JP2010169754A - Image display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique to suppress temperature rise based upon measurement of deterioration over time of a solid light source. <P>SOLUTION: The image display includes: a first light source that emits light of first wavelength; a second light source that emits light of second wavelength; a third light source that emits light of third wavelength; a driving means that drives the first, second and third solid light sources of three kinds in predetermined timing; a heat radiation means that radiates heat from the light sources of three kinds; a light quantity measurement means that measures light quantity of each of the light sources of three kinds; and a control means that determines degree of deterioration of the light source based upon the light quantity measured by the light quantity measurement means, and controls the heat radiation means to allow the light source determined as the one in which the degree of deterioration progresses to sufficiently radiate the heat. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image display device in which a solid light source such as an LED or LD is mounted as a light source.

  In recent years, with the development of solid-state light source technology, a projection video display device equipped with an LED or LD as a light source has been realized. Solid light source is 1) Long life, 2) Wide color reproduction range, 3) Instant lighting and re-lighting, 4) Low power drive, 5) Driving current compared to conventional ultra-high pressure mercury lamp There are many advantages such as relatively easy operation. Of these, paying attention to the advantage 5), a method of controlling the driving current of the solid-state light source has been proposed so that the luminous flux can be provided to the optical system with high efficiency.

  For example, the content described in Patent Document 1 is that in a projector using a plurality of LEDs as light sources, the temperature rise of the LEDs is reduced by dispersing the time during which the LEDs emit light.

Light sources such as LEDs and lasers have the characteristic that the output decreases and the lifetime decreases as the temperature rises. In patent document 1, it is going to implement | achieve suppression of the temperature rise of LED by disperse | distributing the time which a light source light-emits. However, there has been a problem that a technique for suppressing the temperature rise based on the measurement of deterioration with time of the light source has not been disclosed.
JP 2007-171364 A (FIG. 1)

  An object of this invention is to provide the technique which suppresses a temperature rise based on the measurement of a time-dependent deterioration of a solid light source.

  In order to solve the above problems, an image display device according to a first aspect of the present invention includes a first light source that emits light of a first wavelength, a second light source that emits light of a second wavelength, A third light source that emits light having a wavelength of 3, a driving unit that drives the first, second, and third solid light sources at a predetermined timing, and a heat dissipation that dissipates heat from the three light sources. Means, light quantity measuring means for measuring the light quantity of each of the three types of light sources, and determining the degree of deterioration of the light source based on the light quantity measured by the light quantity measuring means, and determining that the degree of deterioration has progressed And a control means for controlling the heat dissipation means so as to perform sufficient heat dissipation by the light source.

According to a second aspect of the present invention, in the image display device according to the first aspect of the present invention, the heat radiating means comprises a Peltier element.
An image display device according to claim 3 is the image display device according to claim 1 or 2, wherein the three types of light sources are light emitting diodes.

  According to a fourth aspect of the present invention, in the image display device according to the first or second aspect, the three types of light sources are laser diodes.

  According to the present invention, it is possible to obtain a technique for suppressing a temperature rise based on measurement of deterioration with time of a solid light source.

Embodiments of the present invention will be described below.
(Embodiment 1)
A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows a perspective view of a projector apparatus according to an embodiment of the present invention. The projector 1 has a dual-purpose input terminal 2 that can accept two types of input signals, analog RGB input and component input. The input terminal 2 is for inputting an analog RGB signal from an external computer or the like and a component video signal (Y / PB / PR) from a video device or the like. The projector 1 has an input terminal 3. The input terminal 3 is for inputting a video signal from a video device or the like. The projector 1 has a projection unit 4. The projection unit 4 is for outputting an image for image projection onto an external screen.

  FIG. 2 is a block diagram of the projector apparatus according to the present embodiment. A projector 1 of an LD (laser diode) light source is connected to, for example, a video signal decoder unit 10 that converts an analog RGB signal 2a or a video signal 3a into a digital signal, for example, a ROM (not shown) and a ROM that stores its firmware. A video image digitized by the video signal decoder unit 10, the control unit 30 composed of a RAM that provides a region, each function in the control unit 30, LD control means 31 that individually controls on / off of each LD for the light source Video processing means 32 for performing video processing such as scaling on the signal is provided.

  Further, the light source LD driving section 40 for driving the LD of each color according to the LD control means 31, the light source LDs 41 to 43 for R, G, B, the liquid crystal 60, the liquid crystal driving circuit 70 for driving the liquid crystal 60, and the projection light 4a. It is comprised from the projection lens 80 which radiates. The brightness data memory 50 serves as a reference for measuring a change in brightness of LD of each color to be described later.

  FIG. 3 shows an example of a PWM signal waveform when the light source LED is controlled at a double speed of the vertical synchronizing signal. As shown in FIG. 3, a PWM (Pulse Width Modulation) signal synchronized with a vertical synchronizing signal (or a multiplication thereof, twice in this example) of the period T of the video signal is sent from the control unit 30 to the LD driving unit 40, and R / G / B Each of the LDs is turned on in order, and the liquid crystal driving unit 40 is controlled in synchronization with the above signals, and each light source is transmitted through the liquid crystal, thereby projecting an image without color foil unlike the case of using a monochromatic light source. I can do things.

  The duty ratio of the time length for turning on each R / G / B LD is a value such as tr: tg: tb = 3: 5: 2. In addition to the so-called digital demming method based on the time length ratio, a method based on analog demming can be employed. Analog deming adjusts the brightness and color composition of an image by adjusting the current value flowing through each LD in synchronization with the PWM signal. Analog deming has the advantage that it is difficult for the user to feel color blur because there is no color timing shift. In the above, digital dimming is performed at double speed, but if the double speed is increased, there is a possibility that it is difficult for the user to feel color blur even with digital demming.

FIG. 4 is a block configuration diagram mainly illustrating an example of the structure unit of the embodiment.
The lasers of the respective colors emitted from the red, green, and blue laser diode (LD) modules R1, G1, and B1 are collimated by the collimator lens L1, and are combined by the reflecting mirror M1 and the combining prism with the same optical axis. Incident on the LCD. The LCD rotates or does not rotate the polarization of light incident on each pixel based on a video signal (not shown). The laser beam that has passed through the LCD is incident on a polarizing beam splitter (PBS). The light whose polarization is rotated by the LCD is reflected in the PBS prism and is incident on the photodetector (PD). Other light passes through PBS and is projected onto a screen (not shown) by a projection lens. In the control indicated by the broken line, the controller 30 detects the output PD1 from the PD and grasps the light amount of each color. It is a light quantity measuring means for measuring the light quantity of each of the three types of light sources.

Further, the time when the laser emitted from each laser diode module (LDM) is incident on the LCD is different for each color as shown in FIG. 3, and is synchronized with the time when each color laser is emitted. By sending a polarization control signal to the LCD, it is possible to generate RGB color images. The above-described detection of PD1 is also performed in synchronization with laser emission and polarization control.

In general laser projectors having such a configuration, it is known that the intensity of the laser output by the LDM decreases with time. Furthermore, the deterioration of LDM with time varies from one solid to another. For this reason, conventionally, the output of the laser for each solid was detected by a PD, and when the output of the laser decreased, the output of lasers of other colors with little deterioration was reduced in order to maintain white balance. As a result, there has been a problem that the maximum luminous flux projected on the screen is reduced.

Further, as LD characteristics, when the LD drive current is the same, the laser output increases as the temperature decreases. For this purpose, in order to cool the LD that is heated by the oscillation of the laser, a Peltier element is attached to the LDM, a radiation fin is provided on the opposite side of the LDM of the Peltier element, and air is blown from the fan to the radiation fin to cool the LDM. The lower the temperature of the LDM, the greater the output because the output increases. However, the amount of heat radiated from the fins is limited depending on the ambient temperature and the maximum airflow of the fan.

In addition, when the fin is shared by each module, the total amount of heat released from each module is equal to the amount of heat released from the fin. For this reason, when the amount of heat radiation from the radiation fin is constant, the temperature of a specific LDM cannot be changed without affecting the temperature of other LDMs.

Under this restriction, in this embodiment, the temperature of the LDM (LDM1) whose output has greatly decreased due to deterioration with time is set lower than the initial temperature, and the set temperature of the LDM (LDM2) with little change over time is set lower than the initial temperature. By increasing the value, the laser output increases more than when the initial temperature is set even when the same drive current is applied. As a result, the maximum luminous flux projected on the screen becomes larger than in the case of the initial temperature setting while maintaining the white balance. As an operation, the controller 30 executes the temperature reduction setting SR1, SG1, SB1 for the Peltier element corresponding to the LDM1 based on the result of detecting the output PD1 from the PD and grasping the light quantity of each color. As a specific means for judging the change over time, for example, a memory of brightness data at the initial shipment is provided, and the brightness at that time is measured every certain time (for example, 1 minute) and compared with the initial shipment. To measure the change with time. That is, the controller 30 reads out the initial brightness data from the brightness data memory 50 as a reference for measuring the temporal change in the brightness of the LD of each color, and depends on what percentage of the result of measuring the brightness from time to time has fallen. The LDM1 is determined. If there are two LDMs corresponding to LDM1, the temperature reduction setting may be apportioned according to the degree of change.

When the light source is a laser, the life of the light source is shortened due to temperature change and the output is greatly reduced compared to the LED. Therefore, the temperature control of the light source needs to be further strengthened. It is necessary to attach.

  In the present embodiment, a Peltier element is attached as a temperature control element, and a device for detecting the output of the light source that changes with this element and the change with time is examined, the magnitude of the change with time is examined based on the detected output data, and the current flowing to the Peltier element is calculated. Change.

By adding a temperature control element such as a Peltier element as an effect and appropriately controlling the temperature control, a more effective temperature control means can be provided.
(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIGS. 1 to 3 and FIG. Description of the parts common to the first embodiment is omitted.
FIG. 5 is a block configuration diagram mainly illustrating an example of the structure unit of the embodiment.
As shown in Fig. 5, even if the heat dissipating fins installed in the LDM are different for each LDM, the air outlet or inlet of the air flowing out from each fan depends on the shape of the duct, and the air resistance depends on the shape of the duct. When this occurs, the air volume applied to each fin does not depend only on the rotational speed of the fan installed on each fin, but affects each other.

In other words, even if the rotation speed of the fan of the R laser module is constant, if the rotation speed of the fan of the G laser module is small, the wind force corresponding to the fin of the R laser module increases, and conversely, the G laser When the fan speed of the module is high, the wind force that hits the fins of the R laser module decreases. For this reason, in the same manner as described in the first embodiment, the rotation speed of the laser fan with large deterioration is increased from the initial setting to lower the temperature of the laser, and the rotation speed of the laser with low deterioration is decreased to reduce the laser speed. By increasing the temperature, the maximum luminous flux projected on the screen can be made larger while maintaining the white balance than when the initial fan speed is set.

As an operation, the controller 30 executes the fan rotation speed increase setting SR2, SG2, SB2 corresponding to the LDM1 based on the result of detecting the output PD2 from the PD and grasping the light quantity of each color.

  In the case of adopting the configuration of the embodiment as described above, the decrease in the luminous flux of the projector due to deterioration with time can be reduced, so that the lifetime of the projector due to the decrease in luminance can be extended. In other words, in a projector having a plurality of independent light source units, white balance is maintained while minimizing the decrease in brightness by preferentially cooling the light source units whose output has decreased due to deterioration over time.

In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary, it can implement in various modifications.
Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements according to different embodiments may be appropriately combined.

1 is a perspective view of an embodiment of a projector device according to the present invention. The block diagram of the LD light source projector of the embodiment of the projector apparatus. 7 is an example of a PWM signal waveform when the light source LD is controlled at a double speed of the vertical synchronization signal of the projector apparatus according to the embodiment. The block block diagram which mainly shows the example of the structure part of the embodiment. The block block diagram which shows mainly the example of the structure part of another embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Projector, 2 ... Input terminal, 3 ... Video signal input terminal, 4 ... Projection part, 10 ... Video signal decoder part, 30 ... Control part, 31 ... LD control function for light sources, 32 ... Video signal processing function, 40 ... LD drive unit for light source, 41 ... red LD, 42 ... green LD, 43 ... blue LD, 60 ... liquid crystal, 70 ... liquid crystal drive unit, 80 ... projection lens.

Claims (4)

A first light source that emits light of a first wavelength;
A second light source that emits light of a second wavelength;
A third light source that emits light of a third wavelength;
Driving means for driving the first, second and third solid light sources at a predetermined timing;
A heat dissipating means for dissipating heat from these three types of light sources;
A light amount measuring means for measuring the light amount of each of the three types of light sources;
Control means for controlling the heat radiating means to determine the degree of deterioration of the light source based on the light quantity measured by the light quantity measuring means and to perform sufficient heat radiation by the light source determined to have progressed the degree of deterioration. An image display device comprising:   The image display apparatus according to claim 1, wherein the heat radiating means is a Peltier element.   The image display device according to claim 1, wherein the three types of light sources are light emitting diodes.   3. The image display device according to claim 1, wherein the three kinds of light sources are laser diodes.

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