Some standard content:
National Standard of the People's Republic of China
Test methods of colour display tubes
Methods of measurement of colour display tubes 1 Subject content and scope of application
This standard specifies the test methods for the optoelectronic parameters of three-electron beam, shadow mask type colour display tubes. GB/T 15427-.-94
This standard applies to the test of optoelectronic parameters of three-electron beam, shadow mask type colour display tubes (hereinafter referred to as display tubes). 2 Test conditions and adjustment procedures
2.1 Test conditions
2.1.1 The display tube test should be carried out after the cathode reaches a stable working state. Unless otherwise specified, it should generally be preheated for at least 5 seconds at the nominal hot wire voltage. min.
2.1.2 When testing the display tube, the influence of external electric and magnetic fields should be reduced or eliminated. The orientation of the display tube screen should comply with the provisions of the detailed specifications. If necessary, the display tube should be placed in a compensation field so that the geomagnetic field does not affect the test results. 2.1.3 The outer conductive layer of the display tube and the explosion-proof device are at the reference ground potential. 2.1.4 When testing by displaying a test pattern, the signal frequency, test pattern and its size should comply with the regulations. The pattern on the fluorescent screen must be stable.
2.1.5 When testing the display tube, a deflection system and a color purity convergence component that comply with the standards should be used. 2.1.6 When testing the display tube, the influence of ambient light should be reduced. 2.1.7 The test equipment (including instruments and meters) should be stable and reliable, with overload protection and deflection protection devices, and prevent the influence of external magnetic fields and electric fields.
2.1.7.1 Under the specified working conditions, the voltage difference supplied to each electrode of the display tube should not exceed the following regulations: Hot wire voltage (): ± 2%
Cathode or modulation electrode voltage (I): ± 2%
Machine voltage (I):
When the beam current is below 1mA: ± 2%
When the beam current is 1~3 mA: ±5%
Other electrode voltage (I): +2%
2.1.7.2 The ripple coefficient of the DC voltage on each electrode of the display tube shall not exceed the following provisions: Hot wire voltage: soil 3%
Cathode or modulation electrode voltage: ±0.3%
Anode voltage: 1%
Other electrode voltage: ±1.5%
2.1.7.3 Unless otherwise specified. The accuracy level of electrical measuring instruments shall not be lower than: Instruments connected to DC circuits: Class 1.0
Instruments connected to AC circuits Class 2.0
Approved by the State Administration of Technical Supervision on December 31, 1994, and implemented on August 1, 1995
Instruments measuring current less than 10±A: Class 1.0 GB/T15427-94
2.1.7.4. The signal generator shall comply with the provisions of the relevant standards. 2.1.7.5 The scanning nonlinearity of the scanning generator shall not exceed 5%. 2.1.7.6 The frequency characteristics of the video amplifier shall not exceed ±3dB within the frequency band that meets the test standards. The amplitude of the output signal of the video amplifier shall be adjustable within the range from zero to the cut-off voltage of the cathode or modulator voltage of the display tube. 2.1.7. The spectral characteristic curve of the optical receiver of the illuminometer and the illuminometer shall be pre-matched with the spectral luminous efficiency of the light source, and the degree of consistency shall comply with the provisions of Appendix A (Supplement). The luminance meter and the photometer shall be 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 light source (display tube) to be measured should be as similar as possible. The determination of the prism coefficient of the spectroradiometer should be carried out in accordance with the provisions of Appendix B (Supplement), and the calibration of the colorimeter should be carried out in accordance with the provisions of Appendix C (Supplement). 2.1.8 Unless otherwise specified, the test of photoelectric parameters should be carried out under standard atmospheric conditions of ambient temperature of 15~35℃, relative humidity of 45%~75%, and air pressure of 86~l0G kPa. 2.1.9 During the test, protective measures should be taken to ensure the safety of the operator. 2.2 Adjustment procedure
2.2.1 According to the provisions of the detailed specifications, apply electric repulsion to each electrode of the display tube. Unless otherwise specified, the following procedure is usually followed: Hot wire voltage:
Deflection scanning voltage:
Cathode or modulation electrode voltage:
Other grid voltages;
Anode electric jade.
2.2.2 Input the test signal to make an image appear on the display tube screen. 2.2.3 Before testing, the display tube should be fully degaussed. 2.2.4 Cut off the blue beam and green beam (diagonal arrangement electron gun) or side beam (inline arrangement electron gun). Use a single beam scanning grating and adjust the color purity magnet (with the help of microscope observation) to make the corresponding single color appear in the center of the thin screen. Submerge the tube axis to move the deflection coil to obtain the best color purity, then turn on the other two electron beams respectively, and fine-tune the deflection line and color purity magnet to make the three single colors have the best color purity. 2.2.5 Input the dot grid signal or comprehensive test pattern. Adjust the electrode voltage to make the electron beam focus best at 1/1 to 3/1 away from the edge on the long axis of the screen.
2.2.6 Adjust the static convergence magnet to make the red, green and blue electron beams in the center of the screen have the best convergence. 2.2.7 Adjust the dynamic convergence to make the full screen converge to the maximum. Re-adjust the convergence as described in 2.2.6. (Check with the help of a microscope). At the center of the screen, the registration should be adjusted to the best state. 2.2.8 Adjust the center position of the grating to make it consistent with the geometric center of the fluorescent screen as much as possible, and adjust the horizontal and vertical scanning linearity. At the same time, adjust the size of the light shed to the specified effective surface size. 2.2.9 After working for 15 minutes at the specified anode current, repeat the procedures of 2.2.4 to 2.2.8 above to obtain the best convergence and color purity at the same time.
2.3 White field balance adjustment procedure
2.3.1 Adjust the white field balance under the specified brightness and chromaticity. 2.3.1.1 Visual method
Adjust the display tube according to 2.2
Visually compare the display tube with the standard white field, and adjust the three-beam current of the display tube until the white field of the tube is at least the same as the standard white field.
2.3.1.2 Instrument method
Measure the brightness and chromaticity of the center of the display tube screen with a photometer or colorimeter, and adjust the three-beam current of the display tube: make the brightness and chromaticity of the center of the screen reach the specified value.
GB/T 15427- 94
2.3.2 Adjust the white field balance under the specified three-beam total current. The display tube is adjusted according to 2.2.
Under the specified three-beam total current, adjust the three-beam current ratio to the specified chromaticity. 3 Photoelectric parameter test
3. 1 Gas-content factor3. 1.1 Definition
The ratio of ion current to the electron current that causes it. 3.1.2 Test procedure
Connect the display tube to the circuit according to the detailed specifications. Apply the specified negative voltage to the electrode that collects the ion current. The second grid and the electrode connected to it are applied with a sufficiently high positive voltage (about 250V) to cause gas ionization. The modulator voltage is adjusted so that the cathode current reaches a specified value (usually hundreds of microamperes). After the ion collector is connected to the power supply, the sum of the ion current and the leakage current is read as quickly as possible with a small damping instrument. The modulator voltage is adjusted to cut off the cathode current, and the leakage current is read. The gas inclusion factor G is calculated according to the following formula:
Where: I1——the sum of the ion current and the leakage current, μA; I,——the current, μA;
I——the cathode current, mA.
The actual value of the gas inclusion factor is partly determined by the electrode structure of the display tube. Different types of display tubes may give different G values, although the absolute gas pressure may be the same in each case. 3.2 Cathode starting time 3.2.1 Definition
The time required for the cathode current to reach a specified percentage of the cathode current measured at the end of a specified time period under specified operating conditions.
3.2.2 Test procedure
Before the test, the display tube should be left at room temperature for at least 1 hour. According to the provisions of the detailed specifications, voltage is applied to each electrode of the display tube, scanning is started, the hot wire circuit is closed, and the relationship between cathode current and time is recorded (see Figure 1). From the moment the hot wire circuit is closed until the cathode current reaches the specified time. The time required for the specified percentage (e.g. 80%) of the cathode current measured at that time is the cathode start-up time t. The three cathodes should be tested separately.
In the test circuit, the indicating instrument should have low damping characteristics. The internal resistance of the hot wire power supply should be much smaller than the cold resistance of the hot wire. To prevent burns, a line frequency asynchronous pulse (e.g., a pulse duty cycle of 0.1) can be added between the cathode and the modulator. 11-
GB/T 15427—94
Endurance,5
3.3 Cathode heating timecathode heating time3.3.1 is the time required for the cathode current to reach the specified value under the specified working conditions. 3.3.2 Test procedure
Before the test, the display tube should be left at room temperature for at least 1 ht
According to the detailed specifications, apply voltage to each electrode of the display tube, start scanning, close the hot wire circuit, and the time recording device measures the time required from the moment the hot wire voltage is applied until the cathode current reaches the specified value 1, the time required (see Figure 2) The three cathodes should be tested separately,
In the test circuit, the indicating instrument should have low damping characteristics. The internal resistance of the hot wire power supply is much smaller than the cold resistance of the hot wire. To prevent burns, a line frequency asynchronous pulse (for example, a pulse convex-to-space ratio of 0.1) can be added between the cathode and the modulating electrode. +
Time, s
3.4 Electrode leakage current 3.4.1 Definition
Conduction current flowing between two or more electrodes in any way (except the current flowing through the vacuum gap between the electrodes). 3.4.2 Leakage current between hot wire and cathode
3.4.2.1 Test procedure
GB/T 15427-94
The specified voltage is applied to the hot wire of the display tube. The absolute value of the voltage between the cathodes at any part of the hot wire at any moment should not be lower than the specified limit value. No voltage is applied to other electrodes. At this time, the current meter in the loop reads the leakage current between the hot wire and the cathode. 3.4.3 Leakage current between cathodes
3.4.3.1 Test procedure
The specified voltage is applied to the hot wire of the display tube. The specified voltage is applied between one cathode and the other two cathodes. No voltage is applied to other electrodes. At this time, the current meter in the loop reads the leakage current between cathodes. The three cathodes should be tested separately.
3.4.4 Leakage current of each grid
3.4.4.1 Test procedure
According to the provisions of the detailed specifications, voltage is applied to each middle electrode of the display tube, and the cathode or modulation electrode voltage is adjusted to fully cut off the cathode current. At this time, the corresponding grid leakage current is read out by the current sink meter in each grid circuit (at this time, the ion current etc. contained can be ignored). 3.4.5 Anode leakage current
3.4.5.1 Test procedure
According to the provisions of the detailed specification, apply voltage to each electrode of the display tube, adjust the cathode or modulation electrode voltage, make the cathode current fully cut off, and at the same time, the focusing electrode is grounded. At this time, the anode leakage current is read out by the current meter in the anode circuit. 3.5 Electrode current
3.5.1 Anode leakage current anadccurrcnt for white light output3. 5. 1. 1 Definition
The sum of the red, green and blue anode currents required for the white light output with the specified color (degree) coordinates and brightness provided by the center of the screen under the conditions of the best focusing voltage and the white full-screen luminous light size meeting the specified effective screen size. 3.5.1.2 Test procedure
The display tube shall be adjusted according to 2.2 and 2.3 so that the center of the screen reaches the specified chromaticity and brightness. At this time, measure the total current of the three electron beams on the anode, that is, the anode current of the white field light output. 3-5.2 Current ratios for white field 3.5.2.1 Definition
The anode current generated by the self-field light output, the barrier current ratios of red to green, red to blue and blue to green: 3.5.2.2 Test procedure
Measure the red, green and blue electron beam currents respectively as described in Section 3.5.1, and calculate the corresponding current ratios according to formulas (2) to (4): Red field current (IR)
Green field current I
Red field current (InR)
Blue field current (2
Blue field current (I)
Green field current 16)
3.5.3 Grid current grid crremt
3. 5. 3. 1 Definition
The current flowing through each grid circuit under specified working conditions. 3.5.3.2 Test procedure
The display tube is adjusted according to 2.2. The current flowing through each cathode path is measured at the specified chromaticity and brightness. 3.6 Cathode emission
(3)
3.6.1 Definition
GB/T 15427
Electron emission from the cathode under specified working conditions. 3.6.2 Test procedure
The display tube is adjusted according to 2.2, and then the cathode and the grid are at the same potential. At this time, measure the current in the cathode circuit. The three cathodes should be tested separately.
Verification: ① The measurement time should be less than 103 to avoid burning of the anode and the phosphor screen; ② During the measurement, the other two cathodes are in the cut-off state. 3.7 Strayemissian
3.7.1 Definition
An unwanted and uncontrolled electron emission. 3.7.2 Test Procedure
Apply positive voltage to the electrodes of the display tube as specified in the detailed specification (the anode voltage is the maximum limit value). Unless otherwise specified, the cathode or modulator voltage shall be adjusted to cut off the electron beam by means of horizontal line strokes. Observe the screen for visible excitation due to parasitic emission within the specified time.
If specified in the detailed specification, a tuning fork-shaped mallet covered with rubber shall be used and tapped against the neck of the tube for the specified time. Unless otherwise specified, four taps per second shall be made. During the tapping of the neck of the tube, the high voltage supply may be switched on and off. Within the specified time after the first tap on the display tube, observe the screen for visible excitation due to parasitic emission. During the measurement, the ambient light illumination on the screen shall not exceed 51x. The observer's vision shall be adapted to observe the screen. Suitable wood is shown in Figure 3.
Rubber tube
Image pulse E.3*6.3×11
3.8 Flashover
3.8. 1 Definition
Multilayer liquid plywood
Rubber support, 4
Tight spring in the hand
9.51.×35
Solid wood forced
Foundation teacher + rod
GB/T1542794
An uncontrolled discharge between any two or more elements of an electron tube: 3. 8. 2 Test procedure
Method A
According to the provisions of the detailed specification, apply voltage to each electrode of the display tube (the anode voltage is the maximum limit value), adopt the specified scanning method, adjust the cathode or modulation electrode voltage to cut off the electron beam or make the grating size and brightness (or beam current) on the fluorescent screen reach the specified value. Within the specified time, observe the screen for flicker and grating jitter caused by inter-electrode discharge, and record the number of flashovers. If specified in the detailed specification, a rubber-covered sound-shaped stick should be used to tap the tube neck within the specified time. Unless otherwise specified, tap four times per second. The ultra-high voltage power supply can be connected and disconnected during the tapping of the tube neck. Observe and record the number of flashovers within 5 seconds after the first tapping of the display tube and within 15 seconds after the tapping stops. Suitable hammers are shown in Figure 3.
During the measurement, the ambient light illumination on the screen should not exceed 51x. The observer's vision should be adapted to observe the screen. : Method B
Apply voltage to each electrode of the display tube as specified in the detailed specification (the anode voltage is the maximum limit value). The circuit should include the specified impedance of the electrode circuit and a counting device suitable for counting the voltage pulses and current pulses formed in the electrode circuit as a result of flashover. Using the specified scanning mode, adjust the cathode or modulating electrode voltage to cut off the electron beam or make the brightness (or beam current) reach the specified value, and the number of flashovers is recorded by the counting device within the specified time. The characteristics of the counting device (input impedance, sensitivity, time interval between consecutive pulses) shall meet the requirements. 3.9 Heater-cathode voltage resistant 3.9.1 Meaning
The ability of the hot wire and cathode to withstand voltage when the hot wire voltage is the maximum limit value under the condition of cathode emission cut-off. 3.9.2 Test procedure
According to the provisions of the detailed specification, apply voltage to the hot wire of the display tube and between the hot wire and the cathode (the hot wire voltage is the maximum limit value; the voltage applied between the hot wire and the cathode should make the absolute value of the cathode voltage at any point of the hot wire at any moment not less than the specified limit value). Adjust the cathode and modulate the voltage to fully cut off the cathode current and maintain it for 1 min. At this time, check whether the hot wire and the cathode are broken down by the short-circuit indicator or other instruments in the circuit.
Change the polarity of the voltage applied between the hot wire and the cathode and repeat the above procedure. 3.10 cut-off voltage
3. 10.1 Definition
Under specified working conditions, the voltage on the cathode or modulator when the focused light spot (or bright line) that has been deflected just disappears. 3.10.2 Test procedure
According to the detailed specifications, apply voltage to each electrode of the display tube, adjust the cathode or modulator voltage, make the focused light spot (or bright line) on the screen just disappear, and measure the voltage on the cathode or modulator at this time. The three cathodes should be tested separately
When measuring, the ambient light illumination on the screen should be less than 1Ix. The observer's vision should be adapted to observe the screen. The cut-off voltage can also be replaced by the cathode or modulator voltage measured at a specified low beam current (typical value is (.1μA). When measuring, the beam current and leakage current should be distinguished. The ratio of the maximum value to the minimum value of the cut-off voltage of the three electron guns measured above is the cut-off voltage ratio. 3.11 Effective screen size useful scrcrn dimcnsians3. 11. 1 Definition
The size of the luminous part of the screen that can be seen when observing along the tube axis. 3.11-2 Test procedure
The display tube is adjusted according to Article 2.2. Under the condition of convex field overscan, the projection size of the luminous part is measured with a measuring tool facing the screen. The measurement results should give the maximum height, maximum width and maximum diagonal size. 3.12 Panel and screen defects
3.12. 1 Definition
Panel defect faceplateblemish
GB/T 15427—94
Glass defects on the effective screen. For cathode ray tubes with protruding screens after installation, panel defects may extend to the non-effective visible part of the panel.
Screen blemish
Fluorescent screen defects other than panel defects appearing on the effective screen under working or non-working conditions: 3.12.2 Test procedure
The display tube operates as described in 3.5.1, and the screen defects under red, green, blue and white fields are observed at a distance of at least 60 cm from the tube screen. During measurement, the ambient light illumination on the fluorescent screen should not exceed 51x. Under non-working conditions, panel defects can be observed under 700~～10001x incandescent light. 3.13 Afterglow time time of persistencc3- 13. 1 Definition
The time from the moment the excitation stops to the moment the brightness drops to a specified percentage of the starting value. 3.13.2 Modulation Pulse Modulation Method
3.13.2.1 Test Equipment
Put a photomultiplier tube with a specified spectral response into a dark box and place it in front of the display tube screen. Unless otherwise specified in the detailed specification, the minimum distance between the tube surface and the cathode of the photomultiplier tube is 50 mm. Send the output signal of the photomultiplier tube to an oscilloscope to display the attenuation characteristics. The oscilloscope should have an oscilloscope with sufficient bandwidth to accommodate very short afterglow phosphors and a sufficiently long scanning duration when displaying long afterglow phosphors. 3.13.2.2 Test Procedure
Apply voltages to the electrodes of the display tube as specified in the detailed specification and produce the specified display. Apply rectangular voltage pulses to the cathode or modulator voltage to drive the display tube from overcut excitation to the specified excitation state and adjust it to the best focus.
Short-circuit the output of the photomultiplier tube and adjust the beam trace of the oscilloscope to a suitable reference level. Short-circuit the output of the photomultiplier tube and adjust the power supply of the photomultiplier tube and the gain of the amplifier to obtain a full screen deflection on the oscilloscope display.
Adjust the trigger knob of the oscilloscope so that the time base scan starts just before the end of the modulation pulse. Then display and (or> record the decay characteristics.
Note:
. To avoid phosphor burns, care should be taken to prevent excessive current density from bombarding the phosphor screen. b: If it is necessary to read at a very small percentage of peak brightness, it is allowed to use a logarithmic amplifier or increase the gain of the amplifier by a known factor). In this case, it must be ensured that the time base trigger level of the oscilloscope is not affected. 3.13.3 Pulse Line Method
3.13.3.1 Test Apparatus
A photomultiplier tube of the specified spectral response is placed in a dark box in front of the display screen. Unless otherwise specified in the detail specification, a minimum distance of 50 mm is allowed between the tube face and the cathode of the photomultiplier tube. The output signal of the photomultiplier tube is fed to an oscilloscope to display the decay characteristics. The oscilloscope shall have an amplifier with sufficient bandwidth to accommodate very short-persistence phosphors and a sufficient scan duration when displaying long-persistence phosphors. 3.13.3.2 Test Procedure
Apply voltages to the electrodes of the display tube as specified in the detail specification and display a pulse line of specified length, duration and repetition rate.
A slit plate with the specified width is placed in front of the screen so that the slit is at right angles to the scan line and only a small part of the pulse line is visible.
GB/T 1542794
Short-circuit the output of the photomultiplier tube and adjust the beam trace of the oscilloscope to the appropriate zero reference voltage. Remove the short circuit of the output of the photomultiplier tube and adjust the voltage of the photomultiplier tube and the gain of the amplifier to obtain a full-screen deflection on the oscilloscope display.
Adjust the trigger knob of the oscilloscope so that the time base scan starts just before the end of the modulation pulse, and then display and (or) record the decay characteristics.
Note:
Day. To avoid phosphor burns, care should be taken to prevent excessive current density from bombarding the phosphor screen. h. If it is necessary to read at a very small percentage of peak brightness, it is allowed to use a logarithmic amplifier or increase the gain of the amplifier (the multiple is known). In this case, it must be ensured that the time base trigger level of the oscilloscope is not affected. c. The slit width and scanning speed should be such that the time required for the light spot to sweep through the slit is shorter than the measured afterglow. 3.13.4 Grating attenuation method (applicable to long afterglow fluorescent screen) 3.13.4.1 Schematic diagram of test equipment
The schematic diagram of the test equipment is shown in Figure 4.
Measurement
Indicating instrument
Reverse receiver
The tube to be tested and the photometer (calibrated for measuring luminous intensity) are placed in a dark room or placed together in a light-proof container. S is the distance between the display tube screen and the photosensitive surface of the photometer. The output of the photometer is inversely proportional to the square of S. S is generally about five times the length of the diagonal line, and the measurement accuracy is 1%.
Another method is to place a photometer of known diameter (calibrated relative to a Lambertian light source) close to the fluorescent screen to measure the brightness. Unless otherwise specified in the detailed specification, the spectral response of the photometer shall be calibrated in advance with the spectral luminous efficiency of bright vision. 3.13.4.2 Test procedure
Apply voltage to each pole of the display tube as specified in the detailed specification and display a grating of specified size and specified focusing conditions. Adjust the cathode or modulator voltage so that the brightness of the phosphor screen reaches the specified value. Unless otherwise specified, the display tube operates under this condition. Adjust the cathode or modulator voltage so that the display tube is cut off and record the time for the phosphor brightness to decay to the specified value. 3.14 Resolution
3.14. 1 Definition
The ability to distinguish light and dark details in an image. 3.14.2 Character generation card method
3.14.2.1 Schematic diagram of test equipment
The schematic diagram of the test equipment is shown in Figure 5.
Character generator
GB/T 15427—94
Standard amplifier
1 Broadcast generator
Fern test kidney
The character generator generates the specified dot matrix or character signal and sends it to the scanning generator and video amplifier. The output signal of the video amplifier is added to the cathode or modulation electrode of the display tube. At this time, the display tube displays the corresponding dot matrix or character. 3.14.2.2 Test procedure
The display tube is adjusted according to Article 2.2. The character signal is added to the cathode or modulation electrode of the display tube so that the brightness of the brightest part of the dot matrix or character reaches the specified value. Adjust the focusing electrode voltage so that the dot matrix and characters at the center and edge of the fluorescent screen are best focused. The resolution of red, green, blue and white fields should be measured separately. During measurement, the ambient light illumination on the fluorescent screen should not exceed 5Ix. The observer's vision should be adapted to observe the fluorescent screen. Method A (applicable to character display)
Display standard characters and observe the screen at a clear visual distance. Change the size and number of characters until they are just distinguishable to obtain the maximum character capacity that can distinguish the full screen.
Method B (applicable to dot matrix display)
Display standard dot matrix and observe the screen at a clear visual distance. Change the dot matrix density until it is just distinguishable to obtain the maximum display capacity that can distinguish the full screen. The display capacity is the number of bright spots in the horizontal direction (m) multiplied by the number of bright spots in the vertical direction (n). 3.14.3 Test pattern signal method
3.14.3.1 Test procedure
The display tube is set to 2.2. Add the specified test pattern signal to the cathode or modulation electrode so that the brightness on the test pattern reaches the specified value. Adjust the focusing electrode voltage so that the resolution at the center and edge of the fluorescent screen is optimal. At this time: measure the resolution of the red, green, blue and white fields at the center and edge of the screen respectively. During measurement, the ambient light illumination on the fluorescent screen should not exceed 51x. The observer's vision should be adapted to observe the fluorescent screen. 3.14.4 Slit method (applicable to line width or spot diameter) 3.14.4.1 Schematic diagram of test equipment
The schematic diagram of the test equipment is shown in Figure 6.
The test tube
GB/T 15427-94
Micro-light ratio
Field lens
Filter and
Light detector
The micro-light meter consists of an objective lens, a diaphragm, a field lens, a filter and a light detector installed in a dark box. The recording device
displays a light spot or beam trace of the specified brightness (or beam current) on the display tube and is imaged onto the aperture through the objective lens or diaphragm. The transmitted light is collected by a photodetector through a suitable field lens and the output of the photodetector is fed to a suitable measuring instrument. Unless otherwise specified in the detailed specification, the spectral response of the microphotometer shall be calibrated in advance with the spectral luminous efficiency of photopic vision. The distance between the objective lens and the aperture is fixed to give a known objective magnification M. The optical axis of the microphotometer shall be perpendicular to the face plate of the tube under test and the microphotometer shall be movable along its optical axis so that the objective lens images the image on the aperture. The aperture shall consist of an opaque black substrate with a single or two rectangular or circular holes on it: the effective diameter or width of the holes shall not be greater than 20% of the actual specified line width or spot diameter. Alternatively, the spot or beam trace may be linearly swept across the tube surface. 3.14.4.2 Test procedure
Apply voltage to the electrodes of the display tube as specified in the detailed specification and display the best focused beam trace or light spot. According to one of the following methods, make the image cross the small hole, record the maximum output of the photodetector, and calculate the line width or spot diameter according to the corresponding formula: Method A (using a fixed single-hole aperture): Observe the display waveform containing a single-peak distribution on the oscilloscope. Measure the distance S1 between the horizontal coordinates at the specified percentage of the maximum value recorded by the photodetector output. Calculate the line width 6 or the spot diameter d by formula (5): b or d=Ks,
Where: K
The calibration coefficient of the X deflection of the oscilloscope relative to the scanning deflection of the measured tube. Method B (using an oscilloscope with two small holes): Observe the display waveform containing a double-peak distribution with a spacing of S on the oscilloscope, and measure S on one peak waveform (see method A). Then measure S2 and calculate the line width b or the spot diameter d by formula (6): b or d-
Where: S is the distance between the two small holes.
Method (using a fixed double-aperture diaphragm and a single-aperture diaphragm of known size):.(5)
Use a fixed double-aperture diaphragm and a single-aperture diaphragm of known size to trace the double-peak and single-peak electron beam intensity distribution curves by a pen-type recorder.
Measure and calculate the line width or spot diameter from the double-peak and single-peak electron beam brightness distribution curves according to the specified peak value brightness percentage. Calculate the line width or spot diameter d by formula (7): Where: L—the spacing of the known fixed double-aperture diaphragm. 3.14.5 Array scanning method
3.14.5.1 Schematic diagram of test equipment
The schematic diagram of the test equipment is shown in Figure 7.
GB/T15427-94
b or d-
Microphotometer
Measured
Photoelectric detection element array
Scanning reading circuit
Gauge
Counting machine
Recording device
The microphotometer consists of an objective lens placed in a dark box, an array of photoelectric detection elements and an amplifier. The photoelectric detection element can be a photodiode, an electrically coupled device or other devices.
Unless otherwise specified in the detailed specification, the spectral response of the microphotometer should be calibrated in advance with the spectral luminous efficiency of bright vision. 3.14.5.2 Test procedure
Use a test pattern of black and white stripes with known spatial period value instead of the tube to be tested to calibrate the test system. Adjust the reading of the computer so that the measured period value displayed by it is the same as the actual period value of the test pattern. Install the display tube into the specified deflection coil assembly and adjust it according to 2.2. Display a beam trace of specified brightness (or beam current) at the specified position of the fluorescent screen, and adjust the focusing electrode voltage to make the beam trace focus optimally. Move the microphotometer along the normal direction of the screen of the measured tube to image the beam trace on the array of photoelectric detection elements, and the beam trace image should be perpendicular to the array of photoelectric detection elements.
The scanning reading circuit reads the output of each photoelectric detection element in turn, and sends it to the computer after amplification, so that the beam trace brightness distribution graph can be displayed on the monitor (or recording device). Through the computer software, the beam trace brightness distribution can be quickly Fourier transform to obtain the modulation transfer function (the relationship between modulation and spatial frequency) curve of the measured beam trace. From this, the spatial frequency under the specified modulation or the resolution represented by the modulation under the specified spatial frequency can be obtained. The resolution of red, green, blue and white fields at the center and edge of the screen should be measured respectively. 3.14.6 Spatial frequency method
3.14.6.1 Schematic diagram of test equipment
The schematic diagram of the test equipment is shown in Figure 8.1 Schematic diagram of test equipment
The schematic diagram of the test equipment is shown in Figure 7.
GB/T15427-94
b or d-
Microphotometer
Measuredwww.bzxz.net
Photoelectric detection element array
Scanning reading circuit
Gauge
Counter
Recording device
The microphotometer consists of an objective lens placed in a dark box, an array of photoelectric detection elements and an amplifier. The photoelectric detection element can be a photodiode, an electrically coupled device or other devices.
Unless otherwise specified in the detailed specification, the spectral response of the microphotometer should be calibrated in advance with the spectral luminous efficiency of bright vision. 3.14.5.2 Test procedure
Use a test pattern of black and white stripes with a known spatial period value instead of the measured tube to calibrate the test system. Adjust the reading of the computer so that the measured period value displayed is the same as the actual period value of the test chart. Install the display tube into the specified deflection coil assembly and adjust it according to 2.2. Display a beam trace of specified brightness (or beam current) at the specified position of the fluorescent screen, and adjust the focusing electrode voltage to make the beam trace focus optimally. Move the microphotometer along the normal direction of the screen of the tube under test so that the beam trace is imaged on the array of photoelectric detection elements, and the beam trace image should be perpendicular to the array of photoelectric detection elements.
The scanning reading circuit reads the output of each photoelectric detection element in turn and sends it to the computer after amplification, so that the beam trace brightness distribution graph can be displayed on the monitor (or recording device). Through the computer software, the beam trace brightness distribution can be quickly Fourier transform to obtain the modulation transfer function (the relationship between modulation degree and spatial frequency) curve of the measured beam trace. From this, the spatial frequency under the specified modulation degree or the resolution represented by the modulation degree under the specified spatial frequency can be obtained. The resolution of red, green, blue and white fields at the center and edge of the screen should be measured respectively. 3.14.6 Spatial frequency method
3.14.6.1 Schematic diagram of test equipment
The schematic diagram of the test equipment is shown in Figure 8.1 Schematic diagram of test equipment
The schematic diagram of the test equipment is shown in Figure 7.
GB/T15427-94
b or d-
Microphotometer
Measured
Photoelectric detection element array
Scanning reading circuit
Gauge
Counter
Recording device
The microphotometer consists of an objective lens placed in a dark box, an array of photoelectric detection elements and an amplifier. The photoelectric detection element can be a photodiode, an electrically coupled device or other devices.
Unless otherwise specified in the detailed specification, the spectral response of the microphotometer should be calibrated in advance with the spectral luminous efficiency of bright vision. 3.14.5.2 Test procedure
Use a test pattern of black and white stripes with a known spatial period value instead of the measured tube to calibrate the test system. Adjust the reading of the computer so that the measured period value displayed is the same as the actual period value of the test chart. Install the display tube into the specified deflection coil assembly and adjust it according to 2.2. Display a beam trace of specified brightness (or beam current) at the specified position of the fluorescent screen, and adjust the focusing electrode voltage to make the beam trace focus optimally. Move the microphotometer along the normal direction of the screen of the tube under test so that the beam trace is imaged on the array of photoelectric detection elements, and the beam trace image should be perpendicular to the array of photoelectric detection elements.
The scanning reading circuit reads the output of each photoelectric detection element in turn and sends it to the computer after amplification, so that the beam trace brightness distribution graph can be displayed on the monitor (or recording device). Through the computer software, the beam trace brightness distribution can be quickly Fourier transform to obtain the modulation transfer function (the relationship between modulation degree and spatial frequency) curve of the measured beam trace. From this, the spatial frequency under the specified modulation degree or the resolution represented by the modulation degree under the specified spatial frequency can be obtained. The resolution of red, green, blue and white fields at the center and edge of the screen should be measured respectively. 3.14.6 Spatial frequency method
3.14.6.1 Schematic diagram of test equipment
The schematic diagram of the test equipment is shown in Figure 8.
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