Image irradiation device, image projection device, and image irradiation method

Abstract

To provide an image irradiation device capable of more accurately controlling temperature of a display device, and to provide an image projection device and image irradiation method.SOLUTION: An image irradiation device is provided, comprising a display unit (11) having a display area (17) for displaying an image, a temperature monitoring unit (20) provided in a non-irradiation area, within the display area (17), not irradiated with an image, and a control unit configured to control temperature of the display unit (11) according to temperature acquired from the temperature monitoring unit (20).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image projection device, an image projection device, and an image projection method. [Background technology]

[0002] Conventionally, dashboards that illuminate icons have been used to display various types of information inside vehicles. As the amount of information to be displayed increases, it has been proposed to embed an image display device in the dashboard or to configure the entire dashboard with an image display device.

[0003] However, because the instrument panel is located below the vehicle's windshield, the driver must move their eyes downward while driving in order to see the information displayed on the instrument panel, which is undesirable. Therefore, a head-up display (hereinafter referred to as HUD) has been proposed, which projects an image onto the windshield so that the driver can read the information when looking ahead of the vehicle.

[0004] In the image projection device of the above-mentioned prior art, an image projection device such as a liquid crystal display device emits light containing an image (hereinafter referred to as "image display light"), which is reflected by one or more free-form surface mirrors, and reaches the eyebox of the driver or the like so that an image (virtual image) is formed in space. As a result, the driver or the like can perceive the image as being displayed at an imaging position in the depth direction in front of the vehicle due to the image display light incident on the eyebox. Patent Document 1 discloses an example of such a prior art HUD. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-156071 Summary of the Invention [Problem to be solved by the invention]

[0006] The image projection device mainly includes a display device such as an LCD (Liquid Crystal Display) that displays an image, and a backlight that illuminates the LCD. The backlight illuminates the LCD from behind, emitting image display light that displays the image displayed in the LCD's display area. The HUD projects this image-containing light onto the windshield to form a virtual image, which the driver can view.

[0007] In general, the image projection device described above is configured to change the brightness of the image viewed by the driver depending on the brightness of the environment around the vehicle. For example, when the image projection device is exposed to direct sunlight in summer, when the driver is directly exposed to the setting sun, or when the vehicle is in a very bright environment such as on a snowy day, the brightness of the backlight is increased to almost maximum, thereby improving the visibility of the projected image to the driver.

[0008] If the brightness of the backlight is increased, the LCD itself may absorb light due to its light transmittance of around 7%, causing the LCD temperature to rise. The heat resistance temperature of LCDs is around 105°C, so if the temperature exceeds this temperature, the composition of the LCD will change and it will be irreversibly destroyed, making it impossible to display images. For this reason, LCD temperature management is an important issue in HUDs.

[0009] A known configuration for LCD temperature management involves monitoring the LCD temperature with a temperature sensor and controlling the LCD brightness based on the monitored temperature. Figure 9 shows a conventional image projection device with such a configuration. As shown in Figure 9, a conventional image projection device 60 includes an LCD 61 having a display area 62 and a connection section 63. The connection section 63 is, for example, formed of an FPC (Flexible Printed Circuit) and functions to connect the LCD 61 to external components. Because of the presence of the display area 62 on which an image is displayed, a temperature sensor cannot be located on the LCD 61 itself. Therefore, the image projection device 60 has a temperature sensor 64 located on the connection section 63. However, this configuration does not allow for direct measurement of the LCD 61 temperature, limiting the image projection device 60's ability to accurately control the LCD 61 temperature. While a method of calculating the relationship between the temperature measured by the temperature sensor 64 and the temperature of the LCD 61 through experiments and then performing conversion could be considered, there is room for improvement in terms of accuracy.

[0010] Therefore, the present invention has been made in consideration of the above-mentioned conventional problems, and aims to provide an image projection device, an image projection device, and an image projection method that are capable of more accurately controlling the temperature of a display device. [Means for solving the problem]

[0011] In order to solve the above problem, the image projection device of the present invention is characterized by comprising a display unit having a display area for displaying an image, a temperature monitoring unit arranged in a non-illumination area of ​​the display area where an image is not projected, and a control unit that controls the temperature of the display unit based on the temperature obtained from the temperature monitoring unit.

[0012] The image projection device of the present invention includes a display unit having a display area for displaying an image, a temperature monitoring unit disposed in a non-illumination area of ​​the display area where no image is projected, and a control unit that controls the temperature of the display unit based on the temperature acquired from the temperature monitoring unit. This allows the temperature monitoring unit to be positioned closer to the display area, thereby enabling more accurate temperature control of the display device.

[0013] In one aspect of the present invention, the display unit has a back surface facing the display area, and further includes a front mask that covers a portion of the display area, and a rear mask that covers a portion of the back surface and blocks light at a position corresponding to the position blocked by the front mask, and the non-illuminated area is at least one of a portion of the front mask and a portion of the rear mask.

[0014] In addition, in one aspect of the present invention, the temperature monitoring unit is arranged in an opening provided in at least one of the front mask and the rear mask, and the temperature monitoring unit is in direct contact with the display area or in contact with it via a heat conductive member.

[0015] In one aspect of the present invention, the height of the temperature monitoring unit is approximately equal to the thickness of at least one of the front mask and the rear mask.

[0016] In one aspect of the present invention, the temperature monitoring unit is disposed in a recess provided in at least one of the front mask and the rear mask.

[0017] In one aspect of the present invention, the temperature monitoring unit is disposed on the surface of at least one of the front mask and the rear mask.

[0018] In addition, one aspect of the present invention is characterized in that it further comprises a wiring section connected to the temperature monitoring section, and the wiring section is taken out to the outside along at least one surface of the front mask and the rear mask.

[0019] In order to solve the above problem, another image projection device of the present invention is characterized by comprising: a display unit having a display area for displaying an image and a back surface facing the display area; an illumination unit for illuminating the display unit from the back surface; a temperature monitoring unit arranged in a part of the illumination unit corresponding to an area of ​​the display area where an image is not projected; and a control unit for controlling the temperature of the display unit based on the temperature obtained from the temperature monitoring unit.

[0020] In order to solve the above problem, the image projection device of the present invention comprises: and an optical system that guides the image projected by the image projection device to a virtual image formation unit.

[0021] In order to solve the above problems, the image projection method of the present invention is an image projection method using an image projection device equipped with a display unit, characterized in that a temperature monitoring unit is placed in an area of ​​the display unit where an image is not projected, and the temperature of the display unit is controlled based on the temperature obtained from the temperature monitoring unit. [Effects of the Invention]

[0022] The present invention can provide an image projection device, an image projection device, and an image projection method that can more accurately control the temperature of a display device. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a block diagram showing an example of a configuration of an image projection device according to an embodiment. [Figure 2] 1A and 1B are a front view and a cross-sectional view, respectively, showing an image projection device according to a first embodiment. [Figure 3] 1 is an exploded perspective view showing an example of a configuration of an image projection device according to an embodiment. [Figure 4] FIG. 2 is a block diagram showing an example of the configuration of a control system of the image projection device according to the embodiment. [Figure 5] 10 is a flowchart showing a flow of processing of a temperature control program executed by the image projection device according to the embodiment. [Figure 6] (a) and (b) are a front view and a cross-sectional view, respectively, of an image projection device according to a first modified example of the first embodiment, and (c) and (d) are a front view and a cross-sectional view, respectively, of an image projection device according to a second modified example of the first embodiment. [Figure 7] 10A and 10B are a front view and a cross-sectional view, respectively, of an image projection device according to a third embodiment. [Figure 8] 10A and 10B are a front view and a cross-sectional view, respectively, of an image projection device according to a fourth embodiment. [Figure 9] FIG. 1 is a front view of an image projection device according to a conventional technique. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be assigned the same reference numerals, and redundant explanations will be omitted as appropriate. In the following explanation, an embodiment in which the image projection device and image projection device of the present invention are applied to a HUD mounted on a vehicle or the like will be described as an example.

[0025] (First embodiment) An image projection device, an image projection device, and an image projection method according to this embodiment will be described with reference to FIGS. 1 to 6. FIG. 1 is a block diagram showing an example of the configuration of an image projection device 80 according to this embodiment. The main body of the image projection device 80 is disposed, for example, below the dashboard of a vehicle. The image projection device 80 exemplifies an image projection device employing an image projection method capable of projecting two forward display images on one screen. That is, the image projection device 80 is capable of displaying a distant image formed as a virtual image relatively far in front of the vehicle, and a near image formed as a virtual image relatively close in front of the vehicle. However, the image projection device according to this embodiment is not limited to a two-screen display, and may be a single-screen display, or may be a three-screen or more display.

[0026] As shown in FIG. 1, an image projection device 80 according to this embodiment includes an image projection device 10, a light branching unit 81, a free-form surface mirror 82, a free-form surface mirror 83, a reflecting mirror 84, and a control unit 50.

[0027] The image projection device 10 projects an image for forming a virtual far image or a near image in front of the vehicle. The image projection device 10 includes, as an example, a display device such as a liquid crystal panel (LCD), a liquid crystal on silicon (LCOS), or a digital micromirror device (DMD). In this embodiment, an LCD is used as the display device. As will be described later, the image projection device 10 is divided into a far display area for displaying an image for forming a far image and a near display area for displaying an image for forming a near image. In FIG. 1, the optical path of the image display light GL1 projected from the far display area is indicated by a dashed line, and the optical path of the image display light GL2 projected from the near display area is indicated by a dashed line.

[0028] The optical branching unit 81 is a component that branches the image display light GL1 emitted from the far display region, and is configured, for example, by a prism. As shown in FIG. 1 , the image display light GL1 emitted from the far display region passes through the optical branching unit 81, is reflected by the free-form surface mirror 82, the free-form surface mirror 83, and the windshield (not shown), and reaches the driver's viewpoint. This causes a virtual image to be formed relatively far in front of the vehicle. On the other hand, the image display light GL2 emitted from the near display region is reflected by the reflecting mirror 84 and the free-form surface mirror 83, and reaches the driver's viewpoint. The windshield is an example of a "virtual image forming unit" according to the present invention. The entire optical branching unit 81, the free-form surface mirror 82, the free-form surface mirror 83, and the reflecting mirror 84 are an example of an "optical system" according to the present invention.

[0029] The control unit 50 controls the entire image projection device 10 and executes a temperature control program, which will be described later. The control unit 50 includes a CPU, a ROM, a RAM, etc., which are not shown. The control unit 50 may be an ECU (Engine Control Unit) of a vehicle in which the image projection device 10 is mounted.

[0030] Next, with reference to FIGS. 2 and 3, an example of the configuration of the image projection device 10 according to this embodiment will be described in more detail. FIG. 2(a) shows a front view of the image projection device 10, and FIG. 2(b) shows a cross-sectional view taken along line AA. As shown in FIG. 2(a), the image projection device 10 includes a display unit 11, a front mask 15, a temperature monitoring unit 20, a substrate 21, a wiring unit 22, and a connection unit 12. The display unit 11 is a display device configured using an LCD or the like. The front mask 15 is a light-shielding body that covers an area of ​​the display area of ​​the display unit 11 that does not display an image. The front mask 15 has two openings, opening 15a and opening 15b. The opening 15a exposes a portion of the display area of ​​the display unit 11, forming a far display area 17a, and the opening 15b exposes a portion of the display area of ​​the display unit 11, forming a near display area 17b. One end of the connection part 12 is connected to the display part 11, and the other end is connected to other components such as the control part 50, and serves as a path for power supply to the display part 11, control signals, etc. Hereinafter, the entire display surface of the display part 11 may be referred to as the "display area 17." In contrast, the area of ​​the display area 17 that is not covered by the mask may be referred to as the "effective display area." The far display area 17a and the near display area 17b are examples of the effective display area. The "front mask 15" and the "rear mask 16" are examples of the "non-irradiated area" according to the present invention.

[0031] The temperature monitoring unit 20 is a temperature sensor that measures the temperature of the display unit 11, is connected to the control unit 50, and sends temperature information that forms the basis for controlling the temperature of the display unit 11 to the control unit 50. As will be described later, the control unit 50 controls the temperature of the display unit 11 based on the temperature information from the temperature monitoring unit 20 so that it remains at or below a certain temperature.

[0032] A method for mounting the temperature monitoring unit 20 will be described in more detail with reference to the cross-sectional view of the image projection device 10 shown in Fig. 2(b). As shown in Fig. 2(b), the image projection device 10 includes an illumination unit 13, a rear mask 16, a display unit 11, and a front mask 15. Details of the illumination unit 13 and the rear mask 16 will be described later.

[0033] As shown in FIG. 2(b), an opening 23 is provided in the front mask 15, and a substrate 21 is mounted to cover the opening 23. The substrate 21 is fixed to the front mask 15 with an adhesive or the like. A temperature monitoring unit 20 is mounted on the substrate 21, and the tip of the temperature monitoring unit 20 abuts against the display area 17 of the display unit 11. As shown in FIG. 2(a), the front mask 15 shields the display area 17 of the display unit 11 from light except for the far display area 17a and the near display area 17b. Therefore, the position corresponding to the front mask 15 is unrelated to the image display of the display unit 11. Therefore, by arranging the temperature monitoring unit 20 in this position, i.e., between the far display area 17a and the near display area 17b, it is possible to measure the temperature without affecting the image projection by the image projection device 10. Furthermore, since this position is located between the illumination light ILa (see FIG. 3) of the far display area 17a and the illumination light ILb (see FIG. 3) of the near display area 17b, it is considered to be the area where the temperature on the display area 17 is the highest or the area close to the highest temperature, which also improves accuracy. However, the position on the front mask 15 where the temperature monitoring unit 20 is located is not limited to the above position, and it may be located at any position depending on design conditions, etc.

[0034] A thermally conductive member such as a thermally conductive adhesive or thermally conductive gel may be interposed between the temperature monitoring unit 20 and the display area 17 to enable more accurate temperature measurement. A wiring unit 22 is connected to the substrate 21, and temperature information measured by the temperature monitoring unit 20 is sent to an external component such as the control unit 50 via the wiring unit 22. As shown in FIGS. 2(a) and 2(b), the wiring unit 22 extends to the outside along the front mask 15. While the present embodiment illustrates a configuration in which the substrate 21 and the wiring unit 22 are separated, they may also be integrated using an FPC or the like. In this embodiment, the temperature monitoring unit 20 is in contact with the display area 17 directly or via a thermally conductive member, so the thickness of the front mask 15 is preferably approximately the same as the height of the temperature monitoring unit 20.

[0035] Next, the configuration of the image projection device 10 will be described in more detail with reference to FIG. 3. As shown in FIG. 3, the image projection device 10 includes a display unit 11, an illumination unit 13, a front mask 15, and a rear mask 16. The front mask 15 is disposed above the display area 17 of the display unit 11. As described with reference to FIG. 2(a), the opening 15a forms the far display area 17a, and the opening 15b forms the near display area 17b. Meanwhile, the rear mask 16 is disposed on the rear surface of the display unit 11. An opening 16a corresponds to the opening 15a, and an opening 16b corresponds to the opening 15b. The illumination unit 13 includes light-emitting units 14a and 14b, each of which is formed by an LED (Light Emitting Diode), for example. The light-emitting unit 14a mainly illuminates the far display area 17a shown in FIG. 2(a) with illumination light ILa, and the light-emitting unit 14b mainly illuminates the near display area 17b shown in FIG. 2(a) with illumination light ILb. Hereinafter, when the light-emitting units 14a and 14b are not distinguished from each other and the light-emitting unit is referred to simply as the "light-emitting unit 14," the light-emitting units 14a and 14b may each be a single light-emitting element, or may be configured by combining multiple light-emitting elements.

[0036] Next, an example of the configuration of a control system of the image projection device 10 according to this embodiment will be described with reference to Fig. 4. As shown in Fig. 4, the image projection device 10 includes a control unit 50, a temperature monitoring unit 20, a display unit 11, an illumination unit 13, and a storage unit 54.

[0037] The control unit 20 includes a processing unit 51, a display control signal generation unit 52, and an illumination control signal generation unit 53. The processing unit 51 controls the illumination unit 13 and the display unit 11 mainly based on monitored temperature information from the temperature monitoring unit 20, each determination temperature (described later) from the memory unit 54, and the like. The illumination control signal generation unit 53 mainly generates a signal that controls the brightness of the illumination unit 13. The display control signal generation unit 52 mainly generates a signal that controls image display on the display unit 11. The memory unit 54 is a storage means for storing each determination temperature in the temperature control process (described later) executed by the image projection device 10, a temperature control program, and the like. The form of the memory unit 54 is not particularly limited, and for example, a ROM, an HDD (Hard Disk Drive), or the like can be used.

[0038] A temperature control method for the display unit 11 in the image projection device 10 according to this embodiment will be described with reference to FIG. 5. FIG. 5 is a flowchart showing the processing flow of a temperature control program that describes the temperature control processing executed in the image projection device 10. This temperature control program is stored in the storage unit 54 or in a storage means such as a ROM (not shown), and is read out by the CPU, expanded into RAM, etc., and executed. In the flowchart shown in FIG. 5, it is assumed that an instruction to start operation has already been sent to the control unit 50. The instruction to start operation may be sent from an ECU or the like, for example, when the start switch of the vehicle equipped with the image projection device 10 is turned on.

[0039] In step S10, the control unit 50 determines whether a signal instructing the termination of the temperature control program has been received. If the determination is negative, the process proceeds to step S11, and if the determination is positive, the temperature control program is terminated. The signal instructing the termination of the temperature control program may be sent from the ECU or the like, for example, when the vehicle operation is stopped.

[0040] In step S11, the control unit 50 acquires the monitored temperature Ts from the temperature monitoring unit 20.

[0041] In step S12, the control unit 50 determines whether the monitored temperature Ts exceeds the maximum rated temperature Tmax. If the determination is negative, the process proceeds to step S13, and if the determination is positive, the process proceeds to step S15. The maximum rated temperature Tmax is the maximum temperature at which the display unit 11 can operate normally. As an example, the maximum rated temperature Tmax for an LCD is around 105°C.

[0042] In step S15, the control unit 50 stops the operation of the display unit 11 and the illumination unit 13 (i.e., stops the display of images by the display unit 11 and the operation of the light-emitting unit 14), and issues a warning in step S16. This is because the temperature exceeds the maximum rated temperature Tmax, which could damage the display unit 11, making it meaningless to display an image. The warning may be issued by any method, such as audio, text, or images. For example, a message such as "A temperature abnormality has occurred, so the HUD display will be stopped" may be displayed on a specified monitor screen inside the vehicle. Thereafter, the temperature control program is terminated.

[0043] In step S13, the control unit 50 determines whether the monitoring temperature Ts exceeds the target temperature To. If the determination is affirmative, the process proceeds to step S14. If the determination is negative, the process returns to step S10 and continues temperature monitoring. The target temperature To is the target temperature during normal operation. Normally, the temperature of the display unit 11 is controlled to be equal to or lower than the target temperature To. The target temperature To can be set in various ways depending on the design conditions, etc., but as an example, it can be set to a temperature with a certain margin relative to the maximum rated temperature Tmax. In this embodiment, an LCD is used, so the target temperature To can be set to, for example, 100°C, with a margin relative to the maximum rated temperature Tmax of 105°C. Here, the present embodiment illustrates an example in which the target surface temperature To is set as an upper limit, but this is not limiting; a lower limit target temperature may also be set. The maximum rated temperature Tmax and the target temperature To may be stored in the memory unit 54.

[0044] In step S14, the control unit 50 controls the illumination unit 13 to reduce the brightness. In the image projection device 10 according to this embodiment, the brightness of the illumination unit 13 is reduced by reducing the power (e.g., current) supplied to the light-emitting unit 14. However, the temperature control method for the illumination unit 13 is not limited to this. For example, the power supplied to the light-emitting unit may be kept constant, and a fan for cooling the illumination unit 13 may be provided and controlled. Furthermore, the power supplied to the light-emitting unit 14 may be subjected to PWM (Pulse Width Modulation) control, and the temperature may be controlled by changing the on / off ratio of the power pulse. Alternatively, temperature control using a Peltier element may be considered. Furthermore, each of the above means may be used in combination.

[0045] As described above in detail, the image projection device, image projection device, and image projection method according to the present embodiment can provide an image projection device, image projection device, and image projection method that can more accurately control the temperature of the display device.

[0046] <First Modification of First Embodiment> A first modified example of the first embodiment will be described with reference to Figures 6(a) and (b). Figure 6(a) is a front view of an image projection device 10A according to this modified example, and Figure 6(b) is a BB cross-sectional view of the image projection device 10A according to this modified example. In the above embodiment, an opening 23 is provided in the front mask 15, and a temperature monitoring unit 20 is disposed inside the opening 23. In this modified example, a recess 24 is formed in the front mask 15 instead of the opening 23, and a temperature monitoring unit 20 is disposed inside the recess 24.

[0047] As shown in FIG. 6( a), a recess 24 is provided on the front mask 15 between the far display area 17a and the near display area 17b, and a temperature monitoring unit 20 is disposed within the recess 24. As shown in FIGS. 6( a) and 6(b), the temperature monitoring unit 20 is connected to a wiring unit 26. The wiring unit 26 is, for example, an FPC, and the temperature monitoring unit 20 is mounted on the wiring unit 26. For example, the wiring unit 26 is fixed along the front mask 15 and extended to the outside. However, this is not limited to this, and the wiring unit 26 may be embedded and extended by removing a portion of the front mask 15. The temperature monitoring unit 20 does not necessarily need to abut the display area 17 of the display unit 11. Depending on design conditions, etc., another object may be interposed between the temperature monitoring unit 20 and the display area 17, as in this modification. The temperature monitoring unit 20 may be fixed within the recess 24 using a thermally conductive adhesive or the like. This modification has the effect of more reliably fixing the temperature monitoring unit 20. In this embodiment, an example in which an opening is made on the surface of the front mask 15 farther from the display unit 11 has been described, but this is not limiting, and an opening may be made on the surface closer to the display unit 11.

[0048] <Second Modification of First Embodiment> A second modified example of the first embodiment will be described with reference to Figures 6(c) and (d). Figure 6(c) is a front view of an image projection device 10B according to this modified example, and Figure 6(d) is a CC cross-sectional view of the image projection device 10B according to this modified example. In the above embodiment, an example was described in which an opening 23 or a recess 24 is provided in the front mask 15, and the temperature monitoring unit 20 is arranged inside the opening 23 or recess 24. In this modified example, neither the opening 23 nor the recess 24 is provided, and the temperature monitoring unit 20 is arranged directly on the front mask 15.

[0049] As shown in FIG. 6(c), the temperature monitoring unit 20 according to this embodiment is disposed directly on the front mask 15 between the far display region 17a and the near display region 17b. As shown in FIG. 6(d), the temperature monitoring unit 20 is fixed to the front mask 15 with a thermally conductive adhesive or the like. The temperature monitoring unit 20 is mounted on a wiring section 26 such as an FPC, which is extended onto the front mask 15 and taken out to the outside. In this way, depending on the design conditions, the temperature monitoring unit 20 may be disposed directly on the front mask 15 without using the opening 23 or recess 24. This modification has the effect of making it easier to mount the temperature monitoring unit 20.

[0050] (Second embodiment) In the above embodiment, an example was described in which the temperature monitoring unit 20 is arranged somewhere on the front mask 15 of the display unit 11, but this embodiment is an example in which the temperature monitoring unit 20 is arranged somewhere on the rear mask 16 of the display unit 11. The configuration of the image projection device according to this embodiment is basically the same as the configuration of the image projection device according to each of the above embodiments, so illustrations are omitted and reference should be made to Figures 2 and 3 if necessary.

[0051] 3, the relationship between the rear mask 16 and the back surface of the display unit 11 is the same as the relationship between the front mask 15 and the display area 17 of the display unit 11, except that the viewing direction is reversed. Therefore, in the above embodiment, the front mask 15 can be read as the rear mask 16, and the display area 17 as the back surface of the display unit 11, and the temperature monitoring unit 20 can be disposed on the back surface of the display unit 11.

[0052] As described above, the image projection device, image projection device, and image projection method according to this embodiment can also provide an image projection device, image projection device, and image projection method that can more accurately control the temperature of a display device. In particular, according to this embodiment, the temperature monitoring unit 20 can be disposed closer to the illumination unit 13, which is expected to have the effect of measuring a temperature closer to the actual value.

[0053] (Third embodiment) An image projection device 10C according to this embodiment will be described with reference to Fig. 7. Fig. 7(a) is a front view of the image projection device 10C according to this embodiment, and Fig. 7(b) is a DD cross-sectional view of the image projection device 10C according to this embodiment. In the above embodiment, the temperature monitoring unit 20 was disposed in either the front mask 15 or the rear mask 16, but in this embodiment, the temperature monitoring unit 20 is disposed in the illumination unit 13.

[0054] As shown in Fig. 7(a), the temperature monitoring unit 20 according to this embodiment is disposed between the far display area 17a and the near display area 17b. As shown in Fig. 7(b), the temperature monitoring unit 20 according to this embodiment is disposed inside a recess 28 provided in the illumination unit 13. The temperature monitoring unit 20 is mounted on a wiring unit 26 such as an FPC, and the wiring unit 26 is, for example, embedded in a groove (not shown) provided in the illumination unit 13 and led to the outside.

[0055] In this embodiment, an opening 25 is provided in the rear mask 16 so that the temperature monitoring unit 20 can come into direct contact with the rear surface of the display unit 11 or can come into contact with the rear surface of the display unit 11 via a heat conductive member. However, this is not limiting, and the temperature monitoring unit 20 may measure the temperature via the rear mask 16 without providing the opening 25 depending on design conditions, etc.

[0056] As described above, the image projection device, image projection device, and image projection method according to this embodiment can also provide an image projection device, image projection device, and image projection method that can more accurately control the temperature of a display device. In particular, according to this embodiment, since the temperature monitoring unit 20 is arranged in the illumination unit 13, it is expected that the temperature measured by the temperature monitoring unit 20 will be a value closer to the actual value.

[0057] (Fourth embodiment) An image projection device 10D according to this embodiment will be described with reference to Fig. 8. Fig. 8(a) is a front view of the image projection device 10D according to this embodiment, and Fig. 8(b) is an E-E cross-sectional view. In the above embodiment, an example in which the present invention is applied to a two-screen HUD has been described, but this embodiment is an example in which the present invention is applied to a one-screen HUD.

[0058] As shown in FIG. 8(a), the image projection device 10D has a mask 29 with a single opening 31 disposed above the display area 17. The display area 17 visible through the opening 31 of the mask 29 forms an effective display area 27 where an image is actually projected. As shown in FIG. 8(b), the temperature monitoring unit 20 is mounted on a wiring portion 26 such as an FPC and disposed inside a recess 30 provided in the mask 29. In this embodiment, the temperature monitoring unit 20 is disposed on the bottom edge of the mask 29, but this is not limiting and the temperature monitoring unit 20 may be disposed on any edge. In this embodiment, the temperature monitoring unit 20 is also disposed in an area where the image projection device 10D does not project an image, so that the temperature can be measured without affecting the image projection of the image projection device 10D. Note that this embodiment corresponds to the first modification of the first embodiment using the dual-screen HUD described above, but is not limited thereto and can also be applied to the first embodiment, the second modification of the first embodiment, the second embodiment, and the third embodiment.

[0059] As described above, the image projection device, image projection device, and image projection method according to the present embodiment can also provide an image projection device, image projection device, and image projection method that can more accurately control the temperature of the display device. In particular, the present embodiment has the effect of enabling more accurate temperature control of the display device even in a single-screen HUD.

[0060] Although the above embodiments have been described by way of example with a single temperature monitoring unit 20, the present invention is not limited to this and may be applied to a configuration with a plurality of temperature monitoring units 20. By using a plurality of temperature monitoring units 20, it becomes possible to perform temperature control taking into consideration the temperature distribution in the display unit 11, for example.

[0061] In addition, in each of the above embodiments, the temperature is controlled by directly using the temperature measured by the temperature monitoring unit 20. However, the present invention is not limited to this. Temperature control may be performed by correcting the measured temperature. For example, the temperature distribution of the display unit 11 may be obtained in advance by experiment or thermal simulation, and the measured temperature may be corrected based on this temperature distribution. In this case, the relationship between the measured temperature and the corrected temperature may be stored in advance in a storage means such as the storage unit 54. [Explanation of symbols]

[0062] 10, 10A, 10B, 10C, 10D...Image irradiation device 11...Display section 12...Connection 13...Lighting section 14, 14a, 14b...light-emitting part 15...Front mask 15a, 15b...opening 16...Rear mask 16a, 16b...opening 17…Display area 17a...Far display area 17b…Near display area 20…Temperature monitoring section 21... Circuit board 22, 26...Wiring section 23, 25, 31...Opening 24, 28, 30...recesses 27...Effective display area 29...Mask 50...Control unit 51... Processing section 52...Display control signal generating unit 53...Lighting control signal generation unit 54...Storage section 60...Image irradiation device 61...LCD 62…Display area 63...Connection 64...Temperature sensor 80...Image projection device 81...Optical branching section 82...Freeform mirror 83...Freeform mirror 84...Reflector GL1, GL2...Image display light ILa, ILb…Illumination light

Claims

1. a display unit having a display area for displaying an image; a temperature monitoring unit disposed in a non-illumination area of ​​the display area where no image is illuminated; a control unit that controls the temperature of the display unit based on the temperature acquired from the temperature monitoring unit.

2. 2. The image projection device according to claim 1, the display unit has a back surface facing the display area, a front mask covering a portion of the display area; a rear mask that covers a portion of the rear surface and blocks light at a position corresponding to a position that is blocked by the front mask; An image projection device, wherein the non-irradiation area is at least one of a part of the front mask and a part of the rear mask.

3. 3. The image projection device according to claim 2, the temperature monitoring unit is disposed in an opening provided in at least one of the front mask and the rear mask; The image projection device is characterized in that the temperature monitoring unit is in direct contact with the display area or in contact with the display area via a heat conductive member.

4. 4. The image projection device according to claim 3, 10. An image projection device, comprising: a temperature monitoring unit having a height substantially equal to a thickness of at least one of the front mask and the rear mask;

5. 3. The image projection device according to claim 2, The image projection device is characterized in that the temperature monitoring unit is disposed in a recess provided in at least one of the front mask and the rear mask.

6. 3. The image projection device according to claim 2, The image projection device is characterized in that the temperature monitoring unit is disposed on the surface of at least one of the front mask and the rear mask.

7. 3. The image projection device according to claim 2, a wiring section connected to the temperature monitoring section, The image projection device is characterized in that the wiring portion is led out to the outside along at least one surface of the front mask and the rear mask.

8. a display unit having a display area for displaying an image and a back surface facing the display area; an illumination unit that illuminates the display unit from the back surface; a temperature monitoring unit disposed in a part of the illumination unit corresponding to an area of ​​the display area where no image is irradiated; a control unit that controls the temperature of the display unit based on the temperature acquired from the temperature monitoring unit.

9. An image projection device according to any one of claims 1 to 8; an optical system that guides the image projected by the image projection device to a virtual image formation unit.

10. An image projection method using an image projection device equipped with a display unit, a temperature monitoring unit disposed in an area of ​​the display unit where no image is projected; an image projection method, characterized in that the temperature of the display unit is controlled based on the temperature acquired from the temperature monitoring unit;

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