Head-up display device

Abstract

Provided is a head-up display device that enables display with more accurate quality. A head-up display device A of the present disclosure comprises: a light source 11 that emits light at a predetermined brightness and that emits illumination light L1; a display element 3 that generates display light L by being illuminated with the illumination light L1; a light sensor 50 that, when illumination light L1 is incident thereon, outputs an illumination light amount signal corresponding to the illumination light amount; and a light source controller 40 that controls the light emission of the light source 11 in response to the illumination light amount signal. The light source controller 40 controls the light source 11, on the basis of deterioration information indicating the degree of deterioration due to aging of the light sensor 50, in a first mode in which light is emitted at a first brightness in a case where the deterioration of the light sensor 50 is small, and in a second mode in which light is emitted at a second brightness lesser than the first brightness in a case where the deterioration of the light sensor 50 is large.

Description

Technical Field

[0001] The present invention relates to a head-up display device.

Background Art

[0002] As a conventional head-up display device, for example, it is disclosed in Patent Document 1. The head-up display device described in such Patent Document 1 is attached inside an instrument panel of a vehicle (hereinafter referred to as an instrument panel), projects display light emitted from a display device onto a front glass (projection member) of the vehicle, and displays a virtual image for a user (driver) of the vehicle.

[0003] In addition, as an optical engine of a conventional head-up display device, there is one using a DMD (Digital Micro Mirror Device), for example, it is disclosed in Patent Document 2. In this optical engine, a detection circuit using a photosensor for detecting the light intensity of each light-emitting diode is provided, and feedback control is performed so that the light source outputs with accurate luminance.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] These head-up display devices are installed in vehicles and are expected to perform well enough to withstand use in a variety of conditions. These conditions include, for example, long-term use for about 10 years, exposure to high temperatures due to changes in the outside temperature environment as well as sunlight and heat generated by the light source elements, and exposure to strong light emitted by the device itself. However, even after being subjected to such conditions, head-up display devices are required to reduce the risk of inaccurate displays.

[0006] Therefore, the object of the present invention is to address the aforementioned problems and provide a head-up display device that reduces the risk of inaccurate displays. [Means for solving the problem]

[0007] The head-up display device of the present invention is A light source that emits light at a predetermined brightness and provides illumination, A display element that generates display light when illuminated by the aforementioned illumination light, A light sensor that outputs an illumination light intensity signal corresponding to the illumination light intensity when the aforementioned illumination light is incident on it, A light source control unit controls the emission of light from the light source in accordance with the illumination light intensity signal, Equipped with, The light source control unit, Based on degradation information representing the degree of aging degradation of the aforementioned optical sensor, If the degradation of the aforementioned light sensor is minimal, a first mode is used in which light is emitted at the first brightness level, If the aforementioned light sensor is significantly degraded, a second mode is activated in which light is emitted at a second brightness level lower than the first brightness level. The light source is controlled by this.

[0008] From another perspective, the head-up display device of the present invention is A light source that emits light at a predetermined brightness and provides illumination, A display element that generates display light when illuminated by the aforementioned illumination light, A light sensor that outputs an illumination light intensity signal corresponding to the illumination light intensity when the aforementioned illumination light is incident on it, A light source control unit controls the emission of light from the light source in accordance with the illumination light intensity signal, Equipped with, The aforementioned light source includes a red LED (Light Emitting Diode), a green LED, and a blue LED. The light source control unit increases the amount of current flowing through the blue LED in accordance with the illumination light intensity signal, and when this reaches a predetermined upper limit, it stops further increasing the amount of current flowing through the light source.

[0009] From another perspective, the head-up display device of the present invention is A light source that emits light at a predetermined brightness and provides illumination, A display element that generates display light when illuminated by the aforementioned illumination light, A light sensor that outputs an illumination light intensity signal corresponding to the illumination light intensity when the aforementioned illumination light is incident on it, A light source control unit controls the emission of light from the light source in accordance with the illumination light intensity signal, Equipped with, The aforementioned light sensor is circuit board and A light-receiving unit fixed on the substrate, An adhesive for fixing the light-receiving part to the substrate, A mask that covers the adhesive so that the illumination light does not enter the adhesive, It has. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows an example of a vehicle installation of a head-up display device A according to the first embodiment of the present invention. [Figure 2] A cross-sectional view showing an example of a vehicle installation of the head-up display device A according to the same embodiment. [Figure 3] A cross-sectional view of head-up display device A according to the same embodiment. [Figure 4] A diagram showing a lighting device according to the same embodiment. [Figure 5]A diagram showing the configuration of a conventional optical sensor 50a. [Figure 6] A diagram showing the configuration of the conventional optical sensor 50a after aging deterioration. [Figure 7] A diagram showing the configuration of the optical sensor 50 according to the third embodiment. [Figure 8] A diagram showing the configuration of the optical sensor 50 according to the same embodiment.

Mode for Carrying Out the Invention

[0011] Aspects of the present disclosure will be described in the following order. [First Embodiment] <1-1. Description of Configuration> <1-2. Description of the Operation of the Light Source Control Unit> [Second Embodiment] [Third Embodiment] [Modification Example]

[0012] [First Embodiment] <1-1. Description of Configuration> A display device according to an embodiment of the present invention is a head-up display device (hereinafter referred to as a HUD device) A shown in FIGS. 1 and 2. As shown in the drawing, the HUD device A is disposed on the dashboard C of the vehicle B and emits display light L representing the generated image (vehicle information) toward the windshield D. The display light L reflected by the windshield D is visually recognized by the observer E (mainly the driver of the vehicle B) as a virtual image F of the image formed in front of the windshield D. In this way, the HUD device A allows the observer E to visually recognize the image as the virtual image F. This image notifies information about the vehicle B (for example, traveling speed, engine speed, navigation information, etc.).

[0013] As shown in FIG. 3, the HUD device A includes a lighting device 1, a lighting optical system 2, a display element 3, a projection optical system 4, a screen 5, a mirror unit 6 including a plane mirror 61 and a concave mirror 62, and a housing 7 having a light-transmitting portion 71. Further, as shown in FIG. 4, the lighting device 1 of the HUD device A includes a light source control unit 40 and an optical sensor 50.

[0014] The lighting device 1 emits light (illumination light L1), which will be described later, toward the illumination optical system 2, and as shown in Figure 4, it comprises a light source 11, a circuit board 12, a wave multiplexing means 13, and a prism 15.

[0015] The light source 11 is composed of light sources 11r, 11g, and 11b, which are, for example, light-emitting diodes (LEDs). Light source 11r emits red light Lr, light source 11g emits green light Lg, and light source 11b emits blue light Lb. Each of the light sources 11r, 11g, and 11b is driven by the first control unit 10 and emits light at a predetermined light intensity and timing. In this embodiment, the light sources 11r, 11g, and 11b are independent light sources 11, but multiple colors of light may be emitted from a common light source 11. Furthermore, the light source 11 only needs to emit multiple colors of light, and may consist of only two colors, or four or more colors (including white). The circuit board 12 is made of a printed circuit board. The light sources 11r, 11g, and 11b are mounted on the circuit board 12.

[0016] The light source control unit 40 can be fitted with an integrated circuit that implements the desired function in hardware. The light source control unit 40 receives an illumination light intensity signal from the light sensor 50 based on the light intensity of the illumination light L1 (blue light Lb, green light Lg, or red light Lr) emitted from the light source 11, generates a drive signal to drive the light source 11 from this illumination light intensity signal, and turns the light source 11 on or off based on this drive signal. In other words, the light source control unit 40 performs feedback control to ensure that the light intensity is appropriate according to the illumination light intensity output from the light source 11. The detailed operation of the light source control unit 40 is described in Section 1-2.

[0017] Furthermore, the light source control unit 40 may include a further control unit. This control unit consists of a microcontroller and may include a CPU, memory (RAM, ROM), etc. The CPU controls each part by reading and executing a program necessary for the operation of the HUD device A, which is pre-stored in the ROM. The control unit receives a video signal for displaying an image from the vehicle ECU (electronic control unit) of vehicle B via LVDS (Low Voltage Differential Signal) communication, etc., and also receives an external illumination signal (dimming signal) from the vehicle ECU of vehicle B. Based on these, the control unit adjusts the light emission intensity of the light source 11 and further displays a desired display image on the display element 3.

[0018] The wave multiplexing means 13 directs the light Lr, Lg, and Lb emitted from the light sources 11r, 11g, and 11b and arriving in approximately one direction (towards the brightness unevenness reduction means 14). Specifically, the wave multiplexing means 13 consists of a reflective section 13a made of a reflecting mirror, and wave multiplexing sections 13b and 13c made of dichroic mirrors that reflect light of a specific wavelength but transmit light of other wavelengths.

[0019] The reflecting section 13a is located on the output side of the light source 11b. The reflecting section 13a reflects the incident blue light Lb toward the multiplexing section 13b. The multiplexing section 13b is located on the output side of the light source 11g. The multiplexing section 13b reflects the incident green light Lg toward the multiplexing section 13c and transmits the blue light Lb from the reflecting section 13a directly. The multiplexing section 13c is located on the output side of the light source 11r. The multiplexing section 13c reflects the incident red light Lr toward the illumination optical system 20 and transmits the light Lb and light Lg from the multiplexing section 13b directly. That is, the illumination light L1 (blue light Lb, green light Lg, or red light Lr) sequentially emitted from the light source 11 is emitted from the multiplexing section 13c in approximately one direction (towards the brightness unevenness reduction means 14). The wave combining means 13 aligns the optical axes of each light source 11r, 11g, and 11b, and may be omitted when multiple colors of light are emitted from a single light source 11.

[0020] A luminance unevenness reduction means may be provided downstream of the wave multiplexing means 13. The luminance unevenness reduction means consists of a mirror box, an array lens, etc., and reduces light unevenness by diffusely reflecting, scattering, and refracting the illumination light L1 from the wave multiplexing means 13.

[0021] The lighting device 1 emits light from the light source 11 towards the lighting optical system 2 as illumination light L1 (blue light Lb, green light Lg, or red light Lr) through the multiplexing means 13 described above and the prism 15 described below.

[0022] The prism 15 is made of a transparent material having a reflectivity of, for example, about 5%, and transmits most of the illumination light L1 that arrives via the wave multiplexing means, but reflects some of the light towards the light sensor 50.

[0023] The light sensor 50 uses, for example, a detection element having a photodiode and is positioned to receive the illumination light L1 reflected by the prism 15. The light sensor 50 receives a portion of the illumination light L1 and detects the light intensity (light quantity) of each of the light components Lr, Lg, and Lb in a time-division manner. The light sensor 50 outputs an illumination light quantity signal according to the detected light intensity. The illumination light quantity signal is a voltage value converted based on the current output from the photodiode, but any electrical signal that can represent the degree of light quantity may be used.

[0024] Furthermore, since the light sensor 50 only needs to be able to detect the light intensity of Lr, Lg, and Lb, it may be installed not in the optical path of the illumination light L1, but for example, at a location where the light intensity of Lr, Lg, and Lb before they are combined can be detected. Alternatively, the light sensor 50 may be installed at a location where it can detect the light intensity of a portion of the illumination light L1 emitted from the illumination optical system 2. The function of the light sensor 50 will be described in detail later.

[0025] The illumination optical system 2 consists of a concave lens and the like, and adjusts the illumination light L1 emitted from the illumination device 1 to a size corresponding to the display element 3.

[0026] The display element 3 can be fitted with a DMD having multiple movable micromirrors, and each mirror is controlled to either be on or off, thereby reflecting the illumination light L1 emitted from the illumination optical system 2 as appropriate. By reflecting the illumination light L1 in this way, the display element 3 projects an image (light for generating an image) towards the projection optical system 4.

[0027] Specifically, electrodes are provided at the bottom of the micromirrors, and these electrodes drive each mirror at a very short period (e.g., a microsecond period), thereby turning each mirror on or off. Each mirror is movable around a hinge, and when the mirror is on, the mirror surface is tilted +12 degrees around the hinge, and when the mirror is off, the mirror surface is tilted -12 degrees around the hinge. The on mirror reflects the illumination light L1 from the illumination optical system 2 in the direction of the projection optical system 4, while the off mirror does not reflect the illumination light L1 in the direction of the projection optical system 4. The display element 3 projects an image (display light L) towards the projection optical system 4 by individually driving each mirror.

[0028] The projection optical system 4 is composed of concave lenses or convex lenses, etc., and is an optical system for efficiently projecting the display light L from the display element 3 onto the screen 5.

[0029] Screen 5 consists of a holographic diffuser, a microlens array, a diffuser plate, etc., and receives the display light L from the projection optical system 4 on its back (the side facing the display element 3) and displays the image on its front (the side facing the mirror unit 6).

[0030] The plane mirror 61 reflects the display light L, which represents the image displayed on the screen 5, toward the concave mirror 62. The concave mirror 62 reflects the display light L that has arrived from the plane mirror 61 with its concave surface, and emits the reflected light toward the windshield D. As a result, the virtual image F that is formed is enlarged compared to the image displayed on the screen 5. The display light L reflected by the concave mirror 62 reaches the windshield D via the light-transmitting section 71.

[0031] The housing 7 houses the illumination device 1, illumination optical system 2, display element 3, projection optical system 4, screen 5, plane mirror 61, concave mirror 62, etc., in predetermined positions. The housing 7 is formed of, for example, a light-shielding material in all parts except the light-transmitting section 71. The light-transmitting section 71 is made of a light-transmitting resin such as acrylic and transmits the display light L from the concave mirror 62. The light-transmitting section 71 is fitted into the housing 7, for example. The light-transmitting section 71 is formed in a curved shape, for example, so that incoming ambient light (for example, sunlight or streetlights) does not reflect towards the observer E.

[0032] <1-2. Explanation of the operation of the light source control unit> (1) The inventors, in their daily design and development work, discovered that head-up display devices equipped with an optical sensor, such as the one disclosed here, may experience changes in display quality after prolonged use. In further investigation, the inventors determined that the optical sensor may undergo degradation over time. This degradation refers to a decrease in the optical sensor's light-receiving sensitivity. Specifically, the inventors discovered that even when the same optical sensor is irradiated with a certain amount of light, the output light intensity signal (illumination light intensity signal) changes before and after use in a certain environment, causing it to appear as if the light intensity is lower than the actual amount of light irradiated.

[0033] When such degradation occurs, even if the light source 11 achieves the desired brightness, the illumination light intensity indicated by the illumination light intensity signal output by the light sensor 50 will be lower than the actual amount of illumination light. Then, because the light source control unit 40 performs feedback control in response to this illumination light intensity signal, the light intensity of the light source 11 is increased, causing it to emit light at a brightness exceeding the desired brightness.

[0034] Therefore, in the HUD device A of this disclosure, the light source control unit 40 is configured to acquire degradation information representing the degree of aging degradation of the light sensor 50. More preferably, the light source control unit 40 is configured to acquire aging degradation information relating to the light receiving sensitivity performance of the light sensor 50.

[0035] The light source control unit 40 controls the light source 11 in a first mode, which emits light at a normal level (first brightness), if the degree of aging degradation of the light sensor 50 indicated by the degradation information is small. In the first mode, the light source control unit 40 controls the light source 11 to the desired light emission operation in accordance with the external illuminance signal and the illumination light intensity signal. For example, when the external illuminance is low, the light source control unit 40 reduces the brightness of the light source 11 by, for example, reducing the duty cycle in the case of PWM control, or reducing the peak values ​​of the current and voltage values.

[0036] If the degradation information indicates that the photosensor 50 has deteriorated significantly over time, the light source control unit 40 controls the light source 11 in a second mode, which emits light at a second brightness level lower than the first brightness level. In the second mode, the light source control unit 40 has determined from the acquired degradation information that the photosensor 50 is deteriorating over time, and therefore adjusts the control of the light emission operation of the light source 11 to suppress the brightness.

[0037] Furthermore, it is preferable that the above-mentioned first and second brightness levels are not a single brightness level, but rather a series of brightness tables. A brightness table is data that shows the appropriate combination of drive signals for each expected external illuminance signal. In other words, the light source 11 is controlled to emit light at various brightness levels according to the external illuminance, but it is often insufficient to switch between the first and second modes at only one brightness level. Therefore, it is preferable that, rather than switching a specific single brightness level, the light source control unit 40 switches the brightness table for controlling the light source 11 between the first and second modes. The second brightness level can be any predetermined brightness level that is relatively low compared to the first brightness level, and includes, for example, a state of zero brightness where the light is completely off. Complete extinguishing of the light source 11 at the second brightness level includes the stopping of the drive signal by the light source control unit 40 and the shutdown of the HUD device A.

[0038] In other words, the head-up display device A of this disclosure is A light source 11 that emits light at a predetermined brightness and emits illumination light L1, A display element 3 that generates display light L when illuminated by illumination light L1, When illumination light L1 is incident on the light sensor 50, it outputs an illumination light intensity signal corresponding to the illumination light intensity, A light source control unit 40 controls the emission of light from the light source 11 according to the illumination light intensity signal, Equipped with, The light source control unit 40 is Based on degradation information representing the degree of aging degradation of the light sensor 50, If the degradation of the light sensor 50 is minimal, the first mode will emit light at the first brightness level, If the light sensor 50 is significantly degraded, a second mode is activated in which it emits light at a second brightness level lower than the first brightness level. This controls the light source 11.

[0039] With this configuration, even if the sensitivity of the light sensor 50 decreases due to aging, the light source 11 can still emit light at normal brightness, resulting in a head-up display device that reduces the risk of inaccurate displays.

[0040] (2) In embodiment (1), the degradation information may have the following configuration. Specifically, the degradation information may be based on, for example, the total emission time of the light source 11, and the light source control unit 40 may calculate, store, and acquire degradation information such that the longer the total emission time of the light source 11, the greater the degree of degradation of the light sensor 50.

[0041] The light source control unit 40 may adjust the degree of the second brightness according to such degradation information.

[0042] In other words, the head-up display device A of this disclosure is The degradation information is based on the total emission time of the light source 11; the longer the total emission time, the greater the degradation of the light sensor 50.

[0043] With this configuration, if the sensitivity of the light sensor 50 decreases due to aging, the light source 11 can emit light at a normal brightness according to the degree of deterioration of the light sensor 50, thereby reducing the risk of inaccurate display in the head-up display device.

[0044] (3) In embodiment (1), the degradation information may be configured as follows. Specifically, for example, it may be based on the total operating time of the light source control unit 40, and the light source control unit 40 may calculate, store, and acquire degradation information such that the longer the total operating time of the light source control unit 40, the greater the degree of degradation of the light sensor 50.

[0045] This total operating time should be the sum of the time spent with the light source control unit 40 excluding the time it is in sleep mode or shut down, for example, the startup period when the light source control unit 40 is awake, and the period when the light source control unit 40 is in an enabled state capable of outputting a drive signal, which is a control signal for the light source 11.

[0046] The light source control unit 40 may adjust the degree of the second brightness according to such degradation information.

[0047] In other words, the head-up display device A of this disclosure is The degradation information is based on the total operating time of the light source control unit 40, and a longer total operating time indicates greater degradation of the light sensor 50.

[0048] With this configuration, if the sensitivity of the light sensor 50 decreases due to aging, the light source 11 can emit light at a normal brightness according to the degree of deterioration of the light sensor 50, thereby reducing the risk of inaccurate display in the head-up display device.

[0049] (4) Furthermore, the head-up display device A of this disclosure is In the embodiment of (1), The degradation information is based on the elapsed time from the user's initial activation time or manufacturing time of the light source control unit 40 to the present time. A longer elapsed time indicates greater degradation of the light sensor 50.

[0050] With this configuration, even if the sensitivity of the light sensor decreases due to aging, the light source 11 can emit light at normal brightness, resulting in a head-up display device that reduces the risk of inaccurate displays.

[0051] (5) In embodiment (1), the HUD device may have the following configuration. HUD device A exhibits variations in display performance from unit to unit due to manufacturing tolerances of its components. To eliminate these variations, HUD device A undergoes calibration during the manufacturing process. This calibration involves modifying the parameters of the control unit so that HUD device A can achieve appropriate display modes for various inputs.

[0052] In this embodiment, the pre-degradation output value is stored in the light source control unit 40 during this calibration process. The pre-degradation output value may be, for example, data from a certain type of table. The table may be data that combines the light emission pattern input to the light source 11 during calibration with the output value of the light sensor 50 when the light source 11 emits light with that light emission pattern. In other words, the pre-degradation output value is data that indicates the output value of the light sensor 50 before degradation in response to the light emission control operation performed by the light source control unit 40 on the light source 11.

[0053] Furthermore, the light source control unit 40 can acquire the degraded output value each time. The degraded output value is, for example, a table data that combines the drive signal (light emission pattern) under the user's operating environment and the illumination light intensity signal when controlled by this drive signal.

[0054] The light source control unit 40 compares the output value before degradation with the output value after degradation. If the output value after degradation is continuously lower than the output value before degradation, it indicates that the illumination light intensity signal is showing a decrease in brightness even in the same operating environment. At this time, the light source control unit 40 may calculate, store, and remember degradation information indicating that the light sensor 50 is degraded.

[0055] In other words, the head-up display device A of this disclosure is The light source control unit 40 is During calibration in the manufacturing stage, the pre-degradation output value, which is the output value of the light sensor 50 when the light source 11 is controlled with a specific light emission pattern (drive signal), is stored. The degraded output value, which is the output value of the light sensor 50 when the light source 11 is controlled by the light emission pattern, is obtained. The more the output value after degradation decreases compared to the output value before degradation, the greater the degradation of the optical sensor, and thus the more degradation the optical sensor is acquired.

[0056] With this configuration, even if the sensitivity of the light sensor 50 deteriorates due to any event (for example, temperature changes or exposure to strong light), the decrease in sensitivity of the light sensor 50 can be appropriately detected in the operating environment, and the light source 11 can emit light at a more normal brightness. In other words, it becomes a head-up display device that reduces the risk of inaccurate displays.

[0057] (6) In embodiment (5), the light source control unit 40 of the head-up display device A further stores an estimated amount of aging degradation of the light emission performance of the light source 11. The estimated amount of aging degradation may be, for example, table data showing the decrease in brightness performance with respect to usage time, where the brightness performance at the time of manufacture is set to 100.

[0058] When comparing the output value before degradation with the output value after degradation, the light source control unit 40 controls the light source 11 in first mode if it determines that the output value after degradation is lower than the output value before degradation, but this decrease is within the range of the estimated aging degradation of the light source 11.

[0059] In other words, the light source control unit 40 controls the light source 11 in the second mode only when the output value after degradation has decreased compared to the output value before degradation, and the degree of that decrease is greater than or equal to the estimated amount of aging degradation of the light emission performance of the light source 11.

[0060] In other words, the head-up display device A of this disclosure is The light source control unit 40 is The light source 11 is controlled in the second mode only if the decrease in the output value after degradation compared to the output value before degradation is greater than the estimated amount of aging degradation of the light source 11's luminous performance.

[0061] This configuration makes it possible to determine whether the drop in output value after degradation is due to the aging of the light sensor 50 or the aging of the light-emitting performance of the light source 11, allowing the light source 11 to emit light at a more normal brightness. Consequently, this results in a head-up display device that reduces the risk of inaccurate displays.

[0062] (7) The inventor carried out further design, development, and verification work on the configuration of (1). During this process, the inventor discovered that as the optical sensor 50 deteriorated, the chromaticity of the virtual image F may shift. In further detailed work, the inventor determined that when this chromaticity shift occurred, there was a deterioration in the optical sensor 50 that had wavelength characteristics.

[0063] Specifically, the light sensor 50 deteriorated over time, reducing its sensitivity to short-wavelength light. As a result, the light source control unit 40 performed feedback control to cause the short-wavelength light in the light source 11 to emit light more strongly, causing a chromaticity shift. The inventor overcame this problem by adopting the following configuration.

[0064] In other words, the head-up display device A of this disclosure is The light source 11 outputs light of multiple wavelengths, The light source control unit 40 reduces the brightness of the light source 11 relatively significantly for the emission of light with relatively short wavelengths.

[0065] With this configuration, even if the sensitivity of the light sensor 50 to short wavelength light decreases due to aging, the light source 11 can still emit light with normal chromaticity, resulting in a head-up display device that reduces the risk of inaccurate displays.

[0066] (8) Furthermore, the head-up display device A of this disclosure is Light source 11 emits red, green, and blue light. The light source control unit 40 reduces the brightness of the blue light Lb emitted from the light source 11 by a relatively large amount.

[0067] (9) Furthermore, the head-up display device A of this disclosure is Light source 11 outputs white light, The light source control unit 40 reduces the brightness of the short-wavelength component of the light emission operation of the light source 11 by a relatively large amount.

[0068] In the embodiment of (9), it is desirable to use a color filter or the like to generate illumination light L1 in a time-division manner.

[0069] [Second Embodiment] The head-up display device of this disclosure may be configured as follows. The second embodiment will be described primarily in terms of the differences from the first embodiment. For configurations not explicitly mentioned in the description of the second embodiment, the configurations mentioned in the description of the first embodiment can be applied as appropriate.

[0070] (10) The head-up display device in the second embodiment is Light source 11 includes a red LED (light source 11r), a green LED (light source 11g), and a blue LED (light source 11b). The light source control unit increases the amount of current flowing through the blue LED in accordance with the illumination light intensity signal, and when this reaches a predetermined upper limit, it stops further increasing the amount of current flowing through the light source 11.

[0071] The inventors discovered that in conventional head-up display devices, the light-receiving sensitivity of the light sensor can change depending on the usage time due to aging. In particular, the inventors found that this change in light-receiving sensitivity can have wavelength characteristics. For example, discoloration (blackening or yellowing) of the components constituting the light sensor could cause the light-receiving sensitivity of the light sensor to decrease only for certain types of light (e.g., blue).

[0072] When this phenomenon occurs, devices equipped with a light source control unit that controls the luminescence of the light source in accordance with the illumination light intensity signal, such as head-up display devices, may display inaccurate information.

[0073] To address such challenges, the head-up display device of this disclosure is configured such that when the current of a light source that emits light of one color (light source 11b) is increased in accordance with the illumination light intensity signal and reaches a predetermined upper limit current, the amount of brightness increase is fixed together with the other color light sources (light sources 11g, light sources 11r).

[0074] This configuration reduces the risk of excessive brightness increases even when the light sensor's light-receiving sensitivity decreases, and consequently reduces the risk of inaccurate displays in the head-up display device.

[0075] The light source 11 emits light when it receives light emission signals such as current, voltage, and a square wave for PWM control. The light source control unit may fix the amount of brightness increase of the light source 11 when the current, voltage, or duty cycle of the square wave for PWM control reaches an upper limit.

[0076] The inventors discovered that the decrease in light-receiving sensitivity of the light sensor occurs particularly with respect to blue light (light with a relatively short wavelength). Therefore, this configuration results in a head-up display device that more preferably reduces the risk of inaccurate displays.

[0077] [Third Embodiment] The head-up display device of this disclosure may be configured as shown in Figures 7 and 8. The third embodiment will be described primarily in terms of the differences from the first embodiment. For configurations not explicitly mentioned in the description of the third embodiment, the configurations mentioned in the description of the first embodiment can be applied as appropriate.

[0078] (11) The head-up display device in the third embodiment is The light sensor 50 is Lead frame 51 (circuit board), A light-receiving unit 52 fixed on the lead frame 51, A silver paste 54 (adhesive) is used to fix the light-receiving unit 52 to the lead frame 51, A mask 56 covers the adhesive so that the illumination light L does not enter the silver paste, It has.

[0079] The inventors discovered that, as described above, a change occurred in the light sensor's light-receiving sensitivity. Further analysis revealed that this change was due to a deterioration of the light sensor itself.

[0080] Here, we will explain the conventional configuration using Figures 5 and 6, which show the configuration of a conventional optical sensor 50a. As shown in Figure 5, a conventional optical sensor 50a has a lead frame 51, which is an example of a substrate, a light receiving part 52, a dielectric film 53, a silver paste 54, and silicon 55.

[0081] The lead frame 51 is a connecting member for electrically connecting a semiconductor device mounted on its surface to a circuit board or the like.

[0082] The light-receiving unit 52 generates an illumination light intensity signal, which is a voltage or current, when a predetermined light is incident on it. The light-receiving unit 52 is composed of, for example, a photodiode.

[0083] The dielectric film 53 is formed to cover the light-receiving surface of the light-receiving unit 52. The dielectric film 53 transmits light and is formed to protect the light-receiving surface of the light-receiving unit 52.

[0084] The silver paste 54 is an adhesive composed of a mixture of silver flakes and epoxy resin, and is used to fix the light-receiving unit 52 to the lead frame 51.

[0085] The silicon 55 is formed to cover the silver paste 54, and assists in protecting the silver paste 54 and fixing the light-receiving part 52.

[0086] In this configuration, the conventional light sensor 50a generates an illumination light intensity signal by sensing not only the light directly incident on the light receiving unit 52, but also the reflected light Li that is incident on the silver paste 54a and reflected.

[0087] However, the inventors discovered that in the aging-degraded light sensor 50a shown in Figure 6, yellowing occurred in the silver paste 54a. When the silver paste 54a yellows, the reflection efficiency of reflected light Li decreases. In particular, the reflectivity decreases significantly with respect to blue light (short-wavelength light) due to yellowing, so the aging-degraded light sensor 50a showed a relatively large decrease in light receiving sensitivity, especially with respect to blue light.

[0088] Therefore, in the light sensor 50 of the head-up display device of the third embodiment, a mask 56 is provided to cover the silver paste 54a. The mask 56 covers the silver paste 54a when viewed from the direction in which the illumination light is incident, and reduces the illumination light incident on the silver paste 54a. The mask 56 can be made of light-shielding tape, a light-transmitting film, a light-shielding case made of synthetic resin, etc.

[0089] This configuration suppresses the aging deterioration of the silver paste 54a, resulting in a head-up display device that can provide more accurate displays.

[0090] In particular, in the head-up display device of the third embodiment, the mask 56 may be a transmissive film that reduces the blue light incident on the silver paste 54. Also, although Figure 8 shows the mask 56 having an opening 56a that allows the light-receiving section 52 to be seen, the mask 56 does not have to have an opening. In that case, the mask may cover not only the silver paste 54a but also the light-receiving section 52.

[0091] [Differentiation] Although the head-up display device of the present invention has been described using the configuration of the above-described embodiment as an example, the present invention is not limited thereto, and various improvements and changes to the display are possible in other configurations without departing from the spirit of the present invention.

[0092] For example, while a light emission pattern is shown as data included in the pre-degradation output value and post-degradation output value, it may be stored as the pattern of the drive signal output from the light source control unit 40 to the light source 11, even if it is not stored as a light emission pattern. Since these two exist in a one-to-one relationship in most cases, the method of storage essentially does not affect the effects of the present invention. [Explanation of symbols]

[0093] 1. Lighting device 2 Illumination optical system 3 Display element 4 Projection optical system 5 screens 6 Mirror Unit 61 Plane mirror 62 Concave mirror 7 cabinets 71 Translucent part 11 Light source 12 Circuit boards 13 Multiplexing means 15 Prisms 50 Light Sensors 51 Lead Frame 52 Light receiving part 53 Dielectric film 54 Silver Paste 54a Silver Paste 55 56 masks A HUD (Head-Up Display) device Vehicle B C Dashboard L display light L1 illumination light D Windshield E Observer F Illusion

Claims

1. A light source that emits light at a predetermined brightness and provides illumination, A display element that generates display light when illuminated by the aforementioned illumination light, A light sensor that outputs an illumination light intensity signal corresponding to the illumination light intensity when the aforementioned illumination light is incident on it, A light source control unit controls the emission of light from the light source in accordance with the illumination light intensity signal, Equipped with, The light source control unit, Based on degradation information representing the degree of aging degradation of the aforementioned optical sensor, If the degradation of the aforementioned light sensor is minimal, a first mode is used in which light is emitted at the first brightness level, If the aforementioned light sensor is significantly degraded, a second mode is activated in which light is emitted at a second brightness level lower than the first brightness level. The light source is controlled Head-up display device.

2. The aforementioned degradation information is based on the total emission time of the light source, meaning that the longer the total emission time, the greater the degradation of the light sensor. The head-up display device according to claim 1.

3. The aforementioned degradation information is based on the total operating time of the light source control unit, meaning that the longer the total operating time, the greater the degradation of the light sensor. The head-up display device according to claim 1.

4. The aforementioned degradation information is based on the elapsed time from the initial startup time or manufacturing time of the light source control unit to the present time, and the longer the elapsed time, the greater the degradation of the light sensor. The head-up display device according to claim 1.

5. The light source control unit, The system stores the pre-degradation output value, which is the output value of the light sensor when the light source is controlled with a specific emission pattern during calibration in the manufacturing stage. The degraded output value, which is the output value of the light sensor when the light source is controlled by the aforementioned light emission pattern, is obtained. The more the degraded output value decreases continuously compared to the pre-degradation output value, the greater the degradation of the light sensor, and thus the more degradation information is acquired. The head-up display device according to claim 1.

6. The light source control unit, The light source is controlled in the second mode only if the decrease in the output value after degradation relative to the output value before degradation is greater than that due to the estimated age-related degradation of the light source's luminescence performance. The head-up display device according to claim 5.

7. The aforementioned light source outputs light of multiple wavelengths, The light source control unit reduces the brightness relatively significantly for the emission of light with relatively short wavelengths during the light emission operation of the light source. The head-up display device according to claim 1.

8. The aforementioned light source emits red, green, and blue light. The light source control unit reduces the brightness of the blue light emitted during the light emission operation of the light source by a relatively large amount. The head-up display device according to claim 1.

9. The aforementioned light source outputs white light, The light source control unit reduces the brightness of the short-wavelength component of the light emission operation of the light source by a relatively large amount. The head-up display device according to claim 1.

10. The light source includes a red LED (Light Emitting Diode), a green LED, and a blue LED. The light source control unit increases the amount of current flowing through the blue LED in accordance with the illumination light intensity signal, and when it reaches a predetermined upper limit current amount, it stops further increasing the amount of current flowing through the light source. The head-up display device according to claim 1.

11. The light sensor is circuit board and A light-receiving unit fixed on the substrate, An adhesive for fixing the light-receiving part to the substrate, A mask that covers the adhesive so that the illumination light does not enter the adhesive, Having, The head-up display device according to claim 1.

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