (one color) is completed, the CPU 16 checks the output of the thermal sensor 14, inputs the checked data, and adjusts the image data in the LUT 18 when the density is high. Allow only a little less time to heat up. This means that the heat accumulated in TPH 12 is combined with the heat generated by the image data, and is expressed at a concentration higher than that caused by the image data, thereby reducing the heat generation time by the data corresponding to the heat accumulated. By the above operation, the concentration change due to the heat storage of TPH 12 is reduced.

However, the conventional circuit which adjusts concentration by the above structure has had the following problems. As shown in FIG. 2, since the TPH 12 and the heat detector 14 are spaced apart from each other, the temperature transmitted to the ceramic substrate by the heat generation of the TPH 12 is not accurately detected, resulting in very poor accuracy and reliability. In addition, the thermal sensor by a thermistor or the like has a considerable difference in temperature sensing characteristics from the actual temperature. Therefore, it is not unreasonable to quickly and accurately detect heat storage caused by heat generation of TPH 12. Therefore, when continuously operating a conventional sublimation type color printer having the configuration as shown in FIG. 1, the variation of the resistance component of the heating element of the TPH, the fan motor to prevent the heat storage of the TPH, and the variation of the power supply for supplying power. Considering the factors, the density of the image data causes a problem that is significantly different from the density of the image represented by the TPH.

Accordingly, an object of the present invention is to provide a sublimation type color printer which prints preset test image data and automatically adjusts the density of the image to be actually printed by the density of the printed image.

The present invention for achieving the above object, the halftone control unit for outputting a heat generation control signal corresponding to the input of the density-adjusted image data, and the heat generation corresponding to the heat generation control signal, the ink on the ink ribbon sublimation recording paper A sublimation type color printer having an automatic density adjusting apparatus having a TPH to be adsorbed on a substrate, the sublimation type color printer comprising: test image generating means for generating test image data having a predetermined density, and a plurality of density adjusting data are stored in a plurality of addresses, A LUT for inputting image data and image density adjustment data as an address and outputting image data corresponding to the input address, density detection means for detecting and outputting the density of the color printed on the recording paper by the heat generation of the TPH; When printing, the test image data is selected and supplied to the LUT for testing And controlling means for printing the image data, supplying image control data corresponding to the sensed printing density to the LUT, and simultaneously supplying the actual image data to be printed from the outside to the LUT to control printing. It features.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings of the embodiments of the present invention, those having substantially the same configuration and function as those in the above-described drawings will use the same reference numerals.

4 is a view for explaining the principle of the present invention, a view for explaining the state of the concentration test by printing test data. 4A, 4B and 4C are exemplary views when yellow, magenta and cyan colors are printed by the automatic concentration control according to the present invention.

1, 3, and 5 in FIGS. 4A, 4B, and 4C show printed areas for testing the concentration according to the exothermic state of TPH 12. First, referring to FIGS. 4A, 4B, and 4C, the principles of solving the problems of the prior art will be briefly described as follows. As described above, the concentration to be printed has many factors such as heat storage state of the TPH, power supply voltage of the power supply, fan motor air volume, and the like. It is the result of the combination of these elements. Therefore, if the 2, 4, 6 areas where the concentration of the 1, 3, 5 area is actually printed before the printing starts, the printing concentration of the actual printer can be detected.

5 is a diagram showing the configuration of a sublimation type color printer having an automatic density control apparatus according to the present invention. First, before referring to the operation of the automatic concentration adjustment according to the embodiment of the present invention with reference to Article 5, the recording sheet 26 is fed for printing and the mechanism is ready for printing as shown in FIG. Assume that there is.

When printing is started, the CPU 16 shown in FIG. 5 is first operated in the test mode to control the multiplexer 38. In other words, the output of the test image data generator 32 which generates preset test image data is supplied to the LUT 18. The test image data is supplied as an address signal of the LUT 18, and the LUT 18 outputs data stored at an address preset to match the characteristics of the recording paper.

The data output from the LUT 18 is supplied to the halftone control unit 20 and converted into a heating control signal. The TPH 12 generates heat by the heating control signal output from the halftone control unit 20 to sublimate the ink of the ink ribbon 28 in the mechanism 34. At this time, the sublimed ink is adsorbed onto the recording sheet 26 to complete printing of the test image data. That is, it is printed at the same position as areas 1, 3, and 5 of FIGS. 4A, 4B, and 4C.

When the test image data is printed as described above, the density detector 34 detects the density of the printed image and supplies it to the CPU 16. At this time, the detection of the density is optically sensed, and the optically sensed density, that is, the value of optical density is converted into a digital value and supplied to the CPU 16.

The CPU 16, which inputs a detected density value output from the density detector 34, compares the density value of the test image data set in advance, and supplies image density control data corresponding to the difference to the address of the LUT 18 to supply the LUT 18 phase. Select one of the multiple tables set in.

As described above, the CPU 16 having selected one of the plurality of tables on the LUT 18 controls the multiplexer 38 such that image data 40 input from the outside is selected and input on the LUT 18. The image data 40 inputted to the address of the LUT 18 is adjusted according to the table of the LUT 18 by the above operation. The data output from the LUT 18 is inputted to the halftone control unit 20 by the adjustment. The concentration is automatically adjusted by feeding to TPH.

As described above, the concentration-adjusted arc day is completed when printing about 3,000 lines is completed. Concentration is also controlled by the same procedure as above for colors such as magenta and cyan.

FIG. 6 is a diagram showing an example of the test image data generator shown in FIG. Referring to FIG. 6, the test image data is 8 bits, and the upper four bits of data DATA01 to DATA04 are pulled up and supplied in a logic high state, and the lower four bits of data DATA05 to DATA08 are pulled down to a logic low state. It can be seen that the setting is supplied.

As described above, the present invention prints test image data having a predetermined concentration in a predetermined area of the front end of the section to be printed, to measure the concentration according to the change of the environmental factors of the system, and to correspond to the measured change in concentration By adjusting the concentration automatically, it is possible to reliably control the concentration.

Claims (4)

A half-tone control unit for outputting a heat generating control signal corresponding to the input of density-adjusted image data, and an automatic density adjusting device having a TPH for generating heat corresponding to the heat generating control signal and adsorbing ink on the ink ribbon onto the sublimation recording paper. A sublimation type color printer comprising: a test image generating means for generating test image data having a predetermined density, and a plurality of data having a plurality of density adjusting data and adjusting the plurality of density in response to an input of a first address; Select one of the data, select the density control data corresponding to the input of the image data and supply it to the halftone control means, the density to detect and output the density of the color printed on the recording paper by the heat of the TPH Selecting the sensing means and the test image data during initial printing to supply to the LUT And control means for printing the test image data, supplying image control data corresponding to the sensed printing density to the LUT, and simultaneously supplying the actual image data to be printed from the outside to the LUT to control printing. Sublimation type color printer having an automatic density control device. The LUT of claim 1, wherein the control unit generates a test mode switching signal in response to one color printing start and supplies a first address corresponding to the density detection signal output from the concentration sensing unit to the LUT. A central processing unit for selecting one of a plurality of density adjustment data set therein, and an input for inputting image data from the outside and preset test image data and supplying the test image data to the LUT in response to the test mode switching signal A sublimation type color printer having an automatic density adjusting device, characterized by comprising means. The sublimation type color printer according to claim 2, wherein the central processing unit outputs an image printing mode switching signal when the density sensing signal is input. 4. The sublimation type color printer according to claim 3, wherein the selection means is switched to input image data from the outside into an address in the LUT in response to the printing mode switching signal.