JPH02200455A - Thermal head heat accumulation predictive arithmetic device - Google Patents

Abstract

PURPOSE:To achieve realization of high quality recording at low cost by a method wherein by conforming to a temperature of a radiating board at a specific point which is measured by multiplying one line content predictive temperature obtained by operation by a constant of 1 or less, said multiplication result is stored in a radiating board line buffer. CONSTITUTION:A divider 33 divides detection temperature by predictive temperature by a value of a detection temperature register 31 and a value of a predictive temperature register 32 which have preliminary established. This result is 1 or less. Thereafter, predicated temperature is read pixel by pixel from a predicted temperature line buffer 37, said value is multiplied by the result of the divider 33 with a multiplier 34, and a result of the multiplier 34 is successively written in a radiating board temperature line buffer 35. One line content radiating board temperature uses the radiating board line buffer 35 as a read mode until printing of a following page is ended. When printing of the following page is started, the radiating board temperature is read from the radiating board line buffer 35, and predicted temperature for each pixel is calculated.

Description

[Detailed Description of the Invention] [Summary] Regarding a heat storage prediction calculation device that predicts the amount of heat stored in a thermal head in a thermal recording device, the current application time is controlled in order to control the applied power according to the amount of heat stored in the thermal head, and printing is performed. This is a thermal head heat storage prediction calculation device for a heating recording device that controls the power applied to the head based on the amount of heat stored in the thermal head, with the aim of improving quality. A heat sink temperature line buffer that divides the predicted temperature, multiplies the division result by the predicted value, and holds the result, a heating amount table associated with the number of gradations, recording cycle, and predicted temperature immediately before the start of the previous recording cycle, and the heating amount. A constant table for scaling the output value of the table, a thermal time constant table associated with each recording cycle, a subtractor for obtaining the difference between the predicted temperature immediately before the start of the previous recording cycle and the heat sink temperature, and a heating value within the previous recording cycle. a first multiplication between the output of the heating amount table and the output of the constant table to find the amount; and the difference between the temperature at the start of the previous recording cycle, which is reached by cooling during the recording cycle, and the heat sink temperature. A multiplier that performs a second multiplication between the output of the thermal time constant table and the output of the subtracter in order to obtain . An accumulator that accumulates the second multiplication result, and an adder that adds a heat sink temperature to the output of the accumulator, and calculates the predicted temperature corresponding to each pixel in the last row of the record of the previous page. Based on the result of multiplying the ratio of the detected heat sink temperature to the predicted temperature, the temperature of the substrate to be recorded on the next page is predicted and calculated.

[Industrial application field]

The present invention relates to a high heat prediction calculation device for predicting the amount of heat stored in a thermal head in a thermal recording device.

In a thermal recording apparatus, a current corresponding to the recording density is passed through a thermal head to heat the head to perform recording, and then a cooling period is provided to return the temperature of the head to a predetermined temperature. However, if a sufficient cooling period is not available due to high-speed recording, the temperature of the thermal head itself increases, and even if the same current is applied to the head, the same recording density cannot be obtained, and the recording density increases. Therefore, in order to perform gradation recording at high speed, it is necessary to control the energization time according to the amount of heat stored in the thermal head.

[Conventional technology]

FIG. 5 is a cross-sectional configuration diagram of a general thermal head.

The phenomenon of heat accumulation in a thermal head occurs due to the rapid heat accumulation in the glaze layer 52 and the substrate 56, corresponding to the physical structure of the head itself.
It can be classified into three types: medium-speed heat storage in the heat sink 53 and low-speed heat storage in the heat sink 53.

High-speed heat storage is a historical phenomenon of the recorded data of the previous line,
Medium-speed heat accumulation is a phenomenon of heat accumulation within the head during color recording, and low-speed heat accumulation is a phenomenon of temperature rise of the entire head and ambient temperature change. The response of each heat storage is on the order of milliseconds between lines in the case of high-speed heat storage, on the order of seconds within a page in the case of medium-speed heat storage, and on the order of minutes between pages in the case of low-speed heat storage. Among these types of heat storage, low-speed heat storage can be measured by a sensor attached to the head heat sink, and high-speed heat storage can be determined by relatively simple calculations because it uses auxiliary heating to cancel out the large history. Medium-rate heat storage is extremely difficult to measure or calculate.

In order to relatively easily determine medium-speed heat storage, a method has been proposed in which the substrate temperature is determined by sequential predictive calculations from the temperature of the heat sink immediately before the start of recording and the amount of heating and cooling within the recording period (Japanese Patent Application Laid-Open No. 1983-1999). 209956). In this conventional method, n
The predicted temperature T immediately after recording the th line can be expressed as T,=T,+ΔT,l+(T11-1-'rll)exp(-t/r).

Here, T is the heat sink temperature, ΔT7 is the amount of heating within the nth line period, T7-3 is the predicted temperature of the immediately previous line,
t is the recording period, and τ is the thermal time constant of the thermal head.

[Problems to be Solved by the Invention] In the conventional method described above, the sensors (for example, thermistors) for detecting the temperature of the heat sink are generally expensive, and even if the sensors are arranged closely, Since only gradual changes occur, three to four sensors are used on one heat sink, and the portions without sensors are used as the temperature of the heat sink at the position corresponding to the printed pixel by linear interpolation. Normally, the temperature change on the heat sink detected by a sensor such as a thermistor is a gradual change, so the actual temperature is detected every time just before recording one page. However, the actual temperature distribution on the heat sink depends on the position. Differences in heating frequency may result in irregularities, and therefore the heat sink temperature distribution predicted by linear interpolation may differ somewhat from the actual distribution, and such errors do not lead to more accurate concentration control. There was a problem.

The purpose of the present invention is to approximate the temperature distribution of the heat sink by linear interpolation in medium-speed and high-temperature heating.
Thermal head high heat prediction that reflects the shape of the predicted temperature for 947 minutes on the actually measured heat sink temperature to make the temperature distribution of the heat sink more realistic, thereby improving the accuracy of predicted temperatures in medium-speed high heat conditions. The purpose of the present invention is to provide a computing device.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle configuration of the present invention. The present invention is a thermal head high temperature prediction calculation device for a heating recording device that controls the power applied to the head based on the high amount of heat of the thermal head, and is based on temperature detection means. A heat sink temperature line buffer (35) that divides the detected temperature of the heat sink and the predicted temperature of the board, multiplies the division result by the predicted value, and holds the result, the number of gradations, the recording cycle,
A heating amount table (38) associated with the predicted temperature immediately before the start of the previous recording cycle, a constant table (4o) for scaling the output value of the heating amount table, and a thermal time constant table (41) associated with each other based on the recording cycle. , a subtractor (39) for obtaining the difference between the predicted temperature immediately before the start of the previous recording cycle and the heat sink temperature, and a subtractor (39) for obtaining the difference between the predicted temperature immediately before the start of the previous recording cycle and the heat sink temperature, and a subtracter (39) between the output of the heating amount table and the output of the constant table to obtain the heating amount within the previous recording cycle. the first multiplication of a multiplier (44) that performs second multiplication; and an accumulator (45) that calculates the total amount of heating and cooling up to the previous recording cycle with respect to the heat sink temperature by accumulating the first and second multiplication results by the multiplier. , an adder (46) that adds the heat sink temperature to the output of the accumulator.
), and calculates the substrate temperature for the next page's record based on the result of multiplying the predicted temperature corresponding to each pixel in the last row of the previous page's record by the ratio of the detected heat sink temperature to the predicted temperature. It is characterized by predictive calculation.

[Effect]

In the conventional method described above, the heat sink temperature for one line corresponding to the printing position is stored in the heat sink line buffer by linear interpolation based on the heat sink temperature measured by three to four sensors attached to the heat sink. In contrast, in the present invention, the predicted temperature for one line obtained by calculation is multiplied by a constant of 1 or less, and the multiplication result is stored in the heat sink line buffer in accordance with the actually measured heat sink temperature at a specific point. be.

〔Example〕

FIG.
2 is a temperature prediction unit, 22 is a thermal head, 23 is a thermal head drive unit that drives the thermal head, 24 is a pulse width table that determines the power to be supplied to the thermal head drive unit 23, and 25 is a thermistor that detects the temperature of the thermal head. , 26 is a temperature detection section that converts the output of the thermistor 25 into a digital signal, and 27 is a thermal head control section that controls each of the above-mentioned blocks.

Immediately before the head 22 starts thermal recording, the thermal head control unit 27 first senses the temperature detected from the thermistor 25 via the temperature detection unit 26, performs control to digitize it, and then controls the temperature to be digitized. Sensed temperature data, the number of gradations of the recorded image, recording speed, and other data necessary for temperature prediction are transferred to the temperature prediction unit 21.

The temperature prediction unit 21 successively predicts the temperature of the thermal head based on these data, and sends the predicted temperature value, number of recording pixel gradations, recording speed, etc. to the pulse width table 24 according to commands from the thermal head control unit 27. . The pulse width table 24 determines the pulse width according to these data.

The thermal head driving section 23 controls the power applied to the thermal head 22 according to the output pulse width of the table 24 to perform optimal thermal recording.

FIG. 3 is a detailed diagram of the temperature prediction unit 21 shown in FIG. In FIG. 3, 31 is a detected temperature register that holds the heat sink temperature picked up by the sensor, 32 is a predicted temperature register that holds the predicted temperature of a specific pixel corresponding to the sensor position, and 33 is a predicted detected temperature. A divider that divides by the temperature and outputs a value of 1 or less; 34 is a multiplier that multiplies the division result by the predicted temperature; 35 is a heat sink temperature line bath sofa that records the heat sink temperature for one line; Signal A is the digitalized temperature detected by the sensor, and signal B is the output of the predicted temperature line buffer 37 and is the predicted temperature obtained by calculation.

This input stage arrangement operates only once, except for updating the predicted temperature register 32, just before each printed page. The predicted temperature of the pixel corresponding to the sensor position is written in the predicted temperature register 32 for each line. When printing of one page is completed, the predicted temperature line knob 37 & is stored in the predicted temperature of the last line of that page, and the predicted temperature register 32 holds the predicted temperature corresponding to the sensor position of the last line. There is.

In this case, immediately after the device is powered on, the detected heat sink temperature is recorded together with the predicted temperature line buffer 37 and the predicted temperature register 32. Immediately before starting printing the next page, the temperature of the heat sink is detected and the value of the detected temperature register 31 is updated. Thereafter, the heat sink temperature line buffer 35 is set to write mode, and the predicted temperature line buffer 37 is set to read mode.

The divider 33 is the detected temperature register 31 that has already been set.
and the value of the predicted temperature register 32, the detected temperature is divided by the predicted temperature. This result is less than 1. After this,
The predicted temperature is read out one pixel at a time from the predicted temperature line buffer 37, the value and the result of the divider 33 are multiplied by the multiplier 34, and the results of the multiplier 34 are sequentially written into the heat sink temperature line buffer 35. The heat sink temperature of 1547 minutes puts the heat sink line/sofa 35 in the read mode until the printing of the next page is completed. When printing of the next page begins, the heat sink temperature is read out from the heat sink line buffer 35 and predicted temperature is calculated for each pixel.

On the other hand, input signals C and D indicate the number of gradations and recording speed for each pixel, which determine the amount of heating. The predicted temperature line buffer 37 stores one line of calculated predicted temperature values for each pixel.

The heating amount table 38 is a table for determining the heating amount between recording lines. Further, 39 is a subtracter for calculating the difference between the predicted temperature T+, -1 in the previous line and the heat sink temperature T, 40 is a constant table that outputs a constant 1, and 41 is a thermal time constant including the glaze layer. table, 36, 42.43
is a multiplexer; 21 is a multiplier that multiplies the output of the heating amount table 38, the output of the constant table 40, the output of the subtracter 39, and the output of the thermal constant table 41; 45 is an accumulator that accumulates the output of the multiplier 44; 46 is an adder that adds the heat sink temperature to the temperature difference with respect to the heat sink temperature, 47 is a register that temporarily stores the output data of the adder 46 for each pixel, and signal E is a signal indicating the predicted temperature to be the calculation output. be.

FIG. 4 is an operation time chart of the configuration shown in FIG. This time chart shows the 1st and 2nd lines that start recording operation.
It represents the representative state of the line and subsequent lines, and relates to the prediction of the first and second pixels at the head of the line.

Signal a is a line signal indicating the period in which predictive calculation is performed for each line, signal A is a first line signal indicating the first line to be predictively calculated, and signal C is a gradation number signal for each pixel in Fig. 3. C1 indicates that the recording speed signal is input, the pixel data input signal generated for the number of pixels in the l line, the signal d is the input/output data of the heat sink line buffer as shown in the enlarged view, and the signal e is the predicted temperature The input/output data of the line bath sofa 37 is data, the signal f is a pixel prediction calculation signal indicating the period for performing prediction calculation of one pixel, the signal g is a basic clock signal for prediction calculation, and the signal ri is an accumulation prior to the accumulation calculation. an accumulator reset signal that resets the accumulator 45; signal i is a control signal for multiplexers 42 and 43; signal jk is a control signal for multiplexer
．． 43 output data, signals! indicates the output data of the accumulator 45, and signal m indicates the final predicted temperature data of the register 47.

In the first line where the prediction calculation starts, as the line signal a becomes 1, the first line signal b becomes 1, indicating that data transfer is accompanied by heat sink temperature data. Using the pixel data input signal C, heat sink temperature data T at the time of recording start is written to the heat sink line buffer for each pixel. At the same time, the first line signal and pixel data input signal C
The multiplexer 36 inputs the heat sink temperature data to the predicted temperature line buffer 37 in response to a control signal (not shown) based on the logical product of . As a result, the heat sink line buffer 35
The same heat sink temperature data is recorded at the memory address corresponding to the same pixel in the predicted temperature line buffer 37, and the predicted temperature line buffer 37 is initialized only at the start of page recording. Furthermore, when the pixel data input signal C becomes 1, the gradation number signal C1 and the recording speed signal are input, the heating amount table 38 and the thermal constant table 41 are determined, and predictive calculation can be performed for the first pixel. When the prediction calculation preparation is completed, the pixel prediction calculation signal f becomes 1 in synchronization with the fall of the basic clock signal g. When the pixel prediction calculation signal f becomes 1,
Generates an accumulator reset signal and a multiplexer control signal i. The accumulator reset signal resets accumulator 45. The control signal i is applied to the output of the multiplexers 42 and 43 by adding the heating amount from the heating amount table 38 necessary for calculating the heating amount at the first pixel of the first line and the output coefficient value of 1 from the constant table 40 to the multiplier 44. input.

The multiplier 44 takes in the output data j and k of the multiplexers 42 and 43 at the rising edge of the basic clock signal g, accumulates the multiplication result ΔT111 in the accumulator 45, and stores the multiplication result ΔT111 in the accumulator 45 at the next rising edge of the basic tally signal g. This is output data 2.

By setting the control signal i to 0 prior to this rise, the multiplexers 42 and 43 subtract the predicted temperature line buffer 37 and the heat sink line buffer 35 necessary for calculating the amount of cooling at the first pixel of the first line. The temperature difference subtracted by 39 and the output of the thermal time constant table 41 are input to the multiplier 44 . That is, the multiplier 44 outputs the calculation result of the heating amount and fetches the data for calculating the cooling amount at the same timing. 35 is zero for all pixels in the first line of recording, so the cumulative result ΔTj211 in the accumulator 45 is the calculation result Δ of the heating amount.
It becomes Th 11 itself.

The operation result becomes accumulator output data l at the next rising edge of basic clock signal g. The heating and cooling bone ΔT obtained for the first pixel of the first line! 11, the temperature value T, l of the first pixel immediately before the start of recording recorded in the heat sink line buffer 35
are added by an adder 46. The result of this addition becomes the predicted temperature after recording of the first pixel on the first line to be determined. The predicted temperature is temporarily stored in the register 47 and sent to the multiplexer 36.
The predicted temperature line buffer 37 via T, 1 + ΔT
Update to 111. Subsequently, the pixel data input signal C becomes 1.
As a result, the gradation number signal C1 and recording speed signal relating to the second pixel are input, the heating amount table 38 and the thermal time constant table 41 are determined, and predictive calculation for the second pixel becomes possible. In step 3, these calculations are repeated until the end of the first line.

From the second line onwards where the prediction calculation starts, only the line signal a becomes l. When the pixel data input signal C becomes 1, the gradation number signal C1 and the recording speed signal are input, and the predicted temperature line buffer 37 has already been updated by the calculation in the previous line, and the heating amount table 38
, the thermal constant table 41 is determined, and predictive calculation for the first pixel becomes possible. When the prediction calculation preparation is completed, the pixel prediction calculation signal f becomes active in synchronization with the fall of the basic clock signal g.

When the pixel prediction calculation signal f becomes 1, an accumulator reset signal and a multiplexer control signal i are generated.

The accumulator reset signal resets accumulator 45.

Multiplexer control signal i is multiplexer 42°43
The heating amount from the heating amount table 38 necessary for calculating the heating amount in the first pixel of the second line and the output coefficient value 1 from the constant table 40 are input to the output of the multiplier 44 . Multiplier 4
4 is the multiplexer 4 at the rising edge of the basic clock signal g.
2. Take in the output data j, k which is the output of 43. The multiplication result ΔTh21 is accumulated in the accumulator 45, and is set as accumulator output data 2 at the next rising edge of the basic clock signal g. By setting the control signal i to 0 prior to this rise, the multiplexers 42 and 43 subtract the predicted temperature line buffer 37 and the heat sink line buffer 35 necessary for calculating the amount of cooling at the first pixel of the second line. The temperature difference subtracted by 39 and the output of the thermal time constant table 41 are input to the multiplier 44 . That is, the output of the calculation result of the heating amount and the fetching of data for calculating the cooling amount are performed at the same timing.

Subsequently, the multiplier 44 multiplies the predicted temperature Tp11 immediately before recording the first pixel of the second line by the thermal time constant table 41 to obtain ΔTc21. Predicted temperature 'rp 11 is the first
It is obtained by adding the heat sink temperature Tal of the first pixel to the heating/cooling amount ΔT/211 at the first pixel of the line.

The calculation result is accumulated by the accumulator 45, and the total heating and cooling amount ΔTh21+ from the start of recording to immediately after recording the first pixel of the second line
ΔTc21 becomes accumulator output data l at the next rising edge of basic clock signal g.

In Figure 4, the total amount of heating and cooling for this heat sink temperature is ΔT
121. Output data ΔTI of this accumulator 45
! , 21, the temperature (!!Tal
are added by an adder 46. The result of this addition becomes the predicted temperature immediately after recording of the first pixel on the second line to be determined. The predicted temperature is temporarily stored in the register 47 and sent to the multiplexer 3.
6 to update the predicted temperature line buffer 37. Thereafter, these calculations are repeated until the prediction line ends to perform prediction calculations for all lines. And this prediction calculation is different from the second one.
The pulse width is sent to the pulse width table 24 shown in the figure, and a pulse width corresponding to this is output to the thermal head drive section 23.

〔Effect of the invention〕

As described above, according to the present invention, the substrate temperature can be predicted with high accuracy even with a single heat sink temperature sensor, so that low-cost and high-quality recording can be realized.

If a plurality of heat sink temperature sensors are used and calculations are performed using the least squares method, even more accurate temperature prediction becomes possible.

[Brief explanation of the drawing]

Figure 1 is a diagram of the principle configuration of the present invention, Figure 2 is a diagram of an embodiment of the present invention, Figure 3 is a detailed diagram of the temperature prediction section of Figure 2, and Figure 4 is the signal time diagram of Figure 3. The chart, FIG. 5, is a cross-sectional structural diagram of a general thermal head. (Explanation of symbols) 21...Temperature prediction unit, 22...Thermal head, 23...Thermal head drive unit, 24...Pulse width table, 25...Thermistor, 26...Temperature detection unit , 27... Thermal head control unit, 35... Heat sink line buffer, 37... Predicted temperature line buffer, 38... Heating amount table, 40... Constant table, 41... Thermal constant table , 53... Heat sink, 56... Board. Principle configuration diagram of the present invention Part 1 Configuration diagram of an embodiment of the present invention Thermal head structure diagram Part 1

Claims (1)

[Scope of Claims] 1. A thermal head high temperature prediction calculation device for a heating recording device that controls the power applied to the head based on the amount of heat stored in the thermal head, which predicts the detected temperature of the heat dissipation plate by the temperature detection means and the substrate. A heat sink temperature line buffer that divides the temperature, multiplies the division result by the predicted value, and holds the result, a heating amount table associated with the number of gradations, recording cycle, and predicted temperature immediately before the start of the previous recording cycle, and the heating amount table. A constant table for scaling the output value of , a thermal time constant table associated with each recording cycle, a subtractor for obtaining the difference between the predicted temperature immediately before the start of the previous recording cycle and the heat sink temperature, and the amount of heating within the previous recording cycle. In order to obtain a multiplier that performs a second multiplication between the output of the thermal time constant table and the output of the subtracter in order to calculate the thermal time constant; It is equipped with an accumulator that accumulates the multiplication results, and an adder that adds the heat sink temperature to the output of the accumulator, and adds the detected heat dissipation to the predicted temperature corresponding to each pixel in the last row of the record on the previous page. A thermal head heat storage prediction calculation device that predicts and calculates the substrate temperature of the next page of recording based on the result of multiplying the ratio of the substrate temperature and the predicted temperature.