JP2005149943A - Light source device and projector using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device, etc. capable of stably illuminating with high luminance and uniformity by using an LED element. <P>SOLUTION: A light emitting unit 11 can irradiate illumination light with high luminance forward a plastic mold 15 by synthesizing light source light irradiated from three LED elements 12a, 12b, 12c with the same color. In this case, heat generated from these LED elements 12a-12c can be moved to a heat slag 13 side quickly so as to support the LED elements 12a-12c onto an upper surface 13a of the heat slag 13. Furthermore, since a Pelletier element 14 is connected to a lower surface 13b of the heat slag 13, the heat moved to the heat slag 13 can be absorbed by the Pelletier element 14 and discharge on a printed board PB side. Therefore, the unit 11 can keep the temperature of the slag 13 constant and keep the junction temperatures at respective LED elements 12a-12c constant. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light source device and a projector that projects an image using a light modulation device such as the light source device and a liquid crystal display panel.

As an illumination device for a liquid crystal display panel in a projector, there is an illumination device in which a planar light-emitting EL element is disposed facing a liquid crystal display panel and the EL element is cooled from the back (see Patent Document 1). Here, the EL element is connected to a flat-plate electronic cooling element via a layered heat sink, and is cooled to a constant temperature during light emission.
WO98 / 13725 publication

  However, in the above illumination device, when a high-luminance chip-like LED element is used instead of the EL element, uniform illumination with high luminance is not always easy. Further, when adjusting the amount of illumination light emitted from the EL element, the supply current to the EL element is adjusted. However, such current control causes a non-linear change in the amount of light and is not easy to control.

  Therefore, an object of the present invention is to provide a light source device capable of stably performing high-intensity and uniform illumination using an LED element, and a projector using the same.

  Another object of the present invention is to provide a light source device capable of easily and precisely controlling the light emission amount and a projector using the same.

  In order to solve the above problems, a light source device according to the present invention supports (a) a plurality of LED elements, and (b) a plurality of LED elements on one side, and heat from the plurality of LED elements on the other side. And (c) a single Peltier element that is connected to the other side of the heat conducting member and cools the other side of the heat conducting means.

  According to the light source device, a plurality of LED elements are supported on one side of the heat conducting member, and the other side of the heat conducting member is cooled by a single Peltier element. Moreover, these LED elements can be stably operated while temperature-controlled by a single Peltier element. At this time, since a single Peltier element is used, the temperature difference between these LED elements can be reduced by cooperation with the heat conducting means.

  In a specific aspect of the invention, in the light source device described above, a plurality of LED elements, a heat conductive member, and a Peltier element are embedded in a package. In this case, the light emitting unit made up of LED elements and the like and the cooling unit such as Peltier elements can be handled as an integral unit, and such a unit can be mounted on a circuit board or the like.

  In another specific aspect of the invention, the plurality of LED elements generate light sources having the same color. In this case, it is possible to provide a light source device that increases the light emission luminance of a specific color.

  In still another specific aspect of the invention, the plurality of LED elements generate light sources of different colors. In this case, it is possible to provide a light source device (for example, a white light source device) in which the emission luminance of a plurality of colors is increased.

  In still another specific aspect of the invention, the heat conducting member is a heat slug that also serves as a mirror. In this case, the heat emitted from the plurality of LED elements can be absorbed by the heat slag, and the light emitted backward can be turned back to the front side by the heat slag, so that the illumination light from the LED elements can be efficiently used and the LED elements can be efficiently used. Cooling and can be achieved.

  According to still another specific aspect of the present invention, an auxiliary drive circuit that controls the light emission luminance of the plurality of LED elements by adjusting the cooling operation by the Peltier element is further provided. In this case, the junction temperature of the LED element is adjusted by the auxiliary drive circuit, but the control of the light emission luminance of the LED element via the junction temperature of the LED element is relatively stable and relatively linear. The control of the light emission luminance of the LED element becomes precise.

  In still another specific aspect of the invention, the light emission luminance of the plurality of LED elements is monitored and the light emission luminance is fed back to the auxiliary drive circuit. In this case, more precise light quantity control is possible by feedback control.

  The first projector according to the present invention is illuminated by (a) the light source device according to any one of claims 1 to 7 that emits illumination light, and (b) illumination light from the light source device. And (c) a projection optical system that projects image light from the light modulation device.

  In the first projector, since the light source device of the present invention having the above-described features is used, the light modulation device can be made bright and stable by efficiently using high-intensity illumination light from a plurality of LED elements. It is possible to illuminate with the illuminating light, and to project an image with high brightness and high image quality.

  The second projector according to the present invention includes: (a) a light source device for each color according to any one of claims 1 to 7 that emits illumination light of each color; and (b) illumination for each color. A light modulating device for each color illuminated by light, (c) a light combining member for combining and emitting image light of each color from each light modulating device, and (d) a projection for projecting image light that has passed through the light combining member And an optical system.

  Since the second projector also uses the light source device of the present invention having the above-described features, the light modulation device can be brightly and stably used by efficiently using high-intensity illumination light from a plurality of LED elements. The illumination light can be illuminated, and a color image with high brightness and high image quality can be projected.

[First Embodiment]
FIGS. 1A and 1B are a side sectional view and a plan view showing the structure of a main part, that is, a light emitting unit of a light source device according to a first embodiment of the present invention.

  The illustrated light emitting unit 11 includes three LED elements 12a, 12b, and 12c that are light emitting sources, a heat slag 13 that supports the three LED elements 12a, 12b, and 12c on an upper surface 13a, and the heat slag 13 And a single Peltier element 14 connected to the lower surface 13b. Among them, the LED elements 12a, 12b, 12c and the upper part of the heat slag 13 are entirely covered and sealed by a transparent plastic mold 15, and the lower part of the heat slag 13 and the side of the Peltier element 14 Is covered with an opaque plastic mold 16.

  Each of the LED elements 12a, 12b, and 12c is a semiconductor chip having the same structure in which discrete light emitting elements are individually formed, and each generates light source light having the same wavelength, for example, red light. Such light source light is emitted in the front direction through the plastic mold 15. The wiring L1 drawn from the chip of each LED element 12a, 12b, 12c is connected to the cathode wiring L2 and the anode wiring L3. These cathode wiring L2 and anode wiring L3 are appropriately attached to the upper surface 13a of the heat slug 13, and are drawn out from the lower side surface of the plastic mold 15.

  The heat slug 13 is a heat conducting member made of an aluminum material having a disk-like outer shape. The heat slug 13 supports the LED elements 12a, 12b, and 12c in an appropriate arrangement by fixing the LED elements 12a, 12b, and 12c to the upper surface 13a using an adhesive layer AD made of an epoxy resin or the like. To do. The upper surface 13a of the heat slug 13 is a concave reflecting surface, and the light source light emitted rearward from the LED elements 12a, 12b, 12c is reflected to the front side.

  The Peltier element 14 is a single cooling unit enclosed in a package, and incorporates a cooling module using the Peltier effect. The upper surface 14a of the Peltier element 14 is a cooling surface, and the lower surface 14b is a heat dissipation surface. A bonding layer 17 made of silver paste or silicone is formed between the upper surface 14a of the Peltier element 14 and the heat slag 13, and the heat from the heat slag 13 is transmitted to the Peltier element 14 side to be absorbed here. It can be done. On the flat lower surface 14b side of the Peltier element 14, a thermal bonding electrode 14d is formed over the entire surface. This thermal bonding electrode 14d is brought into close contact with and bonded to the thermal bonding electrode 18a provided on the wiring board PB by appropriate heating. Thereby, the heat generated on the lower surface 14b side of the Peltier element 14 can be released to the wiring board PB. Note that wiring patterns 18c and 18d are also formed on the wiring board PB, and a pair of wirings L5 and L6 drawn from the Peltier element 14 are connected.

  According to the light emitting unit 11 as described above, illumination light with high luminance can be emitted in front of the plastic mold 15 by combining light source light emitted from the three LED elements 12a, 12b, and 12c of the same color. At this time, since the three LED elements 12a, 12b, and 12c are supported on the upper surface 13a of the heat slug 13, the heat generated from the LED elements 12a, 12b, and 12c can be quickly moved to the heat slug 13 side. it can. Further, since the Peltier element 14 is bonded to the lower surface 13b of the heat slag 13, the heat transferred to the heat slag 13 can be absorbed by the Peltier element 14 and released to the wiring board PB side. Thereby, the temperature of the heat slug 13 can be kept constant, for example, and the junction temperature in each LED element 12a, 12b, 12c can be kept constant, so that each LED element 12a, 12b, 12c is stabilized. It can be made to emit light in the state. If a temperature sensor is embedded in the heat slug 13, the temperature of the heat slug 13 and the LED elements 12a, 12b, 12c can be kept constant by feedback control using the output of the temperature sensor.

  FIG. 2 is a block diagram illustrating a light source device including the light emitting unit 11 shown in FIG. 1 and a circuit for operating the light emitting unit 11. First, the LED elements 12a, 12b, and 12c are connected in series and are supplied with power from the constant current source 61, and a constant current flows through each of the LED elements 12a, 12b, and 12c. That is, each LED element 12a, 12b, 12c is driven with the same current and emits light substantially equally. The Peltier element 14 is connected to a variable voltage type Peltier element power supply 62 that operates as an auxiliary drive circuit, and a voltage necessary for the intended cooling operation is applied to the Peltier element 14. The light source light SL emitted from the LED elements 12a, 12b, and 12c cooled by the Peltier element 14 is monitored by a luminance sensor 63 disposed in a side position that does not block the optical path in the front direction of the light emitting unit 11 shown in FIG. Is done. The luminance sensor 63 is formed of a photodiode or the like, and generates a current signal from the light source light emitted from the LED elements 12a, 12b, and 12c according to the luminance. The output of the luminance sensor 63 is moderately amplified by the amplifier 64, converted into a voltage signal, and input to the control terminal T1 of the Peltier element power supply 62. In the Peltier element power supply 62, the input signal to the control terminal T1 is compared with a predetermined value. If the input signal is larger than the predetermined value, the supply voltage to the Peltier element power supply 62 is appropriately set as excessive luminance. Reduce. As a result, the cooling efficiency of the Peltier element 14 is lowered and the temperature of each LED element 12a, 12b, 12c is increased, so that the light emission luminance of each LED element 12a, 12b, 12c is lowered. On the other hand, when the input signal is smaller than a predetermined value, the supply voltage to the Peltier element power supply 62 is appropriately increased as the luminance is too low. As a result, the cooling efficiency of the Peltier element 14 is increased and the temperature of each LED element 12a, 12b, 12c is decreased, so that the light emission luminance of each LED element 12a, 12b, 12c is increased. In the above description, the luminance sensor 63, the amplifier 64, and a part of the Peltier element power supply 62 constitute feedback means for controlling the emission luminance of the LED elements 12a, 12b, and 12c.

  More specifically, when each of the LED elements 12a, 12b, and 12c is, for example, G light, when the junction temperature changes by 20 ° C., the light emission luminance changes by about 10%. Further, when each LED element 12a, 12b, 12c is, for example, R light, when the junction temperature changes by 20 ° C., the light emission luminance changes by about 15%. However, when each LED element 12a, 12b, 12c is B light, for example, even if the junction temperature changes by 20 ° C., the light emission luminance hardly changes. That is, the luminance control using the Peltier element power supply 62 is suitable for the luminance control of G light and R light.

  When it is desired to forcibly change the light emission luminance of the light emitting unit 11, the predetermined value programmed in the Peltier element power source 62, that is, the reference value of the input signal input to the control terminal T1 may be changed. In the above description, the LED elements 12a, 12b, and 12c are connected in series to the constant current source 61. However, they can be connected to the constant current source 61 in parallel.

  In the above description, the output of the luminance sensor 63 is fed back to the Peltier element power source 62. However, the output of the luminance sensor 63 can also be fed back to the constant current source 61. For example, in the case of B light whose light emission luminance is less dependent on temperature, luminance control is relatively easy.

[Second Embodiment]
FIG. 3 is a block diagram illustrating the projector according to the second embodiment. The projector according to the present embodiment is an apparatus in which the light source device shown in FIGS. 1 and 2 is incorporated.

  The projector 10 includes a lighting device 20, a light modulation device 30, a projection lens 40, and a control device 50. Here, the illuminating device 20 includes a G light illuminating device 21, a B light illuminating device 23, and an R light illuminating device 25 as illuminating units for each color, and a light source driving device 27 for driving them. . The light modulation device 30 outputs drive signals to the three liquid crystal light valves 31, 33, and 35 that are spatial light modulation devices, the cross dichroic prism 37 that is a light combining member, and the liquid crystal light valves 31, 33, and 35. And an element driving device 38.

  In the illumination device 20, the G light illumination device 21 includes a G light source unit 21a and a rod integrator 21b. Among these, the G light source unit 21a is composed of a light emitting unit 11G having a structure similar to that of the light emitting unit 11 shown in FIG. A member 21h is provided on the front side. In this case, the light emitting unit 11G generates G light included in the category of green (G) among the three primary colors. The G light extracted from the light emitting unit 11G, that is, the first light source light LG passes through the condensing optical member 21h and the rod integrator 21b, and then enters the liquid crystal light valve 31 for G light in the light modulator 30. Thereby, the irradiated area on the liquid crystal light valve 31 is illuminated uniformly with the G light.

  The B light illumination device 23 includes a B light source unit 23a and a rod integrator 23b. Among these, the light source unit for B light 23a is composed of a light emitting unit 11B having the same structure as that of the light emitting unit 11 shown in FIG. A member 23h is provided on the front side. In this case, the light emitting unit 11B generates B light included in the blue (B) category of the three primary colors. The B light extracted from the light emitting unit 11B, that is, the second light source light LB passes through the condensing optical member 23h and the rod integrator 23b, and then enters the liquid crystal light valve 33 for B light in the light modulation device 30. Thereby, the irradiated area on the liquid crystal light valve 33 is uniformly illuminated by the B light.

  The R light illumination device 25 includes an R light source unit 25a and a rod integrator 25b. Among these, the R light source unit 25a is composed of a light emitting unit 11R having the same structure as the light emitting unit 11 shown in FIG. A member 25h is provided on the front side. In this case, the light emitting unit 11R generates R light included in the red (R) category of the three primary colors. The R light extracted from the light emitting unit 11R, that is, the third light source light LR passes through the condensing optical member 25h and the rod integrator 25b, and then enters the R light liquid crystal light valve 35 in the light modulator 30. Thereby, the irradiated area on the liquid crystal light valve 35 is illuminated uniformly with the R light.

  Although not described above, in the light source driving device 27 constituting the lighting device 20, a circuit similar to the constant current source 61, the Peltier element power source 62, the luminance sensor 63, etc. shown in FIG. A deformed circuit is incorporated for each color, and the light source light LG, LB, LR of each color is controlled to have a stable desired luminance.

  In the light modulation device 30, the liquid crystal light valves 31, 33, and 35 two-dimensionally modulate the illumination light from the color light illumination devices 21, 23, and 25 incident thereon to form image light of each color. . Note that the image lights of the respective colors that have passed through the liquid crystal light valves 31, 33, and 35 are combined by the cross dichroic prism 37 and emitted from one side surface thereof. The combined light image emitted from the cross dichroic prism 37 enters the projection lens 40 which is a projection optical system, and is projected on a screen (not shown) at an appropriate magnification. That is, the projector 10 projects a color image obtained by combining the images of the colors G, B, and R formed on the liquid crystal light valves 31, 33, and 35 onto the screen as a moving image or a still image. Although not shown, polarizing plates are arranged at appropriate positions around the liquid crystal light valves 31, 33, 35 in order to illuminate and read the liquid crystal light valves 31, 33, 35 with polarized light. ing.

  The control device 50 outputs a control signal to the light source driving device 27, and each light emitting unit 11G, 11B constituting the first to third light source units 21a, 23a, 25a provided in each color light illumination device 21, 23, 25. , 11R are caused to emit light at an appropriate timing corresponding to the projection of the color image. Further, the control device 50 outputs a control signal to the element driving device 38 to form a two-dimensional polarization characteristic distribution corresponding to the brightness of the projected image on each of the liquid crystal light valves 31, 33 and 35.

  Hereinafter, the operation of the projector 10 shown in FIG. 1 will be described. The illumination lights of the respective colors from the GBR light illumination devices 21, 23, and 25 provided in the illumination device 20 are incident on the corresponding liquid crystal light valves 31, 33, and 35, respectively. Each of the liquid crystal light valves 31, 33, and 35 has a two-dimensional refractive index distribution modulated by an element driving device 38 that operates according to an image signal from the outside, and two-dimensional spatial distribution of illumination light of each color. Is modulated in units of pixels. As described above, the illumination light, that is, the image light modulated by the liquid crystal light valves 31, 33, and 35 is combined by the cross dichroic prism 37 and then enters the projection lens 40 which is a projection optical system and is projected onto the screen. . In this case, each color light illuminating device 21, 23, 25 uses the light emitting units 11G, 11B, and 11R having the structure shown in FIG. 1 to control the circuit as shown in FIG. Light can be generated, and a stable and good white balance color image can be formed on the screen with high brightness.

  As described above, the present invention has been described according to the embodiment, but the present invention is not limited to the above embodiment. For example, the number of LED elements incorporated in the light emitting units 11, 11G, 11B, and 11R can be an arbitrary number of 2 or more. In this case, it is desirable to arrange the LED elements evenly around the optical axis.

  In the above embodiment, the three liquid crystal light valves 25a to 25c are illuminated with RGB colors. However, the color display panel is a single liquid crystal light valve or the like in which RGB filters are arranged in each pixel. The light emitting unit 11 shown in FIG. In this case, each LED element 12a, 12b, 12c is made to emit light in each color of GBR.

(A), (b) is a figure explaining the light source device which concerns on 1st Embodiment. It is a block diagram explaining the circuit for operating the light emission unit of FIG. It is a block diagram of the projector which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Projector, 11, 11G, 11B, 11R ... Light emission unit, 12a, 12b, 12c ... LED element, 13 ... Heat slug, 14 ... Peltier element, 15, 16 ... Plastic mold, 20 ... Illuminating device, 21, 23 25 ... Each color light illuminating device, 21a, 23a, 25a ... Light source unit, 27 ... Light source driving device, 30 ... Light modulation device, 31, 33, 35 ... Liquid crystal light valve, 37 ... Cross dichroic prism, 40 ... Projection lens, 61 ... Constant current source, 62 ... Power supply for Peltier element, 63 ... Luminance sensor, 64 ... Amplifier

Claims (9)

A plurality of LED elements;
While supporting the plurality of LED elements on one side, a heat conducting member that transmits heat from the plurality of LED elements to the other side,
A light source device comprising: a single Peltier element connected to the other side of the heat conducting member and cooling the other side of the heat conducting means.   The light source device according to claim 1, wherein the plurality of LED elements, the heat conducting member, and the Peltier element are embedded in a package.   The light source device according to claim 1, wherein the plurality of LED elements generate light sources of the same color.   The light source device according to claim 1, wherein the plurality of LED elements generate light sources of different colors.   The light source device according to claim 1, wherein the heat conducting member is a heat slug that also serves as a mirror.   The light source device according to any one of claims 1 to 5, further comprising an auxiliary drive circuit that controls light emission luminance of the plurality of LED elements by adjusting a cooling operation by the Peltier element.   The light source device according to claim 6, further comprising feedback means for monitoring the light emission luminance of the plurality of LED elements and feeding back the light emission luminance to the auxiliary drive circuit. The light source device according to any one of claims 1 to 7, which emits illumination light;
A light modulation device illuminated by illumination light from the light source device;
A projector comprising: a projection optical system that projects image light from the light modulation device. The light source device for each color according to any one of claims 1 to 7, wherein each color illumination light is emitted.
A light modulation device for each color illuminated by each color illumination light;
A light combining member that combines and emits image light of each color from the light modulation device of each color;
A projector comprising: a projection optical system that projects image light that has passed through the light combining member.

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