Projection display device

Abstract

Provided is a projection display device capable of appropriately suppressing generation of stripes. A projection display device (100) according to an embodiment includes: a light source (101) that emits light in a blue wavelength band; a first display element (106R), a second display element (106G), and a third display element (106B), which are disposed corresponding to red, green, and blue, respectively, and which generate image light corresponding to each color; a heater (161) disposed on the rear surface of the third display element (106B) corresponding to at least the blue color via the heat sink (160); and a temperature sensor (162) provided to the heat sink (160), the light source (101) having a plurality of sets of blue laser light sources having different oscillation wavelengths, and the projection display device (100) is provided with a heating control unit (23) that operates the heater (161) when the temperature detected by the temperature sensor (162) is lower than a predetermined first temperature.

Description

Technical Field

[0001] The present invention relates to a projection display device using a liquid crystal display element. Background Art

[0002] Generally, there is known a projection display device using a reflective liquid crystal display element (for example, see Patent Document 1). In such a projection display device, for example, a light source composed of a single-wavelength blue laser is irradiated with a blue laser to a phosphor to generate white light, and after the white light is decomposed into red, blue, and green light, the light of each color is modulated by the reflective liquid crystal display element and the image is enlarged and projected onto a screen.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2005-227485 Summary of the invention

[0006] However, in conventional projection display devices, generally speaking, the temperature of the liquid crystal display element is lower than the temperature suitable for operation when the device is first used. Therefore, during the period when the temperature of the liquid crystal display element is raised to the appropriate temperature, the temperature distribution in the liquid crystal display element becomes uneven. As a result, in the case of a single wavelength light source such as a laser, for example, stripes (interference stripes) divided into bright and dark areas are sometimes generated when the device is first used, and a projection display device capable of appropriately suppressing the generation of such stripes is required.

[0007] In view of the above problems, an object of the present invention is to provide a projection display device capable of appropriately suppressing the generation of stripes.

[0008] In order to solve the above-mentioned problems and achieve the purpose, the projection display device of this embodiment includes: a light source, which irradiates light in the blue band; a liquid crystal display element, which is respectively arranged corresponding to red, green and blue, and generates image light corresponding to each color; a heating unit, which is arranged on the back of the liquid crystal display element corresponding to at least blue via a heat sink; and a first temperature sensor, which is arranged on the heat sink, the light source has a plurality of groups of blue lasers with different oscillation wavelengths, and the projection display device has a heating control unit, which activates the heating unit when the detection temperature of the first temperature sensor is lower than a specified first temperature.

[0009] According to the present embodiment, since the liquid crystal display element is heated by the operation of the heating unit, the occurrence of streaks can be appropriately suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the display device of this embodiment.

[0011] Figure 2 This is a schematic block diagram of the control unit of this embodiment.

[0012] Figure 3 This is a flowchart showing the operation procedure of the control unit in this embodiment.

[0013] Figure 4 It means to obtain Figure 3 Flow chart of the order of action of the steps of temperature data.

[0014] Figure 5 This is a diagram showing an example of a change state of the element temperature with respect to the ambient temperature. DETAILED DESCRIPTION

[0015] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In addition, the present invention is not limited to the embodiments described below.

[0016] (Structure of projection display device)

[0017] Figure 1 Schematic diagram of the projection display device of this embodiment. The projection display device generates white light by irradiating visible light (such as blue laser) to a phosphor, decomposes the white light into red, blue and green light, and then displays an image synthesized by modulating the light of each color. Figure 1 As shown, the projection display device 100 of this embodiment includes a display mechanism 10 and a control unit 12. The display mechanism 10 includes a light source 101, a fluorescent body 103, polarizing plates 105R, 105G, and 105B, a first display element 106R, a second display element 106G, a third display element (a liquid crystal display element corresponding to blue) 106B, a color synthesis prism 108, a projection lens 109, a λ / 4 plate 110, dichroic mirrors 120 to 122, reflecting mirrors 130 to 132, lenses 140 to 146, and a polarization conversion element 150. The first display element 106R, the second display element 106G, and the third display element 106B have a structure in which a liquid crystal layer is sandwiched between a silicon substrate and a glass substrate, and are reflective liquid crystal display elements provided corresponding to each color described later.

[0018] The dichroic mirrors 120 to 122 have the characteristic of separating incident light by reflection and transmission with separation wavelength as separation boundary. The dichroic mirrors 120 to 122 can be manufactured by forming, for example, a dielectric multilayer film in a predetermined area of ​​a transparent material such as a glass plate or a prism. The optical characteristics can be set according to the material and film thickness of the dielectric constituting the dielectric multilayer film.

[0019] The light source 101 emits illumination light in the visible light wavelength band. In the present embodiment, the light source 101 is a blue laser light source composed of a blue laser element, and emits blue illumination light in the wavelength band of 450 (nm) to 495 (nm).

[0020] In this embodiment, the light source 101 has three groups (plural groups) of a first blue laser light source 101α, a second blue laser light source 101β, and a third blue laser light source 101γ with different oscillation wavelengths. The groups of the first blue laser source 101α to the third blue laser source 101γ are respectively set to have oscillation wavelengths that differ by at least 10 (nm). Specifically, the oscillation wavelength of the first blue laser light source 101α is set to 445 (nm), the oscillation wavelength of the second blue laser light source 101β is set to 455 (nm), and the oscillation wavelength of the third blue laser light source 101γ is set to 465 (nm).

[0021] Generally, when a short-wavelength blue laser light source is used as a single-wavelength light source, due to the uneven thickness (unit thickness) of the liquid crystal display element, stripes (interference stripes) divided into bright and dark areas are generated, and the stripes sometimes overlap with the displayed image. Therefore, it is necessary to strictly manage the thickness of the liquid crystal display element. In contrast, in the present embodiment, as described above, it is configured to have three groups of first blue laser light sources 101α to third blue laser light sources 101γ with oscillation wavelengths that differ by at least 10 (nm), so the interval between stripes and the position of valleys change according to the difference in oscillation wavelength, thereby reducing the stripes of the blue image in particular. As a result, the criteria for managing the thickness of the liquid crystal display element can be relaxed.

[0022] The oscillation wavelengths of the first blue laser light source 101α to the third blue laser light source 101γ are examples, and can be appropriately changed as long as they are included in the blue wavelength band. In addition, the difference in the oscillation wavelengths of the blue laser light sources can be appropriately changed within a range of, for example, 10 (nm) or more and 20 (nm) or less. Furthermore, the number of groups of blue laser light sources can be multiple, and is not limited to three.

[0023] The blue illumination light from the light source 101 is irradiated to the dichroic mirror 120. The dichroic mirror 120 has the characteristic of reflecting the blue illumination light and transmitting the yellow illumination light. In the present embodiment, the dichroic mirror 120 includes dichroic mirrors 120α, 120β, and 120γ arranged corresponding to the first blue laser light source 101α to the third blue laser light source 101γ described above.

[0024] The blue illumination light emitted from the first blue laser source 101α to the third blue laser source 101γ is reflected by the dichroic mirrors 120α to 120γ, and then focused by the lens 140 to irradiate the phosphor 103. The phosphor 103 has a fluorescent layer and a reflecting surface. The fluorescent layer generates yellow illumination light containing a red band component and a green band component of an intensity corresponding to the energy intensity of the blue illumination light irradiated from the first blue laser source 101α to the third blue laser source 101γ. The reflecting surface reflects the blue illumination light transmitted through the fluorescent layer and the yellow illumination light generated by the fluorescent layer.

[0025] The dichroic mirrors 120α, 120β, and 120γ are formed to have an area smaller than the beam width of the reflected light (diffused light) from the fluorescent body 103. In addition, the dichroic mirrors 120α to 120γ are respectively arranged so that the polarization direction of the laser light relative to the dichroic mirrors 120α, 120β, and 120γ is oriented to be s-polarized light. Therefore, the dichroic mirrors 120α to 120γ have the following characteristics: among the blue illumination light incident on the dichroic mirrors 120α to 120γ, the s-polarized light is reflected and the p-polarized light is transmitted, and the yellow illumination light is transmitted regardless of the polarization direction.

[0026] Therefore, the yellow illumination light (fluorescence) containing red and green components excited by the wavelength of the fluorescent body 103 is mixed with the blue illumination light that is not fluorescent, and enters the dichroic mirrors 120α to 120γ again. The yellow illumination light containing red and green components as fluorescence is transmitted through the dichroic mirrors 120α to 120γ and all emitted. On the other hand, the blue illumination light becomes a random polarized light mixed with a plurality of polarized lights when reflected (diffused) by the fluorescent body 103. Therefore, among the components of the blue illumination light irradiated to the dichroic mirrors 120α to 120γ, the p-polarized light component is transmitted through the dichroic mirrors 120α to 120γ and emitted, but the s-polarized light component is reflected by the dichroic mirrors 120α to 120γ and returns to the first blue laser light source 101α to the third blue laser light source 101γ.

[0027] The blue illumination light and the yellow illumination light that have passed through the dichroic mirrors 120α to 120γ are reflected by the reflector 130 and are incident on the lens 141. The lens 141 and the lens 142 are, for example, fly-eye lenses, and a λ / 4 plate 110 is disposed between these lenses 141 and 142. The blue illumination light and the yellow illumination light reflected by the reflector 130 are made uniform in illumination distribution by the lens 141, the λ / 4 plate 110, and the lens 142, and are incident on the polarization conversion element 150. The polarization conversion element 150 has, for example, a polarization beam splitter and a phase difference plate. The polarization beam splitter reflects either the s-polarized light or the p-polarized light and allows the other to pass through. Figure 1 In the example of , the polarization beam splitter reflects s-polarized light and transmits p-polarized light. In addition, the phase difference plate converts either s-polarized light or p-polarized light into the other. Figure 1In the example of FIG. 1 , the phase difference plate converts the s-polarized light into the p-polarized light. The polarization conversion element 150 converts each illumination light into the p-polarized light.

[0028] Each illumination light converted into p-polarized light by the polarization conversion element 150 is irradiated to the dichroic mirror 121 via the lens 143. The lens 143 is, for example, a condenser lens.

[0029] The dichroic mirror 121 separates the incident blue illumination light BL and the yellow illumination light YL. The yellow illumination light YL separated by the dichroic mirror 121 is reflected by the reflection mirror 131 and enters the dichroic mirror 122 .

[0030] The dichroic mirror 122 uses the wavelength between the red light band and the green light band as a separation boundary, and separates the incident yellow illumination light YL into red illumination light RL containing a component of the red band and green illumination light GL containing a component of the green band. Specifically, the dichroic mirror 122 reflects the green wavelength component of the incident yellow illumination light YL and emits the green illumination light GL, and transmits the red wavelength component of the incident yellow illumination light YL and emits the red illumination light RL. In addition, the red illumination light RL is, for example, light in a wavelength band of 620 (nm) to 750 (nm), and the green illumination light GL is, for example, light in a wavelength band of 495 (nm) to 570 (nm).

[0031] The red illumination light RL separated by the dichroic mirror 122 is irradiated to the polarizing plate 105R via the lens 144. The green illumination light GL separated by the dichroic mirror 122 is irradiated to the polarizing plate 105G via the lens 145. The blue illumination light BL separated by the dichroic mirror 121 is reflected by the reflecting mirror 132 and irradiated to the polarizing plate 105B via the lens 146.

[0032] Polarizing plates 105R, 105G, and 105B have a characteristic of reflecting one of s-polarized light and p-polarized light and transmitting the other. Figure 1 In the example of FIG. 1 , the polarizing plates 105R, 105G, and 105B reflect s-polarized light and transmit p-polarized light. The polarizing plates 105R, 105G, and 105B are also referred to as reflective polarizing plates. The polarizing plates 105R, 105G, and 105B are, for example, wire grid polarizing plates.

[0033] The p-polarized red illumination light RL passes through polarizing plate 105R and illuminates first display element 106R. The p-polarized green illumination light GL passes through polarizing plate 105G and illuminates second display element 106G. The p-polarized blue illumination light BL passes through polarizing plate 105B and illuminates third display element 106B.

[0034] The first display element 106R optically modulates the p-polarized red illumination light RL according to the image data of the red component, and generates the s-polarized red image light RM. The second display element 106G optically modulates the p-polarized green illumination light GL according to the image data of the green component, and generates the s-polarized green image light GM. The third display element 106B optically modulates the p-polarized blue illumination light BL according to the image data of the blue component, and generates the s-polarized blue image light BM. That is, the first display element 106R functions as a red image light modulator, the second display element 106G functions as a green image light modulator, and the third display element 106B functions as a blue image light modulator.

[0035] The red image light RM as s-polarized light generated by the first display element 106R is reflected by the polarizing plate 105R and irradiates the color synthesis prism 108. The green image light GM as s-polarized light generated by the second display element 106G is reflected by the polarizing plate 105G and irradiates the color synthesis prism 108. The blue image light BM as s-polarized light generated by the third display element 106B is reflected by the polarizing plate 105B and irradiates the color synthesis prism 108.

[0036] The color synthesis prism 108 reflects the red image light RM and the blue image light BM, transmits the green image light GM, and irradiates the projection lens 109 with the respective image lights.

[0037] The red image light RM, the green image light GM, and the blue image light BM are projected onto a screen (not shown) or the like via the projection lens 109. The red image light RM, the green image light GM, and the blue image light BM display a visible light image.

[0038] In this embodiment, the display mechanism 10 includes three sets of first blue laser light sources 101α to third blue laser light sources 101γ, whose oscillation wavelengths differ by at least 10 (nm) as the light source 101. Therefore, the generation of fringes is suppressed by the difference in oscillation wavelengths of the first blue laser light sources 101α to the third blue laser light sources 101γ.

[0039] On the other hand, in a projection display device using such a reflective liquid crystal display element, stripes (interference stripes) divided into bright areas and dark areas may sometimes be generated at the beginning of use. The liquid crystal display element at the beginning of use is usually at a temperature lower than the temperature suitable for operation, so the temperature distribution in the liquid crystal display element becomes uneven during the period until the temperature of the liquid crystal display element rises to an appropriate temperature. As a result, even in the case of using multiple laser light sources with different oscillation wavelengths, it is required to suppress the generation of stripes at the beginning of use. In particular, in a structure using a blue laser light source as a light source, there is a tendency for blue image light BM to easily generate stripes.

[0040] In this embodiment, if Figure 1 As shown, the display mechanism 10 includes: a heater (heating unit) 161, which is arranged on the back side (the side opposite to the side irradiated with the blue illumination light BL) of the third display element 106B corresponding to the blue color via a heat sink 160; and a temperature sensor (first temperature sensor) 162, which is provided on the heat sink 160. The heat sink 160 is formed of a metal with high thermal conductivity such as aluminum and is a plate-shaped member with a certain thickness. The heat sink 160 is formed larger than the back side of the third display element 106B, and the entire back side is in contact with the heat sink 160.

[0041] The heater 161 heats the third display element 106B via the radiator 160, and a plate-shaped ceramic heater can be used, for example. The heater 161 is arranged on the radiator 160, and can heat the entire radiator 160, and can further heat the third display element 106B uniformly. The temperature sensor 162 is mounted on the radiator 160, and by measuring the temperature of the radiator 160, the temperature of the third display element 106B can be indirectly detected.

[0042] In addition, the third display element 106B includes a bandgap temperature sensor (second temperature sensor) 163 in the element circuit. The bandgap temperature sensor 163 is, for example, a semiconductor temperature sensor that measures temperature based on a voltage value across a diode in a circuit including a diode. The bandgap temperature sensor 163 is provided in the element circuit of the third display element 106B, and thus can directly and accurately measure the temperature of the third display element 106B. On the other hand, if power is not supplied to the third display element 106B, the bandgap temperature sensor 163 cannot measure the temperature. Therefore, in this embodiment, when power is not supplied to the third display element 106B, for example, at the beginning of use of the projection display device 100, the detection data of the temperature sensor 162 is used. In addition, it is also possible to configure that not only the third display element 106B corresponding to blue, but also the back of the first display element 106R and the second display element 106G corresponding to red and green are provided with a heat sink 160, a heater 161, a temperature sensor (first temperature sensor) 162, and a bandgap temperature sensor (second temperature sensor) 163.

[0043] Next, the control unit 12 will be described. Figure 2 is a schematic block diagram of the control unit of this embodiment. Figure 2As shown, the control unit 12 includes a first temperature acquisition unit 21, a second temperature acquisition unit 22, a heating control unit 23, and a fan control unit 24. The heating control unit 23 and the fan control unit 24 can be composed of an integrated circuit as hardware, or can be composed of a CPU (Central Processing Unit) and a memory as a computing device of a computer, and the CPU executes a computer program (software) stored in the memory. In addition, in this embodiment, the part related to the operation control of the heater 161 is described, and the description of other parts is omitted.

[0044] The first temperature acquisition unit 21 acquires temperature data detected by the temperature sensor 162. In the present embodiment, the temperature sensor 162 is different from the bandgap temperature sensor 163, and can detect the temperature of the third display element 106B regardless of whether power is supplied to the third display element 106B. The first temperature acquisition unit 21 outputs the acquired temperature data to the heating control unit 23 and the fan control unit 24.

[0045] The second temperature acquisition unit 22 acquires temperature data detected by the bandgap temperature sensor 163. The second temperature acquisition unit 22 outputs the acquired temperature data to the heating control unit 23 and the fan control unit 24. The second temperature acquisition unit 22 may determine that power is not supplied to the third display element 106B when temperature data is not input from the bandgap temperature sensor 163, and output the determination result to the heating control unit 23 and the fan control unit 24.

[0046] The heating control unit 23 controls the operation of the heater 161 based on the temperature data input from the first temperature acquisition unit 21 or the second temperature acquisition unit 22. In the present embodiment, when the temperature data is input only from the first temperature acquisition unit 21, the heating control unit 23 controls the operation of the heater 161 based on the input temperature data. In addition, when the temperature data is input from the first temperature acquisition unit 21 and the second temperature acquisition unit 22, the heating control unit 23 gives priority to the temperature data input from the second temperature acquisition unit 22 and controls the operation of the heater 161 based on the temperature data. That is, the heating control unit 23 uses the detection data of the temperature sensor 162 when the power is not supplied to the third display element 106B, and uses the detection data of the bandgap type temperature sensor 163 instead of the temperature sensor 162 after the power is supplied to the third display element 106B. According to this structure, the temperature data obtained by directly and accurately measuring the temperature of the third display element 106B can be used.

[0047] The heating control unit 23 controls the heater 161 to be turned on (operated) when the temperature data input from the first temperature acquisition unit 21 or the second temperature acquisition unit 22 is lower than the specified first temperature. The first temperature is set to a temperature lower than the temperature band suitable for the action of the third display element 106B. Through this control, the heater 161 works, so that the third display element 106B is uniformly heated to a temperature suitable for action via the radiator 160. In addition, when the temperature data input from the first temperature acquisition unit 21 or the second temperature acquisition unit 22 reaches a second temperature higher than the first temperature, the heating control unit 23 controls the heater 161 to be turned off (stopped). The second temperature is set to a temperature included in the temperature band suitable for the action of the third display element 106B. In this structure, the third display element 106B is fully heated to a temperature band suitable for action, so the heater 161 is turned off to avoid excessive heating.

[0048] The fan control unit 24 controls the operation of the fan 164 based on the temperature data input from the first temperature acquisition unit 21 or the second temperature acquisition unit 22. The fan 164 is, for example, provided in a housing (not shown) housing the display mechanism 10, and is an exhaust fan for cooling the display mechanism 10 (particularly the third display element 106B) by exhausting the air in the housing and taking in the outside air into the housing. The fan control unit 24, like the above-mentioned heating control unit 23, uses the detection data of the temperature sensor 162 when the third display element 106B is not supplied with power, and uses the detection data of the bandgap temperature sensor 163 instead of the temperature sensor 162 after the third display element 106B is supplied with power.

[0049] When the temperature data input from the first temperature acquisition unit 21 or the second temperature acquisition unit 22 reaches a second temperature higher than the first temperature, the fan control unit 24 controls the fan 164 to operate. Thus, the temperature of the third display element 106B can be prevented from excessively rising. In the present embodiment, the fan 164 is operated when the second temperature at which the heater 161 is turned off is reached, but the temperature at which the fan 164 is operated can also be appropriately changed.

[0050] Next, the control operation of the heater in the control unit will be described. Figure 3 This is a flowchart showing the operation procedure of the control unit according to the present embodiment. Figure 4 Yes means Figure 3 A flowchart of the order of actions of the steps of acquiring temperature data. Figure 5 This is a diagram showing an example of a change state of the element temperature with respect to the ambient temperature.

[0051] like Figure 3As shown, the control unit 12 obtains the temperature data of the third display element 106B (step S10). Specifically, the control unit 12 obtains the temperature data of the third display element 106B through the first temperature acquisition unit 21 or the second temperature acquisition unit 22. When obtaining the temperature data, Figure 4 As shown, the control unit 12 determines whether power is supplied to the third display element 106B through the second temperature acquisition unit 22 (step S20). In the present embodiment, the second temperature acquisition unit 22 of the control unit 12 determines whether temperature data is input from the bandgap temperature sensor 163, and when temperature data is not input from the temperature sensor 163, it is determined that power is not supplied to the third display element 106B. Preferably, the second temperature acquisition unit 22 outputs the determination result that power is not supplied to the third display element 106B to the heating control unit 23 and the fan control unit 24. In addition, of course, a unit for determining whether power is supplied can also be separately provided.

[0052] In this determination, when power is not supplied to the third display element 106B (step S20; No), the control unit 12 acquires the temperature data of the third display element 106B detected by the temperature sensor 162 through the first temperature acquisition unit 21 (step S21). In addition, in this determination, when power is supplied to the third display element 106B (step S20; Yes), the control unit 12 acquires the temperature data of the third display element 106B detected by the bandgap temperature sensor 163 through the second temperature acquisition unit 22 (step S22). The acquired temperature data are output to the heating control unit 23 and the fan control unit 24, respectively.

[0053] Return again Figure 3 , the control unit 12 determines whether the acquired temperature data is below the prescribed first temperature t1 (step S11). More specifically, the control unit 12 determines whether the acquired temperature data is below the prescribed first temperature t1 through the heating control unit 23. In this determination, if the acquired temperature data is not below the prescribed first temperature t1 (step S11; No), the control unit 12 transfers the process to step S13.

[0054] On the other hand, when the acquired temperature data is below the prescribed first temperature t1 (step S11; yes), the control unit 12 controls the heater 161 to be turned on (operated) through the heating control unit 23 (step S12). Here, when the heater 161 is already turned on, this state is maintained and the processing is transferred to step S13. Through this control, the heater 161 is operated, so that the third display element 106B is uniformly heated to a temperature suitable for operation via the radiator 160. Therefore, for example, when the projection display device 100 starts to be used, the temperature of the third display element 106B can also be quickly heated to a temperature suitable for operation, and the generation of stripes at the start of use can be quickly suppressed.

[0055] Next, the control unit 12 determines whether the acquired temperature data reaches the second temperature t2 set higher than the first temperature t1 (step S13). More specifically, the control unit 12 determines whether the acquired temperature data reaches the second temperature t2 set higher than the first temperature t1 through the heating control unit 23. In this determination, if the acquired temperature data does not reach the second temperature t2 (step S13; No), the control unit 12 returns the process to step S10.

[0056] On the other hand, when the acquired temperature data reaches the second temperature t2 (step S13; yes), the control unit 12 controls the heater 161 to be turned off (stopped) through the heating control unit 23 (step S14). Furthermore, the control unit 12 controls the fan 164 to operate through the fan control unit 24 (step S15), and the processing ends. Through these controls, the temperature of the third display element 106B can be prevented from rising excessively, and as shown in FIG. Figure 5 As shown, the element temperature of the third display element 106B can be maintained substantially at the second temperature t2. Therefore, the projection display device 100 can display a stable image with suppressed streaks.

[0057] As described above, the projection display device 100 of this embodiment includes: a light source 101 that irradiates light in the blue wavelength band; a first display element 106R, a second display element 106G, and a third display element 106B, which are respectively arranged corresponding to red, green, and blue and generate image light corresponding to each color; a heater 161, which is arranged at least on the back of the third display element 106B corresponding to blue via a heat sink 160; and a temperature sensor 162, which is provided on the heat sink 160. The light source 101 has a plurality of sets of blue laser light sources with different oscillation wavelengths. The projection display device 100 has a heating control unit 23. When the detected temperature of the temperature sensor 162 is lower than the predetermined first temperature t1, the heating control unit 23 operates the heater 161. According to this structure, the third display element 106B is heated to an appropriate temperature in a state where the temperature distribution of the third display element 106B is reduced, and by making the oscillation wavelength of the laser light multiple, the states of different stripes can be overlapped, and the stripes can be suppressed. Thus, the projection display device 100 can shorten the time until it can be used, and can display a stable image with suppressed streaks.

[0058] In the projection display device 100 of the present embodiment, the light source 101 includes three groups of a first blue laser light source 101α, a second blue laser light source 101β, and a third blue laser light source 101γ having different oscillation wavelengths. According to this structure, the interval between stripes and the position of valleys change according to the difference in oscillation wavelengths, so that the stripes of the blue image are reduced in particular.

[0059] In the projection display device 100 according to the present embodiment, the oscillation wavelengths of the plurality of groups differ by at least 10 (nm). According to this structure, the generation of stripes can be effectively suppressed.

[0060] In the projection display device 100 of the present embodiment, the third display element 106B provided with the heater 161 includes the bandgap temperature sensor 163, and the heating control unit 23 uses the detection data of the temperature sensor 162 when the third display element 106B is not powered, and after the third display element 106B is powered, the detection data of the bandgap temperature sensor 163 is used instead of the temperature sensor 162. According to this structure, the detection data obtained by directly and accurately measuring the temperature of the third display element 106B can be used.

[0061] In the projection display device 100 of the present embodiment, the heating control unit 23 stops the operation of the heater 161 when the detected temperature of the temperature sensor 162 or the bandgap temperature sensor 163 reaches the second temperature t2 set higher than the first temperature t1. Therefore, the temperature of the third display element 106B can be prevented from excessively rising, and the element temperature of the third display element 106B can be maintained at a substantially constant temperature.

[0062] The present embodiment has been described above, but the embodiment is not limited to the content of the embodiment. In addition, the above-mentioned constituent elements include elements that can be easily thought of by those skilled in the art, substantially the same elements, and elements of so-called equivalent scopes. Moreover, the above-mentioned constituent elements can be appropriately combined. Moreover, various omissions, substitutions or changes of constituent elements can be made within the scope of the gist of the above-mentioned embodiment.

[0063] Industrial Applicability

[0064] The projection display device of the present embodiment can be used as a projection display device using a reflective liquid crystal display element, for example.

[0065] Description of reference numerals:

[0066] 10Display Agency

[0067] 12. Control Unit

[0068] 21 first temperature acquisition unit

[0069] 22 Second temperature acquisition unit

[0070] 23Heating control unit

[0071] 24 Fan control unit

[0072] 100 projection display device

[0073] 101 Light Source

[0074] 101α first blue laser source

[0075] 101β second blue laser source

[0076] 101γ The third blue laser source

[0077] 106R first display element (liquid crystal display element corresponding to red)

[0078] 106G second display element (liquid crystal display element corresponding to green)

[0079] 106B: third display element (liquid crystal display element corresponding to blue)

[0080] 160 Radiator

[0081] 161 heater (heating unit)

[0082] 162 temperature sensor (first temperature sensor)

[0083] 163 temperature sensor (second temperature sensor)

[0084] 164 Fan

[0085] t1 first temperature

[0086] t2 second temperature

Claims

1. A projection display device, comprising: A light source, emitting light in the blue band; Liquid crystal display elements are arranged corresponding to red, green and blue colors respectively, and generate image light corresponding to each color; A heating unit is disposed at least on the back side of the liquid crystal display element corresponding to the blue color via a heat sink; and A first temperature sensor is arranged on the radiator. The light source comprises a plurality of groups of blue lasers with different oscillation wavelengths. The projection display device further includes a heating control unit configured to operate the heating unit when the temperature detected by the first temperature sensor is lower than a predetermined first temperature.

2. The projection display device according to claim 1, wherein: The light source includes three groups of blue lasers having different oscillation wavelengths.

3. The projection display device according to claim 1 or 2, wherein: The oscillation wavelengths of the plurality of groups differ from each other by at least 10 nm.

4. The projection display device according to claim 1 or 2, wherein: The liquid crystal display element provided with the heating portion includes a second temperature sensor of a bandgap type, The heating control unit uses detection data of the first temperature sensor when power is not supplied to the liquid crystal display element, and uses detection data of the second temperature sensor instead of the first temperature sensor after power is supplied to the liquid crystal display element.

5. The projection display device according to claim 4, wherein: The heating control unit stops the operation of the heating unit when the temperature detected by the first temperature sensor or the second temperature sensor reaches a second temperature set higher than the first temperature.

Images