JPH09193440A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accelerate printing and to realize a control method with a memory having small capacity simply by a controlling method by providing means for deciding the repetition periods of (N-1) pieces of conducting pulses having a first gradation pulse width and second and following gradation pulse widths previously decided in response to the using environmental temperature. SOLUTION: A microcomputer 200 inputs using environmental temperature information from the thermistor of a temperature detector 108, and selects the heating period T(1) of the first pulse of (N-1) pieces and the period T(k) of the second or following gradation strobe signal to express N gradation within a printing period from the gradation table of a temperature correcting unit 103 corresponding to the information. Simultaneously, to correct the density generated due to the irregularity of a thermal head 104, it reads the preset switch state of a density controller 109, selects the pulse width of the heating period after the second or following gradation corresponding to the state of the switch from the table of a density correcting unit 110, and transfers it to a gradation controller 102.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer using a thermal head such as a thermal sublimation printer, and is characterized by an energizing pulse applied to the thermal head in order to correct the temperature of the thermal head. Is.

[0002]

2. Description of the Related Art In recent years, thermal dye sublimation printers have been equipped with techniques and shapes for accurately controlling the temperature of the thermal head.
Techniques for improving print quality have been put into practical use by improving print media. The conventional temperature correction method will be described below. FIG. 5A is a configuration diagram of a printing unit in the thermal sublimation printer, 101 is image data, 103 is a temperature correction unit, and the image data 101 is the microcomputer 2
00 of RAM, the temperature correction unit 103 is stored in ROM of the microcomputer 200.

A thermal head 104 includes a shift register 105, a latch circuit 106, a heating resistor 107, and a temperature detector 108. A gradation control unit 102 applies a control energizing pulse to the thermal head 104 based on the information of the image data 101. FIG. 5B shows a strobe signal output to the heating resistor 107 at high temperature,
FIG. 5C shows a strobe signal output to the heating resistor 107 at a low temperature. The heating resistor 107 generates heat in response to the rising edge of the strobe signal, and cools down by radiating heat after falling. Hereinafter, the heat generation period of this strobe signal will be referred to as an ON period, and the heat radiation period will be referred to as an OFF period.

The operation of the temperature correction method for the printing unit constructed as described above will be described below by taking an N gradation thermal sublimation printer as an example. Here, for the sake of convenience, the 0th gradation is taken until just before the color is developed on the thermal transfer medium. That is, the 0th gradation indicates the color density of the printing paper itself, and no energizing pulse is applied.

The microcomputer 200 converts the image data for one line from the image data 101 into the gradation control unit 1.
No. 02, and each pixel is sequentially compared with the color density values from 0th to N-2th gradation. First, the image data of each pixel is compared with the color development density value of the 0th gradation, and for image data larger than the color development density value of the 0th gradation, 1 is present at that position, and image data equal to or less than that position. With respect to, the head control pulse train for 1 bit 1 line in which 0 is arranged at that position is output from the gradation control unit 102. That is,
The first output from the gradation control unit 102 is that the image position where 1 is higher than the color density value of the 0th gradation, and 1 is less than or equal to the color density value of the 0th gradation. 0 is placed in the.

This pulse train is set in the shift register 105 of the thermal head 104 by serial communication. The latch circuit 106 latches the data in the shift register 105 according to the latch signal from the gradation control unit 102. In the latch circuit 106, only the heating resistor 107 in the image portion where the data is 1 is selected, and the strobe signal is given from the temperature correction unit 103 by the temperature information of the temperature detection unit 108, Electricity is generated and heat is generated, and printing is performed with a color density of 1 / N-1.

Next, the gradation control unit 102 compares the image data of each pixel for one line with the coloring density value of the first gradation. For density data larger than the coloring density value of the first gradation, 1 is placed at the position of the image, and 0 is placed at the position of the image for image data equal to or less than 1
A pulse train for energizing the head for one bit is output from the gradation control unit 102. This data is stored in shift register 1
By setting it to 05, the same printing is performed. Thereafter, the comparison value is incremented by 1 and the same printing operation is performed, and the printing is repeated until the comparison value reaches N-2, which is one before the maximum image data, and the printing of the color density for one line is completed.

In the printing sequence for one line described above, a temperature correction method will be described in consideration of the operating environment temperature and the temperature rise of the heating resistor 107. FIG. 6 shows the color density characteristics. The characteristic (6-a) in the first quadrant is a target color density characteristic so that the color density is linear with respect to the number of gradations N-1. Optimal image printing is performed. The characteristic (6-b) in the second quadrant is the color density characteristic with respect to the energization time for energizing the heating resistor 107 of the thermal head 104 for each gradation, and shows the S-curve color density characteristic. The γ correction is to correct the S-curve characteristic to the linear color density characteristic.

In other words, if D is the maximum color density,
The γ correction is a correction to make the density change amount D / (N−1) for one gradation constant at each gradation. In order to perform the γ correction in consideration of the temperature correction, the temperature detecting unit 108 is attached to the substrate of the thermal head 104, and the temperature detecting unit 1
The temperature of the thermal head 104 is estimated from the information obtained from 08, and the ON period for each gradation of the strobe signal applied to the thermal head 104 is adjusted.

As this adjusting means, an ON period for each gradation is set to T (1) ... T (n-1) for a pattern of (1) to (m) stages of use environment temperature as shown in FIG. The gradation table of (n-1) * m bytes set as shown in (1) is stored in the ROM of the temperature correction unit 103, and the microcomputer 200 reads the strobe corresponding to the temperature information read from the temperature detection unit 108. The ON period of the signal is selected from the gradation table, and the strobe signal shown in FIG. 5B is used when the operating environment temperature is high, and the strobe signal shown in FIG. 102
Output to the heating resistor 107, an image can be printed with a color density characteristic having a linear characteristic as shown in the first quadrant of FIG. 6 regardless of the operating environment temperature.

[0011]

However, in the above-described conventional temperature correction method, in order to obtain the color density of N gradations, N-1 parameters (the ON period T of the strobe signal T
(1), ..., T (n-1)) needs to be set,
Requires a large amount of memory. Further, if the use environment temperature is low, there is a problem that the ON period of the strobe signal is inevitably long and the printing takes time.

The present invention solves the above-mentioned conventional problems, and controls the ON period for the first gradation of the strobe signal output to the heating resistor and controls the OFF period for the second gradation and thereafter. The purpose of the present invention is to speed up printing and realize the control method with a simple and small-capacity memory.

[0013]

In order to achieve this object, the present invention applies gradation control by applying N-1 energizing pulses to a thermal head in order to express N gradations within one line printing period. Printers that perform
A pulse width of the first gradation of the N-1 energizing pulse and a means for determining a repetition period of the energizing pulse of a predetermined pulse width after the second gradation are provided. .

According to the present invention, it is possible to provide a printer capable of easily changing the temperature of the operating environment and correcting the temperature of the thermal head and capable of printing at high speed.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention uses N-1 to express N gradations within one line printing period.
In a thermal sublimation printer that applies individual energizing pulses to the thermal head to control gradation, depending on the operating environment temperature,
A pulse width of the first gradation of the N-1 energizing pulse and a means for determining a repetition cycle of the energizing pulse of a predetermined pulse width after the second gradation are provided. By reducing the energizing pulse setting parameter, the setting can be easily performed, and a large capacity memory is not required.

Further, since the first pulse of the first gradation is controlled only in the ON period, the printing time corresponding to the OFF period can be shortened. In the control pulse of the second gradation and thereafter, OF
Since the heat radiation amount of the thermal head is reduced by shortening the F period, it is not necessary to lengthen the ON period, and the entire printing time can be compressed. Hereinafter, embodiments of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. The same components as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted.

(Embodiment 1) In FIG. 1A, 1
Reference numeral 01 is image data of an image to be printed which is stored in the RAM of the microcomputer 200, 102 is a gradation control unit for applying a strobe signal to the thermal head 104, and 103.
Is a temperature correction unit stored in the ROM of the microcomputer 200. A thermal head 104 is a shift register 105, a latch circuit 106, and a heating resistor 10.
7. The temperature detecting unit 108 is included, and the difference from the configuration of the conventional example is that a density control unit 109 and a density correcting unit 110 are provided, and the density correcting unit 110 and the temperature correcting unit 103 can be independently controlled. It is in.

FIG. 1B shows a strobe signal output from the gradation control unit 102 to the heating resistor 107 of the thermal head 104 when the operating environment temperature is high, and FIG. 1C shows the same at low temperature. Represents a strobe signal. The heating resistor 107 generates heat in response to the rising edge of the strobe signal in the same manner as the strobe signal in the above-mentioned conventional example, and cools by radiating heat after falling.

The operation of the N gradation temperature correction method configured as described above will be described. However, the N gradation has the color density gradation from the 0th gradation to the (N-1) th gradation. The N-1th gradation is the highest color density and
The gradation is the minimum color density and the color density of the print medium itself is not applied. The image data 101 is stored in the RAM of the microcomputer 200,
The temperature correction unit 103 and the concentration correction unit 110 are stored as a table in the ROM of the microcomputer 200.

FIG. 2 shows the table, and the temperature correction unit 1
03 indicates an ON period (FIG.
The table of the strobe signal waveform T (1) shown in Fig. 2 and the period of the strobe signal after the second gradation (T (k) of the strobe signal shown in Fig. 1) is the operating environment temperature (1) to (m) stages. Pattern is stored as a table of m * 2 bytes, and the density correction unit 110 has a table for controlling the ON period (T (c) in FIG. 1) after the second pulse, which is the density of the thermal head 104. A table having different pulse ON periods from the state (1) to the state (x) is stored as an x-byte table corresponding to the state of the switch of the density control unit 109 preset due to the variation.

The temperature of the temperature detecting section 108 is detected by a thermistor, and the use environment temperature information is stored in the microcomputer 20.
Capture to 0. Further, the control of the density control unit 109 is a switch control in which the pulse width of the predetermined ON period after the second gradation is preset according to the variation of the print density of the thermal head 104.

The control operation of the microcomputer 200 will be described below with reference to the flowchart of FIG. The microcomputer 200 has a temperature detection unit 108.
Input the operating environment temperature information from the thermistor, and turn ON the first pulse corresponding to the operating environment temperature information (see FIG. 1).
(T (1) in FIG. 1) and the period of the strobe signal after the second gradation (T (k) in FIG. 1) are selected from the gradation table of the temperature correction unit 103, and at the same time, the density generated by the variation of the thermal head 104 is generated. For correction, the preset switch state of the density control unit 109 is read, and the pulse width of the ON period after the second gradation corresponding to this switch state is selected from the table of the density correction unit 110. , To the gradation control unit 102.

Therefore, the gradation control unit 102 has the above-mentioned 3
A strobe signal corrected as follows is created from one piece of information and output to the thermal head 104. As in the conventional case, the ON period of the first pulse is the time required for color development to become longer as the temperature becomes lower. Regarding the temperature correction after the first pulse, (1) From the second gradation to the N-1th gradation, that is, the temperature correction after the second pulse has a cycle starting from an OFF period instead of an ON period of the pulse width. By controlling, the first
The first pulse of the gradation has only the ON period, and the OFF period is deleted. (2) After the second pulse, the temperature is corrected by controlling the OFF period, and the ON period is kept constant regardless of the temperature change. (3) The ON period after the second pulse is selected from a plurality of preset values.

FIG. 4 shows a comparison between the temperature correction characteristic in the printing period of one line and the conventional temperature correction characteristic in the color density characteristic of N gradations in the embodiment of the present invention. FIG. 4B shows a strobe signal applied during the printing period of one line at a low temperature of the present invention, and FIG. 4C shows a strobe signal applied during the printing period of a line at a conventional low temperature. Reference numeral 4 shows a color density characteristic of temperature correction according to those strobe signals. As is apparent from FIG. 4, the temperature correction according to the embodiment of the present invention can shorten the printing time at the low temperature and the printing time shown in (d).

In the embodiment of the present invention, the temperature correction unit 103 and the concentration correction unit 110 are provided in the ROM of the microcomputer 200, and the microcomputer 200 controls the temperature detection unit 108 and the concentration control unit 109. However, this control may be an electronic circuit. Further, although the density control unit 109 is a switch, it can be realized by a variable resistor.

[0026]

The OFF period of the first pulse, which is the control pulse of the first gradation, is deleted, and at the same time from the second gradation to the Nth gradation.
By controlling the temperature correction control pulse up to the -1st gradation only during the OFF period, the control parameter can be reduced, and the setting of this control parameter can be simplified. Further, at a low temperature, the amount of heat radiation is reduced by shortening the OFF period, and the desired color density can be obtained without lengthening the ON period, so that the printing time can be shortened.

In the density correction control pulse from the 2nd gradation to the N-1th gradation, the ON period of the preset pulse is selected without changing the cycle, and
The color density can be finely adjusted without extending the line printing period, and the variation in the thermal head can be corrected.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration diagram of a printing unit and a strobe signal waveform of a printer according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a temperature correction table and a density correction table of the printing unit.

FIG. 3 is a flowchart of temperature correction of the printing unit.

FIG. 4 is a comparison diagram of temperature correction characteristics of a printing unit according to an embodiment of the present invention and a conventional example.

FIG. 5 is a diagram showing a configuration diagram of a printing unit and a strobe signal waveform in a conventional thermal sublimation printer.

FIG. 6 is a density characteristic diagram of a print medium in a thermal sublimation printer.

FIG. 7 is a diagram schematically showing a temperature correction table of a printing unit in a conventional thermal sublimation printer.

[Explanation of symbols]

 101 image data 102 gradation control section 103 temperature control section 104 thermal head 105 shift register 106 latch circuit 107 heating resistor 108 temperature detection section 109 density control section 110 density correction section T (1) pulse width of the first gradation T (K) Cycle after the second gradation T (c) Energization period after the second gradation (b) High temperature strobe signal waveform (c) Low temperature strobe signal waveform (d) Printing shortening time

Claims (1)

[Claims] 1. A printer for controlling gradation by applying N-1 energizing pulses to a thermal head in order to represent N gradations within one line printing period,
A pulse width of the first gradation of the N-1 energizing pulse and a means for determining a repetition period of the energizing pulse of a predetermined pulse width after the second gradation are provided. Printer.