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National Standard of the People's Republic of China
Test Methods of Black-and-White Television Picture Tubes
The methods of the measurement of the.black- and-white television picture tubes
This standard applies to the test of the optoelectronic parameters of black-and-white television picture tubes (hereinafter referred to as picture tubes). 1 Test conditions and adjustment procedures
UDC 621.389.83
: 621.317
GB 3212—82
1.1 Test conditions
1.1.1 The test of the picture tube should be carried out after the cathode reaches a stable emission state. For this purpose, the picture tube should generally be preheated for 2 minutes at the rated filament voltage.
1.1.2 When testing the picture tube, the influence of the external electric field and magnetic field should be minimized and eliminated. The outer conductive layer of the picture tube and the explosion-proof device should be at ground potential.
1.1.3 When testing the CRT by displaying test patterns, the test patterns and their sizes shall comply with the regulations, and the patterns on the screen must be stable.
1.1.4 During the test, the CRT shall use a deflection system that complies with the standards and be placed in the correct position. 1.1.5 When testing the CRT, the influence of ambient light shall be reduced. 1.1.6 The test equipment (including instruments and meters) shall be stable and reliable. 1.1.6.1 Under the specified operating conditions, the electrical error supplied to each electrode of the CRT shall not exceed the following provisions: Filament voltage (→)
Cathode or modulation electrode voltage (-)
Final anode voltage (～)
When the beam current is less than 1 mA
When the beam current is between 1 mA and 3 mA
Other anode voltages (-)
1.1.6.2 Ripple coefficient of DC voltage on each electrode of the CRT Should not exceed the following provisions: Filament voltage ·
Cathode or modulator voltage.
Anode voltage ·
1.1.6.3 The accuracy level of the measuring instrument should not be lower than that of the instrument connected to the DC circuit.
Instrument connected to the AC circuit ·
Instrument measuring current less than 10 microamperes
1.1.6.4 The signal generator should meet the requirements of the national standard GB1385-78 "Black and White Television Broadcasting Standard". 1.1.6.5 The scanning nonlinearity of the scanning generator should not exceed 5%. The interlaced ratio should not be less than 55:45. 23%
.1.5 level
1.1.6.6 The frequency characteristics of the video amplifier, the uniformity within the 7.5MHz band should be within the range of ±10%? The uniformity within the range of 7.5~8.5MHz should be within the range of -30%: above 8.5MHz, it will slowly decrease. The nonlinearity of the amplitude characteristic should not exceed ±5%. For the pulse characteristic, the flat-top tilt of the 15kHz and 250kHz rectangular pulses should not exceed 1%. The amplitude of the video amplifier output signal should be adjustable within the range of the cathode or modulation electrode voltage of the picture tube from zero to the cut-off voltage. National Bureau of Standards 198209 01 Issued
1983-09 01 Implementation
GB 8212--82
The drift of the black level within the video signal adjustment range should not be greater than 2%. 1.1.6.7 Requirements for photometric instruments
The spectral characteristic curve of the light receiver of the luminance meter and the illuminance meter should be calibrated in advance to be consistent with the photopic light effect function, and the degree of consistency should comply with the provisions of Appendix A; the luminance meter and the illuminance meter are calibrated with a standard light source of known color temperature and light intensity. The spectral power distribution or correlated color temperature of the standard light source and the measured light source (picture tube) should be as similar as possible. The determination of the correction coefficient of the spectral radiometer should be carried out in accordance with the provisions of Appendix B. The calibration of the colorimeter shall be carried out in accordance with the provisions of Appendix C. 1.1.7 Unless otherwise specified, the electrical parameter test shall be carried out under the atmospheric conditions of an ambient temperature of 15~35℃, a relative humidity of 45%~75%, and an air pressure of 86~106kPa, and the optical parameter test shall be carried out under the atmospheric conditions of an ambient humidity of 18~22℃, a relative humidity of 60%~70%, and an air pressure of 86~106kPa. 1.1.9 Protective measures shall be taken to ensure the safety of the operator during the test. 1.2 Adjustment Procedure
1.2.1 Install the picture tube into the test bench. According to the working specifications of various types of picture tubes, the power supply is usually turned on in the following order, and the specified voltage is applied to each electrode. Filament power supply voltage;
Cathode or modulator power supply voltage, to ensure that the electron beam is cut off: scanning part power supply voltage, anode and focusing electrode power supply voltage, and anode power supply voltage (high voltage)
1.2.2 Adjust the working state of the picture tube according to the following steps. Adjust the cathode or modulator voltage to make a scanning raster appear on the picture tube screen: Adjust the raster size to the specified size:
Adjust the brightness (or the beam current to ensure the brightness) to the specified value, and adjust the focusing electrode voltage to focus the electron beam. If necessary, send the video signal of the standard test pattern. Adjust the cathode or modulator voltage and the video signal amplitude so that the brightness of the brightest part of the screen is the specified brightness (or the beam current to ensure the brightness), and the black level is the level corresponding to the disappearance of the brightness. Adjust the focusing electrode voltage to make the neutron beam focus optimally.
2 Photoelectric parameter test
2.1 Filament heating establishment time
The test circuit schematic diagram is shown in Figure 1, and the power supply voltage is 4 times the rated filament voltage. In order to make the parts of the picture tube at room temperature, the filament voltage should not be applied for at least 1 hour before the test. During the test, close the switch K and use a timer to measure the time required for the voltage across the filament to reach 0.8 times the rated filament voltage. The series resistance R (error ±1%) is specified by the following formula: Formula t: Uf
Rated filament voltage, V:
Rated filament current, A:
-resistance, 2.
GB 321282
In the test circuit, the internal resistance of the power supply should be much smaller than the resistance R, and the internal resistance of the voltmeter should be much larger than the resistance scale. 4bzxz.net
Figure 1 Schematic diagram of the test circuit for the filament heating establishment time 2.2 Cathode start time
2.2.1 Definition
Under specified working conditions, the time required for the beam current of the picture tube to reach a specified percentage of the maximum beam current after the filament voltage is applied. 2.2.2 Test method
The schematic diagram of the test circuit is shown in Figure 2. The voltage of each electrode is the rated working voltage. In order to keep the parts of the picture tube at room temperature, the filament voltage should not be applied for at least 1 hour before the test. A horizontal frequency non-synchronous rectangular pulse (for example, the pulse duty cycle is 0.1) is added between the cathode and the modulator, so that the potential between the modulator and the cathode periodically cuts off and is at the same voltage. Start scanning, close switch K, and use a recorder (or corresponding recording instrument) to measure the time required from the moment of closing until the moment when the indicator instrument indicates that the beam current reaches the specified fraction of the maximum beam current. In the test circuit, the indicator instrument should have a low positive and negative characteristic, and the internal resistance of the filament power supply should be much smaller than the cold resistance of the filament. XY
Recorder
Figure 2 Schematic diagram of cathode start-up time test circuit
2.3 Filament current
The schematic diagram of the test circuit is shown in Figure 3.
During the test, the rated voltage is applied to both ends of the filament, and no voltage is applied to other electrodes. After the filament reaches thermal equilibrium, the filament current can be read from the ammeter in the circuit.
GB321282
The measurement result should be corrected for the shunt current of the voltmeter. 3
Figure 3 Filament current test circuit schematic
2.4 Withstand voltage between filament and cathode
The test circuit schematic is shown in Figure 4.
During the test, the maximum limit voltage is applied to the filament of the picture tube, and the cathode or modulation electrode voltage is adjusted to make its absolute value greater than the specified value of the cut-off voltage to ensure that the cathode current is cut off. The voltage applied between the filament and the cathode should make the absolute value of the cathode voltage at any point of the filament at any moment not lower than the specified limit value, and no voltage is applied to other electrodes. Keep it for 1 minute, and check whether the filament and the cathode are broken down by using a small electric meter or other indicator. .
Short circuit indicator
Figure 4 Schematic diagram of the withstand voltage test circuit between the filament and the cathode 2.5 Electrode leakage current
2.5.1 The schematic diagram of the leakage current test circuit between the filament and the cathode is shown in Figure 5.
GB3212--82
During the test, the rated voltage is applied to the filament of the picture tube, and the voltage applied between the filament and the cathode should make the absolute value of the cathode voltage at any point of the filament at any moment not less than the specified limit value; no voltage is applied to other electrodes. At this time, the leakage current between the filament and the cathode can be read from the ammeter in the circuit.
Figure 5 Schematic diagram of the leakage current test circuit between the filament and the cathode 2.5.2 The schematic diagram of the cathode or modulator leakage current
test circuit is shown in Figure 6 (a) and Figure 6 (b). During the test, the rated working voltage is applied to the picture tube, and the cathode or modulator voltage is adjusted so that its absolute value is a specified value larger than the cut-off voltage to ensure that the cathode current is cut off. At this time, the cathode or modulator leakage current can be read from the ammeter in the cathode or modulator loop. 2.5.3 The schematic diagram of the anode leakage current
test circuit is shown in Figure 6 (a) and Figure 6 (b). During the test, the rated working voltage is applied to the picture tube, and the cathode or modulator voltage is adjusted so that its absolute value is a specified value larger than the cut-off voltage to ensure that the cathode current is cut off. At this time, the leakage current of each corresponding anode can be read from the ammeter in each anode loop. d
Figure 66(a)
Electrode leakage current test circuit schematic diagram for polar modulation 2.6 Electrode current
GB 3212-82
Figure 6(b) Electrode leakage current test circuit schematic diagram for cathode modulation 2.6.1 Anode current, cathode current and beam current 2.6.1.1 Definition
Under specified working conditions, the currents flowing through each anode loop and cathode loop are called anode current and cathode current respectively, and the beam current reaching the fluorescent screen is called beam current. 2.6.1.2 Test method
The test circuit schematic diagram is shown in Figure 7(a) and Figure 7(b), and the switch is set to the "1" position. The picture tube is adjusted according to 1.2. The currents flowing through each anode loop and cathode loop at the specified brightness are the corresponding anode current and cathode current; the current flowing through the last anode loop is the beam current. The measurement results should deduct the respective leakage currents. 2.6.2 Maximum cathode current and maximum beam current 2.6.2.1 Definition
Under specified working conditions, when the cathode and modulator are at the same potential, the electron current emitted by the white cathode is called the maximum cathode current: the electron beam current reaching the fluorescent screen is called the large beam current. 2.6.2.2 Test method
The test circuit schematic diagram is shown in Figure 7 (a) and Figure 7 (b), and the switch is set to the "1" position. The kinescope is connected to the power supply according to the adjustment procedure in 1.2.1, and the rated voltage is applied to each electrode. Then the switch is set to the "2" position to short-circuit the cathode and the modulator. The current measured in the anode loop is the maximum cathode current, and the current measured in the cathode loop is the maximum beam current.
Note that the short-circuit time should be as long as possible (less than 10 seconds) to avoid damage to the cathode and the fluorescent screen. 2.7 Parasitic radiation
2.7.1 Definition
Figure 7(a)
Figure 7(6)
GB3212—82
Electrode current test schematic diagram for modulator electrode current test schematic diagram for modulator electrode current test schematic diagram When the picture tube is working under the cut-off condition, the radiation that causes the fluorescent screen to emit light is called parasitic radiation. 2.7.2 Test method
The picture tube is connected to the power supply according to the adjustment procedure in 1.2.1. The maximum limit operating voltage is applied to each anode and the rated voltage is applied to the filament. Using the specified scanning method, adjust the cathode or modulator voltage to cut off the electron beam. Observe whether there is any luminescence on the fluorescent screen within the specified time. During the measurement, the ambient light illumination on the fluorescent screen should be less than 5 lux. The observer should adapt his eyes to observe the fluorescent screen. 2.8 Sparkover
2.8.1 Definition
GB 3212-82
The phenomenon of uncontrolled discharge between the electrodes of a picture tube is called sparkover. 2.8.2 Test method
Connect the picture tube to the power supply according to the adjustment procedure in 1.2.1, apply the maximum limit voltage to each anode (the last anode voltage is applied once), and apply the rated voltage to the filament. Use the specified scanning method to adjust the cathode or modulator voltage to cut off the electron beam. Within the specified time, observe the flash caused by inter-electrode discharge on the fluorescent screen, the swing of the meter pointer in each electrode circuit, or use the specified instrument to record the number of sparkovers. Then adjust the cathode or modulator voltage and the focusing electrode voltage so that the screen displays a focused grating of the specified size and the specified brightness (or the beam current that guarantees the degree of charge). Within the specified time, observe the flash caused by inter-electrode discharge on the fluorescent screen, the grating jitter, the swing of the meter pointer in each electrode circuit, or use the specified instrument to record the number of sparkovers. 2.9 Cut-off voltage
2.9.1 Cut-off voltage of light spot
2.9. 1.1 Definition
Under specified working conditions, the voltage on the modulator or cathode when the undeflected focused light spot just disappears is called the cut-off voltage of the corresponding electrode.
2.9.1.2 Test method
The kinescope is powered on according to the adjustment procedure in 1.2.1. The rated working voltage is applied to each electrode, and the focusing electrode voltage and the modulator voltage are adjusted so that the focused light spot on the screen just disappears. The modulator voltage measured at this time is the modulator cut-off voltage of the kinescope. The rated working voltage is applied to each electrode, and the focusing electrode voltage and the cathode voltage are adjusted so that the focused light spot on the screen just disappears. The cathode voltage measured at this time is the cathode cut-off voltage of the kinescope. When measuring, the ambient light illumination on the screen should be less than 1 lux. The observer should adapt his eyes to observe the screen. 2.9.2 Beam current cut-off voltage
2.9.2.1 Definition
Under specified working conditions, the voltage on the modulator or cathode when the beam current approaches zero is called the cut-off voltage of the corresponding electrode. 2.9.2.2 Test method
The kinescope is powered on according to the adjustment procedure in 1.2.1. The rated working voltage is applied to each electrode, and a focusing grating of a specified size is displayed on the fluorescent screen. Adjust the modulator voltage: make the beam current drop to a specified value (for example, 0.5 microamperes or less, minus the leakage current). The modulator voltage measured at this time is the modulator cut-off voltage. The rated working voltage is applied to each electrode, and a focusing grating of a specified size is displayed on the fluorescent screen. Adjust the cathode voltage so that the beam current drops to a specified value (for example, 0.5 microamperes or less, minus the leakage current). The cathode voltage measured at this time is the cathode cut-off voltage. 2.10 Cathode coefficient
2. 10.1 Definition
The ratio of the maximum cathode emission current to the absolute value of the cut-off voltage to the cube is called the cathode coefficient. 2.10.2 Test method
Connect the cathode tube to the power supply according to the adjustment procedure in 1.2.1, and apply the rated working voltage to each electrode. Measure the cut-off voltage using the cut-off voltage test method in 2.9, and measure the maximum cathode current using the maximum cathode current test method in 2.6.2. Calculate the cathode coefficient K according to the following formula:
Where: Ikmax--maximum cathode current, μAUr
cut-off voltage, V.
The cut-off voltage U should be statistically corrected according to the following formula: Temax
U =U' + 4..
Wherein: U is the cut-off voltage value measured by the test method of cut-off voltage in Article 2.9; (2)
2. 11 Modulation
2.11.1 Definition
GB 3212-B2
Statistical correction value. For the cut-off voltage of the light spot, this value is set to zero. Under the specified operating conditions, the absolute value of the difference between the cathode or modulator voltage and the cut-off voltage when the screen brightness (or the beam current that guarantees the brightness) is the specified value is called the modulation.
2.11.2 Test method
The picture tube is adjusted according to Article 1.2.
According to the brightness test method in Article 2.21, the cathode or modulator voltage of the picture tube at the specified intensity (or beam current to ensure the brightness) is measured; then the corresponding cut-off voltage is measured according to the cut-off voltage test method in Article 2.9. The absolute value of the difference between the two is the modulation amount. 2.12 Modulation characteristics
2. 12.1 Definition
The relationship between screen brightness (or beam current) and cathode or modulator voltage. 2.12.2. Test method
The picture tube is adjusted according to Article 1.2.
According to the brightness test method in Article 2.21, the screen brightness (or beam current) at different cathode or modulator voltages is measured. Based on the measured data, the modulation characteristic curve can be drawn, that is, the functional relationship curve between cathode or modulator voltage and screen brightness (or beam current). 2.13 External conductive layer resistance
2.13.1 Definition
The resistance within a certain distance on the external conductive layer of the picture tube is called the external conductive layer resistance. 2.13.2 Test method
During the test, no voltage is applied to the electrodes of the picture tube, and the resistance of the outer conductive layer is measured with an ohmmeter with special contacts. The ohmmeter contacts are two copper balls with a diameter of 10 mm (or other contacts that ensure good electrical contact with the outer conductive layer). When measuring the resistance of the outer conductive layer of the picture tube, the effective distance between the contact points of the two contacts of the ohmmeter on the outer conductive layer should be 100 mm. The distance between the contact point and the edge of the outer conductive layer shall not be less than 10 mm. The resistance of the outer conductive layer is measured at three positions with a large distance between them. The test result is the arithmetic average of the resistance of the outer conductive layer measured at the three positions.
2.14 Inter-electrode capacitance
Measure according to the national standard GB3306.16-82 "Test method for static inter-electrode capacitance of low-power electron tubes". 2.15 Gas coefficient
2.15.1 Definition
The ratio of ion current to the electron current that produces ion current is called gas coefficient. 2.15.2 Test method
The test circuit schematic is shown in Figure 8.
The last anode of the picture tube is used as the ion collector, and a specified negative charge (generally -25 volts) is added. The other anodes are connected together and a specified positive voltage (generally +250 volts) is added. Test according to the following steps:
Adjust the modulation electrode voltage and read the cathode current value (usually hundreds of microamperes). After the ion collector is powered on, use a low-damping instrument to read the sum of the ion current and the leakage current as quickly as possible. b. Adjust the modulator voltage to completely intercept the beam and read the leakage current 12. c. Calculate the gas coefficient G
I1-(μA/mA)
（4）
Formula: The sum of the ion current and the leakage current, μA12——Leakage current, μA,
1—Cathode current, mA.
:2.16 Effective working surface
2. 16,1 Definition
GB3212—82
Schematic diagram of gas coefficient test circuit
When observing the picture tube along the tube axis, the size of the luminous part of the fluorescent screen that can be seen is called the effective 1. working surface. 2.16.2 Test method
The picture tube is adjusted according to 1.2.
Use a deflection system that meets the requirements of the standard and is equipped with an electromagnetic or permanent magnet adjustment grating core to adjust the grating to the center position. Under overscan conditions, use a measuring tool to measure the projection size of the luminous part facing the screen. The measurement results should give the maximum height, maximum width and maximum diagonal size. 2.17 Resolution| |tt||2.17.1 Definition
The ability to distinguish the smallest details on an image is called resolution, which is usually expressed by the total number of completely dark and alternating lines that can be distinguished on the screen.
2.17.2 Test method
2.17.2.1 Single-image reporting signal method
The picture tube is adjusted according to 1.2 lines. The video signal of the single-image standard television test pattern is added to the cathode or modulator of the picture tube. In order to make the brightness of the brightest part of the test pattern reach the specified value, the cathode or modulator voltage and the video signal amplitude should be adjusted to reduce the beam current to the level when the test pattern is not fed. The grid reaches a percentage of the beam current value that reaches the specified brightness (the size of the percentage should correspond to the total integrated transmission coefficient of the monocular test chart), and the screen displays as many gray levels as possible that can be seen on the test chart. Then adjust the focusing electrode voltage to make the clarity of the vertical and horizontal lines in the center of the image that mark the resolution most appropriate. At this time, the number of lines read at the place where the line structure in the center of the image is just distinguished is defined as the horizontal and vertical resolution of the center of the screen; the number of lines read at the place where the vertical and horizontal line structures in the four corners of the screen that mark the resolution are just distinguished is defined as the horizontal and vertical resolution of the four corners of the screen. ||t t||2.17.2.2 Test pattern signal method
The picture tube is adjusted according to 1.2. The picture adjustment signal generator generates an image adjustment signal with an amplitude that meets the requirements and only has black level and positive and negative black levels (as shown in Figure 9), and is added to the cathode or modulator of the picture tube through a video amplifier (the video amplifier should clamp the adjustment signal black). Adjust the cathode or modulator voltage so that the brightness contrast of the black level and negative black level corresponding to the image adjustment signal on the screen just disappears, adjust the video amplifier gain, and measure the brightness according to 2.21 so that the brightness of the brightest part of the image is the specified brightness.
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