JP2004037862A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem in which when more electric power is supplied to increase the light emission luminance of an organic electric field light emitting element, photoelectric conversion efficiency decreases and the element has a shorter life. <P>SOLUTION: The image display device which has an electric field light emitting element 1 having pixels capable of individually modulating emitted light and a projection optical system 2 which projects modulated light beams emitted by the individual pixels of the electric field light emitting element and in which a photoelectric light emitting layer of the electric field light emitting element is formed of a material containing an organic phosphor is provided with an element temperature detecting means 20 of detecting the temperature of the electric field light emitting element, an outside temperature detecting means 23 of detecting outside air temperature, cooling means 4 and 5 which are provided on a surface of the electric light emitting element other than its light emission surface, and a temperature control means 21 of controlling the cooling means so that detected temperature of the element temperature detecting means is not higher than detected temperature of the outside air temperature detecting means and the difference from the detected temperature of the outside air detecting means is within a given range. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image display device, such as a projector or a head-mounted display, that enlarges and projects an element that emits an image pattern.
[0002]
[Prior art]
Conventional projection-type image display devices normally use a liquid crystal display panel or a micromirror device as a light modulation element for switching, and control transmission, blocking or deflection of light to project selected light onto a screen. To display the image on the screen.
[0003]
However, in the above-described projection type image display device, since a liquid crystal display panel or a micromirror device is used as a light modulation element, light that does not necessarily contribute to image projection is always used as unnecessary energy as a polarization element or a light absorbing medium. It is assumed that they are absorbed and eliminated.
[0004]
In addition, in the case of liquid crystal, it is established on the assumption that unnecessary illumination light must be present depending on the light transmittance, the aperture efficiency of each pixel, and the polarization control accuracy. The micromirror device is also based on the premise that it is difficult to effectively use an axially symmetric optical system in terms of the aperture efficiency of each pixel, the numerical aperture of a projection lens for oblique incidence illumination, and the NA of an illumination system.
[0005]
Therefore, metal halides and high-pressure mercury lamps are used as light sources in order to brighten the displayed image.However, there are new problems that a high voltage must be used as the light source voltage and that the light source generates high heat. ing.
[0006]
Means for fundamentally solving such low energy use efficiency have been proposed in JP-A-11-67448 and JP-A-2000-66301. In the solution proposed in these publications, a light emitting panel (organic EL panel) in which organic electroluminescent elements (organic EL elements) are arranged in a matrix is configured, and each organic EL element of the light emitting panel is driven to emit light based on video information, The image is projected and displayed on the projection surface by the projection optical system.
[0007]
Since the organic EL element is a self-luminous element, another light source is not necessary. Since the organic EL panel emits light according to video information, a transmissive liquid crystal panel or the like is unnecessary. Therefore, the obtained light can be effectively used for display.
[0008]
This makes it possible to easily obtain a high-luminance display with low power without generating unnecessary light energy. Further, since an image can be output only by the organic EL panel, the configuration is simple, and it is easy to reduce the size and weight of the device.
[0009]
[Problems to be solved by the invention]
However, the organic electroluminescent element has a problem of durability such that the efficiency of the photoelectric conversion efficiency gradually decreases. The organic electroluminescent material itself causes a chemical structural change to anions and cationic excitons and repeatedly emits light energy according to the change in its potential energy, and the organic electroluminescent layer disperses this material with a fluorescent or phosphorescent material. In addition, since the organic electroluminescent material that emits light by causing a chemical structural change and particle aggregation is configured by using a material for transporting charge carriers to the light emitting body, the probability that the organic electroluminescent material changes to a form other than a desired change form. Does not become 0% in principle.
[0010]
The rate of change other than the desired change form includes the state stability of the luminescent material, combination with an environmental medium material such as a charge carrier transporting material serving as a binder, hydrolysis by an applied electric field strength or a humidity environment, generation of a defect potential, etc. The main factor of the deterioration with respect to the speed of the chemical reaction is acceleration of deterioration due to a self-heating temperature parameter due to generation of heat energy in the photoelectric conversion process.
[0011]
This deterioration rate is an accelerated reaction substantially corresponding to the Arrhenius reaction rate relational expression. Therefore, if light emission driving is performed in a low-power state at a low temperature, the change rate of the photoelectric conversion efficiency is slow and the life is long, but in order to increase the emission luminance, the photoelectric conversion efficiency increases as the supply power increases. It decreases exponentially, and the device has a short life. For example, assuming that the quality guarantee period of ordinary consumer products is one year, stable light emission for thousands to tens of thousands of hours is required. In principle, a disadvantage such as deterioration of performance occurs.
[0012]
Also, reducing the rate of deterioration of the photoelectric conversion efficiency of the organic electroluminescent material can be realized by cooling the electroluminescent element itself to a low temperature, but when the cooling temperature is maintained at a temperature lower than the outside air temperature. It is also affected by the humidity of the outside air. For example, in a high-temperature and high-humidity environment of about 80% at 30 ° C., when water vapor is condensed on the electroluminescent element and water droplets are generated in the light emission direction, an image displayed by the electroluminescent element is projected by the projection lens. The image cannot be projected as it is, and is projected as a distorted image.
[0013]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a method for forcibly cooling an organic electroluminescent element to a temperature that is equal to or lower than the outside air temperature and has a temperature difference within a predetermined range with respect to the outside air temperature. By slowing down the chemical change rate, the deterioration of the photoelectric conversion efficiency is delayed, and the quality maintenance period of the image display device is lengthened.
[0014]
However, when dew condensation occurs in the light emission optical path of the element when cooling the organic electroluminescent element using forced cooling means, it adversely affects the projection of light, so at least in the optical path on the light emission side, By arranging the two light transmitting windows in a structure that seals the gas layer, dew condensation is prevented. Further, when cooling is performed so that the temperature difference from the outside air temperature becomes 20 degrees or more, even if the light emission optical path is insulated by two or more windows that seal the gas, the member that holds the electroluminescent element itself does not. The cooling is gradually performed, and the cooling propagates to cool the window disposed on the outermost surface, so that dew condensation occurs. Therefore, in order to prevent such a situation from occurring, the minimum cooling temperature of the electroluminescent element may be controlled within a difference of 20 degrees, preferably about 15 degrees with respect to the outside air temperature.
[0015]
Here, as the electroluminescent device, a device that displays an additive color mixture image formed by a repetitive matrix arrangement of pixels of each color that emits light of three primary colors can be used.
[0016]
Further, the present invention provides three electroluminescent elements that emit one color light different from each other among the three primary colors, and has an optical element having a dichroic wavelength band separation film (for example, a cross dichroic prism, 3P (piece) or 4P ( The present invention can be applied to an image display device that displays an additive color mixture image by combining light emitted from the above three electroluminescent elements by a piece) dichroic prism) and then projecting the light onto a surface to be projected by a projection lens.
[0017]
In addition, as an electroluminescent element having a material containing an organic phosphor or a phosphor in a light emitting layer, an EL (electro luminescence) light emitting element in which modulation pixels which emit light by injection of charge carriers into the light emitting layer are two-dimensionally arranged. Can be used.
[0018]
Further, as the EL light emitting element, an element in which a resonance structure of generated photons is formed by a charge carrier injection electrode film and a light reflection film disposed on an outer surface of the electrode film can be used.
[0019]
Further, as the cooling means, a temperature gradient can be generated by the Seebeck effect of a Peltier element or the like, and the lower temperature side can be used for cooling.
[0020]
Furthermore, a high-temperature side of the cooling means that generates a temperature gradient by the Seebeck effect of a Peltier element or the like and uses the low-temperature side for cooling may be radiated by the air convection by a blower fan using a high thermal conductivity radiator plate such as metal or ceramic. It is good to
[0021]
Note that the image display device to which the present invention is applied projects an image on a screen and allows the projected image to be observed by diffuse reflection light having a predetermined directivity, or to be observed by diffuse transmission light having a predetermined directivity. Or something you can do.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
(1st Embodiment)
FIG. 1 shows a main optical system constituting a projection type image display device according to a first embodiment of the present invention.
[0023]
In this figure, reference numeral 1 denotes an electroluminescent element composed of a plurality of pixels that emit light so as to represent image information as light emission pattern information. The electroluminescent device 1 is electrically controlled based on an electric signal from an image display controller (not shown). An image signal is input to the image display controller from an image information supply device (not shown) such as a personal computer, a DVD player, and a video, and the image display controller causes the electroluminescent element 1 to emit light based on the input image signal. An electric signal for displaying an image is supplied to the electroluminescent element 1. As a result, the electroluminescent element 1 emits image light (modulated light). The detailed configuration of the electroluminescent device 1 will be described later.
[0024]
Light emitted from the electroluminescent element 1 passes through the window 7 and the space filled with nitrogen or dry air, which is shielded from the outside air by the window 7 and the airtight holding member 8, and then projected onto the screen 3 through the projection lens 2. Is done.
[0025]
The screen 3 has a predetermined light diffusion characteristic on its surface, and has a configuration in which an observer can view an image by seeing diffusely reflected light.
[0026]
On the other hand, most of the energy conversion loss in the photoelectric conversion in the electroluminescent device 1 is converted to heat energy. In the present embodiment, the Peltier device 4 is attached to the back surface (the surface other than the light emitting surface) of the electroluminescent device 1.
[0027]
More specifically, a temperature gradient is generated by the Seebeck effect, and the low-temperature gradient surface of the Peltier element 4 that can perform a cooling operation on one side is closely attached to the back surface of the electroluminescent element 1. Thereby, the electroluminescent element 1 can be cooled.
[0028]
21 is a temperature controller. A thermocouple (element temperature detecting means) 20 is connected to the temperature controller 21, and the thermocouple 20 is in contact with the electroluminescent element 1. Thereby, the temperature controller 21 can monitor the temperature of the electroluminescent device 1.
[0029]
The temperature controller 21 is connected to an outside air temperature sensor 23 that detects an outside air temperature as an environmental temperature. The temperature controller 21 compares the potential generated by the thermocouple 20 with the potential from the outside air temperature sensor 23, detects the difference in the temperature of the electroluminescent element 1 with respect to the outside air temperature from the potential difference, and generates the thermocouple 20. The gradient of the potential change is detected, and the power supplied to the Peltier element 4 via the power supply line 22 is controlled so that the temperature difference of the electroluminescent element 1 with respect to the outside air temperature falls within a predetermined range. Thereby, the electroluminescent element 1 is forcibly cooled so that the difference between the temperature and the outside air temperature is within a predetermined range.
[0030]
On the other hand, the high-temperature gradient surface of the Peltier device 4 which is the surface opposite to the electroluminescent device 1 is forcibly cooled by the outside air by the blower fan 5.
[0031]
(2nd Embodiment)
FIG. 2 shows a main optical system constituting a projection type image display device according to a second embodiment of the present invention.
[0032]
In FIG. 1, reference numerals 1R, 1G, and 1B denote electroluminescent elements that emit light of colors that control three primary colors of red, green, and blue, respectively. Each electroluminescent element is composed of a plurality of pixels that emit light so as to represent image information as light emission pattern information. Each electroluminescent element is electrically controlled based on an electric signal from an image display controller (not shown). An image signal is input to the image display controller from an image information supply device (not shown) such as a personal computer, a DVD player, and a video. The image display controller causes each of the electroluminescent elements to emit light based on the input image signal. An electric signal for displaying image information is supplied to each electroluminescent element. As a result, the three electroluminescent elements 1R, 1G, and 1B emit image light (modulated light) of the color assigned to them. The detailed configuration of the electroluminescent elements 1R, 1G, 1B1 will be described later.
[0033]
Light emitted from the electroluminescent elements 1R, 1G, and 1B is supplied to the window 7 and the air-filled space filled with nitrogen or dry air, which are shielded from the outside air, by the windows 7 and the sealing and holding members 8 arranged in the respective electroluminescent elements. , Are combined by the combining prism 6.
[0034]
The synthetic prism 6 is generally called a cross dichroic prism in which a dichroic filter 6R that reflects red and transmits cyan and a dichroic filter 6B that reflects blue and transmits yellow are arranged in a cross shape. It has the property of transmitting light without affecting it.
[0035]
By using the synthetic prism 6, light emitted from the electroluminescent element 1R responsible for emitting red image information is deflected in the direction of the projection lens 2 by the dichroic filter 6R, and responsible for emitting blue image information. The light emitted from the electroluminescent element 1B is deflected by the dichroic filter 6B toward the projection lens 2, and the light emitted from the electroluminescent element 1G responsible for emitting green image information is projected without being deflected. The light travels in the direction of the lens 2.
[0036]
However, the pixels arranged in each of the electroluminescent elements 1R, 1G, and 1B are adjusted or mechanically or electrically compensated so that the respective predetermined pixels relatively overlap with a predetermined accuracy. Further, as the combining prism 6, a 3P prism or a 4P prism often used in a video receiving color separation optical system may be used other than the cross dichroic prism.
[0037]
The synthesized color image light (modulated light) is projected onto a screen 3 through a projection lens 2.
[0038]
The screen 3 has a light diffusion property on its surface, and has a configuration in which an image can be observed by an observer viewing the diffusely reflected light.
[0039]
On the other hand, as described in the first embodiment, a cooling means using a Peltier element 4 and a blower fan 5 is provided on the back surface of each of the electroluminescent elements 1R, 1G, 1B.
[0040]
31 is a temperature controller. Thermocouples (element temperature detecting means) 30a, 30b, 30c are connected to the temperature controller 31, and these thermocouples 30a, 30b, 30c are in contact with the electroluminescent elements 1R, 1G, 1B, respectively. Thereby, the temperature controller 31 can individually monitor the temperature of each of the electroluminescent elements 1R, 1G, 1B.
[0041]
Further, the temperature controller 31 is connected to an outside air temperature sensor 33 for detecting an outside air temperature as an environmental temperature. The temperature controller 31 compares a potential generated by the thermocouples 30a, 30b, 30c with a potential from the outside air temperature sensor 33, and detects a difference in temperature of each of the electroluminescent elements 1R, 1G, 1B with respect to the outside air temperature from the potential difference. At the same time, the change gradient of the potential generated by the thermocouples 30a, 30b, and 30c is detected, and each of the electroluminescent elements 1R, 1G, and 1B with respect to the outside air temperature is set within a predetermined range. The power supplied to the Peltier elements 4 attached to the 1R, 1G, 1B via the power supply lines 32a, 32b, 32c is controlled. Thereby, the three electroluminescent elements 1R, 1G, and 1B are individually and forcibly cooled so that the difference between the temperature and the outside air temperature is within a predetermined range.
[0042]
On the other hand, the high-temperature gradient surface of the Peltier element 4, which is the surface opposite to the electroluminescent elements 1R, 1G, 1B, is subjected to forced cooling using the outside air by the blower fan 5.
[0043]
(About electroluminescent element)
Next, the structure of the electroluminescent device 1 used in the first embodiment will be described with reference to FIG. As shown in FIG. 3 (b), the basic structure of the electroluminescent device 1 is as follows: a transparent glass substrate 10 is used as a base material, and thin film electroluminescent material layers 11, 12, 13 are made of ITO (indium tin oxide) transparent thin film electrode. 14 and a metal thin-film electrode 15. In order to efficiently inject only hole carriers into the electroluminescent material, a hole transport layer 16 is disposed between the ITO transparent thin film electrode 14 and the thin film electroluminescent material layers 11, 12, and 13.
[0044]
When used as a projection-type modulation light source, a dielectric multilayer reflection half is provided outside the ITO transparent thin-film electrode 14 for the purpose of increasing the ratio of capturing light emitted by the projection lens and increasing the photoelectric conversion efficiency. A mirror layer 17 is provided, an optical resonance structure is formed by the light reflection surface of the metal thin film electrode 15, and the light emission direction is set to the vertical direction of the glass substrate 10 by resonance without reaching the state where the stimulated radiation action occurs. It has directivity.
[0045]
Further, there is an effect of realizing the effect of narrowing the band of the emission wavelength spectrum at the same time, and it becomes possible to design the emission light wavelength by designing the resonance distance. The light emitting surface is on the transparent glass substrate 10 side. The above is the basic structure of the electroluminescent element.
[0046]
Each luminescent pixel is constituted by a wiring matrix arrangement of an ITO transparent thin film electrode 14 and a metal thin film electrode 15. The emission wavelength on the order of 1 nanometer is adjusted by the distance between the resonance mirrors. As shown in FIG. 3A, the electroluminescent material for each color is determined by the electroluminescent material, and the electroluminescent material for red is 11, the electroluminescent material for green is 12, and the electroluminescent material for blue is shown in FIG. Are arranged as shown in FIG. 13 to realize the electroluminescent device 1 expressing full color.
[0047]
On the other hand, the patterning of the electroluminescent materials 11, 12, and 13 is generally performed by coating a fluorescent material on a substrate by vapor deposition. In other words, in order to create an electroluminescent element in which three primary color light emitting pixels are arranged, the manufacturing process is multi-step, but mask unnecessary portions for each color are masked by a mask pattern shield or resist patterning, and a resist is formed. In the case of patterning, patterns can be arranged by sequentially coating electroluminescent materials of three primary colors by a lift-off method.
[0048]
As shown in FIGS. 4A and 4B, the structure of the electroluminescent elements 1R, 1G, and 1B used in the second embodiment is different from that of the electroluminescent element 1 used in the first embodiment. The structure in which the electroluminescent materials of the three primary colors are arranged in a pattern is omitted, and the electroluminescent element 1R has the electroluminescent material 11 in charge of red, and the electroluminescent element 1G has the electroluminescent material 12 in charge of green. The electroluminescent element 1B has an electroluminescent material 13 in charge of blue.
[0049]
Next, a method of controlling the temperature of the electroluminescent element performed in each of the above embodiments will be described with reference to FIG.
[0050]
When the power is turned on to the projection type image display device, the temperature controller supplies power to the Peltier device 4 in order to cool the electroluminescent device having a temperature suitable for the room temperature environment.
[0051]
Here, with respect to the cooling rate, if the cooling is performed too rapidly, a situation occurs in which a small amount of water vapor contained in the gas sealed in the window 7, the glass substrate 10, and the sealed holding member 8 is liquefied. Cool with. The predetermined time gradient changes the limit value of the cooling rate depending on the sealing gas. In the present embodiment, the maximum gradient of the power supply to the Peltier element 4 is set so that the maximum gradient becomes a cooling rate of -1 degree in 10 seconds. Value is set.
[0052]
Next, the temperature difference between the temperature of the electroluminescent element detected by the thermocouple and the environmental temperature (outside air temperature) detected by the outside air sensor has reached a predetermined control target value (−15 degrees in the present embodiment). By the way, the temperature controller interrupts the power supply to the Peltier device 4. As a result, the preparation for emitting light from the electroluminescent element is completed, and the electroluminescent element performs pattern modulated light emission in accordance with the image signal. The control target value is actually a value having a certain range.
[0053]
Due to the overshoot of the cooling of the electroluminescent element, the element is temporarily cooled until the temperature difference becomes larger than the control target value. However, when the electroluminescent element is turned on, heat energy is generated and the temperature of the electroluminescent element starts to rise. Then, when the temperature difference becomes smaller than the control target value, the temperature controller restarts the power supply to the Peltier element 4 and cools the electroluminescent element. By repeating such a feedback system, the temperature difference between the temperature of the electroluminescent element and the outside air temperature is maintained substantially constant (the predetermined target value).
[0054]
Note that since the image signal supplied to the electroluminescent element does not have a unique amount, the heat energy generated by the electroluminescent element is not constant. For this reason, it is preferable to form a feedback system while monitoring the temperature of the electroluminescent element with a thermocouple or a radiation temperature system.
[0055]
On the other hand, if feedback control is performed on the electroluminescent element at an absolute temperature, when the outside air temperature becomes high, a situation where air having a high water vapor content enters may occur, and dew condensation occurs on the surface of the window 7. There is.
[0056]
Next, the effect of controlling the cooling of the electroluminescent element will be described. When a benzoxazole zinc complex is used for an organic electroluminescent phosphor, an aluminum quinolinol complex is used for a green light emitter, and DCM is used for a red light emitter. Here, a diagonal of 2 inches is used as a projection type image display device. When the image displayed on the electroluminescent element 1 or 1R, 1G, 1B of the XGA pixel array is magnified and projected to a diagonal of 50 inches, in order to obtain a screen illuminance of 1000 lux, it is necessary to use the electroluminescent element. As described above, the structure has a forward radiation characteristic due to the resonance structure, and the light capture efficiency of the projection lens 2 can be as high as 50% or more. Therefore, the amount of radiation of the electroluminescent element is about 100,000 cd. / M ² is the required amount.
[0057]
However, this can be realized instantaneously by increasing the charge carrier injection amount by 20 times, that is, by supplying 2 A / cm ^2, but most of the electric energy is converted to heat energy, and the electroluminescent element is rapidly heated by self-heating. As the temperature rises, the probability that the organic phosphor, which is an electroluminescent material, is excited to an activated state rapidly increases. As a result, the organic molecules of the phosphor are destroyed, and the half-life of the photoelectric conversion efficiency is exponentially reduced.
[0058]
As an example, when the temperature of the electroluminescent element 1 or 1R, 1G, 1B is substantially controlled to 15 ° C. with an outside air temperature of 30 ° C. and a control target temperature difference of 15 ° C., an organic fluorescent light having an excitation band in a visible light region. The body has an activation energy of about 50 kcal / mol or more. For this reason, the chemical reaction rate is reduced to about 1/10 or less with respect to a normal temperature 23 ° C. environment. Therefore, the half life of the photoelectric conversion efficiency is extended to several 10,000 hours, and the display illuminance quality as the projection type image display device can be maintained for one year or more.
[0059]
On the other hand, as the projection type image display device, the screen 3 may be a reflection type or a transmission type, and if a device having a predetermined diffusivity is used, a display device which recognizes an image by directly looking at the screen 3 is used. If a device having directivity of a hologram or a Fresnel structure is used, the device functions as a display device at a specific position.
[0060]
In each of the above embodiments, the projection type image display device has been described. However, the present invention is also applicable to a head-mounted display or a head-up display for observing a virtual image of a display element.
[0061]
【The invention's effect】
As described above, according to the present invention, the power injected into the organic phosphor material is reduced by cooling the organic electroluminescent element so as to have a temperature difference within a predetermined range with respect to the outside air temperature at or below the outside air temperature. In the case where the amount of light is increased and the emission luminance is increased, the chemical change rate of the organic phosphor material can be slowed down, the deterioration rate of the photoelectric conversion efficiency is reduced, and the quality of the projection type image display device is maintained. The period can be lengthened. Further, even when the electroluminescent device is cooled, it is possible to prevent the formation of dew condensation droplets on the radiation light path from the electroluminescent device.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a main part of a projection type image display device according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram of a main part of a projection type image display device according to a second embodiment of the present invention.
FIG. 3 is a schematic diagram of a main part of the electroluminescent device used in the first embodiment.
FIG. 4 is a schematic view of a main part of an electroluminescent device used in the second embodiment.
FIG. 5 is a view showing a temperature control sequence of the electroluminescent element in each of the embodiments.
[Explanation of symbols]
1, 1R, 1G, 1B Electroluminescent device 2 Projection lens 3 Screen 4 Peltier device 5 Blower fan 6 Synthetic prism 7 Window 8 Seal holding member 10 Glass substrates 11, 12, 13 Electroluminescent material 14 Transparent thin film electrode 15 Metal thin film electrode 16 Hole transport layer 17 Dielectric multilayer reflection half mirror 20, 30a, 30b, 30c Thermocouple 21, 31 Temperature controller 22, 32a, 32b, 32c Power supply line 23, 33 Outside air temperature sensor

Claims (4)

An electroluminescence device having a pixel capable of individual modulation of emitted light, and an image display device having a projection optical system for projecting modulated light emitted from each pixel of the electroluminescence device,
The electroluminescent layer of the electroluminescent device is made of a material containing an organic phosphor or an organic phosphor,
Element temperature detecting means for detecting the temperature of the electroluminescent element,
An outside air temperature detecting means for detecting an outside air temperature;
Cooling means provided on a surface other than the light emission surface of the electroluminescent element,
Temperature control means for controlling the cooling means such that the temperature detected by the element temperature detection means is equal to or lower than the temperature detected by the outside air temperature detection means, and the difference between the temperature detected by the outside air temperature detection means is within a predetermined range. An image display device comprising: The temperature control means is configured such that a difference between the temperature detected by the element temperature detection means and the temperature detected by the outside air temperature detection means falls within the predetermined range at a predetermined time gradient from the time of power supply to the projection type image display device. The image display device according to claim 1, wherein the cooling unit is controlled as described above. The image display device according to claim 1, wherein the cooling unit is a Peltier device. 2. The image display device according to claim 1, wherein at least two light transmission windows are arranged on a light emission surface side of the electroluminescent element in a structure for sealing a gas layer.

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