JP2007149469A - Light source device, direct-viewing picture display device, and projecting display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device which cools a light source to offer pulse lighting so as to keep the light source in a proper temperature condition, prevents a light emitting efficiency of the light source from decreasing, and realizes improvement in service life of the light source. <P>SOLUTION: The light source comprises a light emitting diode 110 which emits light by being supplied with a current; a Peltier device 130 which performs a heat-absorption operation to cool the light source by being supplied with a current; and power sources 201, 202 which supply a driving current for the light emitting diode 110 to the light emitting diode 110, and supply a driving current for the Peltier device 130 to the Peltier device 130, where the driving current for the light emitting diode 110 is a periodic pulse current, and the driving current for the Peltier device 130 is a periodic pulse current having a shorter rise time than the pulse current of the driving current for the light emitting diode 110. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light source device, a direct-view image display device, a projection display device, and the like.

  In recent years, as a light source for direct-view liquid crystal display devices and projection display devices (projectors) capable of large-screen display, it emits monochromatic light with high color purity and can realize a larger color reproduction range than conventional mercury lamps. Solid state light sources such as light emitting diodes and semiconductor lasers have attracted attention.

  Also, in light source devices of image display devices, in order to provide high-quality images even in a bright room, brighter illumination is required, and multiple solid light sources are used, or the amount of current applied to the solid light sources Studies such as increasing the Such use increases the heat generation amount of the solid-state light source light emitting part, and technical means for preventing this are required. Therefore, a cooling method of the light source using a cooling means such as a thermoelectric conversion element (Peltier element) that can be cooled more powerfully by supplying electric power so that the temperature of the light emitting portion does not exceed a certain temperature has been studied. (For example, refer to Patent Document 1).

  FIG. 8 is an example of a configuration diagram of a light source device having such a solid light source and a Peltier element. FIG. 9 is a partially enlarged view of the Peltier element. As shown in FIG. 8, the light source device is connected in series with a light emitting diode 110 including a light emitting unit 101 that is a light source of a semiconductor chip, a Peltier element 130 that is a thermoelectric conversion element, and the light emitting diode 110 and the Peltier element 130. And a power supply 90 for supplying power to them.

  The light emitting diode 110 energizes the pedestal 103 formed of a metal material having high thermal conductivity, the first adhesive layer 102 that joins the chip of the light emitting unit 101 and the pedestal 103, and the light emitting unit 101 in the light emitting diode 110. An electrode 104 electrically connected to an electrode (not shown) for bonding, a metal substrate 106 for enhancing thermal conductivity, a pedestal 103 for fixing a semiconductor chip of the light emitting unit 101, and the metal substrate 106 are joined. The second adhesive layer 105 and the resin lens 108 covering the light emitting portion 101 are configured.

  Further, as shown in FIG. 9, the Peltier element 130 includes an n-type and p-type semiconductor connected to a semiconductor layer 122 formed in series via an electrode 121 on the ceramic 120 side and an electrode 123 on the ceramic substrate 124 side. By causing electricity to flow, a temperature difference is generated between the upper electrode 121 and the lower electrode 123. The ceramic 120 and the ceramic substrate 124 are provided so as to be insulated from the upper and lower electrodes 121 and 123, and are cooled. Is a smooth surface.

  The Peltier device 130 can reverse the temperature lowering surface and the temperature rising surface by reversing the current direction. However, when power is supplied from the power supply 90, the Peltier element 130 is connected so that the light emitting diode 110 side becomes the temperature lowering surface. Has been.

  In such a light source device, when the temperature of the light emitting unit 101 is highest during light emission, and the maximum temperature point reached during the light emission exceeds a specific allowable temperature, the light emitting diode itself may be destroyed. In addition, even if the temperature of the light emitting part is within the allowable range, the higher the temperature of the light emitting part, the lower the light emission efficiency during light emission, the wavelength shift occurs, and the maximum reached temperature during light emission. If the use in a high state continues, there is a problem that the life is shortened. Therefore, the Peltier element 130 is operated to cool the light emitting unit 101 in the light emitting diode 110.

  On the other hand, the solid light source has a feature that can be switched on and off at high speed (hereinafter referred to as pulse lighting), and does not need to be continuously lit. Therefore, a so-called field-sequential image display method that forms images with low power consumption by sequentially turning on red, green, and blue light sources and mixing colors in a time-sharing manner during one image display period is possible. It is.

  When performing time-division lighting as in the field sequential method, the conventional light source device connects the light emitting diode 110 and the Peltier element 130 in series, shares the power supply 90, and generates a periodic pulse current from the light emitting diode 110 and the Peltier element. 130. Accordingly, the light emitting diode 110 is turned on, and the Peltier element 130 is also operated in synchronization with the lighting of the light emitting diode 110.

According to this, the heat absorption operation of the Peltier element 130 is performed following the lighting of the light emitting diode 110, and even when the light amount of the light emitting diode 110 is increased, the efficiency of the Peltier element 130 is increased accordingly, and heat generation is performed. The ratio of the amount and endotherm can be automatically maintained. In addition, since the operation of the Peltier element 130 is stopped during the non-lighting period of the light emitting diode 110, an effect of reducing power consumption can be obtained.
JP 2004-342557 A

  However, when the operation is performed with the configuration of the above-described conventional light source device, the electrode 104 of the light emitting diode 110 and the electrode 104 of the Peltier element 130 and the light emitting diode 110 are insulated between the light emitting diode 110 and the Peltier element 130. 9 is interposed between the ceramic 120, which is an insulator to be used, and the electrode 120 in the Peltier element 130 and the ceramic 120, and an intermediate layer composed of an adhesive layer 190 such as solder shown in FIG. However, there is a time delay until the heat absorption from the Peltier element 130 is transmitted to the light emitting part of the light emitting diode 110 that is most necessary.

  FIG. 10 is a time chart for explaining the operation of the conventional light source device. FIG. 10A shows the change over time of the current value supplied from the power supply 90 to the Peltier element 130. FIG. 10B shows the change over time of the current value supplied from the power supply 90 to the light emitting diode 110. FIG. 10C shows a change over time in the amount of movement of heat generated in the Peltier element 130 by supplying a current from the power supply 90. FIG. 10D shows a change over time in the amount of heat transferred by the light emitting unit 101 of the light emitting diode 110 when the Peltier element 130 is driven. FIG. 10E shows a temporal change in the amount of movement of heat generated in the light emitting unit 101 by supplying a current from the power supply 90. FIG. 10F shows a change over time of the temperature of the light emitting unit 101 caused by light emission of the light emitting diode 110 and heat absorption by driving the Peltier element 130.

  As shown in FIGS. 10A and 10B, the currents supplied to the light emitting diode 110 and the Peltier element 130 are synchronized, and the phase and period are matched, that is, the rising edges of the pulses are completely matched. For this reason, heat absorption by driving the Peltier element 130 (FIG. 10D) and heat generation by driving the light emitting diode 110 (FIG. 10E) occur simultaneously, but the heat absorption action of the Peltier element 130 is caused by the light emitting diode 110. The time delay described above occurs until the light emitting unit 101 that is the heat source is reached. Therefore, the actual temperature change in the light emitting unit 101 becomes steep from the initial state as shown in FIG. Further, as shown in FIGS. 10A and 10B, when the heat absorption amount of the Peltier element 130 is smaller than the heat generation amount generated from the light emitting portion 101 of the light emitting diode 110, the heat absorption action of the Peltier element 130 causes the intermediate layer to be absorbed. Even after reaching the light emitting unit 101, the temperature rise of the light emitting unit continues while the temperature rise of the light emitting unit becomes moderate. After the light emission of the light emitting unit is finished, the temperature of the light emitting unit starts to decrease. However, sufficient cooling is not performed, and the Peltier element 130 ends the driving period in one cycle. The light emitting unit 101 reaches the next driving cycle in a state where the temperature is higher than the initial state. In the next driving cycle, the movement of the amount of heat between the Peltier element 130 and the light emitting unit 101 is the same as described above. Therefore, the heat that could not be moved by driving the Peltier element 130 is further retained in the light emitting unit 101. As a result, the temperature of the light emitting unit 101 continues to rise stepwise and exceeds the temperature range suitable for operation.

  Thus, in the conventional light source device, the temperature rises sharply from the start of light emission. Further, when the amount of heat absorbed by the Peltier element 130 is small compared to the amount of heat generated from the light emitting part 101 of the light emitting diode 110, the temperature gradually decreases after the endothermic action of the Peltier element 130 reaches the light emitting part 101 through the intermediate layer. The rise continues. Therefore, the highest temperature point reached at the time of light emission becomes considerably high. Further, the light emitting unit 101 also rises in steps due to heat that remains due to insufficient cooling within one cycle, so that the light emitting diode 110 itself is destroyed when it exceeds a specific allowable temperature, or lighting failure occurs. There is a risk of shortening the lifetime, and even within the permissible temperature, there is a possibility that a change in light emission amount due to a change in light emission efficiency during the light emission period and a wavelength shift of light may occur.

  As shown in the time chart of FIG. 11, even if the amount of heat generated from the light emitting portion 101 of the light emitting diode 110 is substantially equal to the amount of heat absorbed by the Peltier element 130 (compare FIGS. 11A and 11B). Reference and other conditions (timing shown in FIGS. 11 (c) to 11 (e) are the same as those in FIG. 10), as shown in FIG. 11 (f), the endothermic action of the Peltier element 130 passes through the intermediate layer. Although the temperature does not increase stepwise due to the gradual temperature increase after reaching the light emitting unit 101 and the heat accumulated during each light emission, the maximum temperature point reached by the rapid temperature increase from the start of light emission is There is a risk of exceeding a specific allowable temperature due to the extremely high level, a change in light emission amount during a light emission period, and a wavelength shift of light.

  As described above, in the conventional light source device, the waveform of the current supplied to the Peltier element 130 and the waveform of the current supplied to the light emitting diode 110 coincide with each other, and these are synchronized to operate the light emitting unit 101. Therefore, there is a problem that it is difficult to keep the temperature state appropriate.

  This invention is made | formed in view of such a subject, and it aims at providing the light source device etc. which can be cooled so that a light source may be maintained at a suitable temperature state.

One of the objects is achieved by the following light source device. That is, a light source that emits light when current is supplied;
A thermoelectric conversion element that absorbs heat and cools the light source by being supplied with current;
A light source driving current consisting of a periodic pulse current is supplied to the light source, and a thermoelectric conversion element driving current consisting of a periodic pulse current rising earlier than the rise of the pulse current of the light source driving current is supplied to the thermoelectric conversion element. A light source device including a power source.

  One of the above objects is achieved by the following light source device. That is, the time difference between the rise of the pulse current of the thermoelectric conversion element drive current and the rise of the pulse current of the light source drive current corresponds to the time required for heat transfer from the thermoelectric conversion element to the light source. .

  One of the above objects is achieved by the following light source device. That is, in the light source device, a heat generation amount of the light source in one cycle of the light source driving current and a heat absorption amount by the thermoelectric conversion element in one cycle of the thermoelectric conversion element driving current are substantially the same.

  One of the above objects is achieved by the following light source device. That is, in the light source device, an amount of heat absorbed by the thermoelectric conversion element in one cycle of the thermoelectric conversion element driving current is larger than a heat generation amount of the light source in one cycle of the light source driving current.

  One of the above objects is achieved by the following light source device. That is, the amount of heat absorbed by the thermoelectric conversion element in one cycle of the thermoelectric conversion element driving current is the sum of the amount of heat generated by the light source in one cycle of the light source driving current and the amount of heat received by the light source from other than the thermoelectric conversion element. The light source device is substantially the same.

  One of the above objects is achieved by the following light source device. That is, the thermoelectric conversion element drive current is the light source device described above, wherein the current value is larger than 0 even at the falling edge of the pulse current.

  One of the above objects is achieved by the following light source device. That is, during a period in which the one pulse current of the light source driving current is supplied, a heat generation amount per unit time of the light source and a heat absorption amount per unit time absorbed from the light source by the thermoelectric conversion element The light source device is substantially equal.

  One of the above objects is achieved by the following light source device. That is, in the light source device, the pulse width of the thermoelectric conversion element driving current is substantially the same as the pulse width of the light source driving current.

  One of the above objects is achieved by the following light source device. That is, in the light source device, the waveform of the thermoelectric conversion element driving current and the waveform of the light source driving current are in an expansion or contraction relationship in the current value direction.

One of the objects is achieved by the following direct-view image display device. That is, the light source device,
A transmissive display panel that transmits light obtained from the light source device and displays an image;
Direct-view image display device A direct-view image display device.

One of the above objects is achieved by the following projection display device. That is, the light source device,
The projection display device includes a video display element that forms an image by transmitting or reflecting light obtained from the light source device.

  One of the above objects is achieved by the following light source cooling method. That is, a light source driving current consisting of a periodic pulse current is supplied to the light source, and a thermoelectric conversion element driving current consisting of a periodic pulse current rising earlier than the rise of the pulse current of the light source driving current is supplied to the thermoelectric conversion element. It is the cooling method of a light source provided with the process to supply.

  One of the above objects is achieved by the following program. That is, in the cooling method of the light source, a light source driving current consisting of a periodic pulse current is supplied to the light source, and a thermoelectric conversion element driving consisting of a periodic pulse current that rises earlier than the rise of the pulse current of the light source driving current It is a program for making a computer perform the process of supplying an electric current to the said thermoelectric conversion element.

  One of the above objects is achieved by the following recording medium. That is, it is a recording medium on which the program is recorded, and can be processed by a computer.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the light source device etc. which can be cooled so that a light source may be maintained at a suitable temperature state.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a schematic configuration diagram showing a light source device according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the configuration of the light emitting diode and the Peltier element in the light source device according to the first embodiment is the same as that of the conventional example except for the configuration of the control part described later. Detailed description will be omitted. In the present embodiment, a light emitting diode driving power supply 201 that supplies a light emitting diode driving current composed of a periodic pulse current to the light emitting diode 110, and a periodic pulse current that rises earlier than the rising of the pulse current of the light emitting diode driving current. And a Peltier element driving power source 202 for supplying a Peltier element driving current to the Peltier element 130. The present embodiment further includes pulse control means 203 for controlling the current waveform of the Peltier element driving current and the current waveform of the light emitting diode driving current. The pulse control means 203 can adjust the delay time of the rising timing of the pulse current of the light emitting diode driving current with respect to the rising timing of the pulse current of the Peltier device driving current.

  In the above configuration, the light emitting unit 101 of the light emitting diode 110 is the light source of the present invention, the Peltier element 130 is the thermoelectric conversion element of the present invention, the light emitting diode driving power supply 201 and the Peltier element driving power supply 202 are the power supply of the present invention. The LED driving current corresponds to the light source driving current of the present invention, and the Peltier element driving current corresponds to the thermoelectric conversion element driving current of the present invention. In the following description, the light-emitting diode 110 is used as the light source. However, the light source of the present invention may be a solid-state light source such as a semiconductor laser or a light source capable of high-speed pulse driving by an electric signal such as a laser.

  Hereinafter, the operation of the light source device having the above-described configuration according to the first embodiment of the present invention will be described, and an embodiment of the light source cooling method of the present invention will be described.

  FIG. 2 is a diagram showing a time chart for explaining the operation of the light source device of the present embodiment. FIG. 2A shows a change over time of the current value of the Peltier device driving current. FIG. 2B shows a time change of the current value of the light emitting diode driving current. FIG. 2 (c) shows a change over time in the amount of heat absorbed per unit time of the Peltier element 130. FIG. 2D shows a change over time in the amount of heat per unit time absorbed by the Peltier element 130 from the light emitting diode 110. FIG. 2E shows the change over time in the amount of heat generated per unit time of the light emitting diode 110. FIG. 2F shows a temperature change of the light emitting unit 101 caused by light emission of the light emitting diode 110 and heat absorption due to driving of the Peltier element 130.

  First, a light emitting diode driving current is supplied to the light emitting diode 110 from the light emitting diode driving power source 201 through the electrode 104 (FIG. 2B). The light emitting diode driving current is composed of a periodic pulse current. The light emitting unit 101 is turned on in synchronization with the periodic pulse current of the light emitting diode driving current. The light emission response time for the supply current at this time varies greatly depending on the drive circuit and system configuration, but the rise and fall times can be 1 μs or less, which is very fast. This is possible with the power supply.

  In synchronization with this lighting, heat is generated in the light emitting unit 101 (FIG. 2E). The heat generated in the light emitting unit 101 is transferred to the first adhesive layer 102, the pedestal 103 for holding the light emitting unit, the second adhesive layer 105, and the metal substrate 106 having a larger cross-sectional area and higher thermal conductivity than the pedestal 103. And is diffused to the ceramic 120 on the cooling surface side of the Peltier element 130 through the third adhesive layer 107.

  In a solid-state light source such as the light emitting diode 110, if appropriate cooling is not performed, the temperature of the light emitting unit 101 may exceed a specific allowable temperature, and the light emitting diode 110 itself may be destroyed. Even when the temperature of the light emitting unit 101 is within the allowable range, there is a problem that the higher the temperature is, the lower the light emission efficiency, the light wavelength shift occurs, or the lifetime becomes shorter.

  In the present embodiment, the light emitting diode 110 is appropriately cooled by the Peltier element 130. A Peltier element driving current is supplied from the Peltier element driving power source 202 to the Peltier element 130 (FIG. 2A). The Peltier device driving current is composed of a periodic pulse current. The rise of the pulse current of the Peltier element driving current rises earlier by the time T1 than the rise of the pulse current of the light emitting diode driving current. The Peltier device 130 absorbs the heat of the electrode 121 on the cooling surface side in synchronization with the periodic pulse current of the light-emitting diode driving current (FIG. 2C).

  As described with reference to FIGS. 11A to 11F, even if a current is supplied to the Peltier element 130 and cooling is started, the cooling-side electrode 121 of the Peltier element 130 and the light-emitting part of the light-emitting part 101 In between, there is an intermediate layer composed of a plurality of members such as the ceramic 120 and the metal substrate 106 described above. Since the intermediate layer includes a metal having a high thermal conductivity, a material having a thermal conductivity lower than that of the metal, such as an insulating ceramic 120 or a resin that can be easily processed, may be used. The endothermic effect produced by the 130 electrodes 121 is not transmitted to the light emitting unit 101 instantaneously. Therefore, the heat absorption start received by the light emitting unit 101 by the Peltier element 130 is delayed by the time T2 from the heat absorption start of the Peltier element 130 (FIG. 2D). The time change of the amount of heat per unit time absorbed by the Peltier element 130 from the light emitting diode 110 (FIG. 2D) is the time change of the amount of heat absorbed per unit time of the Peltier element 130 (FIG. 2C). The shape is delayed by time T2.

  In the present embodiment, the power supply start time for starting current supply to the Peltier element 130 is arranged before the light emission start time at which the light emission unit 101 starts light emission, so that the light emission unit 101 is turned on. The cooling effect by the Peltier element 130 appears from the start, and the effect that the temperature highest point at which the temperature of the light emitting unit 101 reaches can be expected to decrease.

  Specifically, the time difference T1 between the rise of the pulse current of the Peltier element driving current and the rise of the pulse current of the light emitting diode driving current is substantially the same as the time T2 required for heat transfer from the Peltier element 130 to the light emitting diode 110. It is comprised so that it may become. The time T2 required for heat transfer from the Peltier element 130 to the light emitting diode 110 can be rephrased as the time required for the heat absorption effect of the Peltier element 130 to reach the light emitting diode 110.

  This is realized by the following method. First, the time T2 required for heat transfer from the Peltier element 130 to the light emitting diode 110 is obtained by calculation or experiment based on the capability of the Peltier element, the shape, material, etc. of each component of the Peltier element and the light emitting diode. Then, the light emitting diode driving power source 201 and the Peltier device driving power source 202 are set so that the obtained time T2 is substantially equal to the time difference T1 between the rise of the pulse current of the Peltier device driving current and the rise of the pulse current of the light emitting diode driving current. Set. Thereby, the time when the temperature drop due to the heat absorption of the Peltier element 130 reaches the light emitting unit 101 through the intermediate layer is the same as the driving start time of the light emitting diode.

  Further, in the present embodiment, the light emitting diode driving current and the Peltier element driving current are synchronized with each other, and the pulse width and the cycle are the same. Further, during the light emission period of the light emitting unit 101, the heat generation amount Q2 per unit time generated in the light emitting unit 101 and the heat absorption amount Q1 per unit time absorbed by the Peltier element 130 are substantially equal. This is realized by setting the current values of the light emitting diode driving current and the Peltier element driving current. Therefore, the actual temperature change in the light emitting unit 101 does not substantially occur when the amounts of heat transfer between the two cancel each other, as shown in FIG. That is, the temperature before lighting is maintained during the light emission period of the light emitting unit 101.

  In addition, the amount of heat generated by the light emitting diode in one cycle of the light emitting diode driving current is substantially the same as the amount of heat absorbed by the Peltier device in one cycle of the Peltier element driving current. This is because the light emitting diode driving current and the Peltier element driving current have the same pulse width and cycle, and the heat generation amount Q2 per unit time generated in the light emitting unit 101 and the Peltier element 130 absorb heat during the light emitting period of the light emitting unit 101. This is because the endothermic amount Q1 per unit time is substantially equal. Therefore, the temperature is maintained throughout the light emission period and the extinguishing period.

  Similarly, the amount of heat generated by the light emitting unit 101 and the amount of heat absorbed by the light emitting unit 101 from the Peltier element 130 are substantially equal during the light emission period of one pulse current of the light emitting unit 101.

  In addition, the waveform of the Peltier element driving current (FIG. 2A) and the waveform of the light emitting diode driving current (FIG. 2B) are similar in the current value direction, and have the same period and pulse width. In addition, the heat generation amount of the light emitting unit 101 and the heat absorption amount absorbed from the light emitting unit 101 by the Peltier element 130 in the light emission period by one pulse current of the light emitting unit 101 are substantially equal. Therefore, during the light emission period of the light emitting unit 101, the heat generation amount Q2 per unit time generated in the light emitting unit 101 is equal to the heat absorption amount Q1 per unit time absorbed by the Peltier element 130.

  The amount of heat per unit time shown in this embodiment indicates the intensity of heat generated or absorbed in a certain time. The same applies to the following embodiments. The “certain time” means a minute time at an arbitrary point, and the light emitting diode 110 may be turned on, may be turned off, or may be the time at the initial stage or the end of the pulse driving of the Peltier element 130. The same shall apply hereinafter.

  Also in the subsequent drive cycle, the movement of the amount of heat between the Peltier element 130 and the light emitting unit 101 occurs at the same timing as described above, so that the temperature of the light emitting unit 101 is maintained in the initial state.

  As described above, according to the present embodiment, the rise of the pulse current of the Peltier device driving current is performed before the rise of the pulse current of the light emitting diode driving current, so that the light emitting diode 110 becomes a light emitting unit. The light emitting unit 101 is turned on and generates heat in accordance with the time when the Peltier element 130 is affected by the heat absorption of the Peltier element 130, so that the heat generation of the light emitting part of the light emitting unit 101 is offset by the heat absorbing action of the Peltier element 130. Thus, the maximum temperature point reached at the time of light emission can be suppressed, and the effect of extending the life of the light emitting diode 110 can be expected.

  Further, in the light emission period of the light emitting unit 101, the heat generation amount Q2 per unit time generated in the light emitting unit 101 and the heat absorption amount Q1 per unit time absorbed by the Peltier element 130 are the same amount. Therefore, it is possible to prevent a decrease in light emission amount due to a decrease in light emission efficiency during the light emission period and a wavelength shift, and further, an effect of extending the life of the light emitting diode 110 can be expected.

  Furthermore, since the amount of heat generated by the light emitting diode in one cycle of the light emitting diode driving current and the amount of heat absorbed by the Peltier element in one cycle of the Peltier element driving current are substantially the same, It is possible to suppress the increase, prevent a decrease in light emission amount due to a decrease in light emission efficiency and wavelength shift, and further increase the life of the light emitting diode 110.

  The configuration of the light emitting diode and the Peltier element shown in FIG. 1 is an example, and the position and shape of the constituent parts of the light emitting diode 110 and the constituent parts of the Peltier element 130 are changed, the function is omitted, or other parts. You may integrate with.

Further, in this embodiment, the current waveform of the Peltier element driving current and the current waveform of the light emitting diode driving current are controlled by the pulse control means 203, and the light emitting diode driving current with respect to the rising timing of the pulse current of the Peltier element driving current is controlled. Although the delay time of the rise timing of the pulse current can be adjusted, the pulse control means 203 may be omitted. In this case, the light emitting diode driving power source 201 and the Peltier element driving power source 202 as the power source have a predetermined delay time of the rising timing of the pulse current of the light emitting diode driving current with respect to the rising timing of the pulse current of the Peltier element driving current. Thus, the Peltier element driving current and the light emitting diode driving current are supplied.
(Embodiment 2)
Since the configuration of the light source device according to the second embodiment of the present invention is the same as that of the first embodiment, FIG. 1 is used for the description, and the detailed description is omitted.

  The light source device according to the second embodiment is obtained by offsetting the waveform of the Peltier element driving current in the first embodiment by a predetermined amount, and is otherwise the same as the embodiment. In other words, a predetermined amount of current is added to the Peltier device driving current in the first embodiment over the entire period.

  Hereinafter, description will be made with reference to the time chart of FIG. FIG. 3A shows a change over time in the current value of the Peltier device driving current. FIG. 3B shows a change over time of the current value of the light emitting diode driving current. FIG. 3C shows a change in the amount of heat absorbed per unit time of the Peltier element 130. FIG. 3D shows the change over time in the amount of heat per unit time absorbed by the Peltier element 130 from the light emitting diode 110. FIG. 3E shows the change over time in the amount of heat generated per unit time of the light emitting diode 110. FIG. 3F shows the change over time in the amount of heat per unit time that the light emitting unit 101 receives in addition to the heat absorption by driving the Peltier element 130. FIG. 3G shows the temperature change of the light emitting unit 101.

  As shown in FIG. 3A, the current value of the Peltier device driving current is larger than 0 even at the falling edge of the pulse current. That is, low-output heat absorption is performed even when the pulse current falls. In synchronism with the lighting of the light emitting diode 110, the timing when the temperature drop due to the heat absorption of the Peltier element 130 reaches the light emitting unit 101 through the intermediate layer and the driving start time of the light emitting diode are the same. Performs high-power endothermic operation with a simple rise. Therefore, the Peltier device 130 periodically performs an endothermic operation at a low output and a high output. On the other hand, the waveform of the LED driving current shown in FIG. 3B is the same as that in FIG. 2B of the first embodiment.

  At this time, since the amplitude of the pulse current at the time of high output of the heat absorption operation of the Peltier element 130 is increased by the offset, as shown in FIG. 3C, the heat absorption amount of the Peltier element 130 also corresponds to this. It grows and works continuously in time. That is, the heat absorption amount of the Peltier element 130 per cycle is larger than the heat generation amount of the light emitting unit 101 per cycle.

  By the above control, as shown in FIGS. 3D and 3E, the heat generation in the light emitting unit 101 and the high-power endothermic action of the Peltier element 130 in the light emitting unit 101 occur simultaneously. The amount of heat generated per unit time Q2 and the amount of heat absorbed per unit time from the light emitting unit 101 (Q3 + Q1) absorbed by the Peltier device 130, excluding the amount of heat Q3 per unit time by the offset unit, are absorbed. The amount of heat Q1 is substantially equal to the amount of heat, and the heat generated during the lighting period of the light emitting unit 101 is offset by the movement of heat to the Peltier element 130, as in the first embodiment.

  Further, in the light source device of the present embodiment, the light emitting unit 101 of the light emitting diode 110 receives the amount of heat Q4 per unit time from other than the Peltier element 130 (FIG. 3 (f)). On the other hand, this constant heat is offset by the offset of the heat absorption amount of the Peltier element 130, that is, the heat absorption of the heat amount Q3 per unit time at the time of low output. In the present embodiment, the amount of heat Q3 per unit time at the time of low output and the amount of heat Q4 per unit time from the light emitting unit 101 of the light emitting diode 110 other than the Peltier element 130 are made substantially equal.

  Therefore, during the light emission period of the light emitting unit 101, the total amount (Q2 + Q4) of the amount of heat generated Q2 per unit time generated in the light emitting unit 101 and the amount of heat Q4 received by the light emitting unit 101 from other than the Peltier element 130, and the Peltier element 130. The amount of heat absorbed per unit time (Q1 + Q3) is the same amount, so the actual temperature change in the light emitting unit 101 is offset by the amount of heat transfer between them as shown in FIG. In effect. That is, the temperature before lighting is maintained during the light emission period of the light emitting unit 101.

  Furthermore, the waveform and the pulse width of the Peltier element driving current waveform (FIG. 3A) and the light emitting diode driving current waveform (FIG. 3B) are the same. Therefore, the amount of heat absorbed by the Peltier element in one cycle of the Peltier element driving current is substantially the same as the sum of the amount of heat generated by the light emitting diode in one period of the light emitting diode driving current and the amount of heat received by the light emitting diode from other than the Peltier element. is there.

  In addition, the waveform of the Peltier element driving current (FIG. 3A) and the waveform of the light emitting diode driving current (FIG. 3B) are similar in the direction of the current value, and the waveform of the Peltier element driving current is offset. The relationship that has been made.

  With the above configuration, the light emitting unit 101 operates constantly without temperature change, as shown in FIG.

  As described above, according to the present embodiment, in addition to the effects described in the first embodiment, since the offset is applied over the entire driving period of the Peltier element 130, the light emitting diodes generate heat from other than the Peltier element. Even when receiving, the state of the light emitting unit 101 can be maintained in a good state.

  The magnitude of the offset in the Peltier element driving current may be arbitrary. However, since the heat absorption amount in one cycle is equal to the entire heat generation amount, the light emitting diode is used in addition to the heat absorption by the Peltier element 130 and the heat generation action by the light emitting unit 101. From the viewpoint of power saving, it is desirable to calculate or estimate in advance the amount of heat that 110 receives from other than the Peltier element 130 and the amount of heat released outside the Peltier element 130 side.

  FIG. 4 shows a modification of the time chart. Similar to FIG. 3A, as shown in FIG. 4A, the waveform of the Peltier element driving current in the present embodiment is obtained by offsetting the waveform of the Peltier element driving current in the first embodiment by a predetermined amount. . In other words, a predetermined amount of current is added to the Peltier device driving current in the first embodiment over the entire period. The Peltier element 130 is the same as that of the second embodiment in that it periodically absorbs heat at a low output and a high output. Therefore, as shown in FIG. Are the same. Further, the second embodiment is the same as the first and second embodiments in that the rise of the pulse current of the Peltier device drive current is advanced by a predetermined time T1 with respect to the rise of the pulse current of the light emitting diode drive current.

  On the other hand, there is no amount of heat Q4 per unit time that the light emitting unit 101 of the light emitting diode 110 receives from other than the Peltier element 130, and the amount of heat generated Q2 per unit time generated in the light emitting unit 101 (see FIG. 4E). Is larger than the endothermic amount Q1 per unit time absorbed by the Peltier element 130 (see FIG. 4D), that is, the amount of heat per unit time is Q2> Q1, and the light emitting section in one cycle The amount of heat generated at 101 is different from the amount of heat absorbed by the Peltier element 130.

  In such a case, as shown in FIG. 4 (f), the temperature rise at the time of light emission of the light emitting unit 101 becomes gentle rather than steep, and the maximum temperature reached is suppressed, and further, during the light emission period. Therefore, a decrease in light emission amount due to a decrease in light emission efficiency during the light emission period and a wavelength shift can be suppressed.

  In this case, the following effects can also be obtained. That is, when the light emitting diode 110 is turned on at the maximum output, the power supply to the Peltier element 130 is turned on, and when the light emitting diode 110 is turned off, the power supply to the Peltier element 130 is also turned off. Then, the amplitude of the current supplied to the Peltier element 130 increases, and the temperature change of the Peltier element 130 increases. On the other hand, the Peltier element 130 is composed of an electrode 121 that is actually cooled by electrical control and a ceramic 120 for insulating the electrode part by an adhesive layer 190 (see FIG. 10B) using solder or the like. The adhesive layer 190 is stressed due to thermal expansion of the electrode 121 and the ceramic 120 when the temperature changes. As described above, when the temperature change of the Peltier element 130 increases, the stress change generated in the adhesive layer increases, so that the deterioration of the adhesive layer is accelerated and the life of the entire Peltier element is shortened.

  On the other hand, according to the present embodiment, the amplitude of the current supplied to the Peltier element 130 can be reduced, and the adhesion between the electrode 121 of the Peltier element 130 and the ceramic 120 for insulating the electrode portion. The effect that the light emitting portion 101 can be efficiently cooled without reducing the stress generated in the layer 190, without accelerating deterioration, and without shortening the lifetime of the entire Peltier element can be obtained.

(Embodiment 3)
Since the configuration of the light source device according to the third embodiment of the present invention is the same as that of the first embodiment, FIG. 1 is used for the description and the detailed description is omitted.

  The light source device according to the third embodiment is different from the first embodiment in that the time width of the pulse heat absorption operation of the Peltier element 130 is made larger.

  Hereinafter, description will be made with reference to the time chart of FIG. FIG. 5A shows the change over time of the current value of the Peltier device driving current. FIG. 5B shows the change over time of the current value of the light emitting diode driving current. FIG. 5C shows the change over time in the amount of heat absorbed per unit time of the Peltier element 130. FIG. 5D shows the change over time in the amount of heat per unit time absorbed by the Peltier element 130 from the light emitting diode 110. FIG. 5E shows the change over time in the amount of heat generated per unit time of the light emitting diode 110. FIG. 5F shows a change over time in the amount of heat per unit time that the light emitting unit 101 receives in addition to heat absorption by driving the Peltier element 130. FIG. 5G shows the temperature change of the light emitting unit 101.

  The time difference between the rise of the pulse current of the Peltier device driving current shown in FIG. 5A and the rise of the pulse current of the light emitting diode drive current shown in FIG. This is the same as in the case of Embodiment 1 in that it corresponds to the time required to reach the light emitting unit 101 via the above. On the other hand, in the present embodiment, the pulse width of the pulse current of the Peltier device driving current is larger than the pulse width of the pulse current of the light emitting diode driving current. Further, the falling edge of the pulse current of the Peltier element driving current coincides with the falling edge of the pulse current of the light emitting diode driving current in time. That is, the pulse width is set to be large by the rise time difference. Each parameter of the LED driving current shown in FIG. 5B is the same as that in FIG. 2B of the first embodiment.

  In this embodiment, since the pulse width of the pulse current of the Peltier device driving current is larger than in the first and second embodiments, the heat absorption amount of the Peltier device 130 is also increased as shown in FIG. The amount of heat increases by q3. Note that the amount of heat generated by the light emitting diode 110 per unit time is substantially the same as the amount of heat absorbed by the Peltier element 130, and this relationship is the same as in the first embodiment (FIG. 2) and the second embodiment (FIG. 3). ). Further, the amount of heat generated by the light emitting diode 110 per cycle, the amount of heat absorbed by the heat absorbing action of the Peltier element 130, and the amount of heat received by the light emitting diode 110 from other than the Peltier element 130 are substantially the same. This is the same as in the case of FIG.

  That is, as shown in FIGS. 5D and 5E, the heat generation in the light emitting unit 101 and the endothermic action of the Peltier element 130 in the light emitting unit 101 occur simultaneously. Further, as shown in FIG. 5D, when the lighting period of the light emitting unit 101 is Δt, the heat generation amount Q2 of the light emitting unit 101 per unit time during the lighting period (Δt) of the light emitting unit 101, and the light emitting unit The endothermic amount Q1 per unit time at which 101 absorbs heat from the Peltier element 130 is substantially equal.

  Further, during the lighting period (Δt) of the light emitting unit 101, the amount of heat absorbed by the light emitting unit 101 from the Peltier element 130, that is, the amount of heat generated by the light emitting unit 101, that is, the product of Q2 and Δt (Q2 · Δt), The product of Q1 and Δt (Q1 · Δt) and the sum of q3 (Q1 · Δt + q3) is larger by the movement amount q3 corresponding to the pulse width extension, but in this embodiment, the pulse width extension is increased. The corresponding amount of moving heat q3 is configured to be equal to the amount of heat received by the light emitting unit 101 from other than the Peltier element 130 per cycle.

  As shown in FIG. 5F, in the present embodiment, the light emitting unit 101 receives a constant amount of heat per unit time from other than the Peltier element 130, and the total amount of heat received in one cycle is q4. By setting the heat quantity q4 and the above-described heat quantity q3 to be equal (q3 = q4), the heat absorption amount (Q1 · Δt + q3) of the Peltier device 130 in one cycle and the heat generation amount (Q2 · Δt) of the light emitting unit 101 In addition, the sum (Q2 · Δt + q4) of the amount of heat (q4) received by the light emitting unit 101 from other than the Peltier element 130 is substantially equal.

  As a result, as shown in FIG. 5D, the light emitting unit 101 receives cooling from the Peltier element 130 by the amount of heat q3 corresponding to the rising difference period even after the light is turned off. As a result, FIG. As shown in (), after the temperature has dropped sharply, the temperature gradually rises until the period of the pulse heat absorption operation of the next Peltier element 130. That is, the light emitting unit 101 periodically changes the temperature in a sawtooth manner. In FIG. 5G, the heat absorption amount (Q1 · Δt + q3) of the Peltier element 130 in one cycle, the heat generation amount (Q2 · Δt) of the light emitting unit 101, and the heat amount received by the light emitting unit 101 from other than the Peltier element 130 (q4). ) (Q2 · Δt + q4) are substantially equal to each other, the average temperature is constant (on the reference line in the figure) in the temperature change of the light emitting unit 101, and the temperature state is always within the range of slight temperature change. Is secured.

  Thus, according to the present embodiment, the pulse width of the pulse current of the Peltier device driving current is larger than the pulse width of the pulse current of the light emitting diode driving current, so that the state of the light emitting unit 101 is further improved. Can be maintained. Further, since the heat balance per cycle of the light emitting unit 101 becomes 0 by increasing the pulse width of the pulse current of the Peltier device driving current, it is possible to more reliably prevent a decrease in light emission efficiency and a wavelength shift, and further light emission. The effect of extending the life of the diode 110 can be expected.

  In the above description, it is assumed that the pulse width of the pulse current of the Peltier device driving current is increased by the difference between the rise of the pulse current of the light emitting diode drive current and the rise of the pulse current of the Peltier device drive current. Although the description has been given, the present invention is not limited to this, and an arbitrary length of time may be taken.

(Embodiment 4)
Since the configuration of the light source device according to the fourth embodiment of the present invention is the same as that of the first embodiment, FIG. 1 is used for the description, and the detailed description is omitted.

  As in the second embodiment, the light source device according to the present embodiment is obtained by offsetting the waveform of the Peltier element driving current in the first embodiment by a predetermined amount. In other words, a predetermined amount of current is added to the Peltier device driving current in the first embodiment over the entire period. Furthermore, the magnitude of the pulse current of the Peltier device driving current is made larger than that in the first embodiment.

  Hereinafter, description will be made with reference to the time chart of FIG. FIG. 6A shows the change over time of the current value of the Peltier element driving current. FIG. 6B shows the change over time of the current value of the light emitting diode drive current. FIG. 6C shows a change over time in the amount of heat absorbed per unit time of the Peltier element 130. FIG. 6D shows the change over time in the amount of heat per unit time absorbed by the Peltier element 130 from the light emitting diode 110. FIG. 6E shows the change over time in the amount of heat generated per unit time of the light emitting diode 110. FIG. 6F shows the change over time in the amount of heat per unit time that the light emitting unit 101 receives in addition to the heat absorption by driving the Peltier element 130. FIG. 6G shows a temperature change of the light emitting unit 101.

  As shown in FIG. 6A, the current value of the Peltier device driving current is larger than 0 even at the falling edge of the pulse current. That is, low-output heat absorption is performed even when the pulse current falls. Then, a high-output heat absorption operation is performed at the rise such that the temperature drop due to the heat absorption of the Peltier element 130 reaches the light emitting unit 101 via the intermediate layer and the driving start time of the light emitting diode is the same timing. Therefore, the Peltier device 130 periodically performs an endothermic operation at a low output and a high output. On the other hand, the time change of the current value of the LED driving current shown in FIG. 6B is the same as that in FIG. 2B of the first embodiment.

  At this time, as shown in FIG. 6A, the amplitude of the supply current at the time of high output of the heat absorption operation of the Peltier element 130, that is, the current value of the pulse current of the Peltier element driving current is added by the offset amount. The amplitude of the pulse current itself is larger than that in the second embodiment. Therefore, as shown in FIGS. 6C and 6D, the amount of heat absorbed per unit time of the Peltier element 130 also increases accordingly.

  With the above control, as shown in FIGS. 6D and 6E, due to the difference in the amplitude of the drive signal, the Peltier element 130 generates more than the amount of heat generated Q2 per unit time generated during the lighting period of the light emitting unit 101. The endothermic amount Q1 per unit time is larger.

  Furthermore, as in the case of the second embodiment, as shown in FIG. 6F, the light emitting unit 101 is always maintained in a state where it receives a constant amount of heat Q4 from other than the Peltier element 130 per unit time. A part of this constant heat is absorbed by the movement of the heat quantity Q3 per unit time generated by the offset of the Peltier element 130 in the entire time zone. The amount of heat Q3 per unit time generated by the offset of the Peltier element 130 in all time zones is smaller than the amount of heat Q4 per unit time that the light emitting unit 101 receives from other than the Peltier element 130 at all times. The amount of heat absorbed by the Peltier element 130 in one cycle is substantially equal to the total amount of heat generated in the light emitting unit 101 and the amount of heat received by the light emitting unit 101 from other than the Peltier element 130.

  Therefore, as shown in FIG. 6 (g), in the light emitting unit 101, when the light source device starts driving, the temperature starts to increase due to the amount of heat transfer Q4 per unit time received from other than the Peltier element 130, and heat generated by lighting is generated. Even if it occurs, the amount of heat absorbed by the Peltier element 130 generated at the same timing exceeds the amount of heat generated by the light emitting unit 101, so that the temperature is switched to a drop. When the lighting of the light emitting unit 101 and the endothermic operation of the Peltier element 130 are finished, the temperature rises due to the heat generation Q4 per unit time from other than the Peltier received by the light emitting unit 101. Therefore, the temperature rise is suppressed and the temperature rises gradually until the next pulse lighting rises.

  That is, as in the third embodiment, the light emitting unit 101 periodically changes in temperature in a sawtooth manner, but the change occurs within a range of slight temperature change, and thus has a great influence on the operation of the light emitting diode 110. Not give.

  Thus, according to the present embodiment, the amplitude of the drive signal at the time of the high output heat absorption operation of the Peltier element is increased compared with the drive control of the low output offset of the second embodiment, Since the maximum temperature point reached by the light emitting unit can be reduced while suppressing power, the light emission amount can be prevented from being reduced due to the decrease in light emission efficiency during the light emission period, and wavelength shift can be prevented, and the life of the light emitting diode 110 can be extended. Can be expected.

  Note that the magnitude of the offset when the Peltier element 130 is driven may be arbitrary, but the heat absorption amount in one cycle is made equal to the entire heat generation amount. In addition to heat absorption by the Peltier element 130 and heat generation by the light emitting unit 101, the amount of heat received by the light emitting diode 110 from other than the Peltier element 130 and the amount of heat released outside the Peltier element 130 side are calculated or estimated in advance. However, it is desirable from the viewpoint of power saving.

  Further, the amplitude of the drive signal of the high-power pulse heat absorption operation of the Peltier device 130 shown in FIG. 6A is larger than the calorific value Q2 per unit time generated by the pulse lighting of the light emitting unit 101 shown in FIG. As long as the amplitude is such that the endothermic amount Q1 per unit time generated by the pulse endothermic operation of the Peltier element 130 shown in FIG.

  In each of the above embodiments, the time for heat transfer from the light emitting unit 101 to the Peltier element 130 also varies depending on variations in the material interposed between the light emitting unit 101 and the Peltier element 130 and the ambient temperature. Therefore, if the pulse control unit 203 can readjust the delay time, amplitude, and pulse width of the pulse heat absorption operation as appropriate in accordance with the operation time and arrangement environment of the light source device, the effect is further enhanced.

  Further, as shown in FIG. 7A, a light output sensor 301 that detects the amount of light emitted from the light emitting unit 101, or a temperature sensor that can detect the temperature in the vicinity of the light emitting unit 101 shown in FIG. 302, and the current waveform of the Peltier device driving current and / or the current waveform of the light emitting diode driving current may be adjusted by the pulse control means 203 based on the detection values of these sensors. Specifically, parameters such as the time difference, amplitude, and pulse width of the pulse current of the Peltier device driving current and the light emitting diode driving current may be adjusted. The light output sensor 301 is desirably provided at a location that does not block an optical path from the light emitting unit 101 to an optical system such as an objective lens (not shown). FIG. 7 (a) is arranged on the side surface of the light emitting unit 101 to detect leakage light from the side. In addition, the temperature sensor 302 is provided on the metal substrate 106 in the example shown in FIG. 7B. However, the temperature sensor 302 is arranged at a position where the temperature of the light emitting unit 101 is easily changed, such as adjacent to the resin lens 108. It is desirable to do.

  In addition, the operation of the pulse control means 203 using these sensors may be appropriately detected every predetermined time, and each control parameter may be readjusted based on the detection value at that time, or the detection may be performed in real time. The delay may be controlled while adjusting the parameters sequentially.

  Further, when the light source device of the present invention is used for at least one of the red, green, and blue light source devices and the transmissive image display element is used, the direct view type image display device is driven by a field sequential method. The light source can be cooled with a small amount of power, and the effects of being brighter, having little change in the color reproduction range, and extending the life of the light source can be obtained.

  Further, when the light source device of the present invention is used as at least one red, green, and blue light source device, and the projection display device using the image display element and the projection means is driven in a field sequential manner. The light source can be cooled with a small amount of power, and the effects of being brighter, having little change in the color reproduction range, and extending the life of the light source can be obtained.

  The program according to the present invention is a program for causing a computer to execute the functions of all or part of the above-described light source device of the present invention, and may be a program that operates in cooperation with the computer. Good.

  Further, the present invention is a medium carrying a program for causing a computer to execute all or part of the functions of all or part of the above-described light source device of the present invention, and is readable and read by a computer. The program may be a medium for executing the function in cooperation with the computer.

  The “part of means” of the present invention means some of the plurality of means, or means a part of functions of one means.

  Further, a part of the device of the present invention means some of the plurality of devices, or means of some of the devices, or one of the devices. It means a part of functions of the means.

  Further, the present invention includes a computer-readable recording medium that records the program of the present invention.

  Further, one usage form of the program of the present invention may be an aspect in which the program is recorded on a computer-readable recording medium and operates in cooperation with the computer.

  Further, one usage form of the program of the present invention may be an aspect in which the program is transmitted through a transmission medium, read by a computer, and operated in cooperation with the computer.

  Further, the recording medium includes a ROM and the like.

  The computer of the present invention described above is not limited to pure hardware such as a CPU, and may include firmware, an OS, and peripheral devices.

  As described above, the configuration of the present invention may be realized by software or hardware.

  The light source device according to the present invention has an effect of cooling the light source so as to be maintained at an appropriate temperature state, prevents a decrease in light emission efficiency and a wavelength shift due to a temperature rise, and further extends the life of the light source. For example, at least one or more of the red, green, and blue light source devices that illuminate an image display element that is driven in a field sequential manner is brighter and has color reproduction. It is useful as an image display device or the like having effects such as a small range change and long life.

Configuration diagram of light source device according to first to fourth embodiments of the present invention (A)-(f) The figure which shows the time chart explaining operation | movement of the light source device of Embodiment 1 of this invention. (A)-(g) The figure which shows the time chart explaining operation | movement of the light source device of Embodiment 2 of this invention. (A)-(f) The figure which shows the time chart explaining the other example of operation | movement of the light source device of Embodiment 2 of this invention. (A)-(g) The figure which shows the time chart explaining operation | movement of the light source device of Embodiment 3 of this invention. (A)-(g) The figure which shows the time chart explaining operation | movement of the light source device of Embodiment 4 of this invention. (A) (b) The block diagram which shows other embodiment of the light source device of this invention Configuration diagram of light source device according to conventional technology Partial enlarged view of Peltier element (A)-(f) The figure which shows the time chart explaining operation | movement of the light source device by a prior art. (A)-(f) The figure which shows the time chart explaining the other example of operation | movement of the light source device by a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Light emission part 102 1st contact bonding layer 103 Base 104 Electrode 105 2nd contact bonding layer 106 Metal substrate 107 3rd contact bonding layer 108 Resin lens 110 Light emitting diode 120 Ceramic 121 Electrode 122 Semiconductor layer 123 Electrode 124 Ceramic substrate 130 Peltier device 201 Light emitting diode driving power source 202 Peltier element driving power source 203 Pulse control means

Claims (15)

A light source that emits light when supplied with current;
A thermoelectric conversion element that absorbs heat and cools the light source by being supplied with current;
A light source driving current consisting of a periodic pulse current is supplied to the light source, and a thermoelectric conversion element driving current consisting of a periodic pulse current rising earlier than the rise of the pulse current of the light source driving current is supplied to the thermoelectric conversion element. A light source device comprising a power source.   2. The light source according to claim 1, wherein the time difference between the rise of the pulse current of the thermoelectric conversion element drive current and the rise of the pulse current of the light source drive current corresponds to a time required for heat transfer from the thermoelectric conversion element to the light source. apparatus.   The light source according to claim 1 or 2, wherein a heat generation amount of the light source in one cycle of the light source driving current and a heat absorption amount by the thermoelectric conversion element in one cycle of the thermoelectric conversion element driving current are substantially the same. apparatus.   3. The light source device according to claim 1, wherein in one cycle of the thermoelectric conversion element driving current, an amount of heat absorbed by the thermoelectric conversion element is larger than an amount of heat generated by the light source in one cycle of the light source driving current.   The amount of heat absorbed by the thermoelectric conversion element in one cycle of the thermoelectric conversion element driving current is substantially the sum of the amount of heat generated by the light source in one cycle of the light source driving current and the amount of heat received by the light source from other than the thermoelectric conversion element. The light source device according to claim 1, wherein the light source device is the same.   6. The light source device according to claim 1, wherein the thermoelectric conversion element drive current has a current value larger than 0 even at a falling edge of a pulse current.   The amount of heat generated per unit time of the light source and the amount of heat absorbed per unit time absorbed by the thermoelectric conversion element from the light source during the period in which the pulse current of the light source driving current is supplied once are substantially equal. The light source device according to claim 1, which is equal to   4. The heat generation amount of the light source and the heat absorption amount absorbed from the light source by the thermoelectric conversion element are substantially equal during a period in which the one pulse current of the light source driving current is supplied. The light source device according to any one of the above.   The light source device according to claim 8, wherein a pulse width of the thermoelectric conversion element driving current is substantially the same as a pulse width of the light source driving current.   The light source device according to claim 9, wherein a waveform of the thermoelectric conversion element driving current and a waveform of the light source driving current are in an expansion or contraction relationship in a current value direction. A light source device according to claim 1;
A transmissive display panel that transmits light obtained from the light source device and displays an image;
Direct-view image display device. A light source device according to claim 1;
A projection display device comprising: an image display element that forms an image by transmitting or reflecting light obtained from the light source device.   A light source driving current consisting of a periodic pulse current is supplied to the light source, and a thermoelectric conversion element driving current consisting of a periodic pulse current rising earlier than the rise of the pulse current of the light source driving current is supplied to the thermoelectric conversion element. A method for cooling a light source, comprising a step.   14. The light source cooling method according to claim 13, wherein a light source driving current comprising a periodic pulse current is supplied to the light source, and a thermoelectric comprising a periodic pulse current that rises earlier than a rise of the pulse current of the light source driving current. A program for causing a computer to execute a step of supplying a conversion element driving current to the thermoelectric conversion element.   A recording medium on which the program according to claim 14 is recorded, wherein the recording medium can be processed by a computer.

Images