Head-up display device

Abstract

To provide a head-up display device which is capable of preventing damage due to sunlight while securing convenience to users.SOLUTION: A head-up display device comprises: a light source for emitting light; a display panel which creates an image to be projected onto a display area of a vehicle by modulating light from the light source; a reflection mirror which reflects and projects the image created by the display panel onto the display area; and a protection processing part which adjusts either a brightness of the light source or on and off of the light source on the basis of sunlight intensity detected by a sunlight sensor, brightness of the light source, and an ambient temperature. The head-up display device is provided with a normal state and a protection state.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a head-up display device, and more particularly to a technique that is effective when applied to a head-up display device that uses AR (Augmented Reality), for example. [Background technology]

[0002] Patent Document 1 shows a head-up display device that can effectively prevent the intrusion of external light such as sunlight. The head-up display device includes a shutter unit having a plurality of shutters, and changes the size of a transparent window portion formed in the shutter unit according to the size of an image displayed by the display unit, thereby preventing the intrusion of external light and, ultimately, damage to the display unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-152746 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, vehicles such as automobiles may be equipped with a head-up display (hereinafter sometimes referred to as "HUD"). HUDs project and display various information, such as driving information such as vehicle speed and engine RPM, and navigation information, onto the windshield or other surfaces. Using an HUD allows the driver to obtain the information necessary for driving without shifting their gaze to the instrument panel built into the dashboard, or the so-called instrument panel. This contributes to safer driving.

[0005] Meanwhile, in recent years, there has been a demand for HUDs to use AR, which adds various information to objects in real-world scenes. In particular, HUDs that use AR (called AR-HUDs) require a large display area. In order to expand the display area, it is necessary to widen the opening on the projection optical path from the display panel to the windshield. If the opening is widened, sunlight becomes more likely to be incident on the display panel, which makes the display panel more susceptible to damage.

[0006] Therefore, as in Patent Document 1, a method of changing the size of the transparent window portion is considered. However, even if the size of the transparent window portion is changed according to the size of the display image, there may still be a spot on the display panel where sunlight is concentrated, so sufficient protection is not necessarily achieved. In order to achieve sufficient protection, it is desirable to completely block the incident optical path of sunlight. However, in this case, the projection optical path from the display panel is also blocked at the same time, resulting in a time period during which the HUD cannot be used. However, even in this case, if the time period during which the HUD cannot be used is shortened as much as possible, it is possible to ensure a certain degree of convenience for the user.

[0007] The present invention has been made in consideration of the above, and one of its objects is to provide a head-up display device that can prevent damage caused by sunlight while ensuring user convenience.

[0008] The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0009] Among the inventions disclosed in this application, a brief summary of representative inventions is as follows.

[0010] A typical head-up display device allows a driver of a vehicle to visually recognize a landscape on which a projected image is superimposed. The head-up display device includes a light source that emits light, a display panel that creates an image to be projected on a display area of ​​the vehicle by modulating the light from the light source, a reflection mirror that reflects the image created by the display panel and projects it on the display area, and a protection processing unit that adjusts the luminance of the light source or the on / off of the light source based on the sunlight intensity detected by a solar radiation sensor, the luminance of the light source, and the ambient temperature. The head-up display device has a normal state and a protection state. Effect of the Invention

[0011] To briefly explain the effects obtained by a representative invention among the inventions disclosed in this application, it is possible to prevent damage caused by sunlight in a head-up display device while ensuring convenience for the user. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing an example of the configuration of a vehicle equipped with a head-up display device according to an embodiment of the present invention. [Diagram 2] 2 is a schematic diagram showing an example of the configuration around the image display unit in FIG. 1. [Diagram 3] 3 is a diagram showing a more detailed example of the configuration and operation of the image display unit and its periphery in FIG. 2. FIG. [Figure 4] 4 is a perspective view showing an example of the external shape of a HUD device including the image display unit of FIG. 3. [Diagram 5] 2 is a block diagram showing an example of the configuration of a main part of a control system included in the head-up display device of FIG. 1. [Figure 6] FIG. 6 is a block diagram showing an example of the configuration of a portion related to acquisition of vehicle information in FIG. 5. [Figure 7] FIG. 6 is a schematic diagram showing an example of the operation of a main part of the protection processing unit in FIG. 5. [Figure 8]FIG. 6 is a diagram for explaining an estimated temperature of the display panel used in the protection processing unit in FIG. 5. [Figure 9] 6 is a flowchart showing an example of processing contents of a protection processing unit in FIG. 5. [Figure 10] 10 is a flow chart showing an example of the processing contents of protection necessity determination in FIG. 9. [Figure 11] 10 is a flow chart showing an example of the process of determining whether or not restoration is possible in FIG. 9. [Figure 12] FIG. 12 is a flow diagram showing an example of the process of determining whether or not recovery is possible in FIG. 11 [1]. [Figure 13] 13 is a flow diagram showing an example of the process of determining whether to cancel degeneration in FIG. 12; [Figure 14A] FIG. 12 is a flow diagram showing an example of the process of determining whether or not recovery is possible in FIG. 11 [2]. [Figure 14B] FIG. 12 is a flow diagram showing an example of the process of determining whether or not recovery is possible in FIG. 11 [2]. [Figure 15] FIG. 6 is a diagram showing an example of the contents of a user notification by a protection processing unit in FIG. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiment, the same members are generally designated by the same reference numerals, and the repeated description will be omitted.

[0014] Overview of the HUD device FIG. 1 is a schematic diagram showing an example of the configuration of a vehicle equipped with a head-up display device according to an embodiment of the present invention. The head-up display (HUD) device 1 in FIG. 1 is mounted on a vehicle 2. The vehicle 2 is typically an automobile, but is not necessarily limited to this, and may be a railroad car or the like in some cases. The HUD device 1 acquires vehicle information 4 from various sensors and the like installed in various parts of the vehicle 2. The various sensors, for example, detect various events that occur in the vehicle 2 and periodically detect the values ​​of various parameters related to the driving situation.

[0015] The vehicle information 4 includes, for example, the speed information and gear information of the vehicle 2, steering wheel steering angle information, lamp illumination information, external light information, distance information, infrared information, engine ON / OFF information, camera image information inside and outside the vehicle, acceleration gyro information, GPS (Global Positioning System) information, navigation information, vehicle-to-vehicle communication information, and road-to-vehicle communication information. The GPS information also includes information on the current time. Based on such vehicle information 4, the HUD device 1 projects a projection image onto the display area 5 of the windshield 3 using the image display unit 12. In this way, the HUD device 1 allows the driver of the vehicle 2 to visually recognize the scenery on which the projection image is superimposed.

[0016] FIG. 2 is a schematic diagram showing an example of the configuration around the image display unit in FIG. 1. The image display unit 12 shown in FIG. 2 includes an image display device 35 and reflecting mirrors M1 and M2. The reflecting mirror M1 is, for example, a concave mirror (magnifying mirror). The image display device 35 is, for example, a projector or an LCD (Liquid Crystal Display), and creates and displays an image based on image data instructed by a control unit. The reflecting mirrors M1 and M2 are, for example, free-form mirrors or mirrors having an asymmetric shape with respect to the optical axis. The reflecting mirror M2 reflects the image created (displayed) by the image display device 35. The reflecting mirror M1 reflects and magnifies the image reflected by the reflecting mirror M2, and projects it onto the display area 5 through the opening 7.

[0017] As a result, the driver 6 visually recognizes the projection image projected onto the display area 5 as a virtual image beyond the transparent windshield 3, superimposed on the scenery outside the vehicle (roads, buildings, people, etc.). The projection image (virtual image) includes various information such as road signs, the current speed of the vehicle, and various information (AR information) added to objects on the scenery. In FIG. 2, for example, the position of the display area 5 on the windshield 3 can be adjusted by adjusting the installation angle of the reflecting mirror M1, and the position of the virtual image visually recognized by the driver 6 can be adjusted in the vertical direction. In addition, for example, the area of ​​the display area 5 can be enlarged by making the reflecting mirror M1 larger, and more information can be projected onto the display area 5. This realizes an AR function that adds and displays various information to objects on the scenery.

[0018] FIG. 3 is a diagram showing a more detailed configuration example and operation example around the image display unit in FIG. 2. FIG. 4 is a perspective view showing an example of the outer shape of a HUD device including the image display unit in FIG. 3. As shown in FIG. 3, the image display device 35 in FIG. 2 specifically has a light source 65 that emits light, and a display panel 64 that creates (displays) an image to be projected on the display area 5 by modulating the light from the light source 65. The light source 65 is typically an LED (Light Emitting Diode) light source. The display panel 64 is typically a liquid crystal panel (LCD), and modulates the transmittance of light from the light source 65 for each pixel according to input image data.

[0019] In addition, a condenser lens 63 is installed between the display panel 64 and the reflecting mirror M2. Therefore, sunlight from the sun 60 may be condensed onto the display panel 64 via the reflecting mirrors M1, M2 and the condenser lens 63. Therefore, a drive mechanism 62 for changing the installation angle of the reflecting mirror M1 is attached to the reflecting mirror M1. The drive mechanism 62 includes a stepping motor and the like. The reflecting mirror M1 to which the drive mechanism 62 is attached constitutes a blocking mechanism 67.

[0020] When the blocking mechanism 67 is off, it forms an optical path for projecting an image between the display area 5 and the display panel 64, and when it is on, it blocks the optical path for projecting the image and the optical path for incident sunlight, which is the opposite direction. Specifically, as shown in Fig. 3, when it is on, the blocking mechanism 67 changes the installation angle of the reflecting mirror M1 via the drive mechanism 62 to change the optical path, thereby blocking the optical path for incident sunlight toward the display panel 64 and, as a result, blocking the optical path for projecting the image.

[0021] The blocking mechanism 67 is not necessarily limited to this configuration, and may be any mechanism capable of blocking the incident optical path of sunlight, for example, a mechanism for changing the installation angle of the reflecting mirror M2, or a mechanism for inserting a sliding shielding plate or the like separately on the incident optical path of sunlight. However, as described above, the driving mechanism 62 in the blocking mechanism 67 in Fig. 3 can also be used when adjusting the position of the virtual image. Therefore, by using the mechanism in Fig. 3, it is possible to use the same parts in combination.

[0022] 3, the image display device 35, the reflecting mirror M1 with the drive mechanism 62, the reflecting mirror M2, and the condenser lens 63 are housed in a housing 61 together with various control units (not shown). Furthermore, a solar radiation sensor 66 for detecting the position of the sun 60 and the intensity of sunlight is provided in the housing 61. Although not shown, the housing 61 may further include a temperature sensor for detecting the ambient temperature Ta. However, for example, when the ambient temperature Ta is acquired from a temperature sensor provided in the vehicle 2, it is not necessary to provide a temperature sensor in the housing 61.

[0023] 4, an opening 7 is formed in a housing 61, and a transparent cover member 71, called a glare trap or the like, is installed in the opening 7. As shown in Fig. 3, a reflecting mirror M1 is installed inside the housing 61 so as to reflect light from a reflecting mirror M2 toward the cover member 71 (opening 7). In addition, a solar radiation sensor 66 is installed in the housing 61, for example, around the cover member 71.

[0024] 4, the solar radiation sensor 66 detects the intensity of sunlight when the position (azimuth and elevation angle) of the sun 60 is within the sunlight detection range 70. For example, depending on the incident angle of sunlight to the reflecting mirror M1 (and thus the position of the sun 60), the incident optical path of the sunlight deviates from the display panel 64, so the possibility of damage to the display panel 64 can be ignored. In other words, depending on the season, time of day, attitude of the vehicle 2, etc., the possibility of damage can be ignored.

[0025] The range of incidence angles where the possibility of damage can be ignored, in other words, the range of incidence angles where the possibility of damage cannot be ignored, can be determined in advance based on the optical conditions (e.g., installation position, installation angle, size, etc.) of the optical system including the reflecting mirrors M1, M2 and the condenser lens 63. Therefore, the solar radiation sensor 66 detects the solar light intensity within the solar light detection range 70, which is the range of incidence angles (position of the sun 60) where the possibility of damage to the display panel 64 cannot be ignored.

[0026] A specific example of the solar radiation sensor 66 configuration is a system in which an opening, a shielding plate, or the like is appropriately provided around a light receiving element such as a photodiode to physically limit the angle of incidence of sunlight incident on the light receiving element. Alternatively, a known solar radiation sensor capable of detecting both the position of the sun 60 and the sunlight intensity (for example, a sensor that detects the position based on the light intensity balance of four light receiving elements) may be used to perform signal processing by combining detected position information and sunlight intensity information.

[0027] <<Configuration of the HUD device control system>> Fig. 5 is a block diagram showing a configuration example of a main part of a control system included in the head-up display device of Fig. 1. Fig. 6 is a block diagram showing a configuration example of a part related to acquisition of vehicle information in Fig. 5. The head-up display (HUD) device 1 shown in Fig. 5 includes a control unit (ECU: Electronic Control Unit) 10, a speaker 11, an image display unit 12, and the solar radiation sensor 66 described in Fig. 4. The image display unit 12 includes an image display device 35, a reflecting mirror M1 with a drive mechanism 62, and the like, as shown in Fig. 3.

[0028] The control unit 10 mainly controls the display of a projected image (virtual image) in the HUD device 1 and controls audio output. The control unit 10 is configured, for example, by a wiring board, and the wiring board is mounted, for example, in a housing 61 in FIG. 4. The control unit 10 includes a vehicle information acquisition unit 15, a microcontroller (MCU) 16, a non-volatile memory 17, a volatile memory 18, an audio driver 19, a display driver 20, and a communication unit 21, which are mounted on the wiring board. As is widely known, the MCU 16 includes various peripheral functions in addition to a CPU (Central Processing Unit). Therefore, each block in the control unit 10 in FIG. 5 except for the MCU 16 may be mounted in the MCU 16 as appropriate.

[0029] The vehicle information acquisition unit 15 is, for example, a CAN (Controller Area Network) interface or a LIN (Local Interconnect Network) interface, and acquires the vehicle information 4 based on a communication protocol such as CAN or LIN. As shown in Fig. 6, the vehicle information 4 is generated by information acquisition devices such as various sensors connected to the vehicle information acquisition unit 15. Fig. 6 shows an example of various information acquisition devices.

[0030] For example, the vehicle speed sensor 41 detects the speed of the vehicle 2 in Fig. 1 and generates speed information as the detection result. The shift position sensor 42 detects the current gear and generates gear information as the detection result. The steering wheel angle sensor 43 detects the current steering wheel angle and generates steering wheel angle information as the detection result. The headlight sensor 44 detects the ON / OFF of the headlights and generates lamp illumination information as the detection result.

[0031] The illuminance sensor 45 and chromaticity sensor 46 detect external light and generate external light information as the detection result. The distance measurement sensor 47 detects the distance between the vehicle 2 and an external object and generates distance information as the detection result. The infrared sensor 48 detects the presence or absence of an object in the vicinity of the vehicle 2 and the distance, and generates infrared information as the detection result. The engine start sensor 49 detects whether the engine is ON / OFF and generates ON / OFF information as the detection result.

[0032] The acceleration sensor 50 and the gyro sensor 51 respectively detect the acceleration and angular velocity of the vehicle 2, and generate acceleration gyro information representing the attitude and behavior of the vehicle 2 as the detection result. The temperature sensor 52 detects the temperature inside and outside the vehicle, and generates temperature information as the detection result. For example, the temperature sensor 52 can detect the ambient temperature Ta of the HUD device 1. However, as described in FIG. 4, a separate temperature sensor may be mounted inside the HUD device 1.

[0033] The road-to-vehicle wireless transceiver 53 generates road-to-vehicle communication information by road-to-vehicle communication between the vehicle 2 and roads, signs, signals, etc. The vehicle-to-vehicle wireless transceiver 54 generates vehicle-to-vehicle communication information by vehicle-to-vehicle communication between the vehicle 2 and other surrounding vehicles. The interior camera 55 and the exterior camera 56 generate interior camera image information and exterior camera image information by capturing images of the interior and exterior of the vehicle, respectively. Specifically, the interior camera 55 is, for example, a camera for a DMS (Driver Monitoring System) that captures the posture, eye position, movement, etc. of the driver 6 in FIG. 2. In this case, the fatigue state and gaze position of the driver 6 can be ascertained by analyzing the captured image.

[0034] On the other hand, the exterior camera 56 captures the surrounding conditions, such as the front and rear of the vehicle 2. In this case, by analyzing the captured image, it becomes possible to grasp the presence or absence of obstacles such as other vehicles and people in the vicinity, buildings and topography, road conditions such as rain, snow, ice, unevenness, and road signs, etc. In addition, the exterior camera 56 also includes, for example, a drive recorder that records the conditions while driving as images.

[0035] The GPS receiver 57 generates GPS information obtained by receiving a GPS signal. For example, the current time can be obtained by the GPS receiver 57. The VICS (Vehicle Information and Communication System, registered trademark) receiver 58 generates VICS information obtained by receiving a VICS signal. The GPS receiver 57 and the VICS receiver 58 may be provided as part of a navigation system. Note that the various information acquisition devices in FIG. 6 can be appropriately deleted, or other types of devices can be added or replaced with other types of devices.

[0036] 5, the MCU 16 receives such vehicle information 4 via the vehicle information acquisition unit 15, and generates audio data for the speaker 11, video data for the video display device 35, and the like, based on the vehicle information 4, etc. Specifically, the MCU 16 includes an audio data generation unit 27, a video data generation unit 28, a distortion correction unit 29, a light source adjustment unit 30, a mirror adjustment unit 31, and a protection processing unit 75. Each of these units is implemented mainly by the CPU executing a program stored in the non-volatile memory 17 or the volatile memory 18.

[0037] The voice data generating unit 27 generates voice data based on the vehicle information 4 etc. as necessary. The voice data is generated, for example, when providing voice guidance for a navigation system or when issuing a warning to the driver 6 by an AR function. The voice driver 19 drives the speaker 11 based on the voice data and causes the speaker 11 to output voice.

[0038] Video data generation unit 28 generates video data that determines the display content of the projection image to be projected onto display area 5 of Fig. 2 etc., based on vehicle information 4 etc. Distortion correction unit 29 generates corrected video data by applying distortion correction to the video data from video data generation unit 28. Specifically, distortion correction unit 29 corrects distortion of the image caused by the curvature of windshield 3 when an image from video display device 35 is projected onto display area 5 as shown in Fig. 2.

[0039] The display driver 20 drives each display element (pixel) included in the display panel 64 in the image display device 35 based on the corrected image data from the distortion correction unit 29. As a result, the image display device 35 creates (displays) an image to be projected onto the display area 5 based on the corrected image data. The light source adjustment unit 30 controls the brightness of the light source 65 in the image display device 35. When it is necessary to adjust the position of the display area 5 on the windshield 3, the mirror adjustment unit 31 changes the installation angle of the reflection mirror M1 in the image display unit 12 via the drive mechanism 62. Furthermore, as described in FIG. 3, the mirror adjustment unit 31 also changes the installation angle of the reflection mirror M1 to a certain degree by a large amount via the drive mechanism 62 when blocking the incident optical path of sunlight.

[0040] The protection processing unit 75 includes a timer 76, and although details will be described later, performs various protection operations mainly based on an estimated temperature of the display panel 64 in the video display device 35, which is estimated using the sunlight intensity from the solar radiation sensor 66, the ambient temperature Ta from the temperature sensor 52 in Fig. 6, etc., and the luminance of the light source 65 in the light source adjustment unit 30. The non-volatile memory 17 mainly stores in advance the programs executed by the CPU in the MCU 16, setting parameters used in the processing of each unit in the MCU 16, specified audio data, video data, etc.

[0041] The volatile memory 18 mainly appropriately holds the acquired vehicle information 4 and various data used in the processing of each unit in the MCU 16. The communication unit 21 communicates with the outside of the HUD device 1 based on a communication protocol such as CAN or LIN. The communication unit 21 may be integrated with the vehicle information acquisition unit 15. Each unit in the control unit (ECU) 10 in Fig. 4 may be implemented in an FPGA (Field Programmable Gate Array) or the like as appropriate.

[0042] <<Outline of Operation of Protection Processing Unit>> FIG. 7 is a schematic diagram showing an example of the operation of the main part of the protection processing unit in FIG. 5. In FIG. 7, a normal mode MN, a protection mode MP, and a degenerate mode MD are provided as operation modes. First, in the normal mode MN, when sunlight is not incident (when the sunlight intensity measured by the solar radiation sensor 66 is zero, for example), the temperature of the display panel 64 in a steady state is determined by the luminance L of the light source 65 and the ambient temperature Ta. The temperature of the display panel 64 in the steady state when sunlight is not incident is called the saturation temperature Tsat. In this example, the saturation temperature Tsat is 80° C. In the normal mode MN, the blocking mechanism 67 in FIG. 3 is off (i.e., the installation angle of the reflection mirror M1 is in the initial state), and the light source 65 is driven in a state in which the luminance L is not limited.

[0043] On the other hand, when sunlight is incident (when the sunlight intensity measured by the solar radiation sensor 66 is non-zero), the temperature of the display panel 64 rises according to the sunlight intensity. The protection processing unit 75 transitions from the normal mode MN to the protection mode MP when the temperature of the display panel 64 reaches the protection start temperature (95° C. in this example) (protection-on time tON'). In the protection mode MP, the cutoff mechanism 67 is on (i.e., the installation angle of the reflection mirror M1 is changed), and the driving of the light source 65 is stopped.

[0044] Here, in each operation mode, it may be difficult to actually measure the temperature of the display panel 64 using a temperature sensor or the like because the display panel 64 is a type of device that makes it difficult to mount components on it. Therefore, the protection processing unit 75 controls the operation mode, including turning on and off the cutoff mechanism 67, based on the estimated temperature of the display panel 64, which is estimated using the sunlight intensity from the solar radiation sensor 66, the luminance of the light source 65, and the ambient temperature Ta. Figure 8 is a diagram for explaining the estimated temperature of the display panel used by the protection processing unit in Figure 5.

[0045] 7 is estimated using, for example, the temperature rise ΔT(L) corresponding to the luminance L of the light source 65 and the ambient temperature Ta, as shown in FIG. 8. The temperature rise ΔT(L) occurs when the display panel 64 absorbs the energy of light from the light source 65. However, when the distance between the display panel 64 and the light source 65 is relatively short, thermal radiation associated with the heat generated by the light source 65 is also taken into consideration. Moreover, the temperature of the display panel 64 when sunlight is incident is estimated by adding the temperature rise (or temperature rise rate) ΔT(I) corresponding to the sunlight intensity I to the saturation temperature Tsat as a reference.

[0046] As a result, it is possible to calculate in advance the time required for the temperature of the display panel 64 to reach the protection start temperature (e.g., 95°C) from the saturation temperature Tsat, assuming a constant sunlight intensity. Then, based on this constant sunlight intensity and the required time, it is possible to determine the on-intensity Ion and continuous detection time TON in FIG. 7. At this time, this continuous detection time TON may be a function of the ambient temperature Ta or the luminance L of the light source 65. In actual operation, when the sunlight intensity is equal to or higher than the on-intensity Ion and this state continues for the continuous detection time TON, the protection processing unit 75 determines that the protection start temperature has been reached and transitions from the normal mode MN to the protection mode MP. As a result, the temperature of the display panel 64 decreases.

[0047] On the other hand, when the sunlight intensity is equal to or lower than a predetermined off intensity Ioff and this state continues for a predetermined continuous non-detection time TOFF, the protection processing unit 75 transitions from the protection mode MP to the degenerate mode MD. In the degenerate mode MD, the cutoff mechanism 67 is off (i.e., the installation angle of the reflecting mirror M1 is in the initial state), and the light source 65 is driven in a state in which the maximum luminance Lmax is limited to a value lower than that in the normal mode MN.

[0048] For example, the maximum brightness Lmax in the degenerate mode MD is limited to 70% of the maximum brightness (Lmax(Ta)) in the normal mode MN. At this time, the protection processing unit 75 determines the maximum brightness (Lmax(Ta)) in the normal mode MN, for example, according to the ambient temperature Ta. Specifically, the protection processing unit 75 determines the maximum brightness (Lmax(Ta)) so that the sum of the temperature rise amount ΔT(L) and the ambient temperature Ta becomes constant, for example, in FIG. 8. Accordingly, the protection processing unit 75 also variably controls the maximum brightness Lmax in the degenerate mode MD according to the ambient temperature Ta. As a specific implementation method, for example, a method of implementing the relationship between the ambient temperature Ta and the maximum brightness Lmax as a calculation formula or a table on the non-volatile memory 17 of FIG. 5 can be mentioned.

[0049] By providing such a degenerate mode MD, it is possible to gradually bring the temperature of the display panel 64 closer to the saturation temperature Tsat, as shown in Fig. 7. On the other hand, if no limitation is imposed on the brightness (i.e., in the case of a direct transition from the protection mode MP to the normal mode MN), the temperature of the display panel 64 may actually overshoot and exceed the saturation temperature Tsat. Using the calculation as shown in Fig. 8, the temperature in a steady state can be estimated, but it is not easy to estimate the temperature in a transient state, such as the amount of such an overshoot and the convergence time.

[0050] For this reason, when an overshoot occurs, a period occurs during which the temperature of the display panel 64 cannot be estimated with high accuracy. In detail, a period may occur during which the actual temperature is slightly higher than the estimated temperature. This may result in the temperature of the display panel 64 exceeding the upper limit temperature in the specifications during the process of control based on the estimated temperature. For example, if the protection mode MP occurs with a relatively high frequency, errors may accumulate, making it difficult to manage the temperature of the display panel 64. Therefore, in order to prevent such an overshoot from occurring and to eliminate error factors that may occur in control based on the estimated temperature, it is beneficial to provide a degenerate mode MD that limits the maximum luminance Lmax.

[0051] In addition, in the case of an LED light source, the brightness of the light source 65 is controlled by the PWM duty ratio (=LED on time / PWM cycle). In this case, the protection processing unit 75 in FIG. 5 limits the maximum value of this PWM duty ratio via the light source adjustment unit 30. In addition, the continuous non-detection time TOFF is, for example, about 3 to 10 minutes, typically 5 minutes. This can be determined, for example, by experiments. Specifically, it has been confirmed by experiments that when the temperature of the display panel 64 transitions from the protection start temperature (for example, 95° C.) to the protection mode MP, if the protection mode MP continues for at least 5 minutes, the temperature of the display panel 64 will be equal to or lower than the saturation temperature Tsat.

[0052] That is, in FIG. 7, if the sunlight intensity becomes zero at the same time as the protection-on time tON', if the protection mode MP continues for 5 minutes from the protection-on time tON', the temperature of the display panel 64 will be equal to or lower than the saturation temperature Tsat. The fact that the temperature of the display panel 64 is equal to or lower than the saturation temperature Tsat means that the protection mode MP may be cancelled. However, if a method is used in which the protection mode MP is cancelled 5 minutes after the protection-on time tON' based on the protection-on time tON', if the sunlight intensity is still maintained at a high value after 5 minutes, it will be necessary to quickly switch to the protection mode MP. Therefore, it is beneficial to cancel the protection mode MP on the condition of the off intensity Ioff and the continuous non-detection time TOFF.

[0053] Also, in this example, the estimated temperature of the display panel 64 is used in a manner that indirectly reflects the on-intensity Ion and continuous detection time TON when transitioning to the protection mode MP, the set luminance in the degenerate mode MD, and the like. However, in some cases, the protection processing unit 75 may successively calculate the estimated temperature of the display panel 64 by the calculation described in Fig. 8, and directly use the calculated estimated temperature to control the operation mode. In this case, however, the processing load of the protection processing unit 75 increases, and from this viewpoint, it is more beneficial to use the method as shown in Fig. 7.

[0054] <<Detailed Operation of Protection Processing Unit>> FIG. 9 is a flow diagram showing an example of the processing contents of the protection processing unit in FIG. 5. FIG. 10 is a flow diagram showing an example of the processing contents of the protection necessity judgment in FIG. 9. FIG. 11 is a flow diagram showing an example of the processing contents of the restoration possibility judgment in FIG. 9. FIG. 12 is a flow diagram showing an example of the processing contents of the restoration possibility judgment [1] in FIG. 11. FIG. 13 is a flow diagram showing an example of the processing contents of the degeneration cancellation judgment in FIG. 12. FIGS. 14A and 14B are flow diagrams showing an example of the processing contents of the restoration possibility judgment [2] in FIG. 11. These flows are repeatedly executed at a predetermined control period.

[0055] First, an outline of these flows will be described. In Fig. 10, as described in Fig. 7, when the sunlight intensity is equal to or greater than the on-intensity Ion and this state continues for a predetermined on-time TON, the protection processing unit 75 transitions from the normal mode MN (or the degenerate mode MD) to the protection mode MP. In Fig. 12, as described in Fig. 7, when the sunlight intensity is equal to or less than the predetermined off-intensity Ioff and this state continues for a predetermined off-time TOFF, the protection processing unit 75 transitions from the protection mode MP to the degenerate mode MD.

[0056] Here, in the degenerate mode MD, the maximum luminance Lmax of the light source 65 is limited, so that it is necessary to return to the normal mode MN under some condition. Therefore, the protection processing unit 75 transitions from the degenerate mode MD to the normal mode MN when it detects that the power of the vehicle 2 is turned on again (for example, the ignition switch is turned off and then on) during a period after the operation in the degenerate mode MD has continued for a predetermined standby time. The standby time is, for example, 3 hours or more, typically 6 hours. In addition, the determination of whether the standby time has continued or not can be made by, for example, acquiring the current time from the GPS receiver 57 in FIG. 6 or the like.

[0057] This waiting time (6 hours) is determined in advance, for example, based on the sunlight detection range 70 in FIG. 4 and the movement of the sun 60. Specifically, first, assuming that the vehicle 2 is stopped, the time period during which the sun 60 is present in the sunlight detection range 70 occurs twice in a day, during the period when the sun 60 rises and during the period when the sun 60 sets. The time from the start of this first time period to the end of the second time period is calculated to be about 6 hours. In this case, after 6 hours have passed since the transition to the protection mode MP, a sufficient time can be secured until the next transition to the protection mode MP becomes necessary (i.e., until the need to consider the sunlight intensity occurs). Therefore, there is no problem even if the mode is transitioned to the normal mode MN after 6 hours have passed.

[0058] Also, if the brightness suddenly changes after six hours while the driver continues driving, the driver may become aware of it and safety may be impaired. Therefore, the condition is that the power of the vehicle 2 must be turned on again. On the other hand, a method may be used in which the maximum brightness Lmax in the degenerate mode MD is gradually increased over time toward the maximum brightness Lmax(Ta) in the normal mode MN. However, in this case, complex processing may be required to estimate the temperature of the display panel 64. From this point of view, it is therefore beneficial to keep the maximum brightness Lmax in the degenerate mode MD at XX% (e.g., 70%) of the maximum brightness Lmax(Ta) in the normal mode MN.

[0059] Also, as an exceptional case, there is a possibility that the driver turns off the power supply of the vehicle 2 during the protection mode MP. For example, if the power supply of the vehicle 2 is turned off immediately after the transition to the protection mode MP and then turned on again immediately thereafter, there is a risk that the display panel 64 cannot be protected if the vehicle 2 is started from the initial state (i.e., the normal mode MN). Therefore, the protection processing unit 75 includes a timer 76 as shown in FIG. 5.

[0060] The timer 76 counts the same time as the off time TOFF (e.g., 5 minutes) from the time when the transition to the protection mode MP is made (protection on time tON' in FIG. 7). This timer 76 continues counting using the battery power even if the power of the vehicle 2 is turned off. Then, in FIG. 14A, if the power of the vehicle 2 is turned on again during the counting operation of the timer (post-protection timer TW) 76, the protection processing unit 75 does not release the protection mode MP until the counting operation of the timer 76 expires. On the other hand, if the counting operation of the timer 76 expires (i.e., 5 minutes after the protection on time tON'), it is possible to release the protection mode MP for the same reason as in the case of the off time TOFF in FIG. 7.

[0061] Furthermore, even if the power supply of the vehicle 2 is turned off immediately after transition to the protection mode MP, there is no need to maintain the protection mode MP if the time when the power supply of the vehicle 2 is turned on thereafter is after the counting operation of the timer (post-protection timer TW) 76 has expired. In this case, the protection processing unit 75 uses either the degenerate mode MD or the normal mode MN depending on whether the time tPON when the power supply of the vehicle 2 is turned on is after the above-mentioned standby time (6 hours) has elapsed in FIG. 14B.

[0062] Next, the details of these processes will be described. In Fig. 9, the protection processing unit 75 first judges the operation mode (step S101). If the judgment result of step S101 is the normal mode MN, the protection processing unit 75 judges whether protection is necessary (step S102), and if the judgment result of step S101 is the protection mode MP, the protection processing unit 75 judges whether recovery is possible (step S105). The recovery possibility judgment at this time (step S105) is a judgment of whether the protection mode MP can be changed to the degenerate mode MD. On the other hand, if the judgment result of step S101 is the degenerate mode MD, the protection processing unit 75 judges both whether protection is necessary (step S103) and whether recovery is possible (step S104). The recovery possibility judgment at this time (step S104) is a judgment of whether the degenerate mode MD can be changed to the normal mode MN.

[0063] In the protection necessity judgment of FIG. 10, the protection processing unit 75 detects the sunlight intensity using the solar radiation sensor 66 (step S201). Next, the protection processing unit 75 judges whether the detected sunlight intensity is equal to or greater than the on intensity Ion (step S202). If the sunlight intensity is equal to or greater than the on intensity Ion, the protection processing unit 75 starts an on timer (TON) that counts the on time TON (step S203). The on timer (TON) is one of the timers 76 of FIG. 5. Also, in step S203, if the on timer (TON) is already counting, the protection processing unit 75 continues the counting operation. On the other hand, in step S202, if the sunlight intensity is less than the on intensity Ion, the protection processing unit 75 resets the on timer (TON) and ends the process (step S209).

[0064] After step S203, the protection processing unit 75 judges whether the on timer (TON) has expired (step S204). If the on timer (TON) is counting, the protection processing unit 75 ends the process. On the other hand, if the on timer (TON) has expired, the protection processing unit 75 transitions to the protection mode MP (step S205). Then, the protection processing unit 75 records the current time acquired from the GPS receiver 57 in FIG. 6 or the like as the protection on time tON' in the non-volatile memory 17 in FIG. 5 or the like (step S206). In addition, the protection processing unit 75 starts the post-protection timer TW (step S207). The post-protection timer TW is one of the timers 76 in FIG. 5, and counts the same time as the off time TOFF.

[0065] After that, the protection processing unit 75 notifies the user (driver) that the protection mode is MP (step S208). That is, in the protection mode MP, the projected image is not displayed in the display area 5, so that the driver's attention is drawn to the image, which may impair safety. Therefore, for example, a warning display as shown in FIG. 15 is displayed on the cluster panel or the navigation panel. FIG. 15 is a diagram showing an example of the contents of the user notification by the protection processing unit in FIG. 5.

[0066] In the example of FIG. 15, when the driver tries to adjust the brightness of the HUD image, the cluster panel or the navigation panel displays a message informing the driver that the protection operation or brightness restriction is in progress and the brightness of the HUD image cannot be adjusted. That is, as described later, such a notification is given not only in the protection mode MP but also in the degenerate mode MD. This is because, in the degenerate mode MD, the brightness of the HUD image is reduced, which may impair safety as in the case of the protection mode MP. Note that such a user notification is given, for example, via the communication unit 21 in FIG. 5. Also, the user notification is not limited to a display, and may be a voice via the speaker 11 in FIG. 5.

[0067] 11, the protection processing unit 75 determines whether or not a power-off operation (turning off the ignition switch) of the vehicle 2 has been detected while the post-protection timer TW is counting (steps S301, S302). If the determination results of both steps S301 and S302 are "Yes", the protection processing unit 75 performs a restoration possibility determination [2] (i.e., an exceptional determination) (step S304), and if either one of the determination results is "No", the protection processing unit 75 performs a restoration possibility determination [1] (i.e., a normal determination) (step S303).

[0068] In the restoration possibility determination [1] in FIG. 12, the protection processing unit 75 performs a degeneration cancellation determination (step S401). Although details will be described later in FIG. 13, depending on the degeneration cancellation determination, the degeneration mode MD is maintained or the degeneration mode MD is shifted to the normal mode MN. In step S402 in FIG. 12, the protection processing unit 75 detects the sunlight intensity using the solar radiation sensor 66 (step S401). Next, the protection processing unit 75 determines whether the detected sunlight intensity is equal to or less than the off intensity Ioff (step S403).

[0069] If the sunlight intensity is equal to or less than the off intensity Ioff in step S403, the protection processing unit 75 starts an off timer (TOFF) that counts the off time TOFF (step S404). The off timer (TOFF) is one of the timers 76 in FIG. 5. If the off timer (TOFF) is already counting in step S404, the protection processing unit 75 continues the counting operation. On the other hand, if the sunlight intensity is higher than the off intensity Ioff in step S403, the protection processing unit 75 resets the off timer (TOFF) and ends the process (step S408).

[0070] After step S404, the protection processing unit 75 judges whether the off timer (TOFF) has expired (step S405). If the off timer (TOFF) is counting, the protection processing unit 75 ends the process. On the other hand, if the off timer (TOFF) has expired, the protection processing unit 75 transitions to the degenerate mode MD (step S406). Thereafter, the protection processing unit 75 notifies the user (driver) that the degenerate mode MD has been entered, as described in FIG. 15 (step S407).

[0071] In the degeneration release judgment of FIG. 13, the protection processing unit 75 judges whether or not it is the degenerate mode MD (step S501). If it is not the degenerate mode MD (i.e., if it is the normal mode MN), the protection processing unit 75 ends the process. On the other hand, if it is the degenerate mode MD, the protection processing unit 75 acquires the most recent power-on operation time (ignition switch ON time) tPON of the vehicle 2 (step S502). Specifically, for example, when the power of the HUD device 1 is turned on in response to the ignition switch being turned on, the protection processing unit 75 acquires the current time at that time from the GPS receiver 57 of FIG. 6 or the like, and records the time as the power-on operation time tPON of the vehicle 2 in the non-volatile memory 17 of FIG. 5 or the like. Alternatively, the protection processing unit 75 may use information from the engine start sensor 49 of FIG. 6.

[0072] Next, the protection processing unit 75 judges whether or not the power-on operation time tPON of the vehicle 2 has passed a standby time (e.g., 6 hours) from the protection-on time tON' recorded in step S206 of Fig. 10 (step S503). If the standby time has passed, the protection processing unit 75 transitions to the normal mode MN (step S504). On the other hand, if the standby time has not passed in step S503, the protection processing unit 75 maintains the degenerate mode MD by terminating the processing.

[0073] In the return possibility judgment [2] of Fig. 14A, the protection processing unit 75 waits until the power-on operation of the vehicle 2 is detected (step S601). Then, when the power-on operation of the vehicle 2 is detected, the protection processing unit 75 judges whether the post-protection timer TW is counting or not (step S602). If the post-protection timer TW is counting, the protection processing unit 75 waits until the post-protection timer TW expires (step S603). During this time, the protection mode MP is maintained.

[0074] Next, when the post-protection timer TW expires in step S603, the protection processing unit 75 starts the HUD device in a state determined as the degenerate mode MD in step S604 (i.e., displays a projected image in the display area 5). Thereafter, the protection processing unit 75 notifies the user (driver) that the degenerate mode MD is in effect (step S605), as described in FIG.

[0075] On the other hand, if the post-protection timer TW is not counting in step S602 (i.e., the timer has expired), the process shown in Fig. 14B is performed. In Fig. 14B, the protection processing unit 75 detects the sunlight intensity using the solar radiation sensor 66 (step S701). Next, the protection processing unit 75 determines whether the detected sunlight intensity is equal to or less than the off intensity Ioff (step S702).

[0076] If the sunlight intensity is equal to or lower than the off intensity Ioff in step S702, the protection processing unit 75 performs the same processing in steps S703 to S705 as in steps S502 to S504 in Fig. 13. That is, the protection processing unit 75 acquires the most recent power-on operation time tPON of the vehicle 2 (step S703), and determines whether the power-on operation time tPON is a time that has passed a standby time (e.g., 6 hours) since the protection-on time tON' (step S704).

[0077] If the waiting time has elapsed in step S704, the protection processing unit 75 starts the HUD device in a state determined as the normal mode MN in step S705 (i.e., displays a projected image in the display area 5). On the other hand, if the waiting time has not elapsed in step S704, the protection processing unit 75 starts the HUD device in a state determined as the degenerate mode MD (step S706). Thereafter, the protection processing unit 75 notifies the user (driver) that the mode is the degenerate mode MD (step S707), as described in FIG.

[0078] <<Major Effects of the Embodiments>> As described above, by using the HUD device of the embodiment, it is possible to prevent damage caused by sunlight and ensure user convenience. That is, while protecting the display panel 64, the time period during which the HUD cannot be used can be shortened as much as possible, in other words, the time period during which the HUD can be used (the time period during which the projected image in the display area 5 is displayed) can be extended.

[0079] Specifically, by having the solar radiation sensor 66 detect the sunlight intensity within the sunlight detection range 70, the time period during which the HUD can be used can be extended without unnecessarily switching to the protection mode MP. Furthermore, even if the protection mode MP is switched to, if the sunlight intensity is low, the time period during which the HUD can be used can be extended by canceling the protection mode MP after the off time TOFF. Furthermore, when the protection mode MP is cancelled, by switching to the degenerate mode MD instead of the normal mode MN, the display panel 64 can be reliably protected.

[0080] The invention made by the present inventor has been specifically described above based on the embodiments, but the present invention is not limited to the above-mentioned embodiments and can be modified in various ways without departing from the gist of the invention. For example, the above-mentioned embodiments have been described in detail to easily explain the present invention, and the present invention is not necessarily limited to those having all of the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0081] 1 HUD device 2 Vehicles 3. Windshield 4. Vehicle Information 5 Display area 6. Driver 7 Openings 10 Control unit (ECU) 11 Speaker 12 Video display unit 15 Vehicle information acquisition unit 16 Microcontrollers (MCUs) 17 Non-volatile memory 18 Volatile Memory 19 Audio Driver 20 Display Driver 21 Communications Department 27 Audio data generation unit 28 Video data generator 29 Distortion correction section 30 Light source adjustment section 31 Mirror adjustment unit 35 Image display devices 41 Vehicle speed sensor 42 Shift position sensor 43 Steering wheel angle sensor 44 Headlight Sensor 45 Illuminance sensor 46 Color Sensor 47 Distance Sensor 48 Infrared Sensor 49 Engine start sensor 50 Acceleration Sensor 51 Gyro sensor 52 Temperature Sensor 53 Radio transmitter / receiver for road-to-vehicle communication 54 Vehicle-to-vehicle communication radio transceiver 55 In-car camera 56 Exterior camera 57 GPS receiver 58 VICS receiver 60 sun 61 Case 62 Drive mechanism 63 Condenser Lens 64 Display Panel 65 Light source 66 Solar radiation sensor 67 Shutdown mechanism 70 Sunlight detection range 71 Cover material 75 Protection Processing Unit 76 Timer Ioff Off Intensity Ion On Intensity M1, M2 reflecting mirror MD Degraded Mode MN Normal mode MP Protection Mode TOFF Off time TON On Time Ta Ambient temperature tON' Protection on time

Claims

1. A head-up display device that allows a driver of a vehicle to visually recognize a landscape on which a projected image is superimposed, A light source that emits light; a display panel that modulates the light from the light source to create an image for projection onto a display area of ​​the vehicle; a reflecting mirror that reflects the image generated by the display panel and projects the image onto the display area; a protection processing unit that adjusts the luminance of the light source or the on / off of the light source based on the sunlight intensity detected by a solar radiation sensor, the luminance of the light source, and an ambient temperature; A normal state and a protection state are provided. Head-up display device.

2. The head-up display device according to claim 1, the protection processing unit counts a time equal to a predetermined off time from a point in time when the transition to the protection state is performed. Head-up display device.

3. The head-up display device according to claim 2, The protection processing unit includes a timer that performs the counting. Head-up display device.

4. The head-up display device according to claim 2, The protection processing unit performs the counting based on time information acquired from the vehicle. Head-up display device.

5. The head-up display device according to claim 2, If the power supply of the vehicle is turned on again during the counting operation, the protected state is not released until the counting operation of the timer expires. Head-up display device.

6. The head-up display device according to claim 2, If the power supply of the vehicle is turned on again during the counting operation, the protected state is released after the counting operation has expired. Head-up display device.

7. The head-up display device according to claim 1, The protection processing unit counts a predetermined on-time from a point in time when the sunlight intensity detected by the sunlight sensor becomes equal to or greater than a predetermined on-time intensity, and continues the counting operation when the sunlight intensity detected by the sunlight sensor is equal to or greater than the on-time intensity and the on-time is being counted. Head-up display device.

8. The head-up display device according to claim 7, transitioning to the protection state when the on-time count expires; Head-up display device.

9. The head-up display device according to claim 1, The protection processing unit counts a predetermined on-time from a point in time when the sunlight intensity detected by the sunlight sensor becomes equal to or greater than a predetermined on-time intensity, and resets the count of the on-time when the sunlight intensity detected by the sunlight sensor is less than the on-time intensity. Head-up display device.

10. The head-up display device according to claim 1, The protection processing unit counts a predetermined off time from a time when the sunlight intensity detected by the sunlight sensor becomes equal to or lower than a predetermined off intensity, and when the sunlight intensity detected by the sunlight sensor is equal to or lower than the off intensity and the off time is being counted, the protection processing unit continues the counting operation. Head-up display device.

11. The head-up display device according to claim 1, The protection processing unit counts a predetermined off time from a point in time when the sunlight intensity detected by the sunlight sensor becomes equal to or lower than a predetermined off intensity, and resets the count of the off time when the sunlight intensity detected by the sunlight sensor is higher than the off intensity and the off time is being counted. Head-up display device.

12. The head-up display device according to claim 1, In the protected state, the driving of the light source is stopped. Head-up display device.

Images