JP2002156704A - Cooling device for projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device for a projection type display device capable of cooling lamp, even in the case that a lamp driver fails to operate and the lamp is not put out. SOLUTION: This cooling device for the projection type display device is provided with a lamp drive circuit, a fan drive circuit for driving a fan for cooling and a photosensor for detecting the light emission state of the lamp and the fan is maintained in a rotation state, while the lamp is lit, by detecting light from the lamp by the photosensor and controlling the fan drive circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display device such as a liquid crystal projector, and more particularly to a cooling device for a lamp as a light source.

[0002]

2. Description of the Related Art Conventionally, liquid crystal projectors have been widely used as projection display devices. This LCD projector is
Light from a light source is applied to a transmission type liquid crystal panel, and the liquid crystal panel is driven based on a television signal or an information signal from a personal computer or the like, thereby emitting modulated light from the liquid crystal panel and passing through a projection lens. This is to project the enlarged image on the screen.

Since a very high-intensity lamp is required as the light source, a discharge tube lamp such as a mercury lamp is used. During the operation of the lamp, the temperature of the lamp becomes extremely high due to the heat generated by the lamp. Therefore, it is generally known to use a blower fan to send cooling air to the lamp to cool it.

The turning on and off of the lamp and the rotation and stop of the cooling fan are controlled by a control circuit in the projector. When the power is turned on, the fan is rotated together with the turning on of the lamp, and when the power is turned off, the lamp is turned off. It also controls the fan to run for a few minutes and stops after the temperature drops. This is what is commonly called cool down.

Further, electric power to the lamp is supplied from a dedicated lamp driver, and on / off control of electric power supply to the lamp is also performed by the above-described control circuit.

[0006] However, when the lamp driver breaks down and cannot receive an instruction from the control circuit, the lamp may continue to be lit despite the instruction to turn off the lamp. In this case, the control circuit may determine that the lamp has been turned off and stop the rotation of the fan, causing the temperature inside the projector to rise due to abnormal overheating of the lamp and causing thermal damage to various parts. Give it.

When the main power of the projector is turned off, there is no problem because the lamp power is also turned off. However, when the projector is used for presentation, video light is sometimes projected, or when the projection is stopped, the projector is put into a standby state. Sometimes. In the standby state, when the power supply voltage is supplied to the lamp and the lamp driver does not respond to the turning-off instruction from the microcomputer, the lamp may not be turned off and the fan may stop operating without being turned on.

Further, as an example of means for coping with an abnormal situation of the projector, there is one disclosed in JP-A-9-130700. The example described in this publication is based on the case where the air flow to the cooling fan deteriorates and the temperature rises, or the lamp does not turn on normally even though the lamp is turned on (when the lamp is not turned on abnormally). ), The power is turned off upon detecting an abnormal state, or a failure is indicated by an LED.

However, in this example, when an abnormal state is correctly detected, a protection operation such as turning off the power is performed. As described above, even though the lamp driver breaks down and an instruction to turn off the lamp is issued, The lamp keeps lighting,
In the case where the fan stops rotating, there is a problem that the protection operation does not work because the abnormality cannot be accurately detected.

[0010]

In the above-mentioned projection type display device, when the lamp driver breaks down and cannot receive an instruction from the control circuit, it is in spite of the instruction to turn off the lamp. There is a disadvantage that the lamp continues to be lit and the fan may stop, and the temperature inside the projector rises due to abnormal overheating of the lamp.

[0011] In addition, even if an abnormal state such as a temperature rise or a lamp non-lighting abnormality is detected and the power is turned off or an abnormality is displayed, if the abnormal state cannot be accurately detected, the protection operation is normally performed. Otherwise, there is a problem that the lamp is overheated abnormally.

In view of the above, it is an object of the present invention to provide a cooling device for a projection display device which can cool a lamp even when a lamp driver fails and the lamp does not turn off. I do.

[0013]

According to the present invention, there is provided a projection display apparatus having a light source in a projector and projecting image light using light from the light source. A lamp drive circuit for driving, a cooling unit for cooling the inside of the projector, and a first light emitting state that detects a light emitting state of the lamp and changes according to the light emitting state
, A first control signal from the light detection unit, and a second control signal for instructing the operation and stop of the cooling unit. Control means for controlling the operation of the cooling means in response to the control signal, and control means for maintaining the cooling means in an operating state while the lamp is lit, It is a cooling device.

According to another aspect of the present invention, there is provided an optical system including a light source, a liquid crystal panel that receives light from the light source and emits image light modulated by a video signal, and a projection lens that projects light emitted from the liquid crystal panel. System, a lamp drive circuit that drives the lamp for the light source, a fan that allows cooling air to flow through the optical system, and a first control that detects a light emitting state of the lamp and changes according to the light emitting state. A photosensor for generating a signal, control means for generating a second control signal for instructing rotation and stop of the fan, and an OR circuit to which the first control signal and the second control signal are respectively input. A fan drive circuit that controls the operation of the fan by the output of the OR circuit, and maintains the fan in a rotating state while the lamp is lit. A cooling device that the projection display device.

According to the present invention, the cooling means is controlled by detecting the light from the lamp by the light detecting means (photo sensor), and the cooling means (fan) is operated while the lamp is lit. The state can be maintained, and the cooling function can be operated normally even when the lamp continues to be turned on despite the instruction to turn off the lamp.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view illustrating a cooling structure of a projection display according to an embodiment of the present invention. FIG. 1 shows R
An example of a three-panel liquid crystal projector having liquid crystal panels for (red), G (green), and B (blue) is shown.

In FIG. 1, reference numeral 10 denotes an optical box, and a lamp house 11 is provided near the box. The lamp house 11 includes a light emitting tube 1 as a light source.
And a lamp 3 comprising a reflector 2.
Light from the arc tube 1 is reflected by a reflector 2, and unnecessary light such as infrared light and ultraviolet light is removed by a filter 12, and then supplied to a dichroic mirror 15 via a condenser lens 13 and a reflection mirror 14.

The dichroic mirror 15 splits the light from the lamp 3 into R light and GB light, and the separated R light is reflected by the mirror 16 and applied to the R liquid crystal panel 18 via the field lens 17. .

The GB light separated by the dichroic mirror 15 is separated into G light and B light by a dichroic mirror 19, the G light is applied to a G liquid crystal panel 21 via a field lens 20, and the B light is relayed. Liquid crystal panel 2 for B through lens 22, reflection mirror 23, relay lens 24, reflection mirror 25 and relay lens 26
7 is irradiated.

Further, the R light, G light and B light transmitted through each of the liquid crystal panels 18, 21 and 27 are applied to the dichroic prism 2.
8, and the combined image light is projected onto a screen (not shown) by the projection lens 29.

Thus, the R, G, B liquid crystal panels 18,
By driving the pixels 21 and 27 with the R, G, and B primary color signals, a color image can be projected. Incidentally, polarizing plates are disposed on the incident side and the exit side of the liquid crystal panels 18, 21, 27, respectively.

On the other hand, in the projection type display device of the present invention, for example, fans 31 and 32 are used to cool the lamp 3, the liquid crystal panel, and the like. That is, the liquid crystal panel 1
A first fan 31 for introducing outside air to the 8, 8, and 27 to blow cooling air, and a second fan 32 for exhausting the wind blown to the lamp 3 to the outside of the projector are provided. .

The fan for circulating the cooling air in the projector is not limited to the first and second fans 31 and 32, but may be provided in other portions, or may be provided on the side or bottom of the projector. good. Although an air path is provided so that the cooling air from the blower fan flows smoothly through the heat generating portion, it is omitted in the figure.

The lamp 3 is provided with a ventilation hole (not shown) on the bottom surface of the reflector 2 and the like, and a plurality of holes 5 are provided in a support portion 4 for supporting the arc tube 1, and the lamp 3 is introduced from the ventilation hole. Cooling air is led out of the plurality of holes 5 and exhausted to the outside by the second fan 32.

Next, the circuit of the cooling device in the projection display device of the present invention will be described with reference to the block diagram of FIG.
In FIG. 2, reference numeral 10 denotes an optical box,
1, including a projection lens 29 and the like. Although the liquid crystal panel is composed of three panels (18, 21, 27) as shown in FIG. 1, the liquid crystal panel 21 is shown as a representative in FIG. The means for synthesizing the image light from the liquid crystal panel is omitted. Reference numeral 11 denotes a lamp box in which a lamp 3 is provided.
Is housed.

In FIG. 2, reference numeral 34 denotes a video processing circuit for processing a video signal supplied to an input terminal 33. The video signal from the video processing circuit 34 is supplied to a liquid crystal drive circuit 35 at the next stage. The liquid crystal panel 21 is driven by the liquid crystal drive circuit 35.

The lamp 3 is controlled to be turned on and off by a lamp drive circuit 36, and a fan 3 for cooling the lamp 3 and the liquid crystal panel 21 is provided.
1 and 32 are driven by a fan drive circuit 37. The fan 31 blows outside air into the optical box 10, and the fan 32 exhausts heat of the lamp 3 to the outside.

The fan drive circuit 37 and the lamp drive circuit 36 are controlled by a microcomputer 38 (hereinafter, referred to as a microcomputer 38) as a control circuit.
The microcomputer 38 has a function as a system microcomputer for controlling the operation of the entire projector.

Further, a photo sensor 39 for detecting light leaked from the lamp is provided in the vicinity of the lamp 3, and the fan drive circuit 37 controls the detection output from the photo sensor 39 and the control from the microcomputer 38. The operation is controlled by a signal. In addition,
Reference numeral 40 denotes a power supply circuit that supplies a power supply voltage + B for operation to the microcomputer 38, the lamp drive circuit 36, the fan drive circuit 37, and the like in the projector 41.
The values of the power supply voltages supplied to the respective circuits are different from each other, but are omitted from the drawing as + B.

A temperature sensor (not shown) is provided in the projector 41, and an output from the temperature sensor is detected by a sub-microcomputer provided in the lamp drive circuit 36, and the temperature inside the projector 41 becomes abnormally high. In such a case, the fact is displayed or the lamp is controlled to be turned off, but is not shown in the figure.

FIG. 3 shows a peripheral circuit around the fan drive circuit 37. Fan drive circuit 3
Reference numeral 7 denotes a photosensor 39 for detecting light leaked from the lamp 3, and an OR circuit 42 for calculating the logical sum of an output signal from the photosensor 39 and a control signal from the microcomputer 38. The driver 43 is controlled to control the rotation and stop of the fans 31, 32.

Next, the operation of the cooling device of the present invention will be described.
When the projector 41 is turned on, the microcomputer 38 controls the lamp drive circuit 36 and the fan drive circuit 37 to turn on the lamp 3 and to rotate the fans 31 and 32 to cool the inside of the project cooler 41. The cooling operation is performed by blowing air for use and exhausting heat inside the projector to the outside.

When the power is turned off, the lamp 3 is turned off, and after the lamp 3 is turned off, the fans 31, 3 are kept for a few minutes.
2 is rotated, and after cooling down, the fans 31 and 32 are stopped.

The power to the lamp 3 is supplied from a dedicated lamp drive circuit 36, and the lamp drive circuit 36 breaks down while the lamp is turned on, and the microcomputer 38
If the control signal for turning on / off the lamp is not received from the microcomputer 38, the microcomputer 38 cannot monitor the signal and may cause an abnormal situation. That is, when the lamp drive circuit 36 does not respond to the lamp turn-off control signal to the lamp drive circuit 36 in response to the instruction from the microcomputer 38 and continues to turn on the lamp 3, the microcomputer 38 In some cases, it is determined that 3 is turned off, and an instruction to stop the fan is given to stop the fans 31 and 32.
In this state, the cooling operation of the lamp 3 is stopped, which causes abnormal heat generation.

Therefore, in the present invention, the light leaking from the lamp 3 is detected by the photo sensor 39, and the fans 31, 32 are not stopped while the lamp 3 is lit.
That is, in FIG. 3, a fan control signal from the microcomputer 38 and a detection output from the photo sensor 39 are transmitted to an OR circuit 42.
The driver 43 is controlled by the logical sum output to control the operations of the fans 31 and 32. The fan control signal from the microcomputer is at a high level when instructing “rotation”, and at a low level when supporting “stop”.
The following description is based on the assumption that a high level signal is output when light from the lamp 3 is detected, and a low level signal is output when no light is detected.

In other words, when the lamp drive circuit 36 fails and does not respond to the "turn off" instruction from the microcomputer 38 and the lamp 3 continues to be turned on, the microcomputer 38 sends a fan control signal (low level) from the OR circuit 42. However, the photosensor 39 detects a leaked light from the lamp 3, so that a high-level signal is supplied to the other input of the OR circuit 42, and the OR output becomes high level, and the 43 operates to keep the fans 31 and 32 rotating. As a result, as long as the lamp 3 is lit, the fans 31 and 32 rotate, so that the cooling operation can be continued.

When the lamp drive circuit 36 is operating normally, the lamp 3 is turned off in response to the "turn off" instruction from the microcomputer 38, and the output from the photo sensor 39 is also at a low level. On the other hand, since the fan control signal from the microcomputer 38 becomes low level after a predetermined time has elapsed after the lamp is turned off, the OR output of the OR circuit 42 becomes low level and the driver 43 operates to stop the fans 31 and 32. .

Therefore, the lamp drive circuit 36
Fan 3 does not turn off normally due to
Since the lamps 1 and 32 rotate while the lamp 3 is lit, the cooling operation can be continued and abnormal heating can be prevented.

In general, the projector 41 projects video light at the time of its operation. However, when the projector 41 is used for a presentation like a data projector, it sometimes projects video light, or stops projection and stands by. In some cases, the lamp 3 can be turned off in the standby state. Therefore, in such a case, if the fans 31 and 32 are stopped while the lamp 3 is not turned off but turned on, abnormal overheating will be caused. However, the present invention can avoid this.

[0040]

As described above, according to the present invention, the cooling function does not stop even when the lamp drive circuit does not operate normally and continues to be turned on despite the light-off instruction. In addition, abnormal heating can be prevented.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a cooling structure of a projection display according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a circuit of the cooling device of the present invention.

FIG. 3 is a block diagram showing a circuit of a main part of the cooling device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Arc tube 2 ... Reflector 3 ... Lamp 10 ... Optical box 11 ... Lamp house 18, 21, 27 ... Liquid crystal panel 29 ... Projection lens 31, 32 ... Cooling fan 36 ... Lamp drive circuit 37 ... Fan drive circuit 38 ... Micro Computer 39 Photo sensor 42 OR circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 9/31 H04N 9/31 E

Claims (8)

[Claims] 1. A projection type display device having a light source in a projector and projecting image light using light from the light source, wherein: a lamp drive circuit for driving a lamp for the light source; Cooling means for cooling the inside of the projector; light detecting means for detecting a light emitting state of the lamp and generating a first control signal which changes according to the light emitting state; first control from the light detecting means A signal and a second control signal for instructing the operation and stop of the cooling unit are input, respectively, and control the operation of the cooling unit in response to the first and second control signals, and the lamp is turned on. And a control means for maintaining the cooling means in an operating state during the operation. 2. The cooling device according to claim 1, wherein the cooling unit includes a fan for flowing cooling air through the projector, and a fan drive circuit for controlling rotation and stop of the fan. Cooling device for projection display devices. 3. The light source cooling device for a projection display device according to claim 1, wherein said light detecting means comprises a photo sensor for detecting light leaked from said lamp. 4. The control means includes a microcomputer and an OR circuit, generates the second control signal from the microcomputer, and outputs the second control signal and a first signal from the light detection means. 2. A cooling device according to claim 1, wherein a control signal is input to said OR circuit, and an operation of said cooling means is controlled by an output of said OR circuit. 5. An optical system including a light source, a liquid crystal panel that receives light from the light source and emits image light modulated by a video signal, and a projection lens that projects light emitted from the liquid crystal panel. A lamp drive circuit that drives the lamp for the light source; a fan that allows cooling air to flow through the optical system; and detects a light emitting state of the lamp and generates a first control signal that changes according to the light emitting state. A photo sensor, a control unit that generates a second control signal for instructing rotation and stop of the fan, and an OR circuit to which the first control signal and the second control signal are respectively input, And a fan drive circuit for controlling the operation of the fan by an output of an OR circuit and maintaining the fan in a rotating state while the lamp is lit. Cooling device shown apparatus. 6. The apparatus according to claim 1, wherein the fan includes a first fan that blows cooling air to the optical system, and a second fan that exhausts air in the optical system to the outside. The cooling device for a projection display device according to claim 5. 7. The cooling device for a projection type display device according to claim 5, wherein wind generated by said fan is circulated through said optical system so as to suppress a rise in temperature of said liquid crystal panel and said lamp section. . 8. The projection display apparatus according to claim 5, wherein said control means includes a microcomputer, and said microcomputer controls operations of said lamp drive circuit and said fan drive circuit. Cooling system.