JPS5853546B2 - Brown Kankidokensa Souchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathode ray tube brightness inspection device that measures the brightness at each point on a cathode ray tube screen and outputs whether the brightness is within a certain range.

In general, a cathode ray tube brightness inspection device is particularly needed in the adjustment and inspection process at a cathode ray tube manufacturing factory.

Conventionally, this type of adjustment and inspection process was performed by a large number of skilled people.

For this reason, there were many problems, such as the boundary between good and defective cathode ray tubes, which varied depending on the person conducting the inspection and the country in which the inspection took place.

An object of the present invention is to realize a cathode ray tube brightness inspection device with a simple configuration that is effective for use in the above-mentioned fields.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a configuration explanatory diagram showing an embodiment of the cathode ray tube brightness inspection device of the present invention.

In the figure, reference numeral 1 denotes a cathode ray tube, which has a cathode ray tube screen 11 (hereinafter simply referred to as screen 11) to be inspected for brightness on its front surface.

2 is a hood that transmits only light from the screen 11 to a light sensor 31 (described later).
It is intended to be given to

3 is a photodetector that measures the brightness of the screen 11.

This photodetector 3 is comprised of a photosensor 31 attached to the hole 21 of the hood 2 and an amplification circuit 32 that amplifies the output of this photosensor 31.

Reference numeral 4 denotes a control circuit which sends a scanning signal to the cathode ray tube 1 to produce a constant image on the screen 11, for example, a solid white image.

Furthermore, to explain the above-mentioned constant image in detail, if it is a normal cathode ray tube, it is an image whose entire surface has uniform brightness. It is.

In addition, this control circuit 4 is configured to perform a
A blanking signal C is output to indicate when a brightness test is not required.

In other words, to explain the concept of a blanking signal using one specific example, in normal cathode ray tube scanning,
The scanning bright spot moves, for example, from the left end to the right end on the cathode ray tube screen, disappears once it reaches the right end, and then reappears at the left end of the cathode ray tube.

Since the bright spot has disappeared from the cathode ray tube until it reappears at the left end, the brightness cannot be measured correctly during that period.

Therefore, in order to prevent the above-mentioned situation, a blanking signal C is output when the brightness is outside the inspection range.

Reference numeral 5 denotes an electric circuit which receives the output signal a of the photodetector 2 and the blanking signal C from the control circuit.

In this electric circuit 5, 51 and 52 are comparators whose respective threshold values are El and E2 (E2>El), and which receive the output signal a of the photodetector 3 as input.

53 is an exclusive OR gate which receives the output signals d and e of the comparators 51 and 52, 54 is an inverter which receives the output signal of the exclusive OR gate 53, and 55 is the output signal of the inverter 54. f and the blanking signal C from the control circuit 4 as inputs.
It is a gate.

Further, 6 is an output terminal for taking out the output signal g of the AND gate 55.

The operation of the embodiment apparatus configured as described above will be explained with reference to FIG.

On the screen 11 of the fluoroun tube 1, a light spot created by an electron beam runs on a predetermined scanning line.

Therefore, if we pay attention to a short period of time, only one light spot exists on the screen 11.

Now, considering this short time, the light emitted from the light spot on the screen 11 passes through the inside of the hood 2 and reaches the optical sensor 31.

Therefore, the photodetector 3 outputs a signal a as shown in FIG. 2A, which corresponds to the brightness of the light spot.

Here, as the comparators 51 and 52, the threshold value El
, a high level signal (
(hereinafter simply referred to as "1"), and thresholds El and E2 are output.
If a device that outputs a low level signal (hereinafter simply referred to as 0'') in response to a smaller input signal is used, the comparators 51 and 52 that receive the signal a will output signals as shown in Figure 2 and C, respectively. Signals d and e are sent to exclusive-or gate 53.

Therefore, the output signal f of the inverter 54 as shown in FIG. 2 is applied to one input terminal of the AND gate 55.

The control circuit 4 sends an image signal to the cathode ray tube 1, causes a light spot by an electron beam to run on a predetermined scanning line of the screen 11, and when this light spot is on the part of the screen 11 to be inspected for brightness, it outputs "1". A signal C shown in FIG.

Therefore, a signal g as shown in FIG. 2 appears at the output terminal 6.

This signal g has a signal a having a magnitude corresponding to the brightness of each light spot, and thresholds El and E2 of comparators 51 and 52.
When it is between the two, it indicates O'', and when it is smaller than El or larger than E2, it indicates 1''.

Therefore, in order to correspond to the upper and lower limits of the permissible brightness variation at each point of the brightness inspected portion of the screen 11,
By selecting the threshold values El and E2 of the comparators 51 and 52, it is possible to determine whether the cathode ray tube 1 is good or defective based on whether the signal g is "1".

Although cathode ray tubes usually have afterglow properties, the present invention is not affected by this afterglow properties.

The reason is as follows. The scanning speed of a cathode ray tube varies depending on the cathode ray tube, but it is usually 1
The scanning time for one screen is about 60 μs, and the scanning time for one screen is 30 msec.

On the other hand, the response speed of the optical sensor 31 can be sufficiently fast compared to these times, for example, 5
A response speed of 0 nse@ can be easily obtained.

Therefore, the scanning bright spot can be captured by the optical sensor as a single point.

In a cathode ray tube with such a scanning speed, if the afterimage time is long, there will be a corresponding measurement error in the brightness of the bright spot, but normally the brightness of the afterimage is sufficiently low compared to the brightness of the bright spot. Since the afterglow spreads over a wide range, no matter where the scanning bright spot is located on the cathode ray tube, the amount of light input to the optical sensor due to the afterglow is constant.

Therefore, the threshold value E1. If the value of E2 is shifted by the amount of the component due to afterglow, it will not be affected by this afterglow.

FIG. 3 shows another embodiment of the cathode ray tube luminance measuring device of the present invention (the same parts as in FIG. 1 are given the same reference numerals).

In this embodiment, the condenser lens 7 is connected to the screen 11 and the optical sensor 31.
In addition, the optical sensor 31 is located near the focal point of the condensing lens 7.

With this configuration, of the light emitted from the light spot on the screen 11, only the light parallel to the optical axis of the condenser lens 7 reaches the optical sensor 31.

Therefore, inspection can be performed with higher accuracy than the apparatus of the embodiment shown in FIG.

Further, the integrating circuit 8 integrates the output signal a of the photodetector 3 for a time specified by the signal from the control circuit 4, and calculates the overall brightness of the area scanned within this integration time. It is outputted to the output terminal 9 as a signal i.

This signal also includes a signal that temporarily suspends the integrating operation of the integrating circuit 8 when a brightness test is not required.

In addition, in the above two embodiment devices, the comparator 5
1, 52, an exclusive-OR gate 53, an inverter 54, and an AND gate 55, various other circuits are possible.

That is, the electric circuit 5 may have any configuration as long as it discriminates the output signal a of the photodetector 3 only when the brightness test indicated by the blanking signal C is not required.

As explained above, the device of the present invention includes a photodetector that measures the brightness of a light spot on the screen, a control circuit that generates a blanking signal, and a control circuit that measures the brightness of the light spot on the screen in relation to the blanking signal. It has a simple configuration consisting of an electric circuit that outputs a signal corresponding to the

Further, according to the present invention, there is no need to use a plurality of optical sensors, so that variations among optical sensor elements do not affect the accuracy of the apparatus, and reproducible inspection can be performed.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing one embodiment of the cathode ray tube brightness inspection apparatus of the present invention, FIG. 2 is an explanatory diagram of the operation of the apparatus of the embodiment shown in FIG. FIG. 2 is a configuration explanatory diagram showing an example. 1... Braun tube, 11... Braun tube screen to be inspected for brightness, 2... Hood, 21...
... Hole, 3... Photodetector, 31...
Optical sensor, 32...Amplification circuit, 4...
Control circuit, 5... Electric circuit, 6, 9...
・Output terminal, 7...Condensing lens, 8...
・Integrator circuit.

Claims (1)

[Scope of Claims] 1. A device for inspecting whether the brightness of a cathode ray tube screen is within a set value, comprising: a photodetector that outputs an electrical signal a corresponding to the brightness of the cathode ray tube screen to be inspected; and to the cathode ray tube. a control circuit that transmits a scanning signal and outputs a blanking signal C indicating when a bright spot is out of the scanning area, inputs the blanking signal C and the electric signal a, and sets the brightness. an electric circuit having thresholds El and E2 corresponding to the values, and when there is an electric signal a that falls outside of the thresholds El and E2 except for the section where the blanking signal C is output; A cathode ray tube brightness inspection device that outputs a signal g to that effect.