Projection display device

Abstract

To provide a projection display device with which it is possible to properly suppress the occurrence of fringes.SOLUTION: A projection display device 100 pertaining to the present embodiment comprises: a light source 101 that irradiates light of a blue wavelength band; a first display element 106R, a second display element 106G, and a third display element 106B that are disposed corresponding to red, green and blue colors, respectively and generate image light corresponding to each color; a heater 161 that is disposed at the rear of at least the third display element 106B corresponding to the blue color via a heat sink 160; and a temperature sensor 162 that is provided to the heat sink 160. The light source 101 has multiple groups of blue laser light sources differing in emission wavelength, and includes a heating control unit that actuates the heater 161 when the detected temperature of the temperature sensor 162 is lower than a prescribed first temperature.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Generally, a projection display device using a reflective liquid crystal display element is known (see, for example, Patent Document 1). In this type of projection display device, for example, white light is generated by irradiating a phosphor with blue laser light from a light source composed of a single wavelength blue laser, and after decomposing this white light into red, blue, and green light of each color, the light of each color is enlarged and projected onto a screen as an image modulated by a reflective liquid crystal display element.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a conventional projection display device, it is common for the liquid crystal display element at the start of use to be at a temperature lower than the appropriate temperature for operation. Therefore, until the temperature of the liquid crystal display element warms up to the appropriate temperature, the temperature distribution inside the liquid crystal display element is non-uniform. As a result, in the case of a light source with a single wavelength such as a laser, for example, fringes (interference fringes) that are divided into bright regions and dark regions may occur at the start of use, and a projection display device that can appropriately suppress the occurrence of these fringes is required.

[0005] In view of the above problems, an object of the present invention is to provide a projection display device that can appropriately suppress the occurrence of fringes.

Means for Solving the Problems

[0006] A projection display device according to one aspect of the present invention includes a light source that emits light in the blue wavelength band, liquid crystal display elements arranged corresponding to red, green, and blue, respectively, which generate image light corresponding to each color, a heating unit disposed on the back of at least the liquid crystal display element corresponding to blue via a heat sink, and a first temperature sensor provided on the heat sink, wherein the light source has a plurality of groups of blue lasers with different oscillation wavelengths, and a heating control unit that operates the heating unit when the temperature detected by the first temperature sensor is lower than a predetermined first temperature. The liquid crystal display element on which the heating element is located includes a bandgap type second temperature sensor, and the heating control unit uses the detection data of the first temperature sensor when power is not supplied to the liquid crystal display element, and after power is supplied to the liquid crystal display element, it uses the detection data of the second temperature sensor instead of the first temperature sensor. ru. [Effects of the Invention]

[0007] According to the present invention, since the liquid crystal display element is heated by the operation of the heating unit, the occurrence of fringes can be appropriately suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram of the display device according to this embodiment. [Figure 2] Figure 2 is a schematic block diagram of the control unit according to this embodiment. [Figure 3] Figure 3 is a flowchart showing the operation procedure of the control unit according to this embodiment. [Figure 4] Figure 4 is a flowchart showing the steps involved in acquiring the temperature data shown in Figure 3. [Figure 5] Figure 5 shows an example of how the element temperature changes in relation to the ambient temperature. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the embodiments described below.

[0010] (Configuration of projection display device) Figure 1 is a schematic diagram of a projection display device according to this embodiment. The projection display device generates white light by irradiating a phosphor with visible light (for example, blue laser light), decomposes this white light into red, blue, and green light, and then modulates each of these colors of light to display a combined image. As shown in Figure 1, the projection display device 100 according to this embodiment comprises a display mechanism 10 and a control unit 12. The display mechanism 10 comprises a light source 101, a phosphor 103, polarizing plates 105R, 105G, 105B, a first display element 106R, a second display element 106G, a third display element (liquid crystal display element corresponding to blue) 106B, a color synthesis prism 108, a projection lens 109, a λ / 4 plate 110, dichroic mirrors 120-122, reflective mirrors 130-132, lenses 140-146, and a polarization conversion element 150. The first display element 106R, the second display element 106G, and the third display element 106B are reflective liquid crystal display elements, for example, having a liquid crystal layer sandwiched between a silicon substrate and a glass substrate, and are provided corresponding to each color, as described later.

[0011] The dichroic mirrors 120-122 have the property of separating incident light by reflection and transmission, with the separation wavelength acting as a separation boundary. The dichroic mirrors 120-122 can be fabricated by forming, for example, a dielectric multilayer film in a predetermined area of ​​a transparent material such as a glass plate or prism. The optical properties can be set according to the material and thickness of the dielectric that constitutes the dielectric multilayer film.

[0012] The light source 101 emits illumination light, which is light in the visible light wavelength range. In this 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 range of 450 nm to 495 nm, for example.

[0013] In this embodiment, the light source 101 has three (or more) groups of blue laser light sources 101α, 101β, and 101γ with different oscillation wavelengths. Each of these groups of blue laser light sources 101α to 101γ has an oscillation wavelength that differs 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.

[0014] Generally, when a short-wavelength blue laser light source is used as a single-wavelength light source, unevenness in the thickness (cell thickness) of the liquid crystal display element can cause fringing (interference fringes) that divide the image into bright and dark regions, and these fringes can be superimposed on the displayed image. For this reason, strict control of the thickness of the liquid crystal display element was necessary. In contrast, in this embodiment, as described above, a configuration is adopted in which the first blue laser light source 101α to the third blue laser light source 101γ are in three groups with oscillation wavelengths that differ by at least 10 nm. As a result, the spacing and position of the peaks and valleys of the fringes change depending on the difference in oscillation wavelength, and fringing, especially in blue images, is reduced. This makes it possible to relax the standards for controlling the thickness of the liquid crystal display element.

[0015] The oscillation wavelengths of the first blue laser light source 101α to the third blue laser light source 101γ described above are examples and can be changed as appropriate, as long as they fall within the blue wavelength range. Furthermore, the difference in oscillation wavelength between each blue laser light source can be changed as appropriate, for example, within a range of 10 nm to 20 nm. Moreover, the number of groups of blue laser light sources is not limited to three, as long as there are multiple groups.

[0016] The blue illumination light from the light source 101 is irradiated onto the dichroic mirror 120. The dichroic mirror 120 has the property of reflecting blue illumination light and transmitting 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.

[0017] The blue illumination light emitted from each of the first blue laser light source 101α to the third blue laser light source 101γ is reflected by each of the dichroic mirrors 120α to 120γ, and further condensed by the lens 140 and irradiated onto the phosphor 103. The phosphor 103 has a fluorescent layer and a reflecting surface. The fluorescent layer generates yellow illumination light including components in the red band and components in the green band having an intensity corresponding to the energy intensity of the blue illumination light irradiated from the first blue laser light source 101α to the third blue laser light 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.

[0018] The dichroic mirrors 120α, 120β, and 120γ are formed to have an area smaller than the beam width of the reflected light (diffuse light) from the phosphor 103. Also, these dichroic mirrors 120α to 120γ are arranged in such a direction that the polarization direction of the laser light with respect to each of the dichroic mirrors 120α, 120β, and 120γ becomes s-polarization. For this reason, the dichroic mirrors 120α to 120γ have the property of reflecting s-polarization and transmitting p-polarization of the blue illumination light incident on the dichroic mirrors 120α to 120γ, and the yellow illumination light is transmitted regardless of the polarization direction.

[0019] Therefore, the phosphor 103 wavelength-excites yellow illumination light (fluorescent light) containing a red component and a green component, which mixes with the non-fluorescent blue illumination light and is incident again on the dichroic mirrors 120α to 120γ. The yellow illumination light containing the red and green components, which is fluorescent light, passes through the dichroic mirrors 120α to 120γ and is all emitted. On the other hand, when the blue illumination light is reflected (diffused) by the phosphor 103, it becomes random polarization in which a plurality of polarizations are mixed. Therefore, among the components of the blue illumination light hitting the dichroic mirrors 120α to 120γ, the p-polarization component passes through the dichroic mirrors 120α to 120γ and is emitted, while the s-polarization 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.

[0020] The blue illumination light and the yellow illumination light that have passed through the dichroic mirrors 120α to 120γ are reflected by the reflection mirror 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 reflection mirror 130 are made to have a uniform 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 retardation plate. The polarization beam splitter reflects either the s-polarization or the p-polarization and transmits the other. In the example of FIG. 1, the polarization beam splitter reflects the s-polarization and transmits the p-polarization. Also, the retardation plate converts either the s-polarization or the p-polarization into the other. In the example of FIG. 1, the retardation plate converts the s-polarization into the p-polarization. By the polarization conversion element 150, each illumination light is aligned to the p-polarization.

[0021] By the polarization conversion element 150, each illumination light aligned to the p-polarization is irradiated to the dichroic mirror 121 through the lens 143. The lens 143 is, for example, a condenser lens.

[0022] The dichroic mirror 121 separates the incident blue illumination light BL from the yellow illumination light YL. The yellow illumination light YL separated by the dichroic mirror 121 is reflected by the reflective mirror 131 and incident on the dichroic mirror 122.

[0023] The dichroic mirror 122 uses a wavelength intermediate between the red and green light bands as a separation boundary to separate the incident yellow illumination light YL into red illumination light RL, which contains a component in the red band, and green illumination light GL, which contains a component in the green band. Specifically, the dichroic mirror 122 reflects the green band component of the incident yellow illumination light YL to emit green illumination light GL, and transmits the red band component of the incident yellow illumination light YL to emit red illumination light RL. The red illumination light RL is, for example, light in the wavelength band between 620 nm and 750 nm, and the green illumination light GL is, for example, light in the wavelength band between 495 nm and 570 nm.

[0024] The red illumination light RL separated by the dichroic mirror 122 is irradiated onto the polarizer 105R via the lens 144. The green illumination light GL separated by the dichroic mirror 122 is irradiated onto the polarizer 105G via the lens 145. The blue illumination light BL separated by the dichroic mirror 121 is reflected by the reflective mirror 132 and irradiated onto the polarizer 105B via the lens 146.

[0025] Polarizers 105R, 105G, and 105B have the property of reflecting either s-polarized or p-polarized light and transmitting the other. In the example in Figure 1, polarizers 105R, 105G, and 105B are shown reflecting s-polarized light and transmitting p-polarized light. Polarizers 105R, 105G, and 105B are also called reflective polarizers. Polarizers 105R, 105G, and 105B are, for example, wire grid polarizers.

[0026] The p-polarized red illumination light RL passes through the polarizer 105R and irradiates the first display element 106R. The p-polarized green illumination light GL passes through the polarizer 105G and irradiates the second display element 106G. The p-polarized blue illumination light BL passes through the polarizer 105B and irradiates the third display element 106B.

[0027] The first display element 106R optically modulates p-polarized red illumination light RL based on image data of the red component to generate s-polarized red image light RM. The second display element 106G optically modulates p-polarized green illumination light GL based on image data of the green component to generate s-polarized green image light GM. The third display element 106B optically modulates p-polarized blue illumination light BL based on image data of the blue component to generate s-polarized blue image light BM. In other words, the first display element 106R functions as an optical modulation element for red images, the second display element 106G functions as an optical modulation element for green images, and the third display element 106B functions as an optical modulation element for blue images.

[0028] The s-polarized red image light RM generated by the first display element 106R is reflected by the polarizer 105R and irradiated onto the color synthesis prism 108. The s-polarized green image light GM generated by the second display element 106G is reflected by the polarizer 105G and irradiated onto the color synthesis prism 108. The s-polarized blue image light BM generated by the third display element 106B is reflected by the polarizer 105B and irradiated onto the color synthesis prism 108.

[0029] The color synthesis prism 108 reflects the red image light RM and the blue image light BM, transmits the green image light GM, and illuminates the projection lens 109 with each of these image lights.

[0030] The red image light RM, green image light GM, and blue image light BM are projected onto a screen or the like (not shown) via the projection lens 109. A visible light image is displayed by the red image light RM, green image light GM, and blue image light BM.

[0031] In this embodiment, the display mechanism 10 includes, as a light source 101, three groups of first blue laser light sources 101α to third blue laser light sources 101γ, whose oscillation wavelengths differ by at least 10 nm. Therefore, the difference in oscillation wavelengths of the first blue laser light source 101α to third blue laser light sources 101γ suppresses the generation of fringes.

[0032] On the other hand, projection display devices using this type of reflective liquid crystal display element may produce fringes (interference fringes) that divide the display into bright and dark areas when first used. Since the liquid crystal display element is generally at a temperature lower than the appropriate operating temperature when first used, the temperature distribution within the liquid crystal display element is uneven until it warms up to the appropriate temperature. As a result, even when using multiple laser light sources with different oscillation wavelengths, it is necessary to suppress the occurrence of fringes, for example, when first used. In particular, in configurations using a blue laser light source, fringes tend to occur easily in the blue image light BM.

[0033] In this embodiment, as shown in Figure 1, the display mechanism 10 includes a heater (heating unit) 161 positioned via a heat sink 160 on the back surface (the side opposite to the side irradiated by the blue illumination light BL) of the third display element 106B corresponding to blue, and a temperature sensor (first temperature sensor) 162 provided on the heat sink 160. The heat sink 160 is a plate-shaped member made of a metal with high thermal conductivity, such as aluminum, and has a certain thickness. The heat sink 160 is formed to be larger than the back surface of the third display element 106B, and the entire back surface is in contact with the heat sink 160.

[0034] The heater 161 heats the third display element 106B via the heat sink 160, and for example, a plate-shaped ceramic heater can be used. By placing the heater 161 on the heat sink 160, the entire heat sink 160 can be heated, and consequently the third display element 106B can be heated uniformly. The temperature sensor 162 is attached to the heat sink 160, and by measuring the temperature of the heat sink 160, the temperature of the third display element 106B can be indirectly detected.

[0035] Furthermore, the third display element 106B includes a bandgap type temperature sensor (second temperature sensor) 163 within its element circuit. The bandgap type temperature sensor 163 is a semiconductor temperature sensor that measures temperature based on the voltage value across a diode in an electrical circuit including a diode, for example. Since this bandgap type temperature sensor 163 is provided within the element circuit of the third display element 106B, it can directly and accurately measure the temperature of the third display element 106B. On the other hand, the bandgap type temperature sensor 163 cannot measure temperature if power is not supplied to the third display element 106B. Therefore, in this embodiment, if power is not supplied to the third display element 106B, such as when the projection display device 100 is started to be used, the detection data of the temperature sensor 162 described above is used. In addition to the third display element 106B which corresponds to blue, the first display element 106R and the second display element 106G which correspond to red and green may also be configured to have a heat sink 160, heater 161, temperature sensor (first temperature sensor) 162, and bandgap type temperature sensor (second temperature sensor) 163 on their backs, respectively.

[0036] Next, the control unit 12 will be described. Figure 2 is a schematic block diagram of the control unit according to this embodiment. As shown in Figure 2, 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 may be composed of integrated circuits, which are hardware, or they may be composed of a CPU (Central Processing Unit) and memory, which are the arithmetic units of a computer, and the CPU may execute a computer program (software) stored in the memory. In this embodiment, only the part relating to the operation control of the heater 161 will be described, and other details will be omitted.

[0037] The first temperature acquisition unit 21 acquires temperature data detected by the temperature sensor 162. In this embodiment, unlike the bandgap type temperature sensor 163, the temperature sensor 162 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.

[0038] The second temperature acquisition unit 22 acquires temperature data detected by the bandgap type 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. If there is no input temperature data from the bandgap type temperature sensor 163, the second temperature acquisition unit 22 may determine that power is not being supplied to the third display element 106B and output this determination result to the heating control unit 23 and the fan control unit 24.

[0039] The heating control unit 23 controls the operation of the heater 161 based on temperature data input from the first temperature acquisition unit 21 or the second temperature acquisition unit 22. In this embodiment, if 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. Furthermore, if temperature data is input from both the first temperature acquisition unit 21 and the second temperature acquisition unit 22, the heating control unit 23 prioritizes the temperature data input from the second temperature acquisition unit 22 and controls the operation of the heater 161 based on this temperature data. In other words, when power is not supplied to the third display element 106B, the heating control unit 23 uses the detection data of the temperature sensor 162, and after power is supplied to the third display element 106B, it uses the detection data of the bandgap type temperature sensor 163 instead of the temperature sensor 162. With this configuration, temperature data obtained by directly and accurately measuring the temperature of the third display element 106B can be used.

[0040] The heating control unit 23 controls the heater 161 to turn on (operate) if the temperature data input from the first temperature acquisition unit 21 or the second temperature acquisition unit 22 is lower than a predetermined first temperature. This first temperature is set to a temperature lower than the temperature range appropriate for the operation of the third display element 106B. As a result of this control, the heater 161 is activated, and the third display element 106B is uniformly heated to a temperature appropriate for operation via the heat sink 160. Furthermore, the heating control unit 23 controls the heater 161 to turn off (stop) if 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. This second temperature is set to a temperature that falls within the temperature range appropriate for the operation of the third display element 106B. In this configuration, the third display element 106B is sufficiently heated to a temperature range appropriate for operation, so the heater 161 is turned off to avoid excessive heating.

[0041] The fan control unit 24 controls the operation of the fan 164 based on temperature data input from the first temperature acquisition unit 21 or the second temperature acquisition unit 22. This fan 164 is, for example, installed inside a housing (not shown) that houses the display mechanism 10, and is an exhaust fan that cools the display mechanism 10 (particularly the third display element 106B) by drawing in outside air by expelling the air inside the housing. Similar to the heating control unit 23 described above, the fan control unit 24 uses the detection data of the temperature sensor 162 when power is not supplied to the third display element 106B, and after power is supplied to the third display element 106B, it uses the detection data of the bandgap type temperature sensor 163 instead of the temperature sensor 162.

[0042] The fan control unit 24 controls the operation of the fan 164 when the temperature data input from the first temperature acquisition unit 21 or the second temperature acquisition unit 22 reaches a second temperature that is higher than the first temperature. This prevents the temperature of the third display element 106B from rising excessively. In this embodiment, the fan 164 is operated when the second temperature that turns off the heater 161 is reached, but the temperature at which the fan 164 is operated may be changed as appropriate.

[0043] Next, the control operation of the heater in the control unit will be described. Figure 3 is a flowchart showing the operation procedure of the control unit according to this embodiment. Figure 4 is a flowchart showing the operation procedure of the step of acquiring the temperature data in Figure 3. Figure 5 is a diagram showing an example of the change in element temperature with respect to ambient temperature.

[0044] As shown in Figure 3, the control unit 12 acquires temperature data of the third display element 106B (step S10). Specifically, the control unit 12 acquires temperature data of the third display element 106B using either the first temperature acquisition unit 21 or the second temperature acquisition unit 22. When acquiring temperature data, the control unit 12 uses the second temperature acquisition unit 22 to determine whether or not power is being supplied to the third display element 106B (step S20), as shown in Figure 4. In this embodiment, the second temperature acquisition unit 22 of the control unit 12 determines whether or not there is input of temperature data from the bandgap type temperature sensor 163, and if there is no input of temperature data from the temperature sensor 163, it determines that power is not being supplied to the third display element 106B. It is preferable that the second temperature acquisition unit 22 outputs the determination result that power is not being supplied to the third display element 106B to the heating control unit 23 and the fan control unit 24. Of course, a means for determining whether or not power is being supplied may be provided separately.

[0045] In this determination, if 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 using the first temperature acquisition unit 21 (step S21). Also, in this determination, if 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 type temperature sensor 163 using the second temperature acquisition unit 22 (step S22). The acquired temperature data is output to the heating control unit 23 and the fan control unit 24, respectively.

[0046] Returning to Figure 3, the control unit 12 determines whether the acquired temperature data is less than or equal to a predetermined first temperature t1 (step S11). More specifically, the control unit 12, with the help of the heating control unit 23, determines whether the acquired temperature data is less than or equal to a predetermined first temperature t1. In this determination, if the acquired temperature data is not less than or equal to the predetermined first temperature t1 (step S11; No), the control unit 12 proceeds to step S13.

[0047] On the other hand, if the acquired temperature data is less than or equal to a predetermined first temperature t1 (step S11; Yes), the control unit 12 controls the heating control unit 23 to turn on (operate) the heater 161 (step S12). If the heater 161 is already on, the process proceeds to step S13 while maintaining that state. As a result of this control, the heater 161 is activated, and the third display element 106B is uniformly heated to a temperature suitable for operation via the heat sink 160. Therefore, for example, even when the projection display device 100 is first put into use, the temperature of the third display element 106B can be quickly heated to a temperature suitable for operation, and the occurrence of fringing at the start of use can be rapidly suppressed.

[0048] Next, the control unit 12 determines whether the acquired temperature data has reached a second temperature t2, which is set higher than the first temperature t1 (step S13). More specifically, the control unit 12, with the help of the heating control unit 23, determines whether the acquired temperature data has reached a second temperature t2, which is set higher than the first temperature t1. In this determination, if the acquired temperature data has not reached the second temperature t2 (step S13; No), the control unit 12 returns to step S10.

[0049] On the other hand, if the acquired temperature data has reached the second temperature t2 (step S13; Yes), the control unit 12 controls the heating control unit 23 to turn off (stop) the heater 161 (step S14). Furthermore, the control unit 12 controls the fan control unit 24 to operate the fan 164 (step S15), and terminates the process. These controls prevent the temperature of the third display element 106B from rising excessively, and, as shown in Figure 5, the element temperature of the third display element 106B can be maintained at approximately the second temperature t2. As a result, the projection display device 100 can display a stable image with suppressed fringing.

[0050] As described above, the projection display device 100 according to this embodiment includes a light source 101 that emits light in the blue wavelength band, a first display element 106R, a second display element 106G, and a third display element 106B arranged in correspondence to red, green, and blue respectively, which generate image light corresponding to each color, a heater 161 arranged on the back of at least the third display element 106B corresponding to blue via a heat sink 160, and a temperature sensor 162 provided on the heat sink 160. The light source 101 has multiple groups of blue laser light sources with different oscillation wavelengths, and includes 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 t1. With this configuration, the temperature distribution of the third display element 106B is reduced, the third display element 106B is heated to an appropriate temperature, and by using multiple laser oscillation wavelengths, different fringe states can be superimposed, thereby suppressing fringe. As a result, the projection display device 100 can reduce the time it takes to become usable and display a stable image with suppressed fringing.

[0051] Furthermore, in the projection display device 100 according to this embodiment, the light source 101 comprises a first blue laser light source 101α, a second blue laser light source 101β, and a third blue laser light source 101γ, each belonging to three groups with different oscillation wavelengths. With this configuration, the spacing of the fringes and the position of the peaks and valleys change depending on the difference in oscillation wavelengths, thus reducing fringes in blue images in particular.

[0052] Furthermore, in the projection display device 100 according to this embodiment, the oscillation wavelengths of multiple groups differ by at least 10 nm. This configuration effectively suppresses the occurrence of fringes.

[0053] Furthermore, in the projection display device 100 according to this embodiment, the third display element 106B on which the heater 161 is located includes a bandgap type temperature sensor 163. When power is not supplied to the third display element 106B, the heating control unit 23 uses the detection data of the temperature sensor 162, and after power is supplied to the third display element 106B, it uses the detection data of the bandgap type temperature sensor 163 instead of the temperature sensor 162. With this configuration, detection data obtained by directly and accurately measuring the temperature of the third display element 106B can be used.

[0054] Furthermore, in the projection display device 100 according to this embodiment, the heating control unit 23 stops the operation of the heater 161 when the temperature detected by the temperature sensor 162 or the bandgap type temperature sensor 163 reaches a second temperature t2 which is set higher than the first temperature t1. This prevents the temperature of the third display element 106B from rising excessively and allows the element temperature of the third display element 106B to be maintained at a nearly constant temperature.

[0055] Although embodiments of the present invention have been described above, the embodiments are not limited to those described herein. Furthermore, the aforementioned components include those that can be easily conceived by those skilled in the art, those that are substantially the same, and those that fall within the so-called equivalent range. Moreover, the aforementioned components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the embodiments described above. [Explanation of symbols]

[0056] 10 Display mechanism 12 Control Unit 21 1st temperature acquisition section 22 Second temperature acquisition section 23 Heating control unit 24 Fan control unit 100 Projection display device 101 Light source 101α First Blue Laser Light Source 101β Second Blue Laser Light Source 101γ Third Blue Laser Light Source 106R First display element (liquid crystal display element corresponding to red) 106G Second display element (Liquid crystal display element corresponding to green) 106B Third display element (liquid crystal display element corresponding to blue) 160 Heatsink 161 Heater (heating section) 162 Temperature sensor (1st temperature sensor) 163 Temperature sensor (second temperature sensor) 164 fans t1 1st temperature t2 2nd temperature

Claims

1. A light source that emits light in the blue wavelength range, Liquid crystal display elements are arranged to correspond to red, green, and blue, respectively, and generate image light corresponding to each color. A heating element is provided on the back of the liquid crystal display element, which is at least compatible with blue, via a heat sink. The heat sink includes a first temperature sensor, The light source has a plurality of groups of blue lasers with different oscillation wavelengths. The heating control unit is provided to operate the heating unit when the temperature detected by the first temperature sensor is lower than a predetermined first temperature. The liquid crystal display element on which the heating element is located includes a bandgap type second temperature sensor. The heating control unit uses the detection data of the first temperature sensor when power is not supplied to the liquid crystal display element, and after power is supplied to the liquid crystal display element, it uses the detection data of the second temperature sensor instead of the first temperature sensor.

2. The projection display device according to claim 1, wherein the light source comprises three groups of blue lasers with different oscillation wavelengths.

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

4. The projection display device according to claim 1, wherein the heating control unit stops operating the heating unit when the temperature detected by the first temperature sensor or the second temperature sensor reaches a second temperature set to be higher than the first temperature.

Images