Projection display device

Abstract

To provide a projection display device capable of promptly projecting an excellent image when a non-display function is canceled.SOLUTION: A projection display device according to the embodiment comprises a light source 101 that emits laser light used for image projection, has a non-display function that makes projection of the image non-display temporarily by stopping light emission from the light source 101 and includes: a light source temperature sensor 172 that detects the temperature of the light source 101; a light source heater 171 that heats the light source 101; a control unit 12 that controls at least the operation of the light source 101 and the light source heater 171; and a change-over switch 165 that instructs execution or cancellation of the non-display function. When the change-over switch 165 instructs execution of the non-display function, the control unit 12 stops light emission from the light source 101, acquires the temperature detected by the light source temperature sensor 172, and controls the light source heater 171 such that the light source 101 maintains the acquired temperature.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a projection display device having a function of temporarily hiding a projected image by turning off a light source. [Background technology]

[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, a blue laser light source is irradiated onto a phosphor with blue laser light to generate white light, and this white light is then decomposed into red, blue, and green light, and each of these colors of light is modulated by a reflective liquid crystal display element to produce an image, which is then enlarged and projected onto a screen. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-227485 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, this type of projection display device is equipped with a hide function that temporarily hides the projected image. With this configuration, by stopping (turning off) the light source that emits the laser light, it is possible to reproduce pitch black on the projection surface, which is highly effective for, for example, the night sky in a planetarium, or for blending processing that projects multiple images in layers.

[0005] On the other hand, in order to maintain good image performance in a projection display device, it is important to keep the temperature of the liquid crystal display element as well as the light source within a certain range. In the conventional configuration, when the non-display function is executed, the light source is temporarily turned off, which lowers the temperature of the light source. Therefore, when the non-display function is released, the output of the light source becomes unstable until the light source is heated to a predetermined temperature, and it is expected that a problem will occur in which a good image cannot be projected quickly.

[0006] SUMMARY OF THE PRESENT DISCLOSURE In view of the above problems, an object of the present invention is to provide a projection display device that can quickly project a good image when the non-display function is released. [Means for solving the problem]

[0007] A projection display device according to one aspect of the present invention has a light source that emits laser light used to project an image, and is equipped with a non-display function that temporarily hides the projection of an image by stopping the light emission of the light source, and is equipped with a light source temperature sensor that detects the temperature of the light source, a light source heating unit that heats the light source, a control unit that controls the operation of at least the light source and the light source heating unit, and a switch that instructs the execution or cancellation of the non-display function, and when the execution of the non-display function is instructed by the switch, the control unit stops the light emission of the light source and acquires the temperature detected by the light source temperature sensor, and controls the light source heating unit so that the light source maintains the acquired temperature.

[0008] In addition, a projection display device according to one aspect of the present invention has a light source that emits laser light used to project an image, and is equipped with a non-display function that temporarily hides the projection of an image by stopping the light emission of the light source, and is equipped with a light source heating unit that heats the light source, an information acquisition unit that acquires information regarding the relationship between the output of the light source and the temperature of the light source, and the relationship between the output of the light source heating unit and the temperature of the light source, a control unit that controls the operation of at least the light source and the light source heating unit, and a switch that instructs the execution or cancellation of the non-display function, and when execution of the non-display function is instructed by the switch, the control unit stops the light emission of the light source, estimates the temperature of the light source corresponding to the output of the light source based on the information acquired by the information acquisition unit, and controls the light source heating unit to an output corresponding to the estimated temperature. Effect of the Invention

[0009] According to the present invention, the temperature of the light source is maintained at the temperature when the non-display function was executed by the operation of the light source heating unit, so that a good image can be quickly projected when the non-display function is released. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a display device according to a first embodiment. [Diagram 2] FIG. 2 is a schematic block diagram of a control unit according to the first embodiment. [Diagram 3] FIG. 3 is a flowchart showing the procedure of the operation of the control unit according to the first embodiment. [Figure 4] FIG. 4 is a schematic diagram of a display device according to the second embodiment. [Diagram 5] FIG. 5 is a schematic block diagram of a control unit according to the second embodiment. [Figure 6] FIG. 6 is a flowchart showing the procedure of the operation of the control unit according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiment described below.

[0012] [First embodiment] FIG. 1 is a schematic diagram of a projection display device according to a first embodiment. The projection display device is a display device that generates white light by irradiating a phosphor with visible light (e.g., blue laser light), decomposes the white light into red, blue, and green light, and then modulates and combines each of these colors to display an image. As shown in FIG. 1, the projection display device 100 includes a display mechanism 10 and a control unit 12. The display mechanism 10 includes a light source 101, a phosphor 103, polarizing plates 105R, 105G, and 105B, a first display element 106R, a second display element 106G, a third display element 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 are, for example, reflective liquid crystal display elements having a configuration in which a liquid crystal layer is sandwiched between a silicon substrate and a glass substrate, and provided corresponding to each color described later.

[0013] The dichroic mirrors 120 to 122 have the property of separating incident light by reflection and transmission, with the separation wavelength as the separation boundary. The dichroic mirrors 120 to 122 can be fabricated by forming, for example, a dielectric multilayer film on a predetermined region 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 material that constitutes the dielectric multilayer film.

[0014] Light source 101 emits illumination light that is light in the wavelength band of visible light. In this embodiment, light source 101 is a blue laser light source configured with a blue laser element, and emits blue illumination light in the wavelength band of, for example, 450 (nm) or more and 495 (nm) or less.

[0015] In this embodiment, light source 101 has three (plural) groups of first blue laser light source 101α, second blue laser light source 101β, and third blue laser light source 101γ with different oscillation wavelengths. The groups of first blue laser light source 101α to third blue laser light source 101γ are set to have oscillation wavelengths that differ from each other by at least 10 (nm). Specifically, the oscillation wavelength of first blue laser light source 101α is set to 445 (nm), the oscillation wavelength of second blue laser light source 101β is set to 455 (nm), and the oscillation wavelength of third blue laser light source 101γ is set to 465 (nm).

[0016] In general, when a blue laser light source having a short wavelength is used as a single wavelength light source, fringes (interference fringes) that are divided into bright and dark regions are generated due to unevenness in the thickness (cell thickness) of the liquid crystal display element, and these fringes are sometimes superimposed on the displayed image. For this reason, strict management of the thickness of the liquid crystal display element is required. In contrast, in this embodiment, as described above, the configuration has three groups of first blue laser light source 101α to third blue laser light source 101γ with oscillation wavelengths that differ by at least 10 (nm) or more, so that the fringe intervals and the positions of peaks and valleys change due to the difference in oscillation wavelength, thereby reducing the fringes in particular in blue images. This makes it possible to relax the standards for managing the thickness of the liquid crystal display element.

[0017] The oscillation wavelengths of the first blue laser light source 101α to the third blue laser light source 101γ are merely examples, and can be changed as appropriate as long as they are included in the blue wavelength band. The difference between the oscillation wavelengths of the blue laser light sources can be changed as appropriate within a range of, for example, 10 (nm) to 20 (nm). Furthermore, the number of groups of blue laser light sources is not limited to three, as long as there are more than one.

[0018] Blue illumination light from light source 101 is irradiated onto dichroic mirror 120. Dichroic mirror 120 has the property of reflecting blue illumination light and transmitting yellow illumination light. In this embodiment, dichroic mirror 120 includes dichroic mirrors 120α, 120β, and 120γ arranged corresponding to the above-mentioned first blue laser light source 101α to third blue laser light source 101γ.

[0019] The blue illumination light emitted from first blue laser light source 101α through third blue laser light source 101γ, respectively, is reflected by dichroic mirrors 120α through 120γ, and then collected by lens 140 to be irradiated onto phosphor 103. Phosphor 103 has a fluorescent layer and a reflective surface. The fluorescent layer generates yellow illumination light containing red band components and green band components with intensities corresponding to the energy intensities of the blue illumination light irradiated from first blue laser light source 101α through third blue laser light source 101γ. The reflective surface reflects the blue illumination light transmitted through the fluorescent layer and the yellow illumination light generated by the fluorescent layer.

[0020] Dichroic mirrors 120α, 120β, and 120γ are formed to have an area smaller than the beam width of the reflected light (diffused light) from phosphor 103. Furthermore, these dichroic mirrors 120α to 120γ are oriented such that the polarization direction of the laser light with respect to dichroic mirrors 120α, 120β, and 120γ is s-polarized light. Therefore, dichroic mirrors 120α to 120γ have the property of reflecting s-polarized light and transmitting p-polarized light of the blue illumination light incident on dichroic mirrors 120α to 120γ, and transmitting yellow illumination light regardless of the polarization direction.

[0021] Therefore, yellow illumination light (fluorescent light) containing red and green components due to wavelength excitation by phosphor 103 and blue illumination light that is not fluorescent are mixed and enter dichroic mirrors 120α to 120γ again. The yellow illumination light containing red and green components, which is fluorescent light, passes through dichroic mirrors 120α to 120γ and is emitted in its entirety. On the other hand, when the blue illumination light is reflected (diffused) by phosphor 103, it becomes randomly polarized light in which multiple polarized lights are mixed. Therefore, of the components of the blue illumination light that hits dichroic mirrors 120α to 120γ, the p-polarized components pass through dichroic mirrors 120α to 120γ and are emitted, but the s-polarized components are reflected by dichroic mirrors 120α to 120γ and return to first blue laser light source 101α to third blue laser light source 101γ.

[0022] The blue illumination light and the yellow illumination light transmitted through the dichroic mirrors 120α to 120γ are reflected by the reflecting mirror 130 and enter the lens 141. The lenses 141 and 142 are, for example, fly-eye lenses, and the λ / 4 plate 110 is disposed between these lenses 141 and 142. The blue illumination light and the yellow illumination light reflected by the reflecting mirror 130 are uniformly distributed by the lenses 141, the λ / 4 plate 110, and the lenses 142, and enter the polarization conversion element 150. The polarization conversion element 150 has, for example, a polarizing beam splitter and a retardation plate. The polarizing beam splitter reflects either s-polarized light or p-polarized light and transmits the other. In the example of FIG. 1, the polarizing beam splitter reflects s-polarized light and transmits p-polarized light. In addition, the retardation plate converts either s-polarized light or p-polarized light into the other. In the example of FIG. 1, the retardation plate converts s-polarized light into p-polarized light. The polarization conversion element 150 converts each illumination light into p-polarized light.

[0023] The illumination light beams converted into p-polarized light by the polarization conversion element 150 are irradiated onto the dichroic mirror 121 via the lens 143. The lens 143 is, for example, a condenser lens.

[0024] 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 reflecting mirror 131 and enters the dichroic mirror 122.

[0025] The dichroic mirror 122 separates the incident yellow illumination light YL into red illumination light RL containing a red band component and green illumination light GL containing a green band component, with a wavelength between the red light band and the green light band as a separation boundary. Specifically, the dichroic mirror 122 reflects the green band component of the incident yellow illumination light YL to emit the green illumination light GL, and transmits the red band component of the incident yellow illumination light YL to emit the red illumination light RL. The red illumination light RL is, for example, light in a wavelength band of 620 (nm) or more and 750 (nm) or less, and the green illumination light GL is, for example, light in a wavelength band of 495 (nm) or more and 570 (nm) or less.

[0026] The red illumination light RL separated by the dichroic mirror 122 is irradiated onto the polarizing plate 105R via the lens 144. The green illumination light GL separated by the dichroic mirror 122 is irradiated onto 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 onto the polarizing plate 105B via the lens 146.

[0027] The polarizing plates 105R, 105G, and 105B have the property of reflecting either s-polarized light or p-polarized light and transmitting the other. 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 called reflective polarizing plates. The polarizing plates 105R, 105G, and 105B are, for example, wire grid polarizing plates.

[0028] The red illumination light RL, which is p-polarized light, is transmitted through the polarizing plate 105R and is irradiated onto the first display element 106R. The green illumination light GL, which is p-polarized light, is transmitted through the polarizing plate 105G and is irradiated onto the second display element 106G. The blue illumination light BL, which is p-polarized light, is transmitted through the polarizing plate 105B and is irradiated onto the third display element 106B.

[0029] The first display element 106R optically modulates p-polarized red illumination light RL based on red component image data to generate s-polarized red image light RM. The second display element 106G optically modulates p-polarized green illumination light GL based on green component image data to generate s-polarized green image light GM. The third display element 106B optically modulates p-polarized blue illumination light BL based on blue component image data to generate s-polarized blue image light BM. That is, the first display element 106R functions as a red image light modulation element, the second display element 106G functions as a green image light modulation element, and the third display element 106B functions as a blue image light modulation element.

[0030] Red image light RM, which is s-polarized light generated by first display element 106R, is reflected by polarizing plate 105R and is irradiated onto color synthesis prism 108. Green image light GM, which is s-polarized light generated by second display element 106G, is reflected by polarizing plate 105G and is irradiated onto color synthesis prism 108. Blue image light BM, which is s-polarized light generated by third display element 106B, is reflected by polarizing plate 105B and is irradiated onto color synthesis prism 108.

[0031] 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 each image light onto a projection lens 109 .

[0032] The red image light RM, the green image light GM, and the blue image light BM are projected onto a screen or the like (not shown) via a projection lens 109. A visible light image is displayed by the red image light RM, the green image light GM, and the blue image light BM.

[0033] Incidentally, the projection display device 100 of the present embodiment is provided with a non-display function (also called a hide function or image mute function) that temporarily hides or displays all black images to be projected. This type of non-display function not only stops the operation of the display elements 106R, 106G, and 106B of each color or displays all black images, but also reproduces pitch black on the projection surface (e.g., a screen) by stopping (turning off) the emission of the light source 101 when the light source 101 uses a device that can be instantly turned on and off, such as an LD (Laser Diode) or an LED (Light-Emitting Diode). For this reason, it is highly effective for, for example, the night sky in a planetarium, or for blending processing in which multiple images are projected in layers. The non-display function can be executed or canceled by operating a changeover switch 165 (described later) provided on the projection display device main body, for example.

[0034] Furthermore, the projection display device 100 of this embodiment allows the user to select between a normal operation mode and a non-display mode (hide mode) as an operation mode. Here, when the non-display mode is selected and execution of the above-mentioned non-display function is instructed, the projection display device 100 stops the operation of the display elements 106R, 106G, and 106B of each color or sets them to all black display, and also stops (turns off) the light source 101 from emitting light, and temporarily hides the projected image until the non-display function is instructed to be released. Also, when the normal operation mode is selected (the non-display mode is not selected), when execution of the above-mentioned non-display function is instructed, the projection display device 100 continues to emit light from the light source 101 and stops the operation of the display elements 106R, 106G, and 106B of each color or sets them to all black display, and temporarily hides the projected image until the non-display function is instructed to be released. In this embodiment, a configuration in which the non-display mode is selected, that is, a configuration in which the light source 101 stops (turns off) emitting light when execution of the non-display function is instructed, will be described.

[0035] As described above, when the non-display mode is selected and execution of the non-display function is instructed (hereinafter, simply referred to as execution of the non-display function is instructed), the projection display device 100 stops the operation of the display elements 106R, 106G, and 106B of each color or displays them all black, and also stops (turns off) the light source 101 from emitting light to temporarily hide the projected image. In this case, by temporarily stopping the display elements 106R, 106G, and 106B and the light source 101, the temperatures of the display elements 106R, 106G, and 106B and the light source 101 drop. For this reason, even if the non-display function is released, the outputs of the display elements 106R, 106G, and 106B and the light source 101 become unstable until the display elements 106R, 106G, and 106B and the light source 101 are heated to a predetermined temperature before being stopped, and it is assumed that a problem such as a failure to quickly project a good image will occur.

[0036] 1, in this embodiment, the display mechanism 10 includes an element heater (element heating unit) 161 disposed via a heat sink 160 on the back surface (the surface opposite to the side irradiated with each illumination light) of the display elements 106R, 106G, and 106B of each color, and an element temperature sensor 162 provided on the heat sink 160. The heat sink 160 is a plate-like member formed of a metal having high thermal conductivity such as aluminum and has a certain thickness. The heat sink 160 is formed larger than the back surface of each display element, and the entire back surface comes into contact with the heat sink 160.

[0037] The element heater 161 heats each of the display elements 106R, 106G, and 106B via the heat sink 160, and may be, for example, a plate-shaped ceramic heater. The element heater 161 is disposed on the heat sink 160, and can heat the entire heat sink 160, and can uniformly heat each of the display elements 106R, 106G, and 106B. The element temperature sensor 162 is attached to the heat sink 160, and can indirectly detect the temperatures of each of the display elements 106R, 106G, and 106B by measuring the temperature of the heat sink 160. The display elements 106R, 106G, and 106B each include a band gap type element temperature sensor (not shown) in the element circuit, and the temperature of each of the display elements 106R, 106G, and 106B may be directly measured using the band gap type element temperature sensor.

[0038] Furthermore, display mechanism 10 includes light source heaters (light source heating units) 171 arranged via heat sinks 170 on the rear surfaces of first blue laser light source 101α, second blue laser light source 101β, and third blue laser light source 101γ, respectively, and light source temperature sensor 172 provided on heat sink 170. Heat sink 170 is a plate-like member made of a metal with high thermal conductivity, such as aluminum, and has a certain thickness. Heat sink 170 is formed larger than the rear surfaces of the laser light sources, and the entire rear surface comes into contact with heat sink 170.

[0039] The light source heater 171 heats each of the laser light sources 101α, 101β, and 101γ via the heat sink 170, and may be, for example, a plate-shaped ceramic heater. The light source heater 171 is disposed on the heat sink 170, and can heat the entire heat sink 170, and can uniformly heat each of the laser light sources 101α, 101β, and 101γ. The light source temperature sensor 172 is attached to the heat sink 170, and can indirectly detect the temperatures of each of the laser light sources 101α, 101β, and 101γ by measuring the temperature of the heat sink 170. In this embodiment, the display mechanism 10 is configured such that each of the laser light sources 101α, 101β, and 101γ is provided with an individual heat sink 170 and a light source heater 171. However, it may also be configured such that a common heat sink is provided for each of the laser light sources 101α, 101β, and 101γ, and a common light source heater is disposed on this heat sink.

[0040] Next, the control unit 12 will be described. FIG. 2 is a schematic block diagram of the control unit according to this embodiment. As shown in FIG. 2, the control unit 12 includes a light source temperature acquisition unit 21, an element temperature acquisition unit 22, a light source heating control unit 23, an element heating control unit 24, a fan control unit 25, a light source control unit 26, an element control unit 27, and a function instruction reception unit 28. The light source heating control unit 23, the element heating control unit 24, the fan control unit 25, the light source control unit 26, and the element control unit 27 may be configured as an integrated circuit, which is hardware, or may be configured as a central processing unit (CPU) and a memory, which are arithmetic devices of a computer, and a computer program (software) stored in the memory is executed by the CPU. In this embodiment, the part related to the operation control of each unit when the non-display function is executed or released will be described, and the other parts will not be described.

[0041] The light source temperature acquisition unit 21 acquires temperature data of each of the laser light sources 101α, 101β, and 101γ detected by the light source temperature sensor 172. The light source temperature acquisition unit 21 outputs the acquired temperature data of each of the laser light sources 101α, 101β, and 101γ to the light source heating control unit 23 and the fan control unit 25.

[0042] The element temperature acquisition unit 22 acquires temperature data of each of the display elements 106R, 106G, 106B detected by the element temperature sensor 162. The element temperature acquisition unit 22 outputs the acquired temperature data of each of the display elements 106R, 106G, 106B to the element heating control unit 24 and the fan control unit 25.

[0043] The light source heating control unit 23 controls the operation of the light source heaters 171 provided in the laser light sources 101α, 101β, and 101γ based on the temperature data of the laser light sources 101α, 101β, and 101γ input from the light source temperature acquisition unit 21. Specifically, the light source heating control unit 23 sets the temperature data of the laser light sources 101α, 101β, and 101γ immediately before the non-display function is executed as the first light source temperature, and controls the operation of driving the light source heaters 171 to heat the laser light sources 101α, 101β, and 101γ so that the laser light sources 101α, 101β, and 101γ maintain the first light source temperature. That is, when the detected temperature of the first blue laser light source 101α is lower than the set first light source temperature, for example, the light source heating control unit 23 controls the light source heater 171 to be turned on (operated) to heat the first blue laser light source 101α. This control activates the light source heater 171, so that even when the non-display function is being executed (the light source 101 is stopped), each of the laser light sources 101α, 101β, and 101γ is uniformly heated to an appropriate temperature via the heat sink 170. Furthermore, when the temperature data input from the light source temperature acquisition unit 21 reaches a second light source temperature that is higher than the first light source temperature, the light source heating control unit 23 controls to turn off (stop) the light source heater 171. This second light source temperature is set to a temperature that is a predetermined temperature (for example, 5°C to 10°C) higher than the first light source temperature. In this configuration, since each of the laser light sources 101α, 101β, and 101γ is sufficiently heated to an appropriate temperature, the light source heater 171 is turned off to avoid excessive heating.

[0044] The element heating control unit 24 controls the operation of the element heaters 161 provided in the display elements 106R, 106G, and 106B based on the temperature data of the display elements 106R, 106G, and 106B input from the element temperature acquisition unit 22. Specifically, the element heating control unit 24 sets the temperature data of the display elements 106R, 106G, and 106B immediately before the non-display function is executed as the first element temperature, and controls the operation of driving the element heaters 161 to heat the display elements 106R, 106G, and 106B so that the display elements 106R, 106G, and 106B maintain the first element temperature. That is, when the detected temperature of the first display element 106R is lower than the set first element temperature, for example, the element heating control unit 24 controls the element heater 161 to be turned on to heat the first display element 106R. This control activates the element heater 161, so that even when the non-display function is being executed (i.e., the display elements are stopped), each of the display elements 106R, 106G, and 106B is uniformly heated to an appropriate temperature through the heat sink 160. Note that the display elements 106R, 106G, and 106B may have a target temperature set in advance, and the element heating control unit 24 may control each element heater 161 to always maintain the target temperature regardless of whether the non-display function is being executed. Furthermore, when the temperature data input from the element temperature acquisition unit 22 reaches a second element temperature that is higher than the first element temperature, the element heating control unit 24 controls to turn off the element heater 161. This second element temperature is set to a temperature that is a predetermined temperature (for example, 1°C to 2°C) higher than the first element temperature. In this configuration, each of the display elements 106R, 106G, and 106B is sufficiently heated to an appropriate temperature, so that the element heater 161 is turned off to avoid excessive heating.

[0045] The fan control unit 25 controls the operation of the fan 164 based on the temperature data input from the light source temperature acquisition unit 21 or the element temperature acquisition unit 22. The fan 164 is provided, for example, in a housing (not shown) that houses the display mechanism 10, and is a fan for cooling the display mechanism 10 (particularly, the laser light sources 101α, 101β, 101γ, and the display elements 106R, 106G, 106B) by blowing air onto the light source and element heat sinks 170, 160. When the temperature data input from the light source temperature acquisition unit 21 or the element temperature acquisition unit 22 reaches, for example, the higher of the second light source temperature and the second element temperature, the fan control unit 25 controls the operation of the fan 164. This makes it possible to prevent the temperatures of the laser light sources 101α, 101β, 101γ, and the display elements 106R, 106G, 106B from rising excessively. In addition, fans for cooling the laser light sources 101α, 101β, 101γ and the display elements 106R, 106G, 106B may be provided inside the housing (not shown), and each fan may be operated when the temperature data input from the light source temperature acquisition unit 21 or the element temperature acquisition unit 22 reaches the second light source temperature and the second element temperature, respectively.

[0046] The function instruction receiving unit 28 receives an instruction regarding the non-display function based on the operation of the changeover switch 165. Specifically, the function instruction receiving unit 28 receives an instruction to execute or cancel the non-display function. The function instruction receiving unit 28 outputs the received instruction regarding the non-display function to the light source control unit 26 and the element control unit 27.

[0047] The light source control unit 26 controls the operation of the light source 101 based on an instruction related to the non-display function input from the function instruction receiving unit 28. Specifically, when the light source control unit 26 receives an instruction to execute the non-display function from the function instruction receiving unit 28 via the operation of the changeover switch 165, the light source control unit 26 controls the light source 101 (laser light sources 101α, 101β, 101γ) to stop emitting light (to turn off). In addition, when the light source control unit 26 receives an instruction to cancel the non-display function from the function instruction receiving unit 28 via the operation of the changeover switch 165, the light source control unit 26 controls the light source 101 (laser light sources 101α, 101β, 101γ) to emit light (to turn on).

[0048] The element control unit 27 controls the operation of each of the display elements 106R, 106G, and 106B based on an instruction related to the non-display function input from the function instruction receiving unit 28. Specifically, when the element control unit 27 receives an instruction to execute the non-display function from the function instruction receiving unit 28 via the operation of the changeover switch 165, the element control unit 27 performs control to stop the operation of each of the display elements 106R, 106G, and 106B or to display all black. In addition, when the element control unit 27 receives an instruction to cancel the non-display function from the function instruction receiving unit 28 via the operation of the changeover switch 165, the element control unit 27 performs control to operate each of the display elements 106R, 106G, and 106B again.

[0049] Next, the control operation of each part in the control unit will be described. FIG. 3 is a flowchart showing the procedure of the operation of the control unit according to this embodiment. In this flowchart, it is assumed that the projection display device 100 is performing image projection and the above-mentioned non-display mode (hide mode) is selected. As shown in FIG. 3, the control unit 12 determines whether or not the execution of the non-display function is instructed by the changeover switch 165 (step S11). More specifically, the control unit 12 determines whether or not the function instruction receiving unit 28 has received an instruction to execute the non-display function via the changeover switch 165. In this determination, if the execution of the non-display function is not instructed by the changeover switch 165 (step S11; No), the control unit 12 ends the process.

[0050] On the other hand, when the changeover switch 165 instructs execution of the non-display function (step S11; Yes), the control unit 12 acquires the temperature data detected by the light source temperature sensor 172 and the element temperature sensor 162 (step S12). More specifically, immediately before the execution of the non-display function is instructed, the control unit 12 acquires the temperature data of each of the laser light sources 101α, 101β, and 101γ detected by the light source temperature sensor 172 using the light source temperature acquisition unit 21, and acquires the temperature data of each of the display elements 106R, 106G, and 106B detected by the element temperature sensor 162 using the element temperature acquisition unit 22.

[0051] Next, the control unit 12 stops the operation of each of the laser light sources 101α, 101β, and 101γ and each of the display elements 106R, 106G, and 106B (step S13). More specifically, when the function instruction receiving unit 28 receives an instruction to execute the non-display function, the control unit 12 causes the light source control unit 26 to stop emitting light from each of the laser light sources 101α, 101β, and 101γ (to turn off), and causes the element control unit 27 to stop the operation of each of the display elements 106R, 106G, and 106B or to display all black. As a result, the projection display device 100 executes the non-display function of temporarily not displaying the image projection.

[0052] Next, the control unit 12 operates the light source heater 171 and the element heater 161 to maintain the temperatures of the laser light sources 101α, 101β, and 101γ and the display elements 106R, 106G, and 106B (step S14). More specifically, the control unit 12 sets the temperatures of the laser light sources 101α, 101β, and 101γ immediately before the non-display function is executed as first light source temperatures, and controls the operation of driving the light source heaters 171 to heat the laser light sources 101α, 101β, and 101γ by the light source heating control unit 23 so that the laser light sources 101α, 101β, and 101γ maintain the first light source temperature. In this case, when the temperatures of the laser light sources 101α, 101β, and 101γ reach a second light source temperature higher than the first light source temperature, the control unit 12 controls the light source heater 171 to be turned off (stopped) by the light source heating control unit 23. This makes it possible to prevent the laser light sources 101α, 101β, and 101γ from being excessively heated.

[0053] Furthermore, the control unit 12 sets the temperatures of the display elements 106R, 106G, and 106B immediately before the non-display function is executed as the first element temperature, and controls the operation of driving the element heaters 161 to heat the display elements 106R, 106G, and 106B by the element heating control unit 24 so that the display elements 106R, 106G, and 106B maintain the first element temperature. In this case, when the temperatures of the display elements 106R, 106G, and 106B reach a second element temperature higher than the first element temperature, the control unit 12 controls the element heaters 161 to be turned off (stopped) by the element heating control unit 24. This makes it possible to prevent the display elements 106R, 106G, and 106B from being overheated.

[0054] Furthermore, when the temperatures of the laser light sources 101α, 101β, 101γ and the display elements 106R, 106G, 106B reach, for example, the higher of the second light source temperature and the second element temperature, the control unit 12 performs control to operate the fan 164. This allows the laser light sources 101α, 101β, 101γ and the display elements 106R, 106G, 106B to be cooled and prevented from being excessively heated.

[0055] Next, the control unit 12 determines whether or not an instruction to cancel the non-display function has been issued by the changeover switch 165 (step S15). More specifically, the control unit 12 determines whether or not an instruction to cancel the non-display function has been accepted by the function instruction accepting unit 28 via the changeover switch 165. In this determination, if an instruction to cancel the non-display function has not been issued by the changeover switch 165 (step S15; No), the control unit 12 returns the process to step S14.

[0056] On the other hand, when the changeover switch 165 has instructed to cancel the non-display function (step S15; Yes), the control unit 12 resumes the operation of each of the laser light sources 101α, 101β, and 101γ and each of the display elements 106R, 106G, and 106B (step S16). More specifically, when the function instruction receiving unit 28 receives an instruction to cancel the non-display function, the control unit 12 resumes the operation of turning on (emitting light from) each of the laser light sources 101α, 101β, and 101γ through the light source control unit 26. In addition, the control unit 12 resumes the operation of turning on each of the display elements 106R, 106G, and 106B through the element control unit 27. As a result, in the projection display device 100, the non-display function for temporarily hiding the image projection is released, and image projection is resumed. At this time, the laser light sources 101α, 101β, 101γ and the display elements 106R, 106G, 106B are maintained at the first light source temperature and the first element temperature, respectively, by the light source heater 171 and the element heater 161. Therefore, when the non-display function is released, the output of the laser light sources 101α, 101β, 101 can be stabilized, and further, the color emitted by the display elements 106R, 106G, 106B can be stabilized, allowing a good image to be projected promptly.

[0057] Next, the control unit 12 stops the operation of the light source heater 171 and the element heater 161 (step S17). More specifically, since the operation of each of the laser light sources 101α, 101β, and 101γ and each of the display elements 106R, 106G, and 106B has been resumed and there is no need for further heating, the light source heating control unit 23 and the element heating control unit 24 stop the operation of the light source heater 171 and the element heater 161. This ends a series of processes.

[0058] As described above, the projection display device 100 according to this embodiment has the laser light sources 101α, 101β, and 101γ that emit laser light used to project an image, and has a non-display function that temporarily hides the projection of an image by stopping the emission of each of the laser light sources 101α, 101β, and 101γ, and is provided with a light source temperature sensor 172 that detects the temperature of each of the laser light sources 101α, 101β, and 101γ, a light source heater 171 that heats each of the laser light sources 101α, 101β, and 101γ, and The device includes a control unit 12 that controls the operations of 101α, 101β, 101γ and the light source heater 171, and a changeover switch 165 that instructs execution or cancellation of a non-display function, and when execution of the non-display function is instructed by the changeover switch 165, the control unit 12 stops the emission of each of the laser light sources 101α, 101β, 101γ, acquires the temperature detected by the light source temperature sensor 172, and controls the light source heater 171 so that each of the laser light sources 101α, 101β, 101γ maintains the acquired temperature. According to this configuration, when the non-display function is canceled, the temperature of each of the laser light sources 101α, 101β, 101 is maintained, so that the output of each of the laser light sources 101α, 101β, 101 can be stabilized, and a good image can be quickly projected.

[0059] In the projection display device 100 according to this embodiment, when the changeover switch 165 is used to instruct the cancellation of the non-display function, the control unit 12 starts the emission of the laser light sources 101α, 101β, and 101γ and stops the heating operation of the light source heater 171. According to this configuration, the start of emission of the laser light sources 101α, 101β, and 101γ makes it possible to maintain the temperatures of the laser light sources 101α, 101β, and 101γ without heating with the light source heater 171, so that a good image can be quickly projected.

[0060] The projection display device 100 according to this embodiment includes display elements 106R, 106G, and 106B that are arranged corresponding to red, green, and blue, respectively, and that irradiate laser light to generate image light corresponding to each color, an element heater 161 that heats each of the display elements 106R, 106G, and 106B, and an element temperature sensor 162 that detects the temperature of each of the display elements 106R, 106G, and 106B. When an instruction to execute a non-display function is given by the change-over switch 165, the control unit 12 stops the operation of each of the display elements 106R, 106G, and 106B, acquires the temperature detected by the element temperature sensor 162, and controls the element heater 161 so that the temperatures of each of the display elements 106R, 106G, and 106B are maintained at the acquired temperatures. When an instruction to cancel the non-display function is given by the change-over switch 165, the control unit 12 starts the operation of each of the display elements 106R, 106G, and 106B, and stops the heating operation of the element heater 161. According to this configuration, when the non-display function is released, the temperature of each of the display elements 106R, 106G, and 106B is maintained, so that the color emitted by each of the display elements 106R, 106G, and 106B can be stabilized, and a good image can be quickly projected.

[0061] [Second embodiment] Next, the second embodiment will be described. FIG. 4 is a schematic diagram of a projection display device according to the second embodiment. FIG. 5 is a schematic block diagram of a control unit according to the second embodiment. The same components as those in the first embodiment of the projection display device 100A according to the second embodiment are denoted by the same reference numerals, and the description thereof will be omitted. As shown in FIG. 4, the projection display device 100A includes a display mechanism 10A and a control unit 12A. In the second embodiment, as shown in FIG. 4, the display mechanism 10A includes light source heaters (light source heating units) 171 arranged on the rear surfaces of the laser light sources 101α, 101β, and 101γ via heat sinks 170, but unlike the first embodiment, no light source temperature sensor is provided. Meanwhile, the display mechanism 10A includes an environmental temperature sensor 175 for detecting the environmental temperature in the display mechanism 10A. The environmental temperature sensor 175 is provided, for example, in a housing (not shown) that houses the display mechanism 10A, and detects the air temperature in the housing.

[0062] As shown in FIG. 5, the control unit 12A includes an element temperature acquisition unit 22, a light source heating control unit 23, an element heating control unit 24, a fan control unit 25, a light source control unit 26, an element control unit 27, a function instruction receiving unit 28, an environmental temperature acquisition unit 29, an information acquisition unit 30, and a light source temperature estimation unit 31. The light source heating control unit 23, the element heating control unit 24, the fan control unit 25, the light source control unit 26, the element control unit 27, and the light source temperature estimation unit 31 may be configured as an integrated circuit, which is hardware, or may be configured as a central processing unit (CPU) and a memory, which are arithmetic devices of a computer, and a computer program (software) stored in the memory is executed by the CPU. In this embodiment, the parts related to the operation control of each unit when the non-display function is executed or released will be described, and the other parts will not be described. In addition, the same members as those in the first embodiment will be given the same reference numerals and will not be described.

[0063] As described above, the light source control unit 26 controls the operation of each of the laser light sources 101α, 101β, and 101γ based on the instruction related to the non-display function input from the function instruction receiving unit 28. When the light source control unit 26 receives an instruction to execute the non-display function from the function instruction receiving unit 28, it stops the emission of each of the laser light sources 101α, 101β, and 101γ. At this time, the light source control unit 26 reads out the output values ​​of each of the laser light sources 101α, 101β, and 101γ immediately before executing the non-display function, and outputs these output values ​​to the light source temperature estimation unit 31.

[0064] The environmental temperature acquisition unit 29 acquires temperature data of the environmental temperature (air temperature) in the housing of the display mechanism 10A detected by the environmental temperature sensor 175. The environmental temperature acquisition unit 29 outputs the acquired temperature data to the light source temperature estimation unit 31.

[0065] The information acquisition unit 30 acquires information on the relationship between the output value (output) of each of the laser light sources 101α, 101β, and 101γ and the temperature of the laser light sources 101α, 101β, and 101γ, and the relationship between the output value (output) of the light source heater 171 and the temperature of each of the laser light sources 101α, 101β, and 101γ from the storage unit 166. Specifically, the storage unit 166 stores information on the temperature of each of the laser light sources 101α, 101β, and 101γ when each of the laser light sources 101α, 101β, and 101γ is caused to emit light at a predetermined output value through a prior experiment or the like. In this case, the storage unit 166 stores information (e.g., table data) on the temperature of each of the laser light sources 101α, 101β, and 101γ corresponding to the change in the environmental temperature and the output value when the environmental temperature and the output value are changed, respectively. Therefore, when each laser light source 101α, 101β, and 101γ is caused to emit light at a predetermined output value under a predetermined environmental temperature, the information acquisition unit 30 can acquire information regarding the temperature of each laser light source 101α, 101β, and 101γ corresponding to this environmental temperature and output value.

[0066] The storage unit 166 also stores information on the temperatures of the laser light sources 101α, 101β, and 101γ when the light source heater 171 is operated at a predetermined output value with the laser light sources 101α, 101β, and 101γ turned off, based on a prior experiment or the like. In this case, the storage unit 166 stores information (e.g., table data) on the temperatures of the laser light sources 101α, 101β, and 101γ corresponding to the change in the environmental temperature and the output value when the environmental temperature and the output value of the light source heater 171 are changed, respectively. Therefore, when the light source heater 171 is operated at a predetermined output value under a predetermined environmental temperature, the information acquisition unit 30 can acquire information on the temperatures of the laser light sources 101α, 101β, and 101γ (temperatures to which the laser light sources 101α, 101β, and 101γ are heated and risen) corresponding to the environmental temperature and the output value. The information acquisition unit 30 outputs the acquired information to the light source temperature estimation unit 31.

[0067] The light source temperature estimation unit 31 estimates the temperatures of the laser light sources 101α, 101β, and 101γ corresponding to the output values ​​of the laser light sources 101α, 101β, and 101γ based on the information acquired by the information acquisition unit 30. Specifically, the light source temperature estimation unit 31 reads information on the temperatures of the laser light sources 101α, 101β, and 101γ corresponding to the output values ​​and environmental temperature of the laser light sources 101α, 101β, and 101γ immediately before the non-display function is executed, which are input from the light source control unit 26, and the environmental temperature, and estimates this temperature as the temperature of the laser light sources 101α, 101β, and 101γ immediately before the non-display function is executed.

[0068] The light source heating control unit 23 controls the light source heater 171 to an output value of the light source heater 171 corresponding to the estimated temperature of each of the laser light sources 101α, 101β, and 101γ based on the above information acquired by the information acquisition unit 30. As a result, each of the laser light sources 101α, 101β, and 101γ is heated by the light source heater 171, and is maintained at the temperature immediately before the non-display function is executed even after the non-display function is executed.

[0069] Next, the control operation of each part in the control unit 12A will be described. FIG. 6 is a flowchart showing the procedure of the operation of the control unit according to this embodiment. In this flowchart, it is also assumed that the projection display device 100A is executing image projection and the above-mentioned non-display mode (hide mode) is selected. As shown in FIG. 6, the control unit 12A determines whether or not the execution of the non-display function is instructed by the changeover switch 165 (step S21). More specifically, the control unit 12A determines whether or not the function instruction receiving unit 28 has received an instruction to execute the non-display function via the changeover switch 165. In this determination, if the execution of the non-display function is not instructed by the changeover switch 165 (step S21; No), the control unit 12A ends the process.

[0070] On the other hand, when the changeover switch 165 instructs execution of the non-display function (step S21; Yes), the control unit 12A acquires the temperature data detected by each of the element temperature sensors 162 (step S22). More specifically, the control unit 12A causes the element temperature acquisition unit 22 to acquire the temperature data of each of the display elements 106R, 106G, and 106B detected by the element temperature sensor 162 immediately before execution of the non-display function is instructed.

[0071] Next, the control unit 12A estimates the temperature of the light source corresponding to the output value of the light source based on the information stored in the storage unit 166 (step S23). More specifically, the control unit 12A acquires, from the storage unit 166, information on the relationship between the output value of each laser light source 101α, 101β, 101γ and the temperature of the laser light sources 101α, 101β, 101γ, and the relationship between the output value (output) of the light source heater 171 and the temperature of each laser light source 101α, 101β, 101γ, using the information acquisition unit 30. Then, the control unit 12A estimates, based on the information acquired by the information acquisition unit 30, the temperature of the laser light sources 101α, 101β, 101γ corresponding to (corresponding to) the output value of each laser light source 101α, 101β, 101γ using the light source temperature estimation unit 31. Specifically, the light source temperature estimation unit 31 reads information regarding the temperatures of each laser light source 101α, 101β, 101γ corresponding to the output values ​​and environmental temperature of each laser light source 101α, 101β, 101γ immediately before executing the non-display function, which are input from the light source control unit 26, and estimates this temperature as the temperature of each laser light source 101α, 101β, 101γ immediately before executing the non-display function.

[0072] Next, the control unit 12A stops the operation of each of the laser light sources 101α, 101β, and 101γ and each of the display elements 106R, 106G, and 106B (step S24). More specifically, when the function instruction receiving unit 28 receives an instruction to execute the non-display function, the control unit 12 causes the light source control unit 26 to stop emitting light from each of the laser light sources 101α, 101β, and 101γ (to turn off), and causes the element control unit 27 to stop the operation of each of the display elements 106R, 106G, and 106B or to display all black. As a result, the projection display device 100 executes the non-display function of temporarily not displaying the image projection.

[0073] Next, the control unit 12A operates the element heater 161 to maintain the temperature of each of the display elements 106R, 106G, and 106B (step S25). More specifically, the control unit 12A sets the temperature of each of the display elements 106R, 106G, and 106B immediately before the non-display function is executed as a first element temperature, and controls the operation of driving each element heater 161 to heat each of the display elements 106R, 106G, and 106B by the element heating control unit 24 so that each of the display elements 106R, 106G, and 106B maintains this first element temperature. In this case, when each of the temperatures of the display elements 106R, 106G, and 106B reaches a second element temperature higher than the first element temperature, the control unit 12 controls the element heater 161 to be turned off (stopped) by the element heating control unit 24. This makes it possible to prevent each of the display elements 106R, 106G, and 106B from being overheated.

[0074] Next, the control unit 12A drives the light source heater with an output corresponding to the estimated light source start based on the information stored in the storage unit 166 (step S26). As described above, the control unit 12A acquires information on the relationship between the output value of each laser light source 101α, 101β, 101γ and the temperature of the laser light sources 101α, 101β, 101γ, and the relationship between the output value (output) of the light source heater 171 and the temperature of each laser light source 101α, 101β, 101γ from the storage unit 166 by the information acquisition unit 30. Then, the control unit 12A controls the light source heater 171 to the output value of the light source heater 171 corresponding to the estimated temperature of each laser light source 101α, 101β, 101γ based on the information acquired by the information acquisition unit 30. As a result, the laser light sources 101α, 101β, and 101γ are heated by the light source heater 171, and are maintained at the same temperature as immediately before the non-display function was executed, even after the non-display function has been executed.

[0075] Next, the control unit 12A determines whether or not an instruction to cancel the non-display function has been issued by the changeover switch 165 (step S27). More specifically, the control unit 12A determines whether or not an instruction to cancel the non-display function has been accepted by the function instruction accepting unit 28 via the changeover switch 165. In this determination, if an instruction to cancel the non-display function has not been issued by the changeover switch 165 (step S27; No), the control unit 12A returns the process to step S25.

[0076] On the other hand, when the changeover switch 165 has instructed to cancel the non-display function (step S27; Yes), the control unit 12A resumes the operation of each of the laser light sources 101α, 101β, and 101γ and each of the display elements 106R, 106G, and 106B (step S28). More specifically, when the function instruction receiving unit 28 receives an instruction to cancel the non-display function, the control unit 12A resumes the operation of turning on (emitting light from) each of the laser light sources 101α, 101β, and 101γ through the light source control unit 26. In addition, the control unit 12A resumes the operation of turning on each of the display elements 106R, 106G, and 106B through the element control unit 27. As a result, in the projection display device 100A, the non-display function for temporarily hiding the image projection is released, and image projection is resumed. At this time, the laser light sources 101α, 101β, 101γ and the display elements 106R, 106G, 106B are maintained at the temperature (for example, the first element temperature) immediately before the non-display function is executed by the light source heater 171 and the element heater 161. Therefore, when the non-display function is released, the output of the laser light sources 101α, 101β, 101 can be stabilized, and further, the color emitted by the display elements 106R, 106G, 106B can be stabilized, so that a good image can be quickly projected.

[0077] Next, the control unit 12 stops the operation of the light source heater 171 and the element heater 161 (step S29). More specifically, since the operation of each of the laser light sources 101α, 101β, and 101γ and each of the display elements 106R, 106G, and 106B has been resumed and there is no need for further heating, the light source heating control unit 23 and the element heating control unit 24 stop the operation of the light source heater 171 and the element heater 161. This ends a series of processes.

[0078] The projection display device 100A according to this embodiment has laser light sources 101α, 101β, and 101γ that emit laser light used for projecting an image, and is equipped with a non-display function for temporarily hiding the projection of an image by stopping the emission of each of the laser light sources 101α, 101β, and 101γ. The projection display device 100A also has a light source heater 171 that heats each of the laser light sources 101α, 101β, and 101γ, and an information acquisition device that acquires information regarding the relationship between the output value of each of the laser light sources 101α, 101β, and 101γ and the temperature of the laser light sources 101α, 101β, and 101γ, and the relationship between the output value of the light source heater 171 and the temperature of each of the laser light sources 101α, 101β, and 101γ. The information acquisition unit 30 includes a control unit 12A that controls the operation of at least each of the laser light sources 101α, 101β, 101γ and the light source heater 171, and a changeover switch 165 that instructs execution or cancellation of a non-display function. When execution of the non-display function is instructed by the changeover switch 165, the control unit 12 stops the emission of each of the laser light sources 101α, 101β, 101γ, and estimates the temperatures of the laser light sources 101α, 101β, 101γ corresponding to the output values ​​of each of the laser light sources 101α, 101β, 101γ based on the information acquired by the information acquisition unit 30, and controls the light source heater 171 to an output value corresponding to the estimated temperature. According to this configuration, each of the laser light sources 101α, 101β, and 101γ can be maintained at a temperature just before the non-display function is executed by the light source heater 171. Therefore, when the non-display function is released, the output of each of the laser light sources 101α, 101β, and 101γ can be stabilized, enabling a good image to be quickly projected.

[0079] Although the embodiment of the present invention has been described above, the embodiment is not limited to the contents of this embodiment. The above-mentioned components include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-mentioned components can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the gist of the above-mentioned embodiment. [Explanation of symbols]

[0080] 10, 10A display mechanism 12, 12A Control section 21 Light source temperature acquisition section 22 Element temperature acquisition section 23 Light source heating control section 24 Element heating control section 25 Fan control unit 26 Light source control unit 27 Element control section 28 Function Instruction Reception Unit 29 Environmental temperature acquisition section 30 Information acquisition department 31 Light source temperature estimation section 100, 100A projection display device 101 Light source 101α 1st blue laser light source 101β Second blue laser light source 101γ 3rd blue laser light source 106R 1st 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 color) 160, 170 Heat sink 161 Element heater (element heating part) 162 Element temperature sensor 164 Fans 165 Changeover switch (switch) 166 Memory section 171 Light source heater (light source heating section) 172 Light source temperature sensor

Claims

1. A liquid crystal display device having a light source that emits a laser beam used for projecting an image, the liquid crystal display device having a non-display function of temporarily hiding the projection of the image by stopping the emission of the light source, a light source temperature sensor for detecting a temperature of the light source; a light source heating unit that heats the light source; A control unit that controls operations of at least the light source and the light source heating unit; a switch for instructing execution or release of the non-display function; When the control unit instructs the switch to execute the non-display function, it stops the light source from emitting light, acquires the temperature detected by the light source temperature sensor, and controls the light source heating unit so that the light source maintains the acquired temperature.

2. A liquid crystal display device having a light source that emits a laser beam used for projecting an image, the liquid crystal display device having a non-display function of temporarily hiding the projection of the image by stopping the emission of the light source, a light source heating unit that heats the light source; an information acquiring unit that acquires information regarding a relationship between an output of the light source and a temperature of the light source, and a relationship between an output of the light source heating unit and a temperature of the light source; A control unit that controls operations of at least the light source and the light source heating unit; a switch for instructing execution or release of the non-display function; When the control unit instructs the switch to execute the non-display function, it stops the light source from emitting light, estimates the temperature of the light source corresponding to the output of the light source based on the information acquired by the information acquisition unit, and controls the light source heating unit to an output corresponding to the estimated temperature.

3. When the switch is operated to instruct the non-display function to be released, The liquid crystal display device according to claim 1 , wherein the control unit starts light emission from the light source and stops a heating operation of the light source heating unit.

4. liquid crystal display elements arranged to correspond to red, green, and blue, respectively, and irradiating the laser light to generate image light corresponding to each color, an element heating unit that heats the liquid crystal display elements, and an element temperature sensor that detects the temperature of the liquid crystal display elements, when the control unit receives an instruction to execute the non-display function from the switch, the control unit stops the operation of the liquid crystal display element or displays all black, acquires a temperature detected by the element temperature sensor, and controls the element heating unit so that each temperature of the liquid crystal display element is maintained at the acquired temperature; 3. The liquid crystal display device according to claim 1, wherein when the switch instructs to release the non-display function, the liquid crystal display element starts to operate and the heating operation of the element heating section stops.

Images