This standard specifies the technical requirements, test methods, quality assessment procedures and marking, packaging, transportation and storage of black and white monitors. This standard applies to all types of black and white monitors that conform to the current television system in my country and use cathode ray tubes as display devices. This standard is the basis for black and white monitor manufacturers to formulate product standards, and is also the rule to be followed in product design, manufacturing and inspection. GB/T 14858-1993 General Technical Requirements for Black and White Monitors GB/T14858-1993 Standard Download Decompression Password: www.bzxz.net

National Standard of the People's Republic of China
GB/T14858—1993
General Specification for Black-White Monitors
General Specification for Black-White Monitors1993-12-30 Issued
State Administration of Technical Supervision
1994-09-01 Implementation
National Standard of the People's Republic of China
General Specification for Black-White Monitors
General Specification for Black-White Monitors1 Subject Content and Scope of Application
GB/T14858—1993
This standard specifies the technical requirements, test methods, quality assessment procedures and marking, packaging, transportation and storage of black-white monitors. This standard applies to all types of black-white monitors that use cathode ray tubes as display devices in accordance with the current television system in my country. This standard is the basis for black-white monitor manufacturers to formulate product standards, and is also the rule that should be followed in product design, manufacturing and inspection. 2 Reference standards
GB1385
GB2828
GB2829
GB3174
GB3659
GB9372
GB9380
Packaging storage and transportation pictorial signs
Black and white television broadcasting standards
Batch inspection counting sampling procedures and sampling tables (applicable to continuous batch inspection) Periodic inspection counting sampling procedures and sampling tables (applicable to manual production process stability inspection) Color television broadcasting
TV video channel test Method
Measurement method for television broadcast receiver
Packaging of color television broadcast receiver
GB9384
Environmental test requirements and test methods for broadcasting radios, broadcasting television receivers, tape recorders, audio power amplifiers (amplifiers)
GB12322
GB14861
3 Terminology
Reliability test method for general-purpose applied television equipment Safety requirements and test methods for applied television equipment 3.1 Composite signal standard range compositesignal standard range a.
Blanking level (reference level): 0V
Peak white level: 0.7V±20mV;
Difference between black level and blanking level, 0V±50mV; c.
Synchronization pulse level: 0.3V±9mV.
3.2 Standard image standardpicture
Send a standard amplitude full television signal with a three white and two black vertical stripes to the input interface of a black and white monitor. Under normal working conditions, adjust the brightness and contrast knobs of the monitor to make the white stripe brightness 80cd/m2 and the black stripe height 2cd/m2. Such an image is called a standard image.
4 Product classification and test conditions
4.1 Classification
Approved by the State Administration of Technical Supervision on December 30, 1993 and implemented on September 1, 1994
GB/T14858—1993
According to the quality level and scope of use, black and white monitors are divided into general application level and broadcast level. Application-level black and white monitors are mainly used in non-broadcasting and television systems. The quality level and functional requirements are general. Broadcast-level black and white monitors are mainly used in broadcasting and television systems. The quality level is higher and the functional requirements are more. 4.2 Test conditions
Temperature: 15~35℃,
Degrees of humidity: 45%~75%;
Atmospheric pressure: 86~106kPa;
Power supply voltage: 220±6.6V;
Power supply frequency: 50±1Hz.
5 Technical requirements and measurement methods
5.1 General requirements
5.1.1 Requirements
Black and white monitors should have video signal input interfaces, video output interfaces and external synchronization signal input interfaces, input impedance (759/high impedance) and internal and external synchronization conversion switches. The appearance of black and white monitors should be neat. There should be no obvious dents, scratches, cracks, deformations, etc. on the surface. The surface coating should not bubble, crack or fall off, and the metal parts should not be rusted or have other mechanical damage. The operation of switches, buttons and knobs should be flexible and reliable, the parts should be fastened without looseness, the installation of the picture tube should match the chassis without obvious gaps, and the whole machine should have sufficient mechanical stability. The text and graphic symbols that describe the functions should be clear, correct and firm. The indicators should be correct.
5.1.2 Inspection method
Inspect by visual inspection.
5.2 Electrical and optical performance
The electrical and optical performance of the black and white monitor shall comply with the requirements of Table 1Table 1
Performance requirements
Basic parameters
Input signal amplitude (75Q input impedance)
External synchronization signal amplitude (75Q input impedance)Image aspect ratio1)
Image reproduction rate
Center offset rate
Not less than
Not greater than
Broadcast level
Positive polarity
Negative polarity
Universal type| |tt||Application level
Positive polarity
Negative polarity
Measurement method
(this standard)
Article 5.3.1.2
Article 5.3.2.2
Article 5.3.3.2
Article 5.3.4.2
Article 5.3.4.2
Full screen maximum brightness 2
Brightness identification level
Horizontal resolution
Grating geometric distortion
Basic parameters
Scanning nonlinear distortion| |tt||Synchronization range
Line lead-in range
Line hold range
Field synchronization range
Interlacing ratio
Anode high voltage stability
Channel video response
—3dB
Channel linear waveform response
Channel DC component distortion
Input impedance
Large area contrast
Grating modulation interference
GB/T14858—1993
Continued Table 1
Not less than|| tt||Not less than
Not less than
Not more than
Not less than
Not less than
Not less than
Not less than
Not less than
Not less than
Not less than
Not less than
Not less than
Not less than
The power supply voltage variation range to maintain image stability is not inferior to the power supply power consumption
Note: 1) The allowable range of image aspect ratio is consistent with the allowable range of grating geometric distortion. 2) 80cd/m2 for above 43cm.
3) Specified by product standards for below 18cm.
5.3 Measurement of electrical and optical performance
5.3.1 Input signal amplitude and polarity
5.3.1.1 Definition
Video signal amplitude to ensure black self-monitor image quality. Full television signal has positive polarity with the sync head pointing downward. 5.3.1.2 Measurement method
Broadcast level
Center 800
Four corners 500
15625±200
15625±400
75±5%
General type
Application level
Center 600
15625±200
15625±400
75±5%
Not obvious
Not obvious
Product standard regulations
The measurement block diagram is shown in Figure 1. The deflection direction of the oscilloscope used to measure the signal amplitude and polarity is known. Measurement method
(this standard)
Article 5.3.5.2
Article 5.3.6.2
Article 5.3.7.2
Article 5.3.8.2
Article 5.3.9.2
Article 5.3.10.2
Article 5.3.11.2
Article 5.3.12.2| |tt||5.3.13.2 items
5.3.14.2 items
5.3.15.2 items
5.3.16.2 items
5 .3.17.2 Articles
5.3.18.2 Articles
5.3.19.2 Articles
5.3.20.2 Articles
5.3.21.1
Multiple signal generator
GB/T14858—1993
Monitoring circuit
Display reader
Use a signal generator with adjustable output amplitude to send a ten-step full television signal to the black-and-white monitor. Under the condition of ensuring the image quality, the full television signal range added to the input end is the amplitude range of the input signal of the black-and-white monitor. The power supply must be turned on and off several times to check the image quality.
5.3.2 External synchronization signal amplitude and polarity
5.3.2.1 Definition
The external synchronization signal amplitude that makes the black-and-white monitor image complete and stable. The synchronization signal is negative when the synchronization pulse is downward. 5.3.2.2 Measurement method
The measurement block diagram is the same as Figure 1.
After the monitor obtains the standard image, send the negative polarity composite synchronization signal of the signal generator to the monitor's "synchronization input" interface, and at the same time turn the monitor's synchronization selection switch from "inside" to "outside" to adjust the amplitude of the composite synchronization signal of the signal generator. Under the condition of ensuring the integrity and stability of the image, the variation range of the added composite synchronization signal is the amplitude range of the external synchronization signal. 5.3.3 Image Aspect Ratio
5.3.3.1 Definition
The ratio of the width and height of the image.
5.3.3.2 Measurement Method
The measurement block diagram is the same as Figure 1.
After the monitor obtains the standard image, switch to the standard amplitude 16×12 grid chessboard signal, and measure the ratio of the width and height of a 12×9 grid rectangle (1612 grids for broadcast level) composed of complete grids on the screen, which passes through the geometric center of the fluorescent screen. 5.3.4 Image relevance and center shift rate
5.3.4.1 Definition
The monitor's ability to reproduce the total effective image of the applied signal. The degree of deviation of the image center from the geometric center of the screen. 5.3.4.2 Measurement method
The measurement block diagram is the same as Figure 1.
After the monitor obtains the standard image, it switches into a standard amplitude chessboard signal. When the image is full screen, the ratio of the number of squares in the horizontal and vertical directions passing through the geometric center of the screen to the corresponding number of squares in the signal (including incomplete grids) is measured, which is the image reproducibility. The percentage of the ratio of the distance between the image center and the geometric center of the screen to the nominal diagonal size of the cathode ray tube is the center shift rate. 5.3.5 Full screen maximum brightness
5.3.5.1 Definition
When the monitor reproduces a full white signal, when the line structure of area A of the screen is distinguishable, the maximum brightness value of area A is measured. 5.3.5.2 Measurement method
The measurement block diagram is shown in Figure 2. The measurement is carried out in a dark room. 4
GB/T14858—1993
Monitor
The illumination in the dark room should be less than 5lx, and the brightness of the fluorescent screen should be less than 0.2cd/m when the monitor is not working. The measurement personnel wear black work clothes. The monitor sends a full white field signal of standard amplitude, adjusts the brightness and contrast, and when the line structure of area A of the fluorescent screen is just indistinguishable, the maximum brightness of the center of the fluorescent screen is measured by a brightness meter, which is the maximum brightness of the full screen. Note: Area A refers to a circular area with the center of the screen as the center and 80% of the screen height as the diameter. 5.3.6 Brightness identification level
5.3.6.1 Definition
The brightness level that can be distinguished between the blackest and the whitest images. 5.3.6.2 Measurement method
The measurement block diagram is the same as Figure 2.
The monitor is fed with a standard amplitude ten-step signal, and the brightness and contrast knobs are adjusted so that the ratio of the brightness of the brightest area to the darkest area is 25:1. The number of distinguishable gray levels observed by visual inspection is the brightness discrimination level. 5.3.7 Horizontal resolution
5.3.7.1 Definition
The ability of the human eye to distinguish image details in the horizontal direction is usually expressed in terms of the number of television lines. 5.3.7.2 Measurement method
The measurement block diagram is the same as Figure 1.
After the black-and-white monitor obtains the standard image, it is replaced with a standard amplitude single-frequency sine wave signal. The sine wave frequency when the vertical thin strips cannot be distinguished at the center and four corners of the grating is Z (the center and four corners can be viewed with a magnifying glass). The horizontal resolution M is calculated using the following formula. M=ZX80
Where: Z is the frequency of the sine wave that just cannot distinguish vertical thin strips, and MHz is also required to be confirmed with a 0.07Vp single-frequency sine wave for broadcast-grade black-and-white monitors. (1)
Note: The four corners of the grating refer to the circular area with the four vertices of a rectangle symmetrical to the symmetry axis of the fluorescent screen as the center and 25% of the height of the fluorescent screen as the diameter. The width of the rectangle is 75% of the width of the fluorescent screen, and the height is 67% of the height of the fluorescent screen. 5.3.8 Grating geometric distortion
5.3.8.1 Definition
The deviation of the outline of the image relative to the quadrilateral formed by the four corners of the outline. Distortion and barrel distortion.
5.3.8.2 Measurement method
The measurement block diagram is the same as Figure 1.
can be generally divided into parallelogram distortion, trapezoidal distortion, and pincushion distortion. After the monitor obtains the standard image, it sends a grid signal instead, and uses the outermost contour of the image composed of a complete grid to measure the geometric distortion. The points at the four corners of the contour are A, B, C, and D, as shown in Figure 3. The maximum offset of the contour line entering the inner side of the straight line AB is a1, and the maximum offset exceeding the outer side is a2. The offsets of the other three sides are b1b2, C1, C2, d1, and d2 respectively. 5
The geometric distortion is calculated according to the following formula:
Horizontal trapezoidal distortion T
Vertical trapezoidal distortion T
Parallelogram distortion P
Upper pincushion distortion CH
Upper barrel distortion B
Lower pincushion distortion CH
Lower barrel distortion Ba
GB/T14858—1993
AD+BC×100%
AD+BC×100%
AD+BC×100%
Ba,= ADBC ​​× 100%
........(3)
+*+**+*****-(4)
…(5)
·（6）
·（7）
Left pincushion distortion Cv
Left barrel distortion BVLeft
j: Right pincushion distortion Cv
Right barrel distortion Bv
5.3.9 Scanning nonlinear distortion
5.3.9.1 Definition
GB/T14858—1993
×100%
·（9）
?（10）
·（12）
On the section through the center of the image, along the horizontal or vertical direction, the percentage of the ratio of the maximum deviation of the electron beam forward scanning at each point to the average speed.
5.3.9.2 Measurement method
The measurement block diagram is the same as Figure 1.
After the monitor obtains the standard image, it switches to the chessboard or grid signal. The number of horizontal grids of the signal is not less than 16, and the number of vertical grids is not less than 12. The width of the two adjacent widest squares in the horizontal direction is recorded as Lmx. The width of the two adjacent narrowest squares is recorded as Lmin. The horizontal scanning nonlinear distortion K is calculated as follows: a.
where; K'—distortion of the widest grid width
K\——distortion of the narrowest grid width,
Lm×100%
mail×100%
·(14)
LM——twice the average grid width. LM=2L/n, L is the image size of a complete horizontal grid, and n is the number of grids in a complete horizontal grid. b. The measurement and calculation method of vertical scanning nonlinear distortion is the same as that of horizontal scanning nonlinear distortion. 5.3.10 Synchronization range
5.3.10.1 Definition
The frequency range in which the synchronization signal can control the scanning circuit. It includes the hold range and the lead-in range. 5.3.10.2 Measurement method
GB/T14858—1993
The measurement block diagram is shown in Figure 4. Before measurement, the black and white monitor's line (field) self-oscillation frequency should be adjusted as close to the nominal value as possible. Monitor
5.3.10.2.1 Lead-in range measurement
or level learning+
Starting from the point where the monitor's line (field) frequency loses synchronization, adjust the signal generator's line (field) frequency point by point toward the synchronization point. Each time the input signal or line (field) synchronization signal is disconnected and then connected, the line (field) synchronization frequency range in which the image can still synchronize itself is the line (field) synchronization lead-in range.
2 Hold range measurement
5.3.10.2.2
After the monitor obtains the standard image, switch to the chessboard signal. Change the signal generator's line (field) frequency to the high and low ends until the image has synchronization defects. The change in the signal generator's line (field) frequency is the line (field) synchronization hold range. 5.3.11 Interlacing ratio
5.3.11.1 Definition
The degree to which each scanning line deviates from uniform mosaic in interlaced scanning 5.3.11.2 Measurement method
The measurement block diagram is the same as Figure 1.
The monitor sends a checkerboard signal of standard amplitude, and measures the distance between any scanning line and two adjacent scanning lines belonging to another field in a certain frame of scanning, which is expressed as a percentage of the distance between two adjacent scanning lines in the same field. The measurement is carried out at several points on the fluorescent screen and observed with a magnifying glass with a ruler, as shown in Figure 5.
Interlaced ratio 40:60
5.3.12 Anode high voltage stability
5.3.12.1 Definition
The percentage of anode high voltage change caused by grating brightness change. 5.3.12.2 Measurement method
GB/T14858—1993
The measurement block diagram is shown in Figure 6. The measurement should be carried out in a dark room with an illumination lower than 51x. The screen brightness when the monitor is not working should be less than 0.2cd/m2.
Central generator
Monitor
Static high stop
The monitor is fed with a full white field signal of standard amplitude. Adjust the brightness and contrast knobs, and use a brightness meter to measure the screen brightness to the full-screen maximum brightness rating. Note the anode high voltage value E at this time. Adjust the brightness and contrast knobs, and use a brightness meter to measure the screen brightness to 1.0% of the maximum brightness rating. Note the anode high voltage value EM at this time. The change rate V of the anode high voltage is calculated as follows: _2(Bm-Bm) × 100%
EHM+Em
5.3.13 Channel video response
5.3.13.1 Definition
The amplification capability of the video channel for signals of different frequencies. 5.3.13.2 Measurement method
The measurement block diagram is the same as Figure 1.
·（15）
After the monitor obtains the standard image, replace the standard amplitude scanning signal and use the oscilloscope to observe the output waveform on the modulation pole of the picture tube (the probe of the oscilloscope should not affect the frequency response). Take the 1MHz response amplitude as the benchmark (0dB). When the oscilloscope used directly observes the swept frequency signal, the high-frequency drop should not exceed 5%. 5.3.14 Channel linear waveform response
5.3.14.1 Definition
When the test signal with limited spectrum is sent to the black and white monitor, the waveform distortion caused by the imperfect amplitude-frequency characteristic and phase-frequency characteristic of the video channel. Including:
a. Line frequency square wave signal response Kb,
b. Field frequency square wave response K50.
5.3.14.2 Measurement method
The measurement block diagram is the same as Figure 1.
5.3.14.2.1 Response of horizontal frequency square wave signal Kb After the monitor obtains the standard image, the standard amplitude 15kHz square wave signal is switched in. The waveform on the modulation pole is observed by an oscilloscope as shown in Figure 7a. The half amplitude points of the step signal are m1 and m2, and the values ​​measured from A and B at the midpoint of the black level and the white level are b. From the two points at the half amplitude of each step H/100 (H is the horizontal period), the top inclination of the square wave is measured to be a, and the K coefficient is: K=×100%
（16）
H one horizontal period
5.3.14.2.2 Response of vertical frequency square wave K50.
GB/T14858—1993
JH/140
V—vertical period
After the monitor obtains the standard image, the standard amplitude 50Hz square wave signal is switched in. The waveform viewed by the oscilloscope on the modulation pole of the picture tube is shown in Figure 7b. A and B are the centers of the bottom and top of the field frequency square wave response waveform, respectively, and their amplitudes are recorded as b; the top surface inclination is measured to be a1 and the bottom surface inclination is a2 between the two points m1 and m2 which are V/100 (V is the field period) away from each step half amplitude point, then the field frequency square wave response K5o coefficient is: a1+42×100%
5.3.15 Channel DC component distortion
5.3.15.1 Definition
When the image content changes, the level corresponding to the black level of the signal on the modulation pole of the picture tube changes. 5.3.15.2 Measurement method
The measurement block diagram is the same as Figure 1.
·(17)
After the monitor obtains the standard image, it switches to the full black field and full white field signals in turn (the full white field signal should have a reference black level area with a width not exceeding 10% of the effective line period). Observe the modulation pole of the picture tube with an oscilloscope, and measure the black level value of the full black field signal as u1; measure the black level value of the full white field signal as u2 and the white level value as 3. The DC component distortion of the channel n is calculated as follows: X100%
5.3.16 Input impedance
5.3.16.1 Definition
The equivalent impedance seen from the input end of the monitor. 5.3.16.2 Measurement method
5.3.16.2.1 Impedance bridge method
The measurement block diagram is shown in Figure 8. The monitor is in 75Q termination state. 10
...**....**....(18)
GB/T14858—1993
The black-and-white monitor is in normal working condition. Sine wave signals of different frequencies are respectively input into the passband of the video channel, and the equivalent impedance of each frequency point is measured, expressed in ohms. 5.3.16.2.2 Reflection loss method
The measurement block diagram is shown in Figure 9.
New generator
Anti-lebao difficult electronic parts
Monitor
The standard amplitude swept frequency signal generated by the swept frequency signal generator is sent to the terminated black and white monitor through the reflection loss bridge, and the loss bridge output is directly sent to the oscilloscope (without passing through the probe). After the monitor is powered on and starts to work normally, the signal amplitudes at the monitor input interface and the reflection loss bridge output at 7.5MHz (broadcast level is 10MHz) are read from the oscilloscope, and are recorded as A1 and A2 respectively. The reflection coefficient K is calculated according to the following formula:
·（19）
Where: K is the reflection coefficient: (if the reflected signal is of the same polarity as the incident signal, K is positive, and if the reflected signal is of the opposite polarity to the incident signal, K is negative); A1 is the peak-to-peak value of the monitor input interface signal, A2 is the peak-to-peak value of the reflected signal.
The input impedance is calculated as follows (in ohms): Z
(20)
Note: The connecting cable loss from the sweep signal generator to the reflection loss bridge, and from the reflection loss bridge to the monitor and oscilloscope should be less than 0.1dB. Www.bzxZ.net
The impedance bridge method is for arbitration.
5.3.17 Large area contrast
5.3.17.1 Definition
The ratio of the brightness of the white band to the brightness of the black band measured on the monitor screen. 5.3.17.2 Measurement method
The measurement block diagram is the same as Figure 2, and the measurement is carried out in a dark room. After the monitor obtains the standard signal, the contrast is adjusted to the maximum position while ensuring that the signal is not defocused, not limited, and the line structure is clearly visible. Adjust the brightness knob to make the black band brightness 3cd/m. The brightness value of the white band in the center of the measured image is L2, and the brightness of the two adjacent black bands is 11 respectively.2 Measurement method
The measurement block diagram is the same as Figure 1.
·(15)
After the monitor obtains the standard image, replace the standard amplitude scanning signal and use the oscilloscope to observe the output waveform on the modulation pole of the picture tube (the probe of the oscilloscope should not affect the frequency response). Take the 1MHz response amplitude as the reference (0dB). When the oscilloscope used directly observes the sweep signal, the high-frequency drop should not exceed 5%. 5.3.14 Channel linear waveform response
5.3.14.1 Definition
When the test signal with a limited spectrum is sent to the black and white monitor, the waveform distortion caused by the imperfect amplitude-frequency characteristic and phase-frequency characteristic of the video channel. Including:
a. Line frequency square wave signal response Kb,
b. Field frequency square wave response K50.
5.3.14.2 Measurement method
The measurement block diagram is the same as Figure 1.
5.3.14.2.1 Response of horizontal frequency square wave signal Kb After the monitor obtains the standard image, the standard amplitude 15kHz square wave signal is switched in. The waveform on the modulation pole is observed by an oscilloscope as shown in Figure 7a. The half amplitude points of the step signal are m1 and m2, and the values ​​measured from A and B at the midpoint of the black level and the white level are b. From the two points at the half amplitude of each step H/100 (H is the horizontal period), the top inclination of the square wave is measured to be a, and the K coefficient is: K=×100%
（16）
H one horizontal period
5.3.14.2.2 Response of vertical frequency square wave K50.
GB/T14858—1993
JH/140
V—vertical period
After the monitor obtains the standard image, the standard amplitude 50Hz square wave signal is switched in. The waveform viewed by the oscilloscope on the modulation pole of the picture tube is shown in Figure 7b. A and B are the centers of the bottom and top of the field frequency square wave response waveform, respectively, and their amplitudes are recorded as b; the top surface inclination is measured to be a1 and the bottom surface inclination is a2 between the two points m1 and m2 which are V/100 (V is the field period) away from each step half amplitude point, then the field frequency square wave response K5o coefficient is: a1+42×100%
5.3.15 Channel DC component distortion
5.3.15.1 Definition
When the image content changes, the level corresponding to the black level of the signal on the modulation pole of the picture tube changes. 5.3.15.2 Measurement method
The measurement block diagram is the same as Figure 1.
·(17)
After the monitor obtains the standard image, it switches to the full black field and full white field signals in turn (the full white field signal should have a reference black level area with a width not exceeding 10% of the effective line period). Observe the modulation pole of the picture tube with an oscilloscope, and measure the black level value of the full black field signal as u1; measure the black level value of the full white field signal as u2 and the white level value as 3. The DC component distortion of the channel n is calculated as follows: X100%
5.3.16 Input impedance
5.3.16.1 Definition
The equivalent impedance seen from the input end of the monitor. 5.3.16.2 Measurement method
5.3.16.2.1 Impedance bridge method
The measurement block diagram is shown in Figure 8. The monitor is in 75Q termination state. 10
...**....**....(18)
GB/T14858—1993
The black-and-white monitor is in normal working condition. Sine wave signals of different frequencies are respectively input into the passband of the video channel, and the equivalent impedance of each frequency point is measured, expressed in ohms. 5.3.16.2.2 Reflection loss method
The measurement block diagram is shown in Figure 9.
New generator
Anti-lebao difficult electronic parts
Monitor
The standard amplitude swept frequency signal generated by the swept frequency signal generator is sent to the terminated black and white monitor through the reflection loss bridge, and the loss bridge output is directly sent to the oscilloscope (without passing through the probe). After the monitor is powered on and starts to work normally, the signal amplitudes at the monitor input interface and the reflection loss bridge output at 7.5MHz (broadcast level is 10MHz) are read from the oscilloscope, and are recorded as A1 and A2 respectively. The reflection coefficient K is calculated according to the following formula:
·（19）
Where: K is the reflection coefficient: (if the reflected signal is of the same polarity as the incident signal, K is positive, and if the reflected signal is of the opposite polarity to the incident signal, K is negative); A1 is the peak-to-peak value of the monitor input interface signal, and A2 is the peak-to-peak value of the reflected signal.
The input impedance is calculated as follows (in ohms): Z
(20)
Note: The connecting cable loss from the sweep signal generator to the reflection loss bridge, and from the reflection loss bridge to the monitor and oscilloscope should be less than 0.1dB.
The impedance bridge method is for arbitration.
5.3.17 Large area contrast
5.3.17.1 Definition
The ratio of the brightness of the white band to the brightness of the black band measured on the monitor screen. 5.3.17.2 Measurement method
The measurement block diagram is the same as Figure 2, and the measurement is carried out in a dark room. After the monitor obtains the standard signal, the contrast is adjusted to the maximum position while ensuring that the signal is not defocused, not limited, and the line structure is clearly visible. Adjust the brightness knob to make the black band brightness 3cd/m. The brightness value of the white band in the center of the measured image is L2, and the brightness of the two adjacent black bands is 11 respectively.2 Measurement method
The measurement block diagram is the same as Figure 1.
·(15)
After the monitor obtains the standard image, replace the standard amplitude scanning signal and use the oscilloscope to observe the output waveform on the modulation pole of the picture tube (the probe of the oscilloscope should not affect the frequency response). Take the 1MHz response amplitude as the reference (0dB). When the oscilloscope used directly observes the sweep signal, the high-frequency drop should not exceed 5%. 5.3.14 Channel linear waveform response
5.3.14.1 Definition
When the test signal with a limited spectrum is sent to the black and white monitor, the waveform distortion caused by the imperfect amplitude-frequency characteristic and phase-frequency characteristic of the video channel. Including:
a. Line frequency square wave signal response Kb,
b. Field frequency square wave response K50.
5.3.14.2 Measurement method
The measurement block diagram is the same as Figure 1.
5.3.14.2.1 Response of horizontal frequency square wave signal Kb After the monitor obtains the standard image, the standard amplitude 15kHz square wave signal is switched in. The waveform on the modulation pole is observed by an oscilloscope as shown in Figure 7a. The half amplitude points of the step signal are m1 and m2, and the values ​​measured from A and B at the midpoint of the black level and the white level are b. From the two points at the half amplitude of each step H/100 (H is the horizontal period), the top inclination of the square wave is measured to be a, and the K coefficient is: K=×100%
（16）
H one horizontal period
5.3.14.2.2 Response of vertical frequency square wave K50.
GB/T14858—1993
JH/140
V—vertical period
After the monitor obtains the standard image, the standard amplitude 50Hz square wave signal is switched in. The waveform viewed by the oscilloscope on the modulation pole of the picture tube is shown in Figure 7b. A and B are the centers of the bottom and top of the field frequency square wave response waveform, respectively, and their amplitudes are recorded as b; the top surface inclination is measured to be a1 and the bottom surface inclination is a2 between the two points m1 and m2 which are V/100 (V is the field period) away from each step half amplitude point, then the field frequency square wave response K5o coefficient is: a1+42×100%
5.3.15 Channel DC component distortion
5.3.15.1 Definition
When the image content changes, the level corresponding to the black level of the signal on the modulation pole of the picture tube changes. 5.3.15.2 Measurement method
The measurement block diagram is the same as Figure 1.
·(17)
After the monitor obtains the standard image, it switches to the full black field and full white field signals in turn (the full white field signal should have a reference black level area with a width not exceeding 10% of the effective line period). Observe the modulation pole of the picture tube with an oscilloscope, and measure the black level value of the full black field signal as u1; measure the black level value of the full white field signal as u2 and the white level value as 3. The DC component distortion of the channel n is calculated as follows: X100%
5.3.16 Input impedance
5.3.16.1 Definition
The equivalent impedance seen from the input end of the monitor. 5.3.16.2 Measurement method
5.3.16.2.1 Impedance bridge method
The measurement block diagram is shown in Figure 8. The monitor is in 75Q termination state. 10
...**....**....(18)
GB/T14858—1993
The black-and-white monitor is in normal working condition. Sine wave signals of different frequencies are respectively input into the passband of the video channel, and the equivalent impedance of each frequency point is measured, expressed in ohms. 5.3.16.2.2 Reflection loss method
The measurement block diagram is shown in Figure 9.
New generator
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Monitor
The standard amplitude swept frequency signal generated by the swept frequency signal generator is sent to the terminated black and white monitor through the reflection loss bridge, and the loss bridge output is directly sent to the oscilloscope (without passing through the probe). After the monitor is powered on and starts to work normally, the signal amplitudes at the monitor input interface and the reflection loss bridge output at 7.5MHz (broadcast level is 10MHz) are read from the oscilloscope, and are recorded as A1 and A2 respectively. The reflection coefficient K is calculated according to the following formula:
·（19）
Where: K is the reflection coefficient: (if the reflected signal is of the same polarity as the incident signal, K is positive, and if the reflected signal is of the opposite polarity to the incident signal, K is negative); A1 is the peak-to-peak value of the monitor input interface signal, and A2 is the peak-to-peak value of the reflected signal.
The input impedance is calculated as follows (in ohms): Z
(20)
Note: The connecting cable loss from the sweep signal generator to the reflection loss bridge, and from the reflection loss bridge to the monitor and oscilloscope should be less than 0.1dB.
The impedance bridge method is for arbitration.
5.3.17 Large area contrast
5.3.17.1 Definition
The ratio of the brightness of the white band to the brightness of the black band measured on the monitor screen. 5.3.17.2 Measurement method
The measurement block diagram is the same as Figure 2, and the measurement is carried out in a dark room. After the monitor obtains the standard signal, the contrast is adjusted to the maximum position while ensuring that the signal is not defocused, not limited, and the line structure is clearly visible. Adjust the brightness knob to make the black band brightness 3cd/m. The brightness value of the white band in the center of the measured image is L2, and the brightness of the two adjacent black bands is 11 respectively.2. The measurement block diagram of the reflection loss method is shown in Figure 9. The standard amplitude sweep signal generated by the sweep signal generator is sent to the terminated black and white monitor through the reflection loss bridge. The loss bridge output is directly sent to the oscilloscope (without the probe). After the monitor is powered on and works normally, the signal amplitudes at the monitor input interface and the reflection loss bridge output at 7.5MHz (broadcast level at 10MHz) are read from the oscilloscope, which are recorded as A1 and A2 respectively. The reflection coefficient K is calculated as follows: (19) Where: K is the reflection coefficient: (K is positive when the reflected signal is the same polarity as the incident signal and negative when the reflected signal is opposite to the incident signal); A1 is the peak-to-peak value of the monitor input interface signal, and A2 is the peak-to-peak value of the reflected signal.
The input impedance is calculated as follows (in ohms): Z
(20)
Note: The connecting cable loss from the sweep signal generator to the reflection loss bridge, and from the reflection loss bridge to the monitor and oscilloscope should be less than 0.1dB.
The impedance bridge method is for arbitration.
5.3.17 Large area contrast
5.3.17.1 Definition
The ratio of the brightness of the white band to the brightness of the black band measured on the monitor screen. 5.3.17.2 Measurement method
The measurement block diagram is the same as Figure 2, and the measurement is carried out in a dark room. After the monitor obtains the standard signal, the contrast is adjusted to the maximum position while ensuring that the signal is not defocused, not limited, and the line structure is clearly visible. Adjust the brightness knob to make the black band brightness 3cd/m. The brightness value of the white band in the center of the measured image is L2, and the brightness of the two adjacent black bands is 11 respectively.2. The measurement block diagram of the reflection loss method is shown in Figure 9. The standard amplitude sweep signal generated by the sweep signal generator is sent to the terminated black and white monitor through the reflection loss bridge. The loss bridge output is directly sent to the oscilloscope (without the probe). After the monitor is powered on and works normally, the signal amplitudes at the monitor input interface and the reflection loss bridge output at 7.5MHz (broadcast level at 10MHz) are read from the oscilloscope, which are recorded as A1 and A2 respectively. The reflection coefficient K is calculated as follows: (19) Where: K is the reflection coefficient: (K is positive when the reflected signal is the same polarity as the incident signal and negative when the reflected signal is opposite to the incident signal); A1 is the peak-to-peak value of the monitor input interface signal, and A2 is the peak-to-peak value of the reflected signal.
The input impedance is calculated as follows (in ohms): Z
(20)
Note: The connecting cable loss from the sweep signal generator to the reflection loss bridge, and from the reflection loss bridge to the monitor and oscilloscope should be less than 0.1dB.
The impedance bridge method is for arbitration.
5.3.17 Large area contrast
5.3.17.1 Definition
The ratio of the brightness of the white band to the brightness of the black band measured on the monitor screen. 5.3.17.2 Measurement method
The measurement block diagram is the same as Figure 2, and the measurement is carried out in a dark room. After the monitor obtains the standard signal, the contrast is adjusted to the maximum position while ensuring that the signal is not defocused, not limited, and the line structure is clearly visible. Adjust the brightness knob to make the black band brightness 3cd/m. The brightness value of the white band in the center of the measured image is L2, and the brightness of the two adjacent black bands is 11 respectively.
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