JPS63317361A - Thermal transfer recording device - Google Patents

Abstract

PURPOSE:To obtain a multi-gradation recording image of high quality without density differences by estimating the temperature of a heat generating body based on the previous measurement results of a plurality of lines and the existing temperature measurement results and driving the heat generating body with energy suitable to the estimated temperature. CONSTITUTION:A thermister 4 is energized and a temperature measurement part 3 calculates the temperature of a heat generating body based on the temperature data of the thermister 4. The results of this measurement are stored in a memory register 6a and initialized. A device drive control part 5 decides recording energy applied to the heat generating body 2 based on the temperature measurement results of the heat generating body, and then a single line is recorded with the recording energy decided. The recording energy is decided, for instance by using an existing temperature T0, a temperature T2 and a temperature T4 two and four lines previous to the existing temperature respectively. When the temperature of the heat generating body 2 is soaring, an estimated temperature which is higher than a measured temperature is decided, while an estimated temperature and a measured temperature are decided same when the temperature of the heat generating body is decreasing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal transfer recording device that melts or sublimates ink on an ink film using a heating element and transfers the ink onto recording paper.

′ of ′r bisono. In general, thermal transfer recording devices perform recording by transferring ink from an ink film using a thermal head in which a large number of heating elements are arranged in a line. A pulse outputted from the main body of the apparatus with a width corresponding to multi-gradation recording data is applied to the heating element of the thermal head, and recording is performed by raising the heating element to a predetermined temperature. When the heating element is continuously recorded, the temperature of the heating element increases due to heat accumulation, and the recording density becomes higher even if the heating element is driven with an applied pulse of the same width.

Therefore, a thermistor is provided as a temperature measuring element in the thermal head to measure the temperature of the heating element, and when the temperature reaches a high temperature, the applied energy is reduced in response.

However, the thermistor built into a conventional thermal transfer recording device is located near the heating element but is not integrated with the heating element and is separated from the heating element. There was a time lag when the information was transmitted. Therefore, even if the temperature of the heating element is detected by the thermistor, accurate correction cannot be made and it is impossible to record the desired number of gradations. There was a problem in that it was heated abnormally and was damaged.

In addition, in the thermal transfer recording device, it is not possible to tell whether the temperature detected by the thermistor is when the heating element is rising or falling, so the amount of heat stored in the heating element is This is unclear, and even if recording is performed with the same applied pulse width, there will be a difference in density, resulting in the problem that a high-quality multi-gradation recorded image cannot be obtained.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a thermal transfer recording apparatus that can obtain high-quality multi-gradation recorded images without density differences.

. In order to achieve the above-mentioned object, the present invention provides a thermal head equipped with a heating element for transferring ink from an ink film onto recording paper, and a temperature measuring element provided in the thermal head. temperature measurement means for calculating the temperature of the heating element based on the temperature measurement results of the current heating element based on the temperature measurement results of the previous plurality of lines and the current temperature measurement result; The present invention is characterized by comprising a heating element drive control means that predicts the temperature and drives the heating element with energy according to the temperature.

According to the above configuration, even if the heating element is located far from the temperature sensing element, the current temperature can be predicted by knowing the temperature measurement data of multiple lines before the line to be recorded. Since it can be determined whether the temperature of the heating element is rising, falling, or remaining constant, it is possible to grasp the temperature change situation in detail and apply more accurate energy to the heating element.

Embodiment 1 An embodiment of the present invention will be described below. FIG. 1 is a block diagram of the main parts of a thermal transfer recording apparatus according to the present invention. In the figure, l is a thermal head equipped with a large number of heating elements 2 for transferring ink from an ink film onto recording paper, and 3 is connected to a thermistor 4 as a temperature measuring element installed in the thermal head 1. A temperature measurement unit 5 calculates the temperature of the heating element 2 based on the detection result of the temperature measurement unit 3, and a RAM 6 that stores a plurality of temperature measurement data calculated by the temperature measurement unit 3 and other information, and a A device drive control section 9 includes a CPU (Central Processing Unit) 7 for controlling operations of the entire device such as paper feeding, and a ROM 8 for storing operation programs, etc.; This is a recording control section that sends recording data to the thermal head 1 at a predetermined timing and also generates a strobe signal and a latch signal.

The thermal head 1 is configured such that a large number of the above-mentioned heating elements 2 are arranged in a line and recording is performed row by row, and a plurality of these heating elements 2 are driven as one group by a driver ICII. The thermistor 4 described above is provided near the heating element 2.

The portion of the RAM 6 that stores temperature measurement data is
As shown in FIG. 2(a), it is composed of a memory register 6a, in which temperature data of the heating element 2 calculated by the temperature measuring section 3 is stored. In the memory register 6a, the current temperature data of the heating element 2 and the temperature data of the heating element 2 when the previous 4 lines including the immediately preceding line were recorded are stored at addresses T0 to T4, and the next line is recorded. Then, as shown in FIG.
The temperature data at that time is stored in To. That is, T is the current temperature of the heating element, T1 is the temperature of the heating element one line before, T2 is the temperature of the heating element two lines before, and T4 is the temperature of the heating element four lines before.

Next, the operation of the thermal transfer recording apparatus of this embodiment will be explained with reference to the flowchart shown in FIG. When the printing operation is started, first, the thermistor 4 is energized, and the temperature measuring section 3 calculates the temperature of the heating element based on the temperature data of the thermistor 4 (step 31). This measurement result is stored in the memory register 6a and initialized (step S2). Then, the device drive control section 5 determines the recording energy to be applied to the heating element 2 based on the temperature measurement result of the heating element (step S3). One line of recording is performed with this determined recording energy (step S4), and the process advances to step S5 to feed the paper one line. Then, it is determined whether all the data has been recorded (step S6), and if there is further recorded data to be recorded, the temperature of the heating element 2 is measured in step S7, and the temperature of the heating element 2 is measured as described above. The contents of 6a are updated (step S8). Thereafter, the process returns to step S3, where the recording energy is determined based on the temperature measurement result, and recording is continued.

In this example, the recording energy is determined based on the current temperature T0.2-line previous temperature T2 and 4-line short temperature T4.
Use. This means that the temperature near heating element 2 is 1
The temperature rises due to the movement. However, the thermistor 4 is provided at a position slightly apart from the heating element 2, and when the temperature of the heating element 2 is rising, it senses a lower temperature.
When the temperature of the heating element 2 is decreasing, it is considered that the temperature near the thermistor 4 is almost the same. However, this is an example in which the thermal head l is not provided with forced cooling means. Also, when the thermistor 4 is at a constant temperature,
This is considered to be when a certain level of concentration continues to be recorded, and the temperature of the heating element 2 is considered to be slightly higher than that of the thermistor 4. Therefore, the temperature T of the heating element 2 to be recorded
can be predicted as follows. That is, when T4 < T z < T 6, 'r='ro+ 'r, -74 = 7o+ - When Ta<'I'z=To, T = To+ (T2 T4) Ta = T z = T When o, T=To+a
When a constant value T a = T z > T o, T '' T.

When T4>Tz>76, T”T.

It is predicted as follows.

The relationship between this predicted temperature and the temperature measured by the thermistor 4 is shown in Figure 4. When the temperature of the heating element 2 is rising, the predicted temperature is determined to be higher than the measured temperature, and when it is falling, the measured temperature is determined to be higher than the measured temperature. and the predicted temperature are determined to be the same.

Once the predicted temperature is determined, the maximum pulse width to be applied to the heating element 2 is determined from this result. Figure 5 shows the pulse width at the maximum gradation (highest density).
It can be seen that as the temperature of the heating element 2 rises, the pulse width is set shorter.

In the above example, the prediction is made at the temperature T2 two lines before the current temperature T0. and the temperature T4 four lines ago, assuming that the time for two lines is the heat conduction time. The number of lines before the temperature to be referred to is determined by the heat conduction time from the heating element position to the thermistor position and the line period.

In addition, for temperature prediction, as shown in Figure 4, linear prediction was performed, but more accurate prediction is possible by curve prediction. When three or more pieces of data are used as the measurement data, the curve prediction described above becomes even more accurate.

As described above, the thermal transfer recording device according to the present invention is provided with a temperature measuring means for calculating the temperature of the heating element based on the detection result of the temperature measuring element provided in the thermal head equipped with the heating element. , a storage means is provided for storing temperature measurement data of multiple lines prior to the line to be recorded, the current temperature of the heating element is predicted from those temperature measurement results, and the heating element is activated with energy according to the temperature. Since a driving heat generating motion control means is provided, it covers the delay in temperature detection caused by the thermistor being installed far from the heat generating element, and prevents the temperature from being affected by the heat stored in the thermal head. You can obtain high-quality recorded images.

Furthermore, since the status of heat accumulation in the heating element can be grasped over time, abnormal overheating can be prevented, and burnout of the heating element can be prevented.

Furthermore, even if the detected temperature is the same, it can be determined whether it is rising, falling, or constant, so it is possible to take detailed measures and obtain accurate multi-tone recorded images.Especially, sublimation type thermal transfer recording Since the device has high gradation depending on energy, it can produce remarkable effects.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of the main parts of a thermal transfer recording device as an embodiment of the present invention, FIG. 2 is a memory map diagram showing the contents of a memory register, and FIG. 3 is a flowchart diagram explaining the operation of the thermal transfer recording device. FIG. 4 is a graph showing the relationship between the temperature measured by the thermistor and the predicted temperature, and FIG. 5 is a graph showing an example of the pulse width applied to the heating element. 1... Thermal head, 2... Heating element, 3...
Temperature measuring unit, 4... Thermistor, 5... Device drive control unit, 6... RAM, 6a... Memory register, 9... Recording control unit. Patent applicant: Minolta Camera Co., Ltd. Figure 1 Figure 2 (a) Figure 2

Claims (1)

[Claims] (1) a thermal head equipped with a heating element for transferring ink of an ink film onto recording paper; a temperature measuring means for calculating the temperature of the heating element based on the detection result of a temperature measuring element provided in the thermal head; and recording. A storage means for storing temperature measurement data of multiple lines previous to the line to be measured, and a storage means for predicting the current temperature of the heating element from the previous multiple lines and the current temperature measurement results, and generating the heating element with energy according to the temperature. A thermal transfer recording device comprising: heating element drive control means for driving;