JP2002100290A - Gas measurement instrument of cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas measurement instrument which improves measurement precision by reducing measurement variations without causing deterioration in its breakdown voltage characteristic by overcoming the problems of a deterioration in the breakdown voltage characteristic and a lack of a measurement precision due to occurrence of stray emission when measuring residual gas for evaluating vacuum of cathode-ray tube. SOLUTION: In this gas measurement instrument, an automatic tracking circuit 24 is disposed between a cathode 57 and a first grid electrode 58 of a color cathode-ray tube 54, and residual gas is measured by holding a second grid current within 500 uA±1% by the automatic tracking circuit 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas measuring apparatus for a cathode ray tube for measuring a residual gas indicating a degree of vacuum in the tube, which is one of the static characteristics of a cathode ray tube such as a color picture tube manufactured.

[0002]

2. Description of the Related Art At present, a color picture tube generally used for a color television receiver, a color terminal display and the like includes a face panel 41 formed in a substantially rectangular shape as shown in FIG. It has an envelope 43 composed of a funnel 42 connected to the face panel 41. A phosphor screen 44 made of a three-color phosphor layer that emits red, blue, and green light is provided on the inner surface of the effective portion having the curved surface of the face panel 41, and the phosphor screen 44 is provided inside the phosphor screen so as to face the phosphor screen 44. , A shadow mask 46 fixed to the mask frame 45 is arranged.

On the other hand, an electron gun 48 is arranged in a neck 47 of the funnel 42. Then, the three electron beams emitted from the electron gun 48 are deflected by a deflection yoke 49 mounted on the outside of the funnel 42, and the electron beams are selected by a shadow mask 46 to horizontally move the phosphor screen 44. Is configured to display a color image by scanning in the vertical direction.

The electron gun 48 generally has three heaters and a cathode, and is composed of a plurality of electrodes including at least a first grid electrode and a second grid electrode from the cathode toward the phosphor screen 44. The final accelerating electrode includes an anode button 50 provided on a large diameter portion of the funnel 42 and a conductive film 5 provided on the inner surface of the funnel 42 electrically connected to the anode button 50.
A high anode voltage is applied via 1 or the like.

On the other hand, a predetermined voltage lower than the anode voltage is applied to the heater, the cathode, and other electrodes via a plurality of stem pins 53 provided on a stem portion 52 sealing the neck 47, respectively. Thus, the color picture tube 54 is configured.

After the color picture tube 54 is manufactured through a predetermined process, a predetermined voltage is applied to each of the heater, the cathode, and the plurality of selected grid electrodes constituting the electron gun 48, and Measurement of static characteristics such as cut-off voltage, emission characteristics, withstand voltage characteristics, and gas measurement is performed.

For example, in order to keep the inside of the color picture tube 54 at a high vacuum, a gas venting process is performed in an exhausting process during the manufacturing process, and a vacuum state of about 10 ⁻⁶ is obtained, and a gettering process is further performed. As a result, a high vacuum state of about 10 ⁻⁸ is obtained.

However, a trouble in the exhaust cart during the exhaust process, a frit penetration occurring in a process after the exhaust process, or a trouble such as a chip crack causes a slow leak or the like, and air leaks into the color picture tube. In some cases, the degree of vacuum was reduced.

In a color picture tube having a reduced degree of vacuum,
The emission generated from the cathode collides with a large amount of residual gas in the tube and does not reach the surface of the phosphor screen 44, thereby causing a significant decrease in luminance.

[0010] In addition, the cathode is eroded by the residual gas in the tube, and the required emission cannot be emitted. This causes a problem that it is difficult to obtain a prescribed brightness.

The gas measuring apparatus for measuring the residual gas serving as an indicator of the degree of vacuum in the pipe has a circuit as shown in FIG.

That is, in FIG. 5, three heaters 56 to which a predetermined 8 V heater voltage is supplied from the power supply 55 are connected in series to the color picture tube 54 as described above. The cathode 57 is directly grounded, and the first grid electrode 58 to the fifth grid electrode 6
2 electrodes, and the third grid electrode 60 has -25 V
Is supplied from the power supply 63 and the second grid electrode 59
, A voltage of 200 V is supplied from the power supply 64.
Ammeters 65 and 66 are provided in the current flow paths of the second grid electrode 59 and the third grid electrode 60, respectively.

A movable terminal 68 of a changeover switch 67 is connected to the first grid electrode 58, and a variable voltage of -150V to 0V is variably supplied to a first fixed terminal 69 of the changeover switch 67. The power supply 70 is connected, and the second fixed terminal 71 has a cut-off voltage of -150 V
Is configured to be connected to the power supply 72. The variable power supply 70 specifically includes a voltage source and a variable resistor.

The gas measuring device configured as described above
The changeover terminal 68 of the changeover switch 67 is connected to the first fixed terminal 69.
Side and switch the variable power supply 70 to adjust the
The voltage of the first grid electrode 58 is adjusted while checking with the ammeter 65 so that the emission current Ie flowing through the grid electrode 59 becomes the specified value of 1000 μA.

When the emission current Ie flows, the gas remaining in the color picture tube 54 collides with the electrons to be ionized. The ionized positive ions are attracted to the third grid electrode 60 having a negative potential and supplied with a voltage of −25 V from the power supply 63, so that the ion current Ii flows through the third grid electrode 60. Thus, this current is measured by the ammeter 66.

Next, the switching terminal 68 of the changeover switch 67 is switched to the second fixed terminal 71 side so that the first grid electrode 5
8 is switched to be biased at -150 V of the power supply 72, thereby cutting off the color picture tube 54,
The emission current Ie flowing through the grid electrode 59 is cut off.

In this state, the leak current Il flowing through the third grid electrode 60 is measured by the ammeter 66. Using the current values of the emission current Ie, the ion current Ii, and the leak current Il measured by these ammeters 65 and 66,
The gas value can be calculated by calculation from the following formula, that is, GAS = (Ii-Il) / Ie.

By obtaining the gas value in this way, it is used as one index for determining the degree of vacuum.

FIG. 6 shows a specific example of the configuration of the gas measuring device of the gas measuring device shown in FIG.

That is, a pair of rail-shaped or groove-shaped guide rails 81 are laid at the installation location of the gas measuring device.
On this guide rail 81, a wheel 82 that rotates while engaging with the guide rail 81 is attached to a lower surface of a support base 83 formed in a box shape or a frame shape.

A color picture tube 54 is mounted on the upper surface of the support 83, and the anode button 50 and the stem pin 53 of the color picture tube 54 are connected to terminals provided on one side of the support 83 by electric wiring. Each of the plurality of contacts 85 implanted in parallel with the plate 84 is electrically connected.

The contact 85 is connected to the guide rail 81
Feeding wall 86 installed at a predetermined interval along
Power supply rails 8 for supplying predetermined voltages respectively provided in
The power supply rail 87 is connected to a power supply 88.

Accordingly, by moving the support base 83 along the guide rail 81, a predetermined voltage from the power supply 88 is supplied to each power supply rail 87, and the power supply rail 8
A voltage necessary for gas measurement is supplied to necessary electrodes via contacts 85 which are in sliding contact with 7. Although not shown, the above-described ammeters 65 and 66, the variable resistors for the variable power supply 70, and the changeover switch 67 can also be installed on the support base 83.

[0024]

As described above, in the conventional gas measuring device for the color picture tube 54, the emission current I having a large value of 1000 μA as the specified value is used.
e, the ion current Ii corresponding thereto and the leak current Il at the time of cut-off of the color picture tube 54 are measured, and the gas value is calculated from a predetermined formula to determine.

However, the emission current Ie having a large value of 1000 μA flows, and the emission current Ie,
To measure the ion current Ii, as shown in FIG. 7, barium (Ba) 9 released from the cathode 57 is used.
1 is attached to the second grid electrode 59 in a large amount, and becomes an emission source because the electrode surface of the second grid electrode 59 is contaminated. As a result, the withstand voltage characteristic is deteriorated. A so-called stray emission, in which a false electron beam other than the above-mentioned electron beam is generated, easily occurs.

This stray emission is highly likely to occur particularly at the second grid electrode 59, and is assumed to occur most frequently.

The emission current Ie is set by manually adjusting the variable power supply 70 provided on the first grid electrode 58. Therefore, the emission current Ie is set for each color picture tube 54 to be measured. Variations occur, and there is a problem that errors occur in measurement accuracy in parallel with the problem of stray emission.

[0028] For this reason, the defect of the stray emission is increased, and it is necessary to repair many defective color picture tubes 54 since the defective products need to be repaired by a pressure-resistant repair device. Was.

The present invention has been made in response to such a problem, and it is possible to reduce the variation in the setting accuracy of the emission current without deteriorating the withstand voltage characteristic of a cathode ray tube such as a color picture tube, and to improve the accuracy. An object of the present invention is to provide a cathode ray tube gas measuring device capable of measuring a residual gas value.

[0030]

According to the present invention, an adjustable variable power supply is connected to a first grid electrode of a cathode ray tube having a cathode and at least first to third grid electrodes, and the variable power supply is connected to the second grid electrode. An automatic tracking circuit is connected between circuits that can obtain a voltage corresponding to the emission current flowing through the grid electrode, and the variable power supply voltage is controlled by the automatic tracking circuit so that the emission current becomes a specified substantially minimum current. , And an ion current corresponding to the emission current flowing through the third grid electrode and a leak current at the time of cutoff are measured, and a gas value is obtained by calculating each of these current values.

[0031] Also, a support base for supporting and moving the cathode ray tube, a power supply rail extending along the movement path of the support base and provided with a plurality of contact receiving portions, and provided on the support base, A supply contact which is electrically slidably engaged with the contact receiving portion and supplies a predetermined voltage to a cathode of the cathode ray tube and each electrode including first and second grid electrodes; and a first grid electrode. And an auto-tracking circuit connected thereto, and the auto-tracking circuit holds and measures the emission current flowing through the second grid electrode so as to be a specified substantially minimum current.

With this configuration, an automatic tracking circuit is provided in the first grid electrode to reduce the emission current, thereby reducing the amount of barium adhering to the second grid electrode.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The circuit configuration of the gas measuring device for a cathode ray tube according to the present invention is configured as shown in FIG.

Since the structure of the color picture tube itself is the same as that of the related art, the same portions are denoted by the same reference numerals and detailed description thereof will be omitted.

In FIG. 1, three heaters 56 to which a predetermined 8 V heater voltage is supplied from the power supply 11 are connected in series to the color picture tube 54.
Are grounded through the series resistors 12 and 13, and further have first to fifth grid electrodes 58 to 62.

The third grid electrode 60 has a voltage of -25 V
Is supplied from the power supply 14 and the second grid electrode 59
, A voltage of 200 V is supplied from the power supply 15.
Ammeters 16 and 17 are provided in the current flow paths of the second grid electrode 59 and the third grid electrode 60, respectively.

The switching terminal 19 of the changeover switch 18 is connected to the first grid electrode 58. The first fixed terminal 20 of the changeover switch 18 is variably supplied with a voltage of -150V to 0V. Variable power supply 21
Is connected, and the second fixed terminal 22 is configured to be connected to a power supply 23 of −150 V serving as a cutoff voltage.

The variable power supply 21 is composed of a voltage-responsive semiconductor circuit such as a transistor or a thyristor and a variable-response power circuit of a voltage source, or a variable resistor and a voltage source that are automatically controlled. An output terminal of the automatic tracking circuit 24 is connected to the variable power supply 21. An input terminal of the automatic tracking circuit 24 can detect a voltage corresponding to the emission Ie flowing through the second grid electrode 59. It is connected to the midpoint between 12 and 13.

The connection point is not limited to the cathode 57 circuit as long as a voltage corresponding to the emission current Ie flowing through the second grid electrode 59 can be detected. It is also possible to configure so that the connection is made in the established path, and it is not limited to the intermediate point between the series resistors 12 and 13.

The gas measuring device configured as described above
The switching terminal 19 of the changeover switch 18 is connected to the first fixed terminal 20.
Side, and the variable power supply 21 is adjusted to
The emission current Ie is set so that the emission current Ie flowing through the grid electrode 59 becomes the specified value of 500 μA.
Is detected by the automatic tracking circuit 24, and the voltage of the first grid electrode 58 is adjusted by controlling the variable power supply 21 with the detected output, and the emission current value can be confirmed by the ammeter 16.

When the emission current Ie flows, the gas remaining in the color picture tube 54 collides with the electrons to be ionized. The ionized positive ions are attracted to the third grid electrode 60 having a negative potential and supplied with a voltage of −25 V from the power supply 14, so that an ion current Ii flows through the third grid electrode 60. Thus, this current is measured by the ammeter 17.

Next, the switching terminal 19 of the changeover switch 18 is switched to the second fixed terminal 22 so that the first grid electrode 5
8 is switched to be biased at -150 V of the power supply 23, thereby cutting off the color picture tube 54,
The emission current Ie flowing through the grid electrode 59 is cut off.

In this state, the leak current Il flowing through the third grid electrode 60 is measured by the ammeter 17. Using the current values of the emission current Ie, ion current Ii, and leak current Il measured by these ammeters 16 and 17,
The gas value can be calculated by calculation from the above formula.

By obtaining the gas value in this way, it is used as one index when judging the degree of vacuum.

A specific configuration example of the gas measuring device of the gas measuring device shown in FIG. 1 is configured as shown in FIG.

That is, a pair of outer ales 31 in the form of rails or grooves are laid at the installation location of the gas measuring device.
On the guide rail 31, a wheel 32 that rotates while engaging with the guide rail 31 is attached to a lower surface of a support base 33 formed in a box shape or a frame shape.

A color picture tube 54 is placed on the upper surface of the support 33, and the anode button 50 and the stem pin 53 of the color picture tube 54 are connected to terminals provided on one side of the support 33 by electric wiring. Each of the plates 34 is electrically connected to a plurality of contacts 35 implanted in parallel with each other.

The contact 35 is connected to the guide rail 31
Power supply wall 36 installed at a predetermined interval along
Power supply rails 3 for supplying predetermined voltages respectively provided in
The power supply rail 37 is connected to a power supply 38. The automatic tracking circuit 24 is connected between the power supply rails 37 for the first grid electrode 58 and the cathode 57.

Accordingly, by moving the support base 33 along the guide rail 31, a predetermined voltage from the power supply 38 is supplied to each power supply rail 37, and the power supply rail 3
The voltage required for gas measurement is supplied to the respective required electrodes via the contacts 35 that are in sliding contact with the electrodes 7.

Although not shown, the aforementioned ammeter 1
6, 17 and the changeover switch 18, or the automatic tracking circuit 24 interposed between the first grid electrode 58 and the cathode 57 can also be installed on the support 33, and furthermore, the signals necessary for the measurement can be obtained. By installing a light source, a measuring instrument, and the like, it can be used also for the measurement of other static characteristics.
6 or the support 33, it is possible to measure continuously.

According to the gas measuring apparatus for a cathode ray tube configured as described above, the emission current Ie flowing through the first grid electrode is set to a small value of 500 μA within the specified value, and this current value is set to ± 1 by the automatic tracking circuit 24. %, The second grid electrode 59 as shown in FIG.
Since the amount of barium 91 adhering to the substrate can be halved, the number of emission sources can be reduced and the variation of the emission current Ie can be suppressed.

When the emission current is 500 μA or less, the emission current is reduced, so that the ion current is also reduced and the gas detection sensitivity may be reduced. The adjustment is performed by the automatic tracking circuit 24 so that the second grid electrode 59 is not contaminated, a stray emission defect in withstand voltage characteristics does not occur, and the emission current I
The variation in e can be suppressed and gas measurement can be performed with high accuracy.

Therefore, even if a predetermined voltage is applied to the anode button 50 and the third grid electrode 60, the emission emitted from the second grid electrode 59 is reduced, so that the generation of the stray emission is reduced and the gas measurement can be performed. Even if the implemented color picture tube 54 is incorporated in a monitor or the like, a stable high voltage can be obtained.

Further, the number of objects to be repaired by the withstand voltage repair device is reduced due to a reduction in the stray emission defect, and a high quality color picture tube 54 can be obtained.

[0056]

As described above, according to the present invention, the amount of barium adhering to the second grid electrode is determined by the automatic tracking circuit provided on the first grid electrode.
Is suppressed to within 500 μA ± 1%, the amount of barium generated from the second grid electrode, which has been particularly problematic in the past, is reduced, so that the stray emission characteristics can be improved. The number of objects to be repaired by the withstand voltage repair device can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a gas measuring device for a cathode ray tube according to the present invention.

FIG. 2 is a configuration diagram showing a gas measuring device for a cathode ray tube according to the present invention.

FIG. 3 is an explanatory diagram for explaining an effect of the gas measuring device for a cathode ray tube according to the present invention.

FIG. 4 is a sectional view for explaining a conventional color picture tube.

FIG. 5 is a circuit diagram showing a conventional gas measuring device for a cathode ray tube.

FIG. 6 is a configuration diagram showing a conventional gas measuring device for a cathode ray tube.

FIG. 7 is an explanatory diagram for explaining a problem of a conventional gas measuring device for a cathode ray tube.

[Explanation of symbols]

 21: Variable power supply 24: Automatic tracking circuit 33: Support base 35: Contact 37: Power supply rail 54: Color picture tube (cathode ray tube) 57: Cathode 58: First grid electrode 59: Second grid electrode 60: Third grid electrode

Claims (4)

[Claims] An adjustable variable power supply is connected to a first grid electrode of a cathode ray tube having a cathode and at least first to third grid electrodes, and the variable power supply and an emission current flowing through the second grid electrode are connected. An automatic tracking circuit is connected between circuits that obtain the same voltage, and the automatic tracking circuit holds the emission current by controlling the variable power supply voltage so that the emission current becomes a specified substantially minimum current. An ion current according to the emission current flowing through an electrode and a leak current at the time of cutoff are measured, and a gas value is obtained from each of these current values. 2. A support base for supporting and moving the cathode ray tube, a power supply rail extending along a moving path of the support base, and provided with a plurality of contact receiving portions, provided on the support base, A supply contact electrically slidably engaged with the contact receiving portion and supplying a predetermined voltage to the cathode of the cathode ray tube and each electrode including the first and second grid electrodes; and the first grid electrode And an automatic tracking circuit connected to the second grid electrode, wherein the automatic tracking circuit holds an emission current flowing through the second grid electrode so as to be a specified substantially minimum current. 3. The method according to claim 1, wherein the minimum current is 500 μA ± 1.
The gas measuring device for a cathode ray tube according to claim 1 or 2, wherein the gas measuring device is set to%. 4. The automatic tracking circuit according to claim 1, wherein the first grid voltage is adjusted according to the change in the cathode current so that the second grid current falls within a specified value. 3. The gas measuring device for a cathode ray tube according to any one of 3.