JP2845906B2 - Apparatus and method for measuring color purity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] A deflection yoke and a magnet (2P, 4P, 6
P) Attach, adjust purity, convergence,
It relates to the quantification of adjustment work, and quantifies visual work.

[Conventional technology]

A conventional device is disclosed in Japanese Patent Application Laid-Open No.
The CPT and raster signals are projected by the TV camera, the arbitrary detection position is set symmetrically from the center of the screen, the sample and hold is performed during the horizontal scanning period, and the hold value is made equal between the left and right sides to achieve balance. The technical scope is limited to color stripe CRTs with stripes, and also the work. Extensive means for moving the deflection yoke was required. At the time, there was no dot-type CDT on the market.

[Problems to be solved by the invention]

The above-described prior art is suitable for a color CRT having a work adjustment allowance of 1.0-3.0 mm, and has a stripe (T
V tube) and was unsuitable for dot-line CDT.

An object of the present invention is to provide an evaluation method and an apparatus capable of evaluating color purity without adjusting a deflection yoke or a 2P magnet.

[Means for solving the problem]

In order to achieve the above object, according to a first aspect of the present invention (claim 1), a beam spot is formed on a phosphor dot at a predetermined position on a tube surface of a display tube by an excitation magnetic field by feeding an excitation coil. In a color purity measuring method for moving in a first direction and a second direction substantially perpendicular to the first direction, measuring the light emission amount of the phosphor dots by the beam spot, and determining the color purity of the display tube, Light emission amount (first light emission amount) of the phosphor dots in a state (first state) before switching the power supply direction of the excitation coil in the moving state in the first direction.
And the light emission amount (second light emission amount) in the state after the power supply direction switching (second state) is detected as a voltage value and compared, and a state in which the two values are equal is determined in the moving state in the first direction. A light emitting amount (third light emitting amount) of the phosphor dots in a state before the power supply direction switching of the exciting coil (third state) in the just-landing state and in the moving state in the second direction; The light emission amount (fourth light emission amount) in the state after the power supply direction switching (fourth state) is detected as a voltage value and compared, and a state in which both values are equal is justified in the movement state in the second direction. Landing state, a state that satisfies the above both just landing is a complete color purity state,
The color purity is evaluated based on a value obtained by multiplying a value obtained by subtracting 1 from the ratio of the light emission amount of the phosphor dots before and after switching the power supply direction of the excitation coil by a mislanding coefficient.

Further, in the second invention (claim 3), at a predetermined position on the tube surface of the display tube, a beam spot is formed on the phosphor dot by the excitation magnetic field supplied to the excitation coil in the first direction and the first direction. In a second direction substantially perpendicular to the direction, and measuring the amount of light emitted from the phosphor dots by the beam spot to determine the color purity of the display tube. The light emission amount (first light emission amount) of the phosphor dot before the power supply direction switching of the excitation coil (first state) and the light emission amount (second state) after the power supply direction switching (second state) Second light emission amount),
In the moving state in the second direction, the light emission amount (third light emission amount) of the phosphor dots in a state before the power supply direction switching of the excitation coil (third state) and a state after the power supply direction switching. Detecting means for respectively detecting the light emission amount (fourth light emission amount) in the (fourth state) as a voltage; storage means for storing the detected voltages; and a moving state in the first direction. A state in which the voltage values are equal before and after switching the power supply direction of the excitation coil is defined as a just-landing state in the movement state in the first direction, and a power supply direction of the excitation coil in the movement state in the second direction. A state in which the voltage values are equal before and after the switching is a just-landing state in the moving state in the second direction, and a state satisfying both the just-landings is a state of perfect color purity. Means for evaluating color purity by a value obtained by multiplying a value obtained by subtracting 1 from the ratio of the voltage value before and after the power supply direction switching of the excitation coil by a mislanding coefficient. .

[Action]

As shown in FIG. 2, a magnetic field is generated in the vertical and horizontal directions by the excitation circuit 3 and the beam passing through the mask is determined, pushed and bent, and the landing state of the remaining beam is inscribed by the beam and the tendency dot. In order to further prevent the occurrence of other color hits, the amount of incident light is detected by a photodiode via a color filter of the corresponding color.

In addition, an alternating magnetic field is generated in the exciting coil during the blanking period of the exciting to demagnetize the mask 10, thereby improving the repeatable measurement accuracy.

Since the above can be miniaturized, it can be set at a local position of the CDT, adjusted, and evaluated.

〔Example〕

FIG. 1 shows an outline of the present invention. Attached to the neck 15 of CDT1. When adjusting the deflection yoke 2 to a perfect state of purity, the fluorescent dots, red 12, green 1
3, each electron beam 7, 8, 9 passed through the hole 11 of the shadow mask 10 so as to be concentric with the blue 14, crossed horizontally on the hole 11, and each fluorescent dot 12, 13, A state in which each of the fluorescent dots emits 100% light upon hitting 14 is called just-landing. It is sufficient if this just-landing can be obtained on the entire surface of the tube surface 16 or 1, but mis-landing is exhibited by fine adjustment of the deflection yoke 2 due to a CDT manufacturing error, that is, an exposure error.
FIG. 1 is a conceptual diagram in which this state is measured by the purity measuring device 3.

FIG. 2 shows the sensor section of the present invention, which is the content of 3 shown in FIG. The electron beams 7, 8, and 9 hit on the fluorescent dot surface 16 emit fluorescent dots 12, 13, and 14 in each of the colors. The color filters 17 (green) are installed on the surface of the CDT1. ), A photodiode 18 having a spectral characteristic matching the wavelength receives an incident light amount corresponding to the emission of the fluorescent dot. At this time, positive and negative exciting currents are intermittently passed through the exciting coils 19 and 20, thereby connecting the ferromagnetic core elements 19-a, 19-b, 20-a, connected to the exciting coil iron core.
By 20-b, the electron beams 7, 8, 9 are shaken, that is, ± 5
By generating magnetic forces 21 and 22 for wobbling by 0 mm, the beam is bent by a fixed amount over the mask 10. As a result, the light emission amounts of the fluorescent dots 12, 13, and 14 change, and the short-circuit current Isc of the photodiode 18 changes in proportion.

Purity is quantitatively evaluated from the amount of change.

further. In order to improve the repetition accuracy, the mask 10 is magnetized by switching the excitation. Therefore, blanking during the excitation period is used in the excitation coils 19 and 20 to supply an alternating magnetic field to perform demagnetization.

As shown in FIG. 3 (C), the excitation current vertically flows iy23 and the horizontal current ix24 flow sequentially, respectively.
Connect the current drivers 25, 26 to the respective excitation coils 20-a, 20
-B, 19-a, and 19-b, thereby obtaining the same amount of magnetic fields 22, 21 in the positive 30 and negative 31 directions.
(B) The exciting current shown in 33 flows, and the incident light amount HV38 is input to the photodiode 18 via the color filter, and the operation amplifier 30 connected to the photodiode 18 through which the corresponding short-circuit current Isc27 flows, OPEAMP), the product of the feedback resistor R28
The voltage conversion output Vout29 is obtained by the following equation: Vout = Isc · R (1)

After Vout29 is read, alternating magnetic fields 36 and 37 are generated, but in each wobbling direction, the initial maximum starting magnetic field
V is generated in ± as 34 and 35 and demagnetized after 5 to 7 cycles.

FIG. 4 shows a time chart of excitation and demagnetization of the present invention. FIG. 5 shows a hardware configuration of the present apparatus showing an embodiment.
FIG. 4 shows the time 50 on the horizontal axis and the voltage level in the vertical direction.

Based on the command from the CPU 67, the output peripheral interface is abbreviated as PIA. ) Based on the data amount loaded on 71,72, and converted to analog amount via D / A converters 74,75,
The DC voltage passes through low-pass filters 76 and 77 and is input to current drivers 25 and 26, where the excitation currents ix23 and iy
24, is output. The current drivers 25, 26
Excitation current is applied to the excitation coils 19 and 20 in the positive direction 32 and the negative direction 33.

At the same time, discharge switcher TRS63 turns on the input light quantity charge charged in capacitor 62 of peak hold circuit 56.
After discharging and discharging, wait for the time when the electron beam is stably bent, that is, 34 msec of the delay dime Dt40, and during this time, input the converter pulse 43 from the output PIA85 to the A / D converter 64 with the peak-held voltage, and convert the converted data. Enter
Latch to PIA65. The CPU 67 stores this in the RAM 68.
When the storage is completed, an alternating magnetic field 34 is generated and demagnetized for demagnetization of the mask. Then negative (-) direction flows an exciting current, measures the amount of input light in the same manner, CPU 67 stores the data to RAM 68, + an A / D conversion value Vout ₁ 46 in the forward direction 34 in the negative direction excitation
The A / D conversion value Vout ₂ 48 is compared and calculated, and data is displayed on the display monitor 70.

[{(Vout ₁ / Vout ₂ ) × 100} −100] × α (2) Expression α: Correlation coefficient with eye measurement is about 3 μm. Ask for.

When Vout ₁ = Vout ₂ , 100% is displayed. And just strike.

Similarly, after the positive and negative measurements in the horizontal direction, the positive and negative directions in the vertical direction are measured.

After the voltage Vout obtained from the input light amount current Isc27 of FIG. 5 by P28 is input to the common noise canceller circuit 83 and obtained as the output of the operational amplifier 55. High-speed peak hold circuit 58
The set pulse 39, which is charged in the capacitor C62, A / D-converted and stored in the RAM 68, is used to repeat the peak-held voltage and discharge it in advance when measuring.

FIG. 6 shows a state in which the fluorescent dots 13 and the beam 8 are just-landed when a green raster signal is input. At this time, the red dots 12 and the blue dots 14 do not emit light.

In this embodiment, the dot pitch 87 of the CDT indicates 0.31 mm.

 In other words, it indicates a condition that should be purity.

FIG. 7 (a) shows a green landing similarly, but the beam 8 is inscribed in the dot 13 and the dot 13
Although 0% light is emitted, blue dots 14 and red dots 12 exhibiting mislanding due to a change in geomagnetism do not emit light because the signal is turned off.

FIG. 7B shows a mislanding, in which the beam 8 emits only the dots 13 -G, and the area of the dots 13 -D shows a dot break. In (C), the beam 8 exhibits a large mislanding, causing the green dots 13-G to emit light and at the same time slightly emitting the blue dots 14-G to be in a state of other colors.

According to the conventional method, if the left and right sides of the screen are balanced even in such a state, it is regarded as just landing.

FIGS. 8 and 9 illustrate this embodiment more specifically. As shown in FIG. 8 (a), in order to obtain concentric circles between the dot 13 and the beam 8, (b) shows a state where the beam 8 is shaken downward, and (C) shows a state where it is shaken upward (b). when the light emission amount Vout ₁ = Vout ₂ of (C) is obtained (a).
FIG. 9 is an explanatory diagram in the case where the left and right sides are similarly considered.

FIG. 10 shows a simple embodiment in which the measuring instrument 3 is installed at arbitrary positions of the CDT 1 and the deflection yoke is automatically adjusted by controlling the motor 87 and the motor driver 88 in accordance with the algorithm described above.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, since the just-running of a beam can be measured accurately and there is no fear of magnetization by excitation, there is an effect of improving the reliability of repeated measurement.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an embodiment of the present invention, FIG. 2 is a diagram showing the arrangement of a wobbling control and a detector in the embodiment, and FIG. 3 is a diagram showing a relationship between a photodiode and a short-circuit current in a detailed explanation of detection. , FIG. 4 is a time chart of measurement and degaussing, FIG. 5 is an explanatory diagram of hardware of this embodiment, FIG. 6 and FIG.
The figure explains the principle of purity and the conventional limitations.
FIG. 9 and FIG. 9 are explanatory diagrams of a specific operation of this embodiment, and FIG. 10 is an explanatory diagram of another embodiment of the automatic purity adjustment. 1 ... CDT, 2 ... Dy, 3 ... Detector, 19,20 ... Exciting coil, 18 ... Sensor photodiode, 30 ... Detection opeA
mp, 83… Common noise canceller Amp, 56… peak hold circuit, 64… A / D converter, 67… CPU, 78…
Programmable excitation generator.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takeshi Hirayama 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Pref. Yokohama Plant, Hitachi, Ltd. (56) References JP-A-64-7456 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) H01J 9/44 H04N 17/04

Claims (3)

(57) [Claims] At a predetermined position on a display tube surface of a display tube, a beam spot is formed on a phosphor dot by a excitation magnetic field supplied to an excitation coil in a first direction and a second direction substantially perpendicular to the first direction. In a color purity measuring method for measuring the light emission amount of the phosphor dots by the beam spot and determining the color purity of the display tube, wherein the power supply of the excitation coil is performed in a state where the beam spot is moved in the first direction. Light emission amount (first light emission amount) of the phosphor dot in a state before the direction switching (first state)
And the light emission amount (second light emission amount) in the state after the power supply direction switching (second state) is detected as a voltage value and compared, and a state in which the two values are equal is determined in the moving state in the first direction. A light emitting amount (third light emitting amount) of the phosphor dots in a state before the power supply direction switching of the exciting coil (third state) in the just-landing state and in the moving state in the second direction; The light emission amount (fourth light emission amount) in the state after the power supply direction switching (fourth state) is detected as a voltage value and compared, and a state in which both values are equal is justified in the movement state in the second direction. Landing state, a state that satisfies the above both just landing is a complete color purity state,
The color purity is evaluated based on a value obtained by multiplying a value obtained by subtracting 1 from a ratio of the voltage value corresponding to the light emission amount of the phosphor dot before and after switching the power supply direction of the excitation coil to a mislanding coefficient. A method for measuring color purity, characterized in that: 2. The color purity measuring method according to claim 1, wherein AC power is supplied to said exciting coil in advance for each of said power supply operations, so that a magnetic substance in a magnetic field is demagnetized. 3. A beam spot for a phosphor dot at a predetermined position on a tube surface of a display tube, and a second direction substantially perpendicular to the first direction and a second direction substantially perpendicular to the first direction by an excitation magnetic field supplied to an excitation coil. In a color purity measuring apparatus for measuring the amount of light emitted from the phosphor dots by the beam spot to determine the color purity of the display tube, wherein the power supply direction of the exciting coil is switched in the moving state in the first direction. A light emitting amount (first light emitting amount) of the phosphor dot in a previous state (first state), a light emitting amount (second light emitting amount) in a state (second state) after power supply direction switching, In the moving state in the second direction, the light emission amount (third light emission amount) of the phosphor dots in a state before the power supply direction switching of the excitation coil (third state) and a state after the power supply direction switching. (The fourth Detecting means for detecting the light emission amount (fourth light emission amount) of each of the states (state) as a voltage, storage means for storing the detected voltages, and the exciting coil in the moving state in the first direction. The state in which the voltage values are equal before and after the switching of the power supply direction is referred to as a just-landing state in the movement state in the first direction, and the state before and after the power supply direction switching of the exciting coil in the movement state in the second direction. A state in which the voltage values are equal is referred to as a just-landing state in the movement state in the second direction, a state in which both the just-landings are satisfied is referred to as a complete color purity state, and the state of the voltage value before and after switching the power supply direction of the excitation coil is referred to. Means for evaluating color purity by a value obtained by multiplying a value obtained by subtracting 1 from the ratio by a mislanding coefficient, and Color purity measurement apparatus according to symptoms.