Rapid detection and analysis system for defective pixels of head piece of thermal printer

Abstract

The invention relates to the technical field of thermo-sensitive sheet detection, and particularly discloses a thermo-sensitive printer head sheet dead pixel rapid detection and analysis system comprising a signal acquisition module which is used for placing a thermo-sensitive sheet to be detected on a test tool and fixing the thermo-sensitive sheet; the detection execution module is used for traversing all pixel points to carry out a power-on test and calculating an initial state resistance value of each pixel point; the initial detection module is used for judging whether the initial state resistance value of each pixel point on the to-be-detected thermosensitive sheet is in a resistance value domain or not, and calculating to obtain an initial state qualified rate value of the resistance value to obtain an initial state qualified signal; the internal inspection module is used for calculating and obtaining a pixel point operation state performance value based on the initial state qualified signal; and the judgment module is used for comparing the pixel point operation state expression value with the pixel point operation state expression threshold value to obtain a thermosensitive sheet operation qualified signal, rapidly discharging the thermosensitive sheet with an unqualified initial state, and accurately and effectively realizing the qualification detection of the thermosensitive sheet.

Description

Technical Field

[0001] The invention relates to the technical field of thermal sheet detection, and in particular to a thermal printer head sheet bad point rapid detection and analysis system. Background Art

[0002] The basic principle of thermal printing is to heat thermal paper through a thermal sheet. The thermal sheet is the core component of a thermal printer. When some of the controllable heat source pixels on the thermal sheet are damaged, the thermal paper will not be fully displayed during printing because some pixels are not heated normally. The existing method of detecting whether there are bad pixels on the thermal sheet requires the thermal sheet to be assembled into the whole machine for printing test to find out whether there are bad pixels on the thermal sheet. When the existing detection method performs detection and analysis during the production and processing of thermal films, all pixel points are fully detected, the detection efficiency is slow, and multi-angle and multi-directional detection cannot be achieved, and the detection effect is not accurate enough. Summary of the invention

[0003] The purpose of the present invention is to provide a thermal printer head chip bad pixel rapid detection and analysis system to solve the above-mentioned background problems.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A thermal printer head chip bad pixel rapid detection and analysis system, comprising: Signal acquisition module: Place the thermal sheet to be tested on the test fixture and fix it, obtain the contact gap value between the thermal sheet to be tested and the fixed substrate through the distance meter, compare the contact gap value with the contact fixation threshold, and obtain a fixation completion signal; Detection execution module: based on the fixed completion signal, triggers the detection execution, marks the pixel points on the thermistor to be tested as n, where n is 1, 2, 3, etc., traverses all the pixel points for power-on test, and calculates the initial resistance value RXn of each pixel point; Initial inspection module: determine whether the initial resistance value RXn of each pixel on the thermistor to be tested is within the resistance value range [RXmin, RXmax], calculate the initial qualified rate value CTHG of the resistance value, and compare it with the initial qualified rate threshold CTY to obtain the initial qualified signal; Internal inspection module: Based on the initial qualified signal, the test current is maintained at the pixel current value IXn to continue the power-on test, and the pixel operating voltage value UYn after the detection time T is obtained through AD monitoring sampling, and then the pixel operating temperature value WTn is obtained through the temperature sensor, and the pixel operating state performance value ZBZ is calculated; Determination module: compares the pixel point operation status performance value ZBZ with the pixel point operation status performance threshold ZBZY to obtain a thermal film operation qualified signal.

[0005] As a further solution of the present invention: in the signal acquisition module: comparing the contact gap value with the contact fixed threshold value: If the contact gap value is greater than or equal to the contact fixed threshold, a fixed abnormal signal is generated; If the contact gap value is less than the contact fixation threshold, a fixation completion signal is generated.

[0006] As a further solution of the present invention: in the detection execution module, the method for obtaining the initial resistance value RXn of the pixel point includes: The test fixture is connected to the test current, and then the electrical signal data of the pixel point is obtained through AD monitoring sampling, wherein the electrical signal data includes the pixel point current value IXn and the pixel point voltage value UXn; Then pass The initial resistance value RXn of each pixel is calculated and obtained.

[0007] As a further solution of the present invention: the calculation method of the initial state qualified rate value CTHG includes: Determine whether the initial resistance value RXn of each pixel on the thermistor to be tested is within the resistance value range [RXmin, RXmax]: If the initial resistance value RXn is within the resistance value range [RXmin, RXmax], a resistance initial state good signal is generated; If the initial resistance value RXn is not in the resistance value range [RXmin, RXmax], a resistance initial state bad signal is generated; Obtain the number of good initial resistance signals in the pixels on the thermistor to be tested, and record it as i; pass The initial qualified rate value CTHG of the resistance value is calculated.

[0008] As a further solution of the present invention: the initial state qualified rate value CTHG is compared with the initial state qualified rate threshold CTY: If the initial state qualified rate value CTHG is greater than or equal to the initial state qualified rate threshold CTY, an initial state qualified signal is generated; If the initial state qualified rate value CTHG is less than the initial state qualified rate threshold CTY, an initial state unqualified signal is generated.

[0009] As a further solution of the present invention: the pixel point running state performance value ZBZ is obtained in the following manner: The pixel point operating resistance value RYn is calculated based on the pixel point operating voltage value UYn, and the pixel point resistance operating stability performance value ZBR on the thermistor to be tested is calculated; Based on the operating temperature value WTn of the pixel point, the initial temperature state value WTO of the pixel point is obtained; it should be noted that the initial temperature state values ​​of all the pixels are the same; the thermal conversion performance value ZRH of the pixel point is calculated; Based on the pixel resistance running stability performance value ZBR and the pixel thermal conversion performance value ZRH, The pixel point operation status performance value ZBZ is calculated and obtained; wherein g is the preset pixel point resistance operation stability performance coefficient, and k is the preset pixel point thermal conversion performance coefficient.

[0010] As a further solution of the present invention: the calculation method of the pixel point operating resistance value RYn is: based on the pixel point operating voltage value UYn, The pixel operating resistance value RYn is obtained by calculation.

[0011] As a further solution of the present invention: the calculation method of the pixel point resistance running stable performance value ZBR is: Get the initial resistance value RXn by Calculate and obtain the resistance operation change rate RTLn; Get the maximum value RTLmax of the resistance operation change rate among the resistance operation change rates RTLn; The average value of the resistance operation change rate RTLn is calculated to obtain the mean value RJB of the resistance operation change rate, and then the standard deviation of the resistance operation change rate RTLn is calculated to obtain the standard deviation value BC of the resistance operation change; Then pass The pixel point resistance operation stability performance value ZBR is calculated and obtained, wherein a and b are preset proportional coefficients, and both a and b are greater than 0.

[0012] As a further solution of the present invention: the calculation method of the pixel point thermal conversion performance value ZRH is: pass Calculate and obtain the pixel point thermal conversion performance value ZRHn, where d is the heat loss coefficient; Based on the pixel point thermal conversion performance value ZRHn, the pixel point thermal conversion performance mean value ZRJ is calculated; further, the pixel point thermal conversion performance standard deviation value ZRC is calculated by the standard deviation formula; Then through The pixel point thermal conversion performance value ZRH is calculated and obtained, wherein e is a preset proportional coefficient for the mean value of the pixel point thermal conversion, and f is a preset proportional coefficient for the standard deviation of the pixel point thermal conversion performance; and both e and f are greater than 0.

[0013] As a further solution of the present invention: comparing the pixel point operation state performance value ZBZ with the pixel point operation state performance threshold value ZBZY; If the pixel point operation status performance value ZBZ is greater than or equal to the pixel point operation status performance threshold ZBZY, a thermal film operation qualified signal is generated; If the pixel point operation status performance value ZBZ is less than the pixel point operation status performance threshold value ZBZY, a thermal film operation abnormality signal is generated.

[0014] Beneficial effects of the present invention: First, the resistance value of the pixel points on the thermal sheet is tested for initial on-current to determine whether the pixel point qualification rate of the pixel points on the thermal sheet meets the requirements. If the qualification rate of the pixel point resistance in the initial state meets the requirements, the pixel points on the thermal sheet are tested for operation to further determine whether the thermal sheet in the operation process can meet the use requirements. The thermal sheets that are unqualified in the initial state can be quickly discharged without subsequent testing, thus shortening the testing time and improving the testing efficiency. By conducting a heating test on each pixel on the thermistor for a certain period of time, it is determined whether the stability of the resistance of the pixel during operation can meet the requirements. At the same time, since the pixel needs to be heated during operation, the thermal conversion of the resistance on the pixel is further calculated to determine whether the thermal performance of the pixel resistance can meet the requirements. Finally, the qualification of the thermistor is comprehensively judged based on the resistance operation and thermal conversion of the pixel, which can achieve more accurate and effective qualified detection of thermistors from multiple angles. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described below in conjunction with the accompanying drawings.

[0016] Figure 1 is a system block diagram of the present invention; Figure 2 It is a flow chart of the detection method in the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Embodiment 1

[0018] See also Figure 1 As shown, the present invention is a method for quickly detecting and analyzing bad pixels of a thermal printer head chip, comprising: Signal acquisition module: Place the thermal sheet to be tested on the test fixture and fix it, obtain the contact gap value between the thermal sheet to be tested and the fixed substrate through the distance meter, compare the contact gap value with the contact fixation threshold, and obtain a fixation completion signal; Detection execution module: based on the fixed completion signal, triggers the detection execution, marks the pixel points on the thermistor to be tested as n, where n is 1, 2, 3, etc., traverses all the pixel points for power-on test, and calculates the initial resistance value RXn of each pixel point; Initial inspection module: determine whether the initial resistance value RXn of each pixel on the thermistor to be tested is within the resistance value range [RXmin, RXmax], calculate the initial qualified rate value CTHG of the resistance value, and compare it with the initial qualified rate threshold CTY to obtain the initial qualified signal; Internal inspection module: Based on the initial qualified signal, the test current is maintained at the pixel current value IXn to continue the power-on test, and the pixel operating voltage value UYn after the detection time T is obtained through AD monitoring sampling, and then the pixel operating temperature value WTn is obtained through the temperature sensor, and the pixel operating state performance value ZBZ is calculated; Determination module: compares the pixel point operation status performance value ZBZ with the pixel point operation status performance threshold ZBZY to obtain a thermal film operation qualified signal.

[0019] The detection system is the core of this solution. It is connected to the host computer through communication cables such as USB, serial port or network port. The ejector pins and cables establish an electrical connection with the thermal sheet to be tested. When the thermal sheet is fixed in place, the detection switch transmits this information to the detection execution module, and the detection execution module starts automatic detection. After the detection work is completed, the test data is automatically saved to the local SD memory card or uploaded to the host computer, and the detection result OK or NG status indicator is lit.

[0020] The host computer is a computer, which is connected to the detection module through a communication cable, and the computer is installed with thermal film detection data statistical analysis software.

[0021] On the one hand, the software performs engineering configuration for thermal film detection, and on the other hand, it performs statistical analysis on the detection data and outputs the statistical analysis results. Embodiment 2

[0022] See also Figure 2 As shown, the present invention is a method for quickly detecting and analyzing bad pixels of a thermal printer head chip, comprising: S1: Place the thermal sheet to be tested on the test fixture and fix it, obtain the contact gap value between the thermal sheet to be tested and the fixed substrate through the distance meter, compare the contact gap value with the contact fixation threshold, and obtain a fixation completion signal; Compare the contact gap value to the contact fixation threshold: If the contact gap value is greater than or equal to the contact fixation threshold, a fixation abnormality signal is generated; at this time, secondary fixation is required; If the contact gap value is less than the contact fixation threshold, a fixation completion signal is generated; S2: Based on the fixed completion signal, the detection execution is triggered, and the pixel points on the thermistor to be tested are marked as n, where n is 1, 2, 3, etc., and all the pixel points are traversed for power-on test, and the initial resistance value RXn of each pixel point is calculated; Specifically, the method for obtaining the initial resistance value RXn of the pixel includes: The test fixture is connected to the test current, and then the electrical signal data of the pixel point is obtained through AD monitoring sampling, wherein the electrical signal data includes the pixel point current value IXn and the pixel point voltage value UXn; Then pass Calculate and obtain the initial resistance value RXn of each pixel; S3: Determine whether the initial resistance value RXn of each pixel on the thermistor to be tested is within the resistance value range [RXmin, RXmax], calculate the initial qualified rate value CTHG of the resistance value, and compare it with the initial qualified rate threshold CTY to obtain an initial qualified signal; The method for obtaining the initial qualified signal of the resistance value of the pixel point on the thermistor to be tested includes: S31: Determine whether the initial resistance value RXn of each pixel on the thermistor to be tested is within the resistance value range [RXmin, RXmax]: If the initial resistance value RXn is within the resistance value range [RXmin, RXmax], a resistance initial state good signal is generated; If the initial resistance value RXn is not in the resistance value range [RXmin, RXmax], a resistance initial state bad signal is generated; S32: Obtain the number of good initial resistance signals in the pixel points on the thermistor to be tested, and record it as i; pass Calculate and obtain the initial qualified rate value CTHG of the resistance value; S33: Compare the initial state qualified rate value CTHG with the initial state qualified rate threshold CTY: If the initial state qualified rate value CTHG is greater than or equal to the initial state qualified rate threshold CTY, an initial state qualified signal is generated; If the initial state qualified rate value CTHG is less than the initial state qualified rate threshold CTY, an initial state unqualified signal is generated; at this time, it means that the resistance value of the pixel points on the thermal sheet to be tested has many unqualified conditions during the initial production process, and at this time, the thermal sheet is marked; First, the resistance value of the pixel points on the thermal sheet is tested for initial on-current to determine whether the pixel point qualification rate of the pixel points on the thermal sheet meets the requirements. If the qualification rate of the pixel point resistance in the initial state meets the requirements, the pixel points on the thermal sheet are tested for operation to further determine whether the thermal sheet in the operation process can meet the use requirements. The thermal sheets that are unqualified in the initial state can be quickly discharged without subsequent testing, thus shortening the testing time and improving the testing efficiency. S4: Based on the initial qualified signal, the test current is maintained at the pixel current value IXn to continue the power-on test, and the pixel operation voltage value UYn after the detection time T is obtained through AD monitoring sampling, and then the pixel operation temperature value WTn is obtained through the temperature sensor, and the pixel operation state performance value ZBZ is calculated; Specifically include: S41: Calculate the pixel point operating resistance value RYn based on the pixel point operating voltage value UYn, and calculate the pixel point resistance operating stability performance value ZBR on the thermistor to be tested; The calculation method for the pixel resistance stable performance value ZBR is: S411: Based on the pixel point operating voltage value UYn, Calculate and obtain the pixel point operating resistance value RYn; Get the initial resistance value RXn by Calculate and obtain the resistance operation change rate RTLn; S412: Obtain the maximum value RTLmax of the resistance operation change rate among the resistance operation change rates RTLn; S413: Calculate the average value of the resistance operation change rate RTLn to obtain the resistance operation change rate mean value RJB, and then calculate the standard deviation of the resistance operation change rate RTLn to obtain the resistance operation change standard deviation value BC; S414: Then through Calculate and obtain the pixel point resistance operation stability performance value ZBR, where a and b are preset proportional coefficients, and both a and b are greater than 0; S42: based on the operating temperature value WTn of the pixel point, obtaining the initial temperature state value WTO of the pixel point; it should be noted that the initial temperature state values ​​of all the pixels are the same; and calculating and obtaining the thermal conversion performance value ZRH of the pixel point; The calculation method of the pixel thermal conversion performance value ZRH is: S421: Pass Calculate and obtain the pixel point thermal conversion performance value ZRHn, where d is the heat loss coefficient; S422: Calculate the pixel point thermal conversion performance mean value ZRJ based on the pixel point thermal conversion performance value ZRHn; further calculate the pixel point thermal conversion performance standard deviation value ZRC through the standard deviation formula; S423: Pass again Calculate and obtain the pixel point thermal conversion performance value ZRH, where e is the preset proportional coefficient of the pixel point thermal conversion mean value, and f is the preset proportional coefficient of the pixel point thermal conversion performance standard deviation; both e and f are greater than 0; S43: Based on the pixel point resistance running stable performance value ZBR and the pixel point thermal conversion performance value ZRH, through Calculate and obtain the pixel point operation state performance value ZBZ; wherein g is the preset pixel point resistance operation stability performance coefficient, and k is the preset pixel point thermal conversion performance coefficient; S5: Compare the pixel point running state performance value ZBZ with the pixel point running state performance threshold ZBZY; If the pixel point operation status performance value ZBZ is greater than or equal to the pixel point operation status performance threshold value ZBZY, a thermal film operation qualified signal is generated; at this time, the next thermal film is tested; If the pixel point operation status performance value ZBZ is less than the pixel point operation status performance threshold value ZBZY, a thermal sheet operation abnormality signal is generated; at this time, it means that the thermal sheet will become unstable during operation, which will lead to abnormal operation, that is, there is an unqualified problem.

[0023] By conducting a heating test on each pixel on the thermistor for a certain period of time, it is determined whether the stability of the resistance of the pixel during operation can meet the requirements. At the same time, since the pixel needs to be heated during operation, the thermal conversion of the resistance on the pixel is further calculated to determine whether the thermal performance of the pixel resistance can meet the requirements. Finally, the qualification of the thermistor is comprehensively judged based on the resistance operation and thermal conversion of the pixel, which can achieve more accurate and effective qualified detection of thermistors from multiple angles. Embodiment 3

[0024] Based on the above embodiments, this embodiment provides a test fixture, which is assembled from epoxy resin boards to provide fixation and support for the thermal film and the detection system. The test fixture panel is equipped with ejectors with cables, buckles, detection switches, buttons and indicator lights. The ejectors and cables provide electrical and communication connections between the thermal film to be tested and the detection system. The buckles serve to fix the thermal film. The detection switch detects whether the thermal film has been installed in place and fixed. The button is used to trigger the detection function. The indicator light is used to display the status of power supply, detection results, etc.

[0025] The above formulas are all dimensionless and numerical calculations. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters in the formula are set by technicians in this field according to actual conditions.

[0026] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A thermal printer head chip bad pixel rapid detection and analysis system, characterized in that: include: Signal acquisition module: Place the thermal sheet to be tested on the test fixture and fix it, obtain the contact gap value between the thermal sheet to be tested and the fixed substrate through the distance meter, compare the contact gap value with the contact fixation threshold, and obtain a fixation completion signal; Detection execution module: based on the fixed completion signal, triggers the detection execution, marks the pixel points on the thermistor to be tested as n, where n is 1, 2, 3, etc., traverses all the pixel points for power-on test, and calculates the initial resistance value RXn of each pixel point; Initial inspection module: determine whether the initial resistance value RXn of each pixel on the thermistor to be tested is within the resistance value range [RXmin, RXmax], calculate the initial qualified rate value CTHG of the resistance value, and compare it with the initial qualified rate threshold CTY to obtain the initial qualified signal; Internal inspection module: Based on the initial qualified signal, the test current is maintained at the pixel current value IXn to continue the power-on test, and the pixel operating voltage value UYn after the detection time T is obtained through AD monitoring sampling, and then the pixel operating temperature value WTn is obtained through the temperature sensor, and the pixel operating state performance value ZBZ is calculated; Determination module: compares the pixel point operation status performance value ZBZ with the pixel point operation status performance threshold ZBZY to obtain a thermal film operation qualified signal.

2. A thermal printer head chip bad pixel rapid detection and analysis system according to claim 1, characterized in that: In the signal acquisition module: the contact gap value is compared with the contact fixed threshold: If the contact gap value is greater than or equal to the contact fixed threshold, a fixed abnormal signal is generated; If the contact gap value is less than the contact fixation threshold, a fixation completion signal is generated.

3. A thermal printer head chip bad pixel rapid detection and analysis system according to claim 1, characterized in that: In the detection execution module, the method for obtaining the initial resistance value RXn of the pixel point includes: The test fixture is connected to the test current, and then the electrical signal data of the pixel point is obtained through AD monitoring sampling, wherein the electrical signal data includes the pixel point current value IXn and the pixel point voltage value UXn; Then pass The initial resistance value RXn of each pixel is calculated and obtained.

4. A thermal printer head chip bad pixel rapid detection and analysis system according to claim 1, characterized in that: The calculation method of the initial state qualified rate value CTHG includes: Determine whether the initial resistance value RXn of each pixel on the thermistor to be tested is within the resistance value range [RXmin, RXmax]: If the initial resistance value RXn is within the resistance value range [RXmin, RXmax], a resistance initial state good signal is generated; If the initial resistance value RXn is not in the resistance value range [RXmin, RXmax], a resistance initial state bad signal is generated; Obtain the number of good initial resistance signals in the pixels on the thermistor to be tested, and record it as i; pass The initial qualified rate value CTHG of the resistance value is calculated.

5. A thermal printer head chip bad pixel rapid detection and analysis system according to claim 4, characterized in that: Compare the initial state pass rate value CTHG with the initial state pass rate threshold CTY: If the initial state qualified rate value CTHG is greater than or equal to the initial state qualified rate threshold CTY, an initial state qualified signal is generated; If the initial state qualified rate value CTHG is less than the initial state qualified rate threshold CTY, an initial state unqualified signal is generated.

6. A thermal printer head chip bad pixel rapid detection and analysis system according to claim 1, characterized in that: The pixel point running state performance value ZBZ is obtained as follows: The pixel point operating resistance value RYn is calculated based on the pixel point operating voltage value UYn, and the pixel point resistance operating stability performance value ZBR on the thermistor to be tested is calculated; Based on the operating temperature value WTn of the pixel point, the initial temperature state value WTO of the pixel point is obtained; it should be noted that the initial temperature state values ​​of all the pixels are the same; the thermal conversion performance value ZRH of the pixel point is calculated; Based on the pixel resistance running stability performance value ZBR and the pixel thermal conversion performance value ZRH, The pixel point operation status performance value ZBZ is calculated and obtained; wherein g is the preset pixel point resistance operation stability performance coefficient, and k is the preset pixel point thermal conversion performance coefficient.

7. A thermal printer head chip bad pixel rapid detection and analysis system according to claim 6, characterized in that: The calculation method of the pixel point operating resistance value RYn is: based on the pixel point operating voltage value UYn, The pixel operating resistance value RYn is obtained by calculation.

8. A thermal printer head chip bad pixel rapid detection and analysis system according to claim 7, characterized in that: The calculation method of the pixel point resistance stable performance value ZBR is: Get the initial resistance value RXn by Calculate and obtain the resistance operation change rate RTLn; Get the maximum value RTLmax of the resistance operation change rate among the resistance operation change rates RTLn; The average value of the resistance operation change rate RTLn is calculated to obtain the mean value RJB of the resistance operation change rate, and then the standard deviation of the resistance operation change rate RTLn is calculated to obtain the standard deviation value BC of the resistance operation change; Then pass The pixel point resistance operation stability performance value ZBR is calculated and obtained, wherein a and b are preset proportional coefficients, and both a and b are greater than 0.

9. A thermal printer head chip bad pixel rapid detection and analysis system according to claim 6, characterized in that: The calculation method of the pixel thermal conversion performance value ZRH is: pass Calculate and obtain the pixel point thermal conversion performance value ZRHn, where d is the heat loss coefficient; Based on the pixel point thermal conversion performance value ZRHn, the pixel point thermal conversion performance mean value ZRJ is calculated; further, the pixel point thermal conversion performance standard deviation value ZRC is calculated by the standard deviation formula; Then through The pixel point thermal conversion performance value ZRH is calculated and obtained, wherein e is a preset proportional coefficient for the mean value of the pixel point thermal conversion, and f is a preset proportional coefficient for the standard deviation of the pixel point thermal conversion performance; and both e and f are greater than 0.

10. A thermal printer head chip bad pixel rapid detection and analysis system according to claim 1, characterized in that: Compare the pixel point running state performance value ZBZ with the pixel point running state performance threshold ZBZY; If the pixel point operation status performance value ZBZ is greater than or equal to the pixel point operation status performance threshold ZBZY, a thermal film operation qualified signal is generated; If the pixel point operation status performance value ZBZ is less than the pixel point operation status performance threshold value ZBZY, a thermal film operation abnormality signal is generated.

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