Projection display device

Abstract

A projection display device (100) is provided with a third display element (106B) having a built-in bandgap-type temperature sensor (163), a heater (161), a temperature sensor (162), a fan, and a control unit (12) that controls the operation of the third display element (106B), the heater (161), and the fan on the basis of the temperatures detected by the temperature sensors (162, 163), and the control unit (12) controls the operation of the third display element (106B), the heater (161), and the fan on the basis of the temperatures detected by the temperature sensors (162, 163) when the projection display device (100) is in a standby state. When the projection display device (100) is started, power is supplied to the third display element (106B), the heater (161) is operated on the basis of the temperature detected by the temperature sensor (162) to control the third display element (106B) to a target temperature, and when the projection display device (100) is started, power is supplied to the third display element (106B). On the basis of the temperature detected by the temperature sensor (163), at least one of the heater (161) and the fan is operated, and the third display element (106B) is controlled to a target temperature.

Description

Technical Field

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

[0002] Generally, there is known a projection display device that has used a reflective liquid crystal display element (e.g., see Patent Document 1). In such a projection display device, in order to maintain the image performance displayed well, it is important that the temperature of the liquid crystal display element is maintained substantially constant at a temperature higher than the operating environment temperature.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2005-227485 Summary of the Invention

[0006] However, projection display devices are required to deliver excellent image quality immediately after startup. Therefore, a configuration in which a heater is provided to heat the liquid crystal display element is envisioned. However, even with a configuration in which a heater is provided, the heater is activated after the projection display device is started, so it takes time for the liquid crystal display element to reach the desired temperature. This leads to unstable image quality immediately after startup, leaving room for improvement.

[0007] In view of the above-mentioned problems, the present disclosure aims to provide a projection display device capable of achieving stable image performance immediately after startup.

[0008] A projection display device according to one embodiment of the present invention includes: a liquid crystal display element having a built-in first temperature sensor; a heating unit arranged on the liquid crystal display element via a heat sink; a second temperature sensor arranged on the heat sink; an air supply fan for air-cooling the heat sink; and a control unit for controlling the operation of the liquid crystal display element, the heating unit, and the air supply fan based on the temperatures detected by the first temperature sensor and the second temperature sensor. When the projection display device is in a standby state, the control unit does not supply power to the liquid crystal display element, but operates the heating unit based on the temperature detected by the second temperature sensor to control the liquid crystal display element to a target temperature. When the projection display device is started, power is supplied to the liquid crystal display element, and at least one of the heating unit and the air supply fan is operated based on the temperature detected by the first temperature sensor to control the liquid crystal display element to a target temperature.

[0009] According to this embodiment, in the standby state before startup of the projection display device, the heating unit is operated based on the temperature detected by the second temperature sensor to control the liquid crystal display element to a target temperature, thereby achieving stable image performance immediately after startup. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0012] Figure 3 This is a timing chart showing an example of the operation of the temperature sensor and the bandgap temperature sensor according to the present embodiment.

[0013] Figure 4 This is a flowchart showing the operation procedure of the control unit according to this embodiment. DETAILED DESCRIPTION

[0014] Hereinafter, this embodiment will be described in detail based on the drawings. However, the present disclosure is not limited to the embodiment described below.

[0015] (Configuration of Projection Display Device)

[0016] Figure 1 Schematic diagram of the projection display device involved in this embodiment. The projection display device is a display device that generates white light by irradiating visible light (such as blue laser) to a phosphor, decomposes the white light into red, blue and green light, and then modulates the light of each color to display a synthesized image. Figure 1 As shown, a projection display device 100 according to this embodiment 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 have a structure in which a liquid crystal layer is sandwiched between a silicon substrate and a glass substrate, and are reflective liquid crystal display elements provided corresponding to each color, which will be described later.

[0017] The dichroic mirrors 120-122 have the following characteristics: they separate incident light by reflection and transmission, with the separation wavelengths serving as the separation boundaries. The dichroic mirrors 120-122 can be fabricated by forming a dielectric multilayer film, for example, in predetermined areas of a transparent material such as a glass plate or prism. The optical characteristics can be customized by the material and thickness of the dielectric material constituting the dielectric multilayer film.

[0018] The light source 101 emits illumination light in the visible wavelength range. In this embodiment, the light source 101 is a blue laser source composed of a blue laser element, and emits blue illumination light in the wavelength range of, for example, 450 nm to 495 nm.

[0019] In this embodiment, the light source 101 includes three (or more) groups of different oscillation wavelengths: a first blue laser source 101α, a second blue laser source 101β, and a third blue laser source 101γ. Each of these groups of first to third blue laser sources 101α, 101γ is configured to have an oscillation wavelength that differs by at least 10 nm. Specifically, the oscillation wavelength of the first blue laser source 101α is set to 445 nm, the oscillation wavelength of the second blue laser source 101β is set to 455 nm, and the oscillation wavelength of the third blue laser source 101γ is set to 465 nm.

[0020] The oscillation wavelengths of the first through third blue laser sources 101α, 101γ are examples and can be modified as appropriate, as long as they fall within the blue wavelength band. Furthermore, the difference in oscillation wavelength between the blue laser sources can be modified as appropriate within a range of, for example, 10 nm to 20 nm. Furthermore, the number of blue laser sources can be modified as appropriate, and may be limited to one (single wavelength).

[0021] The blue illumination light from light source 101 is irradiated onto dichroic mirror 120. Dichroic mirror 120 has the characteristic of reflecting the blue illumination light and transmitting the yellow illumination light. In this embodiment, dichroic mirror 120 includes dichroic mirrors 120α, 120β, and 120γ arranged corresponding to the first to third blue laser light sources 101α to 101γ.

[0022] The blue illumination light emitted from the first to third blue laser sources 101α to 101γ is reflected by dichroic mirrors 120α to 120γ, then focused by lens 140 and irradiated onto phosphor 103. Phosphor 103 comprises a phosphor layer and a reflective surface. The phosphor layer generates yellow illumination light, which contains red and green components with intensities corresponding to the energy intensity of the blue illumination light emitted from the first to third blue laser sources 101α to 101γ. The reflective surface reflects the blue illumination light that has passed through the phosphor layer, as well as the yellow illumination light generated by the phosphor layer.

[0023] The dichroic mirrors 120α, 120β, and 120γ are formed to have an area smaller than the beam width of the reflected light (diffused light) from the phosphor 103. Furthermore, these dichroic mirrors 120α to 120γ are positioned so that the polarization direction of the laser light relative to the dichroic mirrors 120α, 120β, and 120γ becomes s-polarized light. Therefore, the dichroic mirrors 120α to 120γ reflect the s-polarized light in the blue illumination light incident on them, transmit the p-polarized light, and transmit the yellow illumination light regardless of its polarization direction.

[0024] Therefore, the yellow illumination light (fluorescence), which is wavelength-excited by phosphor 103 and contains red and green components, mixes with the blue illumination light, which does not emit fluorescence, and then enters dichroic mirrors 120α to 120γ again. The yellow illumination light, which contains red and green components and is fluorescent, passes through dichroic mirrors 120α to 120γ and is completely emitted. On the other hand, the blue illumination light, when reflected (diffused) by phosphor 103, becomes randomly polarized light, a mixture of multiple polarized light components. Therefore, of the components of the blue illumination light entering dichroic mirrors 120α to 120γ, the p-polarized light component passes through dichroic mirrors 120α to 120γ and is emitted, while the s-polarized light component is reflected by dichroic mirrors 120α to 120γ and returns to the first to third blue laser sources 101α to 101γ.

[0025] The blue illumination light and the yellow illumination light that have passed through the dichroic mirrors 120α to 120γ are reflected by the reflector 130 and enter the lens 141. The lens 141 and the lens 142 are, for example, fly-eye lenses, and a λ / 4 plate 110 is arranged between these lenses 141 and 142. The blue illumination light and the yellow illumination light that have been reflected by the reflector 130 are uniformly distributed by the lens 141, the λ / 4 plate 110, and the lens 142, and enter the polarization conversion element 150. The polarization conversion element 150 has, for example, a polarization beam splitter and a phase difference plate. The polarization beam splitter reflects either the s-polarized light or the p-polarized light and transmits the other. Figure 1 In the example of , the polarization beam splitter reflects s-polarized light and transmits p-polarized light. In addition, the phase difference plate converts either s-polarized light or p-polarized light into the other. Figure 1 In the example of FIG, the phase difference plate converts s-polarized light into p-polarized light. The polarization conversion element 150 converts each illumination light into p-polarized light.

[0026] The illumination lights unified into p-polarized lights 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.

[0027] The dichroic mirror 121 separates the incident blue illumination light BL and the yellow illumination light YL. The yellow illumination light YL separated by the dichroic mirror 121 is reflected by the reflection mirror 131 and enters the dichroic mirror 122.

[0028] The dichroic mirror 122 separates the incident yellow illumination light YL into red illumination light RL containing a component in the red wavelength band and green illumination light GL containing a component in the green wavelength band, using the wavelength midway between the red and green wavelength bands as the separation boundary. Specifically, the dichroic mirror 122 reflects the green wavelength component of the incident yellow illumination light YL to emit the green illumination light GL, while transmitting the red wavelength 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 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.

[0029] 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.

[0030] Polarizing plates 105R, 105G, and 105B have the property of reflecting either s-polarized light or p-polarized light and transmitting the other. Figure 1 In the example shown, 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.

[0031] The p-polarized red illumination light RL passes through polarizing plate 105R and illuminates first display element 106R. The p-polarized green illumination light GL passes through polarizing plate 105G and illuminates second display element 106G. The p-polarized blue illumination light BL passes through polarizing plate 105B and illuminates third display element 106B.

[0032] The first display element 106R optically modulates p-polarized red illumination light RL based on image data for the red component, generating s-polarized red image light RM. The second display element 106G optically modulates p-polarized green illumination light GL based on image data for the green component, generating s-polarized green image light GM. The third display element 106B optically modulates p-polarized blue illumination light BL based on image data for the blue component, generating s-polarized blue image light BM. Specifically, the first display element 106R functions as a red image light modulator, the second display element 106G functions as a green image light modulator, and the third display element 106B functions as a blue image light modulator.

[0033] The red image light RM, which is s-polarized light, generated by the first display element 106R is reflected by the polarizing plate 105R and illuminates the color synthesis prism 108. The green image light GM, which is s-polarized light, generated by the second display element 106G is reflected by the polarizing plate 105G and illuminates the color synthesis prism 108. The blue image light BM, which is s-polarized light, generated by the third display element 106B is reflected by the polarizing plate 105B and illuminates the color synthesis prism 108.

[0034] The color synthesis prism 108 reflects the red image light RM and the blue image light BM, transmits the green image light GM, and irradiates the projection lens 109 with the respective image lights.

[0035] The red image light RM, the green image light GM, and the blue image light BM are projected onto a screen (not shown) via the 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.

[0036] However, projection display devices using such reflective liquid crystal display elements are required to exhibit stable image performance immediately after startup. However, stripes (interference fringes) that are divided into bright and dark areas may sometimes appear in the displayed image immediately after startup. The liquid crystal display element immediately after startup is generally at a temperature lower than the temperature suitable for operation. Therefore, during the period until the temperature of the liquid crystal display element rises to an appropriate temperature, the temperature distribution within the liquid crystal display element becomes uneven, and undesirable conditions such as stripes are likely to occur. In particular, in a configuration using a blue laser light source as a light source, there is a tendency for stripes to be easily generated in the blue image light.

[0037] In order to solve the above-mentioned disadvantages, in this embodiment, as Figure 1As shown, the display mechanism 10 includes a heater (heating unit) 161 disposed on the back surface (opposite to the side irradiated with blue illumination light BL) of the third display element 106B corresponding to the blue color, with a heat sink 160 interposed therebetween; and a temperature sensor (second temperature sensor) 162 provided on the heat sink 160. The heat sink 160 is a plate-shaped member having a certain thickness and is formed of a metal with high thermal conductivity, such as aluminum. The heat sink 160 is formed larger than the back surface of the third display element 106B, and the entire back surface is in contact with the heat sink 160.

[0038] Heater 161 heats third display element 106B via heat sink 160. For example, a plate-shaped ceramic heater can be used. Heater 161, placed on heat sink 160, heats the entire heat sink 160, thereby uniformly heating third display element 106B. Temperature sensor 162 is attached to heat sink 160 and indirectly detects the temperature of third display element 106B by measuring the temperature of heat sink 160.

[0039] Furthermore, the third display element 106B includes a bandgap temperature sensor (first temperature sensor) 163 within its element circuit. The bandgap temperature sensor 163 is, for example, a semiconductor temperature sensor that measures temperature based on the voltage across a diode in a circuit including the diode. Since the bandgap 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 temperature sensor 163 cannot measure the temperature when the third display element 106B is operating, that is, when power (electricity) is not being supplied to the third display element 106B. Therefore, in this embodiment, the detection data of the temperature sensor 162 is used when the projection display device 100 is not activated and power is not being supplied to the third display element 106B, such as when the projection display device 100 is in standby mode.

[0040] Here, the standby state refers to the state in which the projection display device 100 is in the standby state, which means that although power is supplied to the projection display device 100, the image light is not irradiated. That is, in the standby state, power is not supplied to the light source 101 and the display elements of each color (the first display element 106R, the second display element 106G, and the third display element 106B). On the other hand, startup refers to the state in which the projection display device 100 starts operating and starts irradiating image light, that is, the normal operating state. When the projection display device 100 is started, power is supplied to the light source 101 and the display elements of each color (the first display element 106R, the second display element 106G, and the third display element 106B). The power supply is usually a commercial power supply, but is not limited to this, and a battery power supply can also be used.

[0041] In addition, it can also be configured so that not only the back side of the third display element 106B corresponding to blue, but also the back sides of the first display element 106R and the second display element 106G corresponding to red and green are provided with a heat sink 160, a heater 161, a temperature sensor (second temperature sensor) 162 and a bandgap temperature sensor (first temperature sensor) 163.

[0042] Next, the control unit 12 will be described. Figure 2 This is a schematic block diagram of a control unit according to this embodiment. Figure 3 1 is a timing chart showing an example of the operation of the temperature sensor and the bandgap temperature sensor according to this embodiment. Figure 2 As shown, the control unit 12 includes a first power supply control unit 21 , a second power supply control unit 22 , a first temperature acquisition unit 23 , a second temperature acquisition unit 24 , a heating control unit 25 , a fan control unit 26 , and a timer control unit 27 , each of which is connected to a bus 30 .

[0043] The control unit 12 may be composed of an integrated circuit as hardware, or may be composed of a CPU (Central Processing Unit) as a computer computing device and memory, with the CPU executing a computer program (software) stored in the memory. In this embodiment, the description will focus on the portion related to the operation control of the heater 161, and descriptions of other portions will be omitted.

[0044] The first power supply control unit 21 controls the power supply to the projection display device 100 when the projection display device 100 is in standby mode. Specifically, when the projection display device 100 is in standby mode, the first power supply control unit 21 supplies power to at least the heater 161 and the temperature sensor 162, enabling the heater 161 and the temperature sensor 162 to operate. In this case, the first power supply control unit 21 does not supply power to the light source 101 and the display elements of each color (the first display element 106R, the second display element 106G, and the third display element 106B). In this configuration, the power used during standby mode can be reduced.

[0045] The second power supply control unit 22 controls the power supply to the projection display device 100 during normal operation after startup. Specifically, when the projection display device 100 is started, the second power supply control unit 22 supplies power to the light source 101 and the display elements of each color (the first display element 106R, the second display element 106G, and the third display element 106B). This also supplies power to the bandgap temperature sensor 163 provided in the third display element 106B. In this embodiment, the second power supply control unit 22 supplies power to all electrical components except the temperature sensor 162.

[0046] The first temperature acquisition unit 23 acquires temperature data detected by a bandgap temperature sensor (first temperature sensor) 163. When power is supplied to the third display element 106B under the control of the second power supply control unit 22, the bandgap temperature sensor 163 detects the temperature of the third display element 106B. The first temperature acquisition unit 23 outputs the acquired temperature data to the heating control unit 25 and the fan control unit 26. Alternatively, if no temperature data is input from the bandgap temperature sensor 163, the first temperature acquisition unit 23 may determine that power is not being supplied to the third display element 106B and output this determination result to the heating control unit 25 and the fan control unit 26.

[0047] Second temperature acquisition unit 24 acquires temperature data detected by temperature sensor (second temperature sensor) 162. In this embodiment, temperature sensor 162, unlike bandgap temperature sensor 163, detects the temperature of third display element 106B under the control of second power supply control unit 22 when projection display device 100 is at least in the standby state. Second temperature acquisition unit 24 outputs the acquired temperature data to heating control unit 25.

[0048] The heating control unit 25 controls the operation of the heater 161 based on the temperature data (detected temperature) input from the first temperature acquisition unit 23 or the second temperature acquisition unit 24. In this embodiment, when the projection display device 100 is in a standby state, the heating control unit 25 controls the operation of the heater 161 based on the temperature data input from the second temperature acquisition unit 24. Specifically, when power is not supplied to the third display element 106B, the heating control unit 25 uses the detection data from the temperature sensor 162 to control the operation of the heater 161 so that the third display element 106B reaches a predetermined target temperature. This target temperature is, for example, a temperature within the temperature range in which the third display element 106B operates appropriately.

[0049] Furthermore, when the projection display device 100 is activated and in normal operation, the heating control unit 25 controls the operation of the heater 161 based on the temperature data input from the first temperature acquisition unit 23. Specifically, after power is supplied to the third display element 106B, the heating control unit 25 uses the detection data from the bandgap temperature sensor 163, rather than the detection data from the temperature sensor 162, to control the operation of the heater 161 so that the third display element 106B reaches a predetermined target temperature. This configuration allows the use of temperature data directly and accurately measured to accurately control the third display element 106B to the target temperature.

[0050] As described above, since the temperature sensor 162 is provided on the heat sink 160, there is an error in the temperature detected compared to the bandgap temperature sensor 163. Therefore, it is desirable to minimize this error so that the third display element 106B can be accurately controlled to the target temperature even when the projection display device 100 is in the standby mode. In this embodiment, for example, when the projection display device 100 is activated, the heating control unit 25 calculates and stores the difference (temperature difference) between the temperature sensor 162 and the bandgap temperature sensor 163 based on the temperature data input from the first temperature acquisition unit 23 and the second temperature acquisition unit 24. Then, when the projection display device 100 is in the standby mode for at least the next time, the heating control unit 25 controls the operation of the heater 161 based on the corrected temperature data corrected using the difference in the stored temperature data input from the second temperature acquisition unit 24. This difference can be stored and used repeatedly, or a newly calculated value can be stored and used again each time. According to this configuration, in the second and subsequent standby states, the third display element 106B can be controlled to the target temperature with high accuracy.

[0051] The fan control unit 26 controls the operation of the fan 164 based on the temperature data input from the second temperature acquisition unit 24. The fan 164 is, for example, located within a housing (not shown) housing the display unit 10. It is an exhaust fan that cools the display unit 10 (particularly the third display element 106B) by exhausting air from the housing and drawing in outside air. When the projection display device 100 is in standby mode, i.e., when power is not being supplied to the third display element 106B, the fan control unit 26 does not operate the fan 164, as there is no need to cool the third display element 106B. On the other hand, when the projection display device 100 is activated and in normal operation, i.e., when power is being supplied to the third display element 106B, the fan control unit 26 controls the fan 164 to operate when the temperature data input from the second temperature acquisition unit 24 exceeds, for example, a target temperature. This prevents the temperature of the third display element 106B from rising excessively.

[0052] The timer control unit 27 controls the start-up time for starting the projection display device 100. The timer control unit 27 can set the start-up time (target start-up time) TM2 (see TM2) for starting the projection display device 100, for example, through user operation. Figure 3). The start time TM2 is the time when the projection display device 100 is actually started. When the start time TM2 is set, the timer control unit 27 sets the standby start time (standby time) TM1 before the specified time of the start time TM2. The specified time is, for example, a time sufficient to heat the third display element 106B to a temperature near the target temperature at which the third display element 106B operates properly. The specified time can be a pre-set time, but can also be a time calculated based on the actual temperature of the third display element 106B, the target temperature, and the capacity of the heater 161.

[0053] In this embodiment, when the projection display device 100 reaches the standby start time TM1, it enters the standby state under the control of the timer control unit 27. When the projection display device 100 enters the standby state, Figure 3 As shown, through the first power control unit 21 ( Figure 2 ) is controlled to the temperature sensor 162 and the heater 161 ( Figure 1 ) supplies power, and controls the operation of the heater 161 based on the temperature detected by the temperature sensor 162. In addition, when the projection display device 100 reaches the start time TM2, it is started up and enters the normal operation state under the control of the timer control unit 27. When the projection display device 100 enters the normal operation state, the second power supply control unit 22 ( Figure 2 ), power is supplied to bandgap temperature sensor 163 instead of temperature sensor 162, and the operation of heater 161 is controlled based on the temperature detected by temperature sensor 163. Thus, control unit 12 includes timer control unit 27, which can set both startup time TM2 for activating projection display device 100 and standby start time TM1 for placing projection display device 100 in a standby state a predetermined time before startup time TM2. Therefore, a stable image with suppressed streaks, for example, can be displayed at a desired time by the user.

[0054] Next, the control operation of the heater in the control unit will be described. Figure 4 1 is a flowchart showing the operation sequence of the control unit involved in this embodiment. Figure 4 As shown, when the standby start time TM1 is reached (step S11), the projection display device 100 enters the standby state, and the control unit 12 controls the first power supply control unit 21 ( Figure 2 ) is controlled to supply power to the temperature sensor 162 and the heater 161 (step S12). By this power supply, power is started to be supplied to the heater 161, and the third display element 106B is heated.

[0055] Next, the control unit 12 determines whether a detected temperature difference is stored (step S13). Specifically, the control unit 12, through the heating control unit 25, determines whether a detected temperature difference between the temperature sensor 162 and the bandgap temperature sensor 163 is stored. If a detected temperature difference is stored (step S13: Yes), the control unit 12, through the heating control unit 25, controls the operation of the heater 161 based on a corrected temperature obtained by correcting the detected temperature of the temperature sensor 162 by the difference, so that the third display element 106B reaches the target temperature (step S14). This configuration allows, for example, the third display element 106B to be controlled to the target temperature with high precision in the second and subsequent standby states.

[0056] On the other hand, if the difference in detected temperatures is not stored (step S13; No), the control unit 12 controls the operation of the heater 161 via the heating control unit 25 based on the detected temperature of the temperature sensor 162 so that the third display element 106B reaches the target temperature (step S15). With this configuration, for example, in the initial standby state, although the accuracy is not as high as that of the bandgap temperature sensor 163, it is possible to suppress power consumption and control the third display element 106B to approximately the target temperature.

[0057] Next, the control unit 12 determines whether the start time TM2 has arrived (step S16). Specifically, the control unit 12 determines whether the preset start time TM2 has arrived via the timer control unit 27. If the start time TM2 has not arrived (step S16: No), the control unit 12 returns the process to step S13 and repeats steps S13 through S16. On the other hand, if the start time TM2 has arrived (step S16: Yes), the control unit 12 activates the projection display device 100 and places it in normal operation, supplying power to all electrical components except the temperature sensor 162 via the second power supply control unit 22 (step S17). Specifically, the control unit 12 supplies power to the light source 101 and the display elements of each color (the first display element 106R, the second display element 106G, and the third display element 106B) via the second power supply control unit 22. This allows power to be supplied to the bandgap temperature sensor 163 provided in the third display element 106B instead of to the temperature sensor 162.

[0058] Next, the control unit 12 calculates and stores the difference between the detected temperatures of the temperature sensor 162 and the bandgap temperature sensor 163 (step S18). When the projection display device 100 is activated, both the temperature sensor 162 and the bandgap temperature sensor 163 operate at approximately the same time. Therefore, the control unit 12, via the heating control unit 25, calculates and stores the difference between the detected temperatures of the temperature sensor 162 and the bandgap temperature sensor 163 based on the temperature data input from the first temperature acquisition unit 23 and the second temperature acquisition unit 24. This stored difference is used to calibrate the detected temperature in the next standby state (e.g., step S14).

[0059] The control unit 12 controls the operation of the heater 161 and the fan 164 based on the temperature detected by the bandgap temperature sensor 163 so that the third display element 106B reaches the target temperature (step S19). With this configuration, the bandgap temperature sensor 163 can directly and accurately measure the temperature of the third display element 106B, thereby enabling the third display element 106B to be controlled to the target temperature with high accuracy.

[0060] The control unit 12 determines whether an end operation has been performed (step S20). Specifically, it determines whether the user has operated, for example, the stop button. If no end operation has been performed (step S20: No), the control unit 12 returns to step S19 and repeats the processes of steps S19 and S20. On the other hand, if an end operation has been performed (step S20: Yes), the control unit 12 ends the process.

[0061] As described above, the projection display device 100 according to this embodiment includes the third display element 106B having a built-in bandgap temperature sensor 163, the heater 161 disposed on the third display element 106B via the heat sink 160, the temperature sensor 162 disposed on the heat sink 160, the fan 164 for air-cooling the heat sink 160, and the control unit 12 for controlling the operation of the third display element 106B, the heater 161, and the fan 164 based on the temperatures detected by the temperature sensors 162 and 163. When the projection display device 100 is in a standby state, the control unit 12 does not supply power to the third display element 106B, but controls the third display element 106B to a target temperature by operating the heater 161 based on the temperature detected by the temperature sensor 162. When the projection display device 100 is activated, the control unit 12 supplies power to the third display element 106B and controls the third display element 106B to a target temperature by operating at least one of the heater 161 and the fan 164 based on the temperature detected by the temperature sensor 163. With this configuration, heater 161 is activated from the standby state of projection display device 100 to control third display element 106B to a target temperature. When projection display device 100 is activated, power is supplied to third display element 106B, and based on the temperature detected by temperature sensor 163, at least one of heater 161 and fan 164 is activated to control third display element 106B to the target temperature. This allows for rapid and stable image performance immediately after activation. Furthermore, since power is not supplied to third display element 106B while projection display device 100 is in the standby state, power consumption can be suppressed.

[0062] In the projection display device 100 according to this embodiment, the control unit 12 obtains the difference between the temperatures detected by the bandgap temperature sensor 163 and the temperature sensor 162 at the timing of supplying power to the third display element 106B. At least in the next standby state, the control unit 12 controls the heater 161 based on the corrected temperature obtained by correcting the temperature detected by the temperature sensor 162 using the difference. With this configuration, by correcting the detection error of the temperature sensor 162 using the difference, the third display element 106B can be controlled to a target temperature with high precision in the standby state.

[0063] In the projection display device 100 involved in this embodiment, the control unit 12 includes a timer control unit 27, and the timer control unit 27 can set the start time TM for starting the projection display device 100 and the standby start time TM1 for putting the projection display device 100 into a standby state a predetermined time before the start time TM2. According to this configuration, a stable image with suppressed streaks, for example, can be displayed at a desired time by the user.

[0064] In the projection display device 100 according to this embodiment, the first display element 106R, the second display element 106G, and the third display element 106B are arranged corresponding to the colors red, green, and blue, respectively, and generate image light corresponding to each color. The temperature sensor 162 and the heater 161 are arranged at least on the third display element 106B corresponding to blue, via the heat sink 160. With this configuration, the temperature of the third display element 106B corresponding to blue can be controlled with high precision to a target temperature, thereby achieving stable image performance immediately after startup.

[0065] The present embodiment has been described above, and the embodiment is not limited by the contents of the embodiment. In addition, the above-mentioned constituent elements include constituent elements that are easily conceivable to those skilled in the art, substantially the same constituent elements, and constituent elements within the so-called equivalent scope. Furthermore, the above-mentioned constituent elements may also be appropriately combined. Furthermore, various omissions, replacements, or changes to the constituent elements can be made without departing from the scope of the gist of the above-mentioned embodiment. For example, in the present embodiment, the projection display device 100 is controlled to be in a standby and startup state by the action of the timer control unit 27, but is not limited to this. For example, before the user operates the operation start button to start the projection display device 100, the temperature sensor 162 and the heater 161 are supplied with power by pre-operating the standby button, so that the projection display device 100 is put into a standby state.

[0066] In addition, in this embodiment, the target temperature in the standby state and the target temperature after startup are set to the same temperature. However, these target temperatures can also be different. For example, the target temperature in the standby state (first target temperature) can be set lower than the target temperature after startup (second target temperature). When the projection display device 100 is started, excessive heat may be supplied to the display elements of each color (first display element 106R, second display element 106G, and third display element 106B) by heat sources other than the heater 161 of the light source 101, etc. Therefore, by presetting the target temperature in the standby state to be lower than the target temperature after startup, the convergence time to the target temperature after startup can be controlled to be shorter.

[0067] Industrial availability

[0068] The projection display device of this embodiment can be used as a projection display device using a reflective liquid crystal display element, for example.

[0069] Explanation of symbols

[0070] 10: Display mechanism; 12: Control unit; 21: First power supply control unit; 22: Second power supply control unit; 23: First temperature acquisition unit; 24: Second temperature acquisition unit; 25: Heating control unit; 26: Fan control unit; 27: Timer control unit; 100: Projection display device; 101: 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: Heat sink; 161: Heater (heating unit); 162: Temperature sensor (second temperature sensor); 163: Temperature sensor (first temperature sensor); 164: Fan (air supply fan); TM1: Standby start time; TM2: Start time.

Claims

1. A projection display device, comprising: A liquid crystal display element having a first temperature sensor built therein; a heating portion, disposed on the liquid crystal display element via a heat sink; a second temperature sensor, disposed on the heat sink; an air supply fan for cooling the heat sink with air; as well as a control unit that controls the operations of the liquid crystal display element, the heating unit, and the air supply fan based on the temperatures detected by the first temperature sensor and the second temperature sensor; When the projection display device is in a standby state, the control unit does not supply power to the liquid crystal display element, and operates the heating unit based on the temperature detected by the second temperature sensor to control the liquid crystal display element to a target temperature. When the projection display device is activated, the control unit supplies power to the liquid crystal display element and controls the liquid crystal display element to the target temperature by operating at least one of the heating unit and the ventilation fan based on the temperature detected by the first temperature sensor.

2. The projection display device according to claim 1, wherein: The control unit acquires a difference between the detected temperatures of the first temperature sensor and the second temperature sensor at a timing when power is supplied to the liquid crystal display element. At least in the next standby state, the heating unit is controlled based on a corrected temperature obtained by correcting the temperature detected by the second temperature sensor by the difference.

3. The projection display device according to claim 1 or 2, wherein: The control unit includes a timer control unit capable of setting a target activation time for activating the projection display device and a standby time for placing the projection display device in the standby state a predetermined time before the target activation time.

4. The projection display device according to claim 1 or 2, wherein: The liquid crystal display elements are arranged corresponding to red, green, and blue, respectively, to generate image light corresponding to each color. The second temperature sensor and the heating unit are arranged at least on the liquid crystal display element corresponding to the blue color via the heat sink.

Images