JP2009086273A - Light source element for projection type video display device and projection type video display device equipped with light source unit constituted of light source element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a projection type video display device which is stably actuated whatever environment it exists in and whose reliability is improved by protecting a semiconductor laser device array of a light source element having the semiconductor laser element array as a light source from effect due to dew condensation in the projection type video display device. <P>SOLUTION: The light source element for the projection type video display device is constituted by disposing the semiconductor laser device array where a plurality of semiconductor laser devices are arranged on the same substrate on a heat receiving plate and forming a synthetic resin layer on a part where the semiconductor laser device array is disposed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  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. Therefore, there is a problem that the color purity of the generated single color is poor and high color reproducibility cannot be realized. In addition, the discharge lamp has a problem that it is necessary to take measures to compensate for the light quantity in the red wavelength band because the light quantity in the red wavelength band is not sufficient compared to the light quantity in the green and blue wavelength bands in the emission spectrum. It was.

  In spite of these problems, projection display devices that employ discharge lamps have recently become increasingly demanding for larger images projected on screens in the business market, etc. Increasing the amount of light emission is a problem. However, there is a limit to increasing the output of the light source, and at the same time, there is a problem that an increase in the amount of light that can be used effectively cannot be realized due to a decrease in efficiency when a plurality of light sources are used. Therefore, in order to solve the problem in the case where the above-described discharge lamp is employed, an attempt has been made to employ a semiconductor laser element array as an element of a light source particularly intended to increase output (see Patent Document 1). .

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

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

  When a semiconductor laser element is used as a light source, it can be turned on and off instantaneously as compared with the case where a discharge lamp is used, and has a feature of wide color reproducibility and long life. However, as the temperature of the semiconductor laser element rises, the light emission efficiency decreases and the crystal defects increase. Along with this, the ratio of non-emissive transition increases, so even in the transition mechanism that operates as the original light emission principle, heat is generated, the temperature of the element rises, and the light emission capability decreases at an accelerated rate, and the operating temperature If you don't manage it, it will lead to a shortened lifespan.

  The present invention is premised on a configuration for synthesizing three primary colors emitted from a semiconductor laser element array in which a plurality of semiconductor laser elements having such optical properties are arranged. Is provided with characteristics that are greatly affected by temperature, and when the temperature of the element changes, the wavelength, luminance, and emission spot diameter of the emitted light change. When such a state is reached, the amount of light of each color changes individually, resulting in a state where the white balance is lost. As a result, accurate color gradation expression cannot be performed, and contrast and the like are affected.

  Therefore, the semiconductor laser element array must be constantly maintained at a constant laser operation set temperature at which stable operation is maintained. For example, a semiconductor laser device can obtain a high output at a temperature relatively lower than room temperature (about 20 ° C.) and can maintain a long life, so that the laser operation set temperature is kept constant regardless of how the environmental temperature changes. A cooling means for maintaining the temperature is necessary, and it is ideal to keep the temperature within a range of ± 1 ° C., for example.

  However, the cooling means disclosed in Patent Document 1 has 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 that a plurality of semiconductor laser element arrays are provided for each of the three primary colors. It is not possible to employ the light source element having a configuration in which the individual semiconductor laser element arrays are temperature-controlled. Further, the cooling means disclosed in Patent Document 2 is difficult to grasp the temperature state of each semiconductor laser element, and is an extremely large-scale apparatus that is individually provided with a cooling refrigerant flow rate adjusting means. The leakage of the cooling medium is always a concern.

  Further, if the semiconductor laser element array is forcibly cooled to reach the laser operation set temperature, the temperature will be lower than the environmental temperature in the room or the like, so that dew condensation will inevitably occur. If the condensed water droplets generated in this way penetrate into the semiconductor laser element array, problems such as short-circuiting of the electrode wiring and a decrease in light emission output occur. Although the degree of such condensation varies depending on the environmental temperature and humidity, once condensation occurs and the water droplets adhere to the semiconductor laser element array, there is no way to remove them other than by natural evaporation. However, it is difficult to expect this during the period in which the apparatus is operating and the semiconductor laser element array is cooled, and therefore, even when condensation occurs, the semiconductor laser element array can be reliably protected from the influence. Must do so.

  Therefore, the present invention solves the above problems by means described below. That is, according to the first aspect of the present invention, a semiconductor laser element array in which a plurality of semiconductor laser elements are arranged on the same substrate is provided on a heat receiving plate, and a synthetic resin is provided at a portion where the semiconductor laser element array is provided. A layer is formed so as to be a light source element of the projection display apparatus.

  According to a second aspect of the present invention, a plurality of light source elements are arranged in a layered manner by arranging a semiconductor laser element array in which a plurality of semiconductor laser elements are arranged on the same substrate on a heat receiving plate, and the heat receiving plate is further cooled. A light source unit is formed by connecting to the means, and then a synthetic resin layer is formed in a portion where the semiconductor laser element array is disposed and a portion exposed to the outside air of the heat receiving plate to form a light source element of the projection display apparatus To be.

  According to a third aspect of the present invention, there is provided the light source element of the projection display apparatus according to the first or second aspect, wherein a synthetic resin layer is formed on a surface other than the light emitting surface of the semiconductor laser element array.

  According to a fourth aspect of the invention, there is provided a light source for the projection display apparatus according to the first or second aspect, wherein a synthetic resin is formed on a surface other than the contact surface between the semiconductor laser element array and the heat receiving plate. To do.

  5. A projection display apparatus in which projection light is obtained by modulating and synthesizing a plurality of laser beams according to image information, comprising the light source element according to any one of claims 1 to 4. Projection type image display device provided with a light source unit.

  According to the first aspect of the present invention, since the synthetic resin layer is formed on the outer surface exposed to the outside air of the semiconductor laser element array, the outside air is blocked by the synthetic resin layer. It is possible to prevent condensation on the outer surface.

  According to the second aspect of the present invention, since the synthetic resin layer is formed on the light source element after the light source unit is constructed, the assembly workability can be improved.

  According to the third aspect of the present invention, in addition to the effect of the first or second aspect, the light emitted from the semiconductor laser element array is effectively emitted without being blocked by the synthetic resin layer.

  According to the invention described in claim 4 of the present invention, in addition to the effect of the invention described in claim 1 or 2, the heat generated by the semiconductor laser element array is efficiently transmitted to the heat receiving plate, so that the semiconductor laser element array is effective. Cooling becomes possible.

  According to the fifth aspect of the present invention, the light source unit can be constituted by the light source elements which are not affected by dew condensation, and a highly reliable projection display apparatus can be provided.

  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 shows components of the light source unit. FIG. 4 shows the cooling structure of the light source unit, FIG. 5 shows an example of the cooling means, and FIG. 6 shows an example of the refrigerant piping. FIG. 7 is a perspective view showing a specific configuration of the light source element of the present invention, and a sectional view thereof is shown in FIG. FIG. 9 is a diagram for explaining the processing steps of the light source element of the present invention, and FIG. 10 shows another example of this processing step.

  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 lenses) 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 identically, and several tens or more semiconductor laser elements are provided at the tips of heat receiving plates 8a, 9a, and 10a formed of a metal having excellent thermal conductivity. The arrayed semiconductor laser element arrays 8b, 9b, 10b are fixed by, 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 primary color laser beams emitted from the thus configured semiconductor laser element arrays 8b, 9b, and 10b must be incident on the combining prism 2 with a predetermined amount of light. Therefore, it is important as a design problem to consider the amount of light emitted from each semiconductor laser element for each primary color, determine the number of elements to be arranged, or 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, this projection light exits from the exit surface 2S and is projected onto the screen via the projection lens L.

  Since the light source elements 8, 9, and 10 are configured as described above, the heat generated by the semiconductor laser element arrays 8b, 9b, and 10b is absorbed by the heat receiving plates 8a, 9a, and 10a. As shown in FIG. 3, one end of heat pipes 11, 12, and 13 bent in an L shape are fixed to the heat receiving plates 8a, 9a, and 10a, and the other ends of the heat pipes 11, 12, and 13 are heated. The heat sinks 14, 15, and 16 formed of a metal having excellent conductivity are fixed. The heat transported to the heat radiating plates 14, 15, 16 via the heat pipes 11, 12, 13 of the light source elements 8, 9, 10 is connected to the evaporator by means such as brazing as shown in FIG. Are absorbed by the heat exchange portions 17R-1, 17G-1, and 17B-1 of the refrigerant pipes 17R, 17G, and 17B.

  FIG. 5 is a diagram showing an example of a refrigerant circuit of a refrigerator that supplies the refrigerant to the light source unit 1 configured as described above, and constitutes a refrigerant compressor 30, a condenser 31, a decompressor 32, and an evaporator. The refrigerant pipes 17R, 17G, and 17B and the accumulator 33 are connected in an annular shape in this order. The high-temperature and high-pressure refrigerant compressed by the refrigerant compressor 30 in this refrigerant circuit is heat-exchanged with the outside air (in the case of air cooling) by the blower fan 34 of the condenser 31 and the temperature is lowered to become a low-temperature and high-pressure refrigerant. Subsequently, after the flow rate is reduced by the decompressor 32, the refrigerant pipes 17R, 17G, and 17B constituting the evaporator are evaporated. The heat radiating plates 14, 15 and 16 are cooled by the heat absorbing action at this time. In the decompressor 32, the squeeze is adjusted so that the evaporation temperatures of the refrigerant pipes 17R, 17G, and 17B constituting the evaporator are constant.

  FIG. 6 shows the heat sinks 14R, 17G-1 and 17B-1 connected to the heat exchangers 17R-1, 17G-1 and 17B-1 of the refrigerant pipes 17R, 17G and 17B constituting the evaporator omitted. Thus, the refrigerant pipes 17R, 17G, and 17B are independently configured so that the light source elements 8, 9, and 10 can be individually cooled. Therefore, if each evaporator (refrigerant pipes 17R, 17G, and 17B) is individually provided with a flow rate adjustment valve so that the flow rate of the refrigerant can be individually adjusted, the heat generation state of each of the light source elements 8, 9, and 10 is achieved. Even when they are different from each other, it is possible to appropriately cool the temperature and to control the temperature with high accuracy.

  As described above, the light source elements 8, 9, and 10 can be cooled to the laser operation set temperature by the cooling means as in the above example. In the present invention, the cooled light source elements 8, 9, and 10 are further cooled. Measures are taken when condensation occurs in As shown in FIG. 7, the light source elements 8, 9, and 10 include semiconductor laser element arrays 8 b, 9 b, and 10 b, a lower electrode 8 b-1 fixed to the heat receiving plates 8 a, 9 a, and 10 a with a heat conductive adhesive or the like. 9b-1, 10b-1 and upper electrodes 8b-2, 9b-2, 10b-2 are supported and modularized with the light emitting surface facing the tip.

  With this configuration, when the semiconductor laser element arrays 8b, 9b, and 10b are operated to generate heat, the generated heat is absorbed by the cooled heat receiving plates 8a, 9a, and 10a, and thereby the lower electrode 8b− 1, 9b-1, 10b-1 and upper electrodes 8b-2, 9b-2, 10b-2 are also cooled. When such a state is reached, there is a possibility that condensation occurs on the outer surface of each of the upper and lower electrodes which has become lower than the environmental temperature.

  If condensation occurs and the water droplets penetrate into the interior of each of the upper and lower electrodes or from the gaps between the light emitting surfaces of the semiconductor laser element arrays 8b, 9b, and 10b, the electrode wiring is short-circuited or the light emission output is reduced. Therefore, in the present invention, in order to protect the semiconductor laser element arrays 8b, 9b, and 10b from dew condensation, the portion where the semiconductor laser element arrays 8b, 9b, and 10b are disposed as shown in FIG. A synthetic resin layer R having low thermal conductivity is formed on the outer surfaces of 1, 9b-1, 10b-1 and upper electrodes 8b-2, 9b-2, 10b-2. The material of the synthetic resin layer has a high sealing property when an epoxy resin, a silicon resin or the like is used, and a high heat insulating property is obtained when a foamed resin is used.

  In this way, by forming the synthetic resin layer in the portion where the semiconductor laser element arrays 8b, 9b, and 10b are disposed, the semiconductor laser element arrays 8b, 9b, and 10b are sealed and insulated to avoid the influence of dew condensation. can do. In this case, as shown in FIG. 8, the synthetic resin layer R is not formed on the light emitting surfaces of the semiconductor laser element arrays 8b, 9b, and 10b, and the emitted light is effectively emitted without being blocked.

  When the synthetic resin layer R is applied after the light source unit is assembled as shown in FIG. 4, jigs J are attached to the individual light source elements 8, 9, and 10 as shown in FIG. In this case, the synthetic resin layer R is prevented from being formed on the light emitting surfaces of the semiconductor laser element arrays 8b, 9b, and 10b.

  As described above, according to the present invention, since the synthetic resin layer is formed on the portion of the heat receiving plate where the semiconductor laser element array is disposed, the semiconductor laser element array can be sealed and heat-insulated, and condensation occurs. Even in the situation, the semiconductor laser element array can be stably operated.

  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.

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 FIG. It is a perspective view which shows the component of the light source unit of FIG. It is a perspective view which shows the cooling structure of the light source unit of FIG. It is a figure which shows the example of the cooling means employ | adopted as this invention. It is a perspective view which shows the example of the light source unit refrigerant | coolant piping of FIG. It is a perspective view which shows the specific structure of the light source element of this invention. It is sectional drawing of the light source element completed by this invention. It is a figure explaining the processing process of the light source element of this invention. It is a figure explaining the other example of the manufacturing process of the light source element of this invention.

Explanation of symbols

P ... Projection type image display device L ... Projection lens J ... Jig R ... Synthetic resin layer 1 ... Light source unit 2 ... Synthetic prism 3R, 3G, 3B ... Liquid crystal panel 4R, 4G, 4B ... Incident side polarizing plate 5R, 5G, 5B ... Outgoing side polarizing plate 6R, 6G, 6B ... ..Condenser lenses 7R, 7G, 7B ... Integrators 8, 9, 10 ... Light source elements 8a, 9a, 10a ... Heat receiving plates 8b, 9b, 10b ... Semiconductor Laser element array

Claims (5)

  A projection characterized in that a semiconductor laser element array in which a plurality of semiconductor laser elements are arranged on the same substrate is disposed on a heat receiving plate, and a synthetic resin layer is formed at a site where the semiconductor laser element array is disposed. Type light source element A plurality of light source elements in which a semiconductor laser element array in which a plurality of semiconductor laser elements are arranged on the same substrate are arranged on a heat receiving plate are arranged in a hierarchy, and further the light receiving plate is connected to a cooling means to provide a light source unit. Configure
Thereafter, a synthetic resin layer is formed at a portion where the semiconductor laser element array is disposed and a portion exposed to the outside air of the heat receiving plate.   The light source element of the projection display apparatus according to claim 1, wherein a synthetic resin layer is formed on a surface other than the light emitting surface of the semiconductor laser element array.   3. The light source element of a projection display apparatus according to claim 1, wherein a synthetic resin is formed on a surface other than a contact surface between the semiconductor laser element array and the heat receiving plate. 5. A projection type image display apparatus in which projection light is obtained by modulating and synthesizing a plurality of laser beams according to image information. The projection type image display apparatus includes the light source element according to any one of claims 1 to 4. A projection display apparatus comprising a light source unit.

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