JPS6332824A - Cathode-ray tube device - Google Patents

Abstract

PURPOSE:To detect leakage of liquid exactly, by detecting the amount of cooling liquid on the basis of changes in resistance between a frame filled with the cooling liquid and electrodes inserted into the cooling liquid. CONSTITUTION:An upper side electrode 12A is disposed on a detection level, where allowable leakage of cooling liquid 10 is detected when a cathode-ray tube device 20 is mounted on a floor, and on the external upper position in the horizontal direction against a screen which is formed on a front panel 1A of a CRT 1. A lower side electrode 12B is disposed on the same detection level as the upper side electrode where the leakage of liquid is detected when the cathode-ray tube device is hung upside-down. Hence, whether the amount of the cooling liquid 10 is below the detection level or not, where the leakage of liquid is detected and the CRT 1 is in danger, can be found by detecting changes in resistance between the upper or lower side electrode 12A, 12B, and the frame 2, depending on the cooling liquid 10 existing between them.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a cathode ray tube device, and is suitable for application to, for example, a high brightness cathode ray tube device used in a color video projector or the like.

B. Summary of the Invention The present invention relates to a cathode ray tube device in which a cathode ray tube is cooled using a cooling liquid. By detecting the amount of coolant based on the above, liquid leakage can be reliably detected.

C. Prior Art Conventional color video projectors use CRTs with higher brightness and lower resolution than cathode ray tubes (CRTs) used in ordinary television receivers in order to obtain bright and detailed color images. It is used.

CRTs for color video projectors use high-output electron beams, so a thick glass panel is used as the front panel coated with phosphor to sufficiently absorb the emitted X-rays. It is being

Therefore, while the CRT is in operation, it becomes difficult to dissipate the heat from the front panel, and there is a possibility that the temperature in the center of the panel in particular will rise significantly. When the temperature of the front panel rises, a phenomenon called temperature quenching occurs, in which the brightness of the phosphor decreases.
It is inevitable that the image quality of color images will deteriorate due to a decrease in white balance.

Furthermore, if the front panel becomes hot, there is a risk that the phosphor coated on the front panel may peel off, the front panel may crack, and the CRT itself may implode.

In order to solve these problems, a cathode ray tube device 20 has been proposed in which the front panel IA of the CRTl is cooled using a cooling liquid 10, as shown in FIG. No. 60-137038).

In FIG. 7, the front panel IA of the CRTI is made of glass with a refractive index n=1.52, for example, and a phosphor is coated on the inner surface to form a phosphor screen.

Further, the frame 2 made of a conductive metal material has a first
The back surface of the first spacer 3 is adhered to the front panel IA of the CRTl with a sealing material 5 such as silicone resin, and
The spacer 3 and the second spacer 4 are hermetically fixed to each other via a first O-ring 6, for example, by screwing.

Furthermore, a second O ring 9 is provided on the front surface of the second spacer 4.
For example, a lens 8 having a refractive index n=1.52 and capable of absorbing X-rays is connected to the second spacer 4 by the lens barrel 7.
For example, by screwing it with a bolt (not shown), it is sealed and fixed.

Further, the sealed space formed by the front panel LA of the CRTI, the frame 2, and the lens 8 has a refractive index n=1.
A conductive cooling liquid 10 made of a mixture of glycol liquid and water (43) is injected to fill about 90% of the sealed space, thus effectively cooling the front panel IA of the CRT 1. being done.

In the above configuration, the cathode ray tube device 20 is operated to
When the temperature of the front panel IA of the RTl increases, the heat generated by the front panel IA is conducted to the coolant 10. This heat is transmitted to the frame 2 by convection of the cooling liquid 10, and is radiated from the frame 2.

In this way, the front panel IA of the CRTI can be effectively cooled. In addition to this, the coolant 10 can reduce the reflections that occur between the glass surfaces facing each other between the front panel IA and the lens 8 of the CRTl, thereby avoiding a reduction in contrast, so that the coolant 10 can avoid the so-called L C” (lquid cooling and c
It has the function of upling.

Furthermore, when replacing the CRTI, lens 8, coolant IO, etc., the labor required to peel off and adhere the sealing material 5 is limited to only a few parts, and the other first and second spacers 3. 4. Members such as the lens barrel and the lens 8 have the advantage that they can be loosened and tightened by extremely simple operations such as loosening and tightening bolts (not shown) via the first and second O-rings.

D Problems to be Solved by the Invention However, in the conventional cathode ray tube device 20 of this type, C
RTI replacement work, lens replacement work and coolant 10
When replacing the first and/or second O-ring 6,
．． If the bolts 9 are not tightened enough, foreign objects are caught during tightening, or the sealant 5 is not sufficiently filled, the coolant 10 may leak or may naturally evaporate (over a long period of time). There is a possibility that the coolant 10 will gradually decrease due to the above reasons.

If the cathode ray tube device 20 is used in this state, the difference in refractive index between the coolant 10 and the air will cause out-of-focus on the color image, and if it is used in this state for a long time, the front panel There is a risk that the CRTl will implode due to insufficient cooling of the IA or thermal distortion due to uneven temperature distribution.

The present invention has been made in consideration of the above points, and attempts to propose a cathode ray tube device that can reliably detect leakage of coolant lOO inside the cathode ray tube device using a liquid leakage detection device with a simple configuration. It is something.

E Means for Solving Problems In order to solve these problems, the present invention provides a cathode ray tube 1, a conductive frame 2 attached to the front LA of the cathode ray tube 1, and a conductive frame 2. a lens 8 attached to the front opening of the lens barrel 7, and a front panel I of the cathode ray tube 1.
A. In a cathode ray tube device 20 in which a cooling liquid 10 is sealed in a sealed space formed by a conductive frame 2 and a lens 8,
An electrode 12A is attached to the through hole 3C13D of the conductive frame 2 via an insulator 21, and is designed to derive the resistance between the tip 23A inserted into the coolant 10 and the conductive frame 2. , 12B and the tips 2 of the electrodes 12A and 12B.
3A and a detection circuit that detects the amount of the coolant 10 in the sealed space based on a change in resistance between the conductive frame 2 and the conductive frame 2.

F action 4 Electrodes 12A and 12B provided on the conductive frame 2 so as to protrude into the coolant 10 via an insulator, and the conductive frame 2
The resistivity changes by a practically sufficient amount depending on whether or not the coolant 10 is filled between the two.

By detecting this change in resistivity, it can be detected whether the amount of the coolant 10 is filled to a predetermined level position where the electrodes 12A, 12B are provided.

Embodiment G An embodiment in which the present invention is applied to a color video projector will be described in detail below with reference to the drawings.

In FIGS. 1 to 6, parts corresponding to those in FIG. , two electrodes 12A and 12B are provided.

The upper electrode 12A is equal to the permissible leakage detection level of the coolant 10 when the cathode ray tube device 11fe20 is placed on the floor, and is located horizontally outside of the screen formed on the front panel IA of the CRTI. It is placed in the upper position.

The lower electrode 12B is arranged at the same leakage detection level as the upper electrode 12A when the cathode ray tube device is upside down and hung from the ceiling, and thus the amount of the coolant 1o is at the same level as the leakage detection level, which is dangerous for CRTI. The cooling liquid 10 between the upper or lower electrode L2A or 12B and the frame 2
This can be determined by detecting the change in resistance due to the presence or absence of .

The upper and lower electrodes 12A and 12B are constructed as shown in FIG. That is, the first spacer 3 is provided with a through hole 3C that penetrates from the outer surface 3A to the inner surface 3B, and a screw hole 3D having a larger diameter than the inner portion is formed in the outer surface 3A side of the first spacer 3. A stepped portion 3E is formed by leaving the thread uncut between the screw hole 3D and the screw hole 3D.

A needle 23 having a bushing 21 welded around its periphery is inserted into the screw hole 3D and the through hole 3C from the outside of the spacer 3. A plug 22 screwed into the screw hole 3D is disposed around the outer end of the bushing 21 so that the bushing 21 can be tightened.

The bushing 21 is made of an insulating material such as Teflon, and has an inner part 21A having an outer diameter that is approximately the same as the inner diameter of the through hole 3C, and an inner diameter of a stepped part 3E (therefore, A connector sleeve portion 21C having approximately the same outer diameter as the inner diameter of the screw hole 3D and having a hole 21D formed at its outer end is integrally formed.

Further, the tip 21E of the inner side 21A of the bushing 21 is selected to have a length that projects inward from the inner side 3B of the spacer 3, and the inner tip 23A of the needle 23 is
1, and this protruding portion forms the electrode portion 23A.

In contrast, the connector sleeve portion 21 of the bushing 21
G is selected to have a length such that it can be wrapped within the plug 22, and the outer tip 23B of the needle 23 is exposed inside the hole 2LD formed at the outer end thereof to form a connector. .

Thus, between the electrode part 23A of the needle 23 and the inner surface 3B of the spacer 3, there is an inner part 21A of the bushing 21.
A practically sufficient creepage distance is formed along the outer surface of the As a result, when the cooling liquid 10 is filled between the electrode part 23A and the inner surface 3B, the electrode part 23A and the inner surface 3B
By reducing the resistivity between the electrode parts 23A and 3B, a state in which a sufficiently large current flows for practical purposes can be obtained.
When the resistivity between the inner surface 3B and the inner surface 3B becomes high and no current flows, it can be determined that the coolant has fallen below the level of the electrode 12A (or 12B).

Further, the plug 22 is made of a conductive metal material, has a cylindrical shape, and is connected to the connector sleeve portion 21 of the bushing 21.
A threaded portion 22A having the same inner diameter as the outer diameter of C, and a male thread provided on the outer periphery so as to be screwed into the threaded hole 3D of the first spacer 3, and a bolt for screwing the threaded portion 22A using a tool. The portion 22B and a connector portion 22C that extends around the connector sleeve portion 21C of the bushing 21 and forms a connector together with the hole portion 21D are integrally formed.

The upper and lower electrodes 12A and 12B with the above configuration are assembled by inserting the needle 23 and the bushing 21 into the through hole 3C of the spacer 3 so that the spacer ring 24 is interposed between the bolt part 22B and the outer surface 3A, and then bolting Part 22B
Using this, tighten the plug 22 to the screw hole 3D with the specified tightening torque.
When screwed in, the tip of the threaded portion 22A of the plug 22 presses the ring portion 21B of the bushing 21, thereby reliably fixing the electrodes 12A, 12B to the first spacer 3.

At the same time, the ring portion 21B deforms while being pressed against the step 3E between the through hole 3C and the screw hole 3D, thereby creating a sealing function, preventing the coolant 10 from leaking from the inside to the outside, and ensuring a secure seal. It is made to be obtained.

The electrodes 12A and 12B1 and the first spacer 3 are connected to a liquid leak detection circuit via a connector cable 13, as shown in FIG.

The liquid leakage detection circuit connects the power supply ■cC to voltage dividing resistors R11 and Rt.
2 and Rtlz R2□ to electrodes 12A and 12B, respectively.

The connection midpoint of resistors RII% RIz and R21% R22 is grounded via capacitors C8 and C2 for noise prevention, and a first OR circuit 15 having a CMOS configuration with high input impedance is used as measurement voltages S1 and S2. It has been like being connected to.

Here, the resistances R, Rt, and Rt2 and R1□ are the coolant 10 between the electrode 12A or 12B and the first spacer 3.
When the cooling liquid 10 is flowing, a relatively large current flows through the coolant 10, so that the voltage of the power supply VCC increases.
The voltages S1 and S2 are divided to a value lower than the threshold level of the CMOS OR circuit 15, that is, the logic rLJ level. On the other hand, coolant 10
is not between the electrodes 12A, 12B and the spacer 3, the measured voltages S1 and S2 are 1! between the electrodes 12A, 12B and the spacer 3. Power supply voltage due to no current flowing
. , that is, the logical rHJ level.

Incidentally, in the above embodiment, the resistance R3 between the electrodes 12A, 12B and the first spacer 3 when the coolant 10 is filled is approximately R5=2°4 (MΩ), and accordingly Power supply VCC: c=12 (V), resistors R11 and R
21 as Rz = Rz1 = 6.8 (MΩ), resistance R
IZ and Ro are R+ z = Rz z = 1 (M
Ω].

Thus, the logic output Sa+ of the first OR circuit 15 is input to the second OR circuit 16 together with the liquid leakage detection logic outputs Sc and Ss obtained from each CRT of the color video projector, so that the entire liquid leakage detection device red,
When a liquid leak is detected in either the green or blue CRT, the detection output S is at the logic rHJ level. ut is sent to, for example, a protection circuit (not disclosed) or the like, thereby performing predetermined processing such as cutting off the power circuit of the color video projector and blinking a warning lamp.

In the above configuration, for example, when the cooling liquid 10 of the CRTl is filled with a predetermined amount, the electrodes L2A, 12
A current flows between B and the first spacer 3 via the coolant 10, and the measured voltages S1 and S2 both have a value indicating the logic rLJ level, and the logic output S of the first OR circuit 15
R has a logic rLJ indicating that there is no liquid leakage in the CRTl.
The level value is output.

On the other hand, if the level of the CRTI coolant 10 drops to a position where the electrode 12A is exposed due to natural evaporation, liquid leakage, etc., no current will flow between the electrode 12A and the first spacer 3. , one of the measured voltages S, becomes a value indicating the logic rHJ level, and regardless of the value of the measured voltage St detected by the electrode 12B, the logic output S,l of the first OR circuit 15 indicates that there is no liquid in the CRTl. A logic rHJ level value is output indicating that a leak has occurred.

According to the above configuration, the front panel lA of the CRTl, the frame 2
The electrodes 12A and 12B are inserted through the frame 2 into the sealed space formed by the lens 8 and the electrode 12A.
By measuring the resistance R8 between , 12B and frame 2,
The absence of the coolant 10 can be directly determined, thus the coolant 10
It is possible to accurately detect liquid leaks and decreases due to natural evaporation.

In the above embodiment, the bushings 21 of the upper and lower electrodes 12A and 12B are connected to the inner surface 3B of the spacer 3.
However, in consideration of ease of manufacturing and installation, the bushing 21 is welded to the bushing part to be welded to the needle and to the inside of the plug, for example. For example, the connector sleeve portion may be divided at the center of the ring portion into a connector sleeve portion in which a through hole through which a needle can be inserted is formed.

Furthermore, the above-described embodiments can be used in both floor-mounted and ceiling-mounted versions. In order to detect liquid leakage in the color video projector, electrodes 12A and 12B are provided at two locations on the side of the frame 2, but if the color video projector is dedicated to either a floor-mounted type or a ceiling-mounted type, the electrodes can be reduced to one, and the first OR circuit 15 of the liquid leak detection circuit can also be omitted.

H Effects of the Invention As described above, according to the present invention, in a cathode ray tube device in which the front panel of the cathode ray tube is cooled by a coolant, electrodes are provided on the side of the frame in which the coolant is sealed through an insulator. By inserting the frame and detecting the resistance between the frame and the electrode, the presence or absence of liquid can be reliably detected with a simple detection circuit.

In this way, it is possible to easily realize a cathode ray tube device that can prevent a decrease in contrast due to liquid leakage and implosion of the cathode ray tube due to insufficient cooling liquid.

[Brief explanation of the drawing]

FIG. 1 is a linear sectional view showing an embodiment in which the present invention is applied to a color video projector, FIG. 2 is a plan view showing the first spacer, and FIG. 3 is a plan view showing the first spacer [-II
A cross-sectional view taken along line I, FIG. 4 shows the first spacer at T
5 is a cross-sectional view taken along line V-IV; FIG. 5 is an enlarged cross-sectional view of the main part of the first spacer taken along line ■-■; FIG.
The figure is a connection diagram showing a liquid leak detection circuit, and FIG. 7 is a line sectional view showing a conventional example. 1...CRT, 2...Metal frame, 3...
...First spacer, 4...Second spacer, 5...Seal material, 6...First O
Ring, 7... Lens barrel, 8... Lens, 9... Second 0 ring, 10...
・Liquid, 12A, B... Electrode, 20...
・Cathode ray tube equipment.

Claims (2)

[Claims] (1) a cathode ray tube, a conductive frame attached to the front surface of the cathode ray tube, a lens attached to the front opening of the conductive frame with a lens barrel, a front panel of the cathode ray tube; In a cathode ray tube device in which a cooling liquid is sealed in a sealed space formed by a conductive frame and the lens, the tube is installed in a through hole of the conductive frame via an insulator and inserted into the cooling liquid. an electrode configured to derive a resistance between the tip and the conductive frame; and an electrode configured to derive the resistance between the tip of the electrode and the conductive frame, and the sealed space based on the change in resistance between the tip of the electrode and the conductive frame. A cathode ray tube device comprising: a detection circuit for detecting the amount of the coolant in the tube. (2) The electrode inserted into the conductive frame projects inside the conductive frame, and has a stepped portion formed between the through hole and the screw hole formed in the conductive frame. a bushing in which a ring part facing the and a tip part inserted into the through hole are integrally molded from an insulating material; a needle-like needle inserted into the bushing and welded thereto; and a cylindrical needle. a plug having a shape and a threaded portion that can be screwed into a screw hole drilled in the conductive frame, the needle being inserted into the through hole and the screw hole of the conductive frame; Further, by screwing the plug, the electrode can be fixed to the conductive frame, and the conductive frame can be sealed to prevent leakage of the coolant sealed inside the conductive frame. The cathode ray tube device according to scope 1.