JP5118929B2 - Projection display device - Google Patents

Description

  The present invention employs a light source array in a projection display apparatus (projector) that generates projection light by modulating and synthesizing light of three primary colors with image information and projects an image on a screen via a projection lens. The present invention relates to the improvement of the light source unit.

  In many conventional projection display apparatuses, a discharge lamp such as a metal halide lamp or an ultra-high pressure mercury lamp is used as a light source for generating light of the three primary colors. The emitted white light is separated into three primary colors of red (R), green (G), and blue (B) by a dichroic mirror, and the three primary colors are modulated by image information and synthesized by a synthesis prism (dichroic prism), and then projected. The image is displayed on the screen through the lens.

  In order to respond to the demand for higher brightness (higher output) in a projection display apparatus that employs such a discharge lamp, it has been attempted to employ a high output discharge lamp or to increase the number of lamps. Yes. However, such countermeasures increase the amount of heat generated from the discharge lamp, so that the cooling structure increases in size, and measures such as noise and increase in the size of the power source are indispensable. In addition, since the emission spectrum of the discharge lamp has a peak in yellow, it is necessary to mix yellow with red or green in order to effectively use the emitted light. Accordingly, there is a problem that the color purity of the generated single color is poor and high color reproducibility cannot be expected. Furthermore, the discharge lamp has a problem in that the light quantity in the red wavelength band is not sufficient as compared with the light quantity in the green and blue wavelength bands in the emission spectrum, and thus a countermeasure to supplement the light quantity in the red wavelength band is necessary. It was.

  In spite of these problems, projection-type image display devices that employ discharge-type lamps have recently become increasingly demanding for larger images projected on the screen in the business market, etc. Increasing the amount of emitted light is a market demand. Therefore, in order to solve the problem when the discharge lamp as described above is employed, an attempt has been made to employ a light source array as an element of a light source particularly intended for high output (see Patent Document 1).

  In this light source array, for example, several tens or more of light source elements are monolithically arranged on the same substrate at a high density, and light emission spots corresponding to the number of arrangements are formed. . When such a light source array is employed, it is an important issue to keep the light source array operation set temperature constant in order to stably emit and oscillate each element of the light source array.

When the light source array operation set temperature fluctuates, the light emission output from the light source element fluctuates, which affects the result of color synthesis and shortens the lifetime. Therefore, in the technique disclosed in Patent Document 1, a light source array is cooled by combining a Peltier element and a heat sink. Further, as another means for forcibly cooling the light source array, there is one in which the cooling medium passage is arranged in parallel to the light source array from the cooling device so as to cool to a predetermined temperature (Patent Document 2). reference).
JP 2007-201285 A Japanese Patent Laying-Open No. 2005-026575

  When a light source array is used as a light source, it can be turned on and off instantaneously, and has a characteristic that it has a wide color reproducibility and a long life compared with a case where a discharge lamp is used. However, when the temperature of the light source element rises, the light emission efficiency decreases and the crystal defects increase. Along with this, the ratio of non-emissive transition increases, so heat is generated even in the transition mechanism that operates as the original light emission principle, the temperature of the element rises, and the light emission capability decreases at an accelerated rate. It will also lead to shortening.

  The present invention is premised on a configuration in which the three primary colors emitted from the light source array in which a plurality of light source elements having such optical properties are arranged. As described above, the light source elements depend on the temperature. It has characteristics that are greatly affected. When the temperature of the element changes, the wavelength and luminance of the emitted light change. When such a state is reached, the white balance is lost, and accurate color gradation expression cannot be achieved, which affects the contrast and the like.

  Therefore, the light source array must always be maintained at a constant operating set temperature at which stable operation is maintained. For example, since the light source element can obtain a high output at a temperature relatively lower than room temperature and can maintain a long life, a cooling means is required to keep the light source array operating set temperature constant regardless of how the environmental temperature changes. Therefore, it is necessary to strictly control the temperature within a specified range.

  However, the cooling means disclosed in Patent Document 1 is based on a composite structure of a Peltier element and a heat sink, and the peripheral portion of the light source element is complicated and large, so a plurality of light source arrays are arranged for each of the three primary colors. Such a light source element cannot be employed, and the temperature of each light source array cannot be accurately controlled. Further, the cooling means disclosed in Patent Document 2 is difficult to grasp the temperature state of each light source array, and is an extremely large-scale apparatus that is individually provided with a cooling refrigerant flow rate adjusting means. .

  The present invention relates to a projection type image display apparatus including a light source unit in which a plurality of light source elements each having a light source array arranged on a heat receiving plate are arranged in a layered manner toward the irradiation surface of a synthetic prism for every three primary colors. In this case, the temperature condition of each light source array is constantly monitored, and all the light source arrays are maintained at a desired operation set temperature by the interaction of the cooling means and the heating means. The object is to enable color reproduction with high accuracy and to keep the life of the light source array long.

  Therefore, the present invention solves the above problems by means described below. That is, according to the present invention, a projection-type image display apparatus is configured to obtain projection light by modulating and synthesizing light of at least three primary colors according to image information, and a light source in which a plurality of light source elements are arranged on the same substrate. The array is arranged on the heat receiving plate, and a plurality of light source elements each having heating means and temperature detecting means arranged on the heat receiving plate are guided to the irradiation surface of the synthesis prism for each of the three primary colors. A plurality of light source elements which are arranged in a shape to constitute a light source unit and which connect the light source element to a cooling means and which connect the heating means and the temperature detection means to a control means and are simultaneously cooled by the cooling means The cooling means is controlled so that the light source element showing the maximum temperature value among the temperature values detected by the temperature detecting means becomes the desired light source array operation set temperature. By raising the temperature of the other light source elements in each of the heating means to reach the desired light source array operation setting temperature.

  According to the present invention, it is possible to control the temperature of the light source element with a simple configuration, and the light source element that shows the maximum temperature value among the temperature values detected from each light source element becomes the light source array operation set temperature by the cooling means. The temperature of the other light source elements is adjusted to the desired setting temperature of the light source array by each heating means, and the accuracy is always high over a long period regardless of the environmental temperature and the structural aging of the light source element itself. Color reproduction is possible, and the lifetime of the light source element can be kept long.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view showing a basic configuration of a light source unit according to the present invention, and FIG. 2 shows a perspective view of an assembled state of the light source unit. FIG. 3 is a diagram showing the configuration of the main part of the present invention. FIG. 4 shows an example of the cooling means employed in the present invention, and FIGS. 5 to 9 show the cooling mode of the light source unit.

  FIG. 1 is a plan view showing a basic configuration of a light source unit 1 that is a main part of a projection display apparatus P according to the present invention. Three primary colors of laser light are applied to three side surfaces of a synthesis prism 2 arranged in the center. Irradiation surfaces 2R, 2G, and 2B are formed. The irradiation surface 2R is irradiated with red laser light, the irradiation surface 2G is irradiated with green laser light, and the irradiation surface 2B is irradiated with blue laser light.

  In addition to the liquid crystal panels 3R, 3G, and 3B, incident-side polarizing plates 4R, 4G, and 4B and outgoing-side polarizing plates 5R, 5G, and 5B are arranged in parallel to face each irradiation surface 2R, 2G, and 2B. In order to allow a specific linearly polarized light component to enter the liquid crystal panels 3R, 3G, and 3B, the light beams of the respective primary colors are aligned in a predetermined polarization direction (P-polarized light) in the incident-side polarizing plates 4R, 4G, and 4B. After being modulated by the panels 3R, 3G, and 3B, only the S-polarized light component of the modulated light is transmitted from the exit-side polarizing plates 5R, 5G, and 5B.

  Condenser lenses 6R, 6G, and 6B for obtaining a uniform illuminance distribution are arranged in parallel to face the incident side polarizing plates 4R, 4G, and 4B, and further uniformize the luminance of each laser beam. Integrators (fly eye lens pairs) 7R, 7G, and 7B are arranged in parallel to face the condenser lenses 6R, 6G, and 6B. The integrator 7 </ b> R receives red laser light from the light source element 8, the integrator 7 </ b> G receives green laser light from the light source element 9, and the integrator 7 </ b> B receives blue laser light from the light source element 10.

  The light source elements 8, 9, and 10 are all configured in the same manner, and at the tips of heat receiving plates 8a, 9a, and 10a formed of a metal having excellent thermal conductivity, several tens or more serving as light source elements are formed. The semiconductor laser element arrays 8b, 9b, and 10b in which the semiconductor laser elements are arranged are fixed with, for example, a heat conductive adhesive. For example, the semiconductor laser element array 8b has a red wavelength band around 650 nm, the semiconductor laser element array 9b has a green wavelength band around 550 nm, and the semiconductor laser element array 10b has a blue wavelength band of 440 nm. Near laser light is emitted.

  The laser beams of the three primary colors emitted from the semiconductor laser element arrays 8b, 9b, and 10b configured in this way must be incident on the combining prism 2 with a predetermined light amount. Accordingly, it is important as a design problem to consider the amount of light emitted from each semiconductor laser element for each of the three primary colors and to determine the number of elements to be arranged or to set and supply the drive current for each of the three primary colors.

  The light source elements 8, 9, and 10 are configured as described above, and a plurality of light source elements 8, 9, and 10 that emit the same primary color within the irradiation range of the same primary color as shown in FIG. 2G and 2B are arranged in layers. In the figure, the arrangement state of the light source element 10 that emits blue light toward the irradiation surface 2B of the composite prism 2 is illustrated, but the light source element 8 that emits red light and the light source element 9 that emits green light are also irradiated. It arrange | positions similarly toward 2R and 2G. Note that the light source elements 8, 9, and 10 between layers need to be arranged in a zigzag or the like so that the irradiation light is dispersed.

  When the light source unit 1 configured as described above is driven, laser light of three primary colors is emitted from the light source elements 8, 9, 10 toward the irradiation surfaces 2 R, 2 G, 2 B of the synthesis prism 2. The luminance of each color laser beam is made uniform in the integrators 7R, 7G, and 7B, and the illuminance distribution is made uniform in the condenser lenses 6R, 6G, and 6B, and is incident on the incident side polarizing plates 4R, 4G, and 4B.

  The laser beams of the three primary colors made uniform in this way are incident on the liquid crystal panels 3R, 3G, and 3B, and are subjected to gradation (intensity) modulation to form an image. Then, the light enters the combining prism 2. The laser light of the three primary colors subjected to the gradation modulation is combined in the combining prism 2. Then, the projection light exits from the exit surface 2S and is projected onto the screen via the projection lens L.

  When the light source elements 8, 9, and 10 are bonded to the heat receiving plates 8a, 9a, and 10a with the semiconductor laser element arrays 8b, 9b, and 10b by a heat conductive adhesive or screwed, If even a small amount of air is present, an error occurs in the contact thermal resistance, resulting in a difference in the amount of heat absorbed by the heat receiving plates 8a, 9a, 10a. The cause of such an error may be due to an assembly error in the manufacturing process, or may be due to structural aging, but in any case, the semiconductor laser element array 8b, When 9b and 10b are caused to emit light, the amount of emitted light is not uniform due to the difference in thermal conditions, and the lifetime is also different.

  Therefore, in the present invention, by taking the measures described below, all the light source arrays can be operated within an allowable range of the operation set temperature. That is, as shown in FIG. 3, an electric heater 20 as a heating means and a temperature sensor 21 as a temperature detection means are arranged on all the heat receiving plates 8a, 9a, 10a of the light source elements 8, 9, 10 and this electric heater. 20 and the temperature sensor 21 are connected to the control device 22 by lead wires L1 and L2. In addition, a Peltier element etc. can also be employ | adopted for the said heating means, and it is not limited to an electric heater.

  The heat receiving plates 8a, 9a, and 10a are provided in the refrigerant circuits 24R, 24G, and 24B that extend from the refrigerator 23 that serves as a cooling unit and face the irradiation surfaces 2R, 2G, and 2B of the synthetic prism 2 separately. The heat absorber (evaporator) 25 is fixed by appropriate means such as a heat conductive adhesive so that heat of the heat receiving plates 8a, 9a and 10a is absorbed by the heat absorber 25.

  FIG. 4 shows an example of the refrigerant circuit in the refrigerator 23. The refrigerant compressor 23a, the condenser 23b, the decompressors 23R, 23G, and 23B, the heat absorber 25, and the accumulator 23c are connected in an annular shape in this order. . The high-temperature and high-pressure refrigerant compressed by the refrigerant compressor 23a of this refrigerant circuit is heat-exchanged with the outside air (in the case of air cooling) by the blower fan 23d of the condenser 23b, and the temperature is lowered to become a low-temperature and high-pressure refrigerant. Next, after the flow rate is reduced by the decompressors 23R, 23G, and 23B, the heat absorber 25 evaporates. The heat receiving plates 8a, 9a and 10a are cooled by the heat absorbing action at this time. Note that the degree of cooling of the heat absorber 25 for each of the three primary colors can be adjusted by adjusting the amount of refrigerant throttle in the decompressors 23R, 23G, and 23B.

  Furthermore, in the present invention, a control device that receives signals from the temperature sensors 21 of the light source elements 8, 9, 10 and performs heat generation control of the electric heater 20 and refrigerant flow rate adjustment control by the pressure reducers 23R, 23G, 23B. 22, the heat receiving plates 8a, 9a, and 10a can be controlled mutually for cooling and heating, and all the semiconductor laser element arrays 8b, 9b, and 10b are set to the operation set temperature.

  Here, the example of the aspect of control by the said control apparatus 22 is demonstrated below. Before starting the projection display apparatus P, the temperature T of the light source elements 8, 9, 10 is assimilated to the environmental temperature. For example, when the environmental temperature is 26 ° C., as shown in FIG. The light source elements 8, 9, and 10 are 26 ° C. In the figure, for easy understanding, a blue light source element 10 is illustrated as a representative example, and the temperature state of each light source element 10 can be grasped by a branch number. Further, the temperatures of the light source elements 8, 9, and 10 are individually grasped by the control device 22 that inputs the detection signal of each temperature sensor 21.

  In such a state, when the projection display apparatus P of the present invention is activated and the refrigerator 23 starts driving, the light source elements 8, 9, and 10 are cooled and fall within an allowable range of a preset temperature (for example, 20 ° C.). The refrigerator 23 cools the refrigerant to be (for example, ± 1 ° C.) and is supplied to the heat absorber 25. In this way, the heat absorber 25 comprehensively cools the light source elements 8, 9, and 10 and absorbs the heat generated from the semiconductor laser element arrays 8b, 9b, and 10b to reach a stable state. When there is an error in thermal resistance or the like, a temperature difference occurs between the light source elements 10-1 to 10-n as shown in FIG.

  In the example shown in the figure, the light source elements 10-2 and 10-4 are out of the target light source array operation set temperature allowable range (19 to 21 ° C.). Therefore, the control device 22 extracts the maximum temperature value from the plurality of light source elements 8, 9, and 10 connected to the same refrigerant circuit, and this maximum temperature value (in the example shown in FIG. 4, 23 ° C.) is controlled to lower the allowable upper limit value (21 ° C.) of the light source array operation set temperature (20 ° C.).

  As a result, as shown in FIG. 7, the light source element 10-4 can be matched with the allowable upper limit value of the light source array operation set temperature of 21 ° C., but the temperature of the other light source elements also changes. Therefore, when the temperature is detected again by the temperature sensor 21 of each light source element 8, 9, 10 and the maximum temperature of the light source elements other than the light source element 10-4 exceeds the allowable upper limit value of the light source array operation set temperature ( In the example shown in FIG. 7, the refrigerator is controlled to lower the light source element 10-2 to the allowable upper limit value (21 ° C.) of the light source array operation setting temperature.

  As a result, as shown in FIG. 8, the light source element 10-2 can be set to the allowable upper limit value (21 ° C.) of the light source array operation set temperature, but the light source element (e.g., out of the allowable temperature lower limit value (19 ° C.)) 10-1, 10-6). Therefore, the control device 22 compares the temperature value detected by the temperature sensor 21 of each light source element 8, 9, 10 with the light source array operation setting temperature (20 ° C.) and compensates for the difference temperature to set the light source array operation setting. A current is passed through the electric heater 20 so that the allowable range (19-21 ° C.) of the temperature (20 ° C.) is maintained, and the temperature of the light source element is increased.

  That is, in FIG. 8, for example, since the light source element 10-1 is 1 ° C. lower than the allowable lower limit value of the light source array operation set temperature (20 ° C.), the controller 22 raises the temperature by 1 ° C. by the electric heater 20, The temperature of the light source element 10-6 is increased by 2 ° C. In this way, the temperature of each light source element is complemented, and as shown in FIG. 9, all the light source elements 10-1 to 10-n are allowed to have an allowable temperature range (19 ° C.) of the target light source array operation setting temperature (20 ° C.). ˜21 ° C.).

  As described above, in the present invention, in cooling the light source elements connected to the same refrigerant pipe, the maximum temperature value indicated by the specific light source element is lowered to the allowable upper limit value of the target operation set temperature by the refrigerator. Since the temperature of the light source element that is below the lower temperature limit is raised by the electric heater, the temperature sensor detection signal and the light source array operation set temperature are always collated. Even when the contact thermal resistance changes due to secular change, accurate temperature control becomes possible.

  Accordingly, it is possible to stably operate a light source element array such as a semiconductor laser element array so that color reproduction with high accuracy is always possible and a long life can be maintained, and a highly reliable projection display apparatus is provided. The effects unique to the present invention can be obtained.

  In the above-described embodiment, an example in which a transmissive liquid crystal panel is used has been described. However, as an alternative display element, for example, when a light source unit is configured in a three-plate type or a single plate type using a reflective liquid crystal panel. Can achieve the same effect. In the above-described embodiment, the projection display apparatus using a semiconductor laser element as the light source element has been described as an example. However, the present invention can be implemented without being limited to the type of the light source element. is there.

It is a top view which shows the basic composition of the light source unit of this invention. It is a perspective view which shows the assembly state of the light source unit of this invention. It is a figure which shows the structure of the principal part of this invention. It is a figure which shows the example of the cooling means employ | adopted as this invention. It is a figure explaining the aspect of cooling of the light source element in this invention. It is a figure explaining the aspect of cooling of the light source element in this invention. It is a figure explaining the aspect of cooling of the light source element in this invention. It is a figure explaining the aspect of cooling of the light source element in this invention. It is a figure explaining the aspect of cooling of the light source element in this invention.

Explanation of symbols

P ... Projection type image display device L ... Projection lens 1 ... Light source unit 2 ... Synthetic prism 3R, 3G, 3B ... Liquid crystal panel 4R, 4G 4B: Incident side polarizing plate 5R, 5G, 5B: Output side polarizing plate 6R, 6G, 6B: Condenser lens 7R, 7G, 7B: Integrator 8, 9, 10: Light source element 8a, 9a, 10a: Heat receiving plate 8b, 9b, 10b: Light source array (semiconductor laser element array)
20 ... Electric heater (heating means)
21 ... Temperature sensor (temperature detection means)
22... Control device 23... Refrigerator 24R, 24G, 24B... Refrigerant circuit 25.

Claims (1)

A projection-type image display device configured to obtain projection light by modulating and synthesizing light of at least three primary colors according to image information;
A light source array in which a plurality of light source elements are arranged on the same substrate is arranged on a heat receiving plate, and a plurality of light source elements each having heating means and temperature detecting means arranged on the heat receiving plate are synthesized for every three primary colors. The light source unit is configured in a hierarchical arrangement so as to guide light to the irradiation surface of the prism,
The light source element is connected to cooling means, and the heating means and temperature detection means are connected to control means ,
The cooling means is controlled so that the light source element showing the maximum temperature value among the plurality of light source elements cooled simultaneously by the cooling means has a desired light source array operation set temperature. On the other hand, a projection-type image display apparatus characterized in that the temperature of the other light source elements is raised by the respective heating means so as to reach a desired light source array operation set temperature .

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