JP6390893B2 - DMD display device, head-up display device - Google Patents

Description

  The present invention relates to a DMD display device and a head-up display device that display an image by spatially modulating light of a plurality of colors from a light source using a DMD (Digital Micromirror Device) that is a spatial light modulator.

  Conventionally, various head-up display devices that project a display image on a transmission / reflection surface called a windshield or combiner of a vehicle and display a virtual image have been proposed. As shown in FIG. 1, the head-up display device 1 is disposed in the dashboard of the vehicle. The display light N projected by the head-up display device 1 is reflected by the windshield 2a, and the user 3 is a virtual image. It is possible to visually recognize V superimposed on the landscape.

  In such a head-up display device, a DMD that is a reflective display device may be used as a spatial light modulation element that generates an image. When this DMD is used in a high temperature environment such as an in-vehicle environment, if the DMD is driven in the same manner as in a normal temperature environment, the DMD mirror is fixed to either a fixed state, either on or off, and an irreversible brightness. There has been a problem that a point defect or a black spot defect occurs, resulting in a deterioration in display quality.

  On the other hand, within one frame for generating a display image, a display period in which an image is displayed by driving the light source and the DMD, and a non-display period in which the output of the light source is reduced and the DMD is appropriately driven are provided. Japanese Patent Application Laid-Open No. 2004-228688 discloses a head-up display device that drives a DMD during a non-display period so that the ratio of ON and OFF in each frame of each mirror is substantially equal. Further, the head-up display device disclosed in Patent Document 2 changes the ratio of the display period provided in one frame (in other words, the ratio of the non-display period provided in one frame) as necessary. .

JP-A-5-193400 JP 2012-212095 A

  However, as disclosed in Patent Document 2, when the ratio between the display period, which is a period for generating a display image in one frame, and the non-display period, in which a display image is not generated, is changed, it is generated in one frame. The display brightness of the displayed image also changes, giving the user a sense of discomfort and degrading the display quality.

  Therefore, in view of the above-described problems, the present invention provides a DMD display device and a head-up display device that can extend the life of a DMD even when used in a high-temperature environment and can suppress deterioration in display quality. It is to provide.

In order to solve the above-described problems, the DMD display device according to the first aspect of the present invention includes a light source that emits a predetermined amount of colored light for each subframe, and spatial light modulation of the colored light from the light source in a predetermined direction. A plurality of mirror elements for at least turning on and turning off the colored light in a direction different from the on, and generating a display image for each frame in the predetermined direction, the light source, and the DMD a control unit for controlling, and a temperature detector for detecting the DMD or the temperature in the vicinity of, the frame, the light source is turned on, and a display period for generating the display image on the DMD, the light source extinguished, anda non-display period which does not generate the display image on the DMD, the control unit may satisfy the predetermined conditions including that the temperature of the temperature detecting unit detects is equal to or higher than a predetermined temperature If you, outputs the time course of the light source, or gradually decreased with the increase of the temperature, and, then, substantially the reduce the ratio of the display period in the frame until the percentage to be determined by the temperature At the same timing, a protection process is performed to increase the output of the light source so as to suppress a change in display brightness of the display image. With such a configuration, the life of the display element can be extended even when used in a high-temperature environment, and further, a sense of incongruity due to a change in luminance of the display image can be prevented.

  According to a second aspect of the present invention, there is provided a head-up display device that expands a DMD display device, a screen that displays the display image generated by the DMD display device, and display light that displays the display image displayed on the screen. And a relay optical system facing the transmission / reflection surface.

  The present invention can extend the life of a display element even when used in a high-temperature environment, and can suppress deterioration in display quality.

It is a general-view figure in the embodiment of the present invention. It is a conceptual diagram of the HUD apparatus which shows the said embodiment. It is a conceptual diagram of the illuminating device of the said embodiment. It is electrical configuration explanatory drawing of the said embodiment. It is a time chart showing the operation | movement in 1 frame when not providing the non-display period in the said embodiment. It is a figure explaining transition of the display period rate based on temperature in the above-mentioned embodiment. It is a figure explaining operation | movement with the mirror element and light source in the display period and non-display period in the said embodiment. It is a time chart showing the operation | movement in 1 frame at the time of providing the non-display period in the said embodiment. It is an operation | movement flowchart figure of the protection process in the said embodiment. It is explanatory drawing showing transition of the display period ratio based on the temperature in the said embodiment, drive power, and light emission period, (a) is a temperature characteristic of a display period ratio, (b) is a temperature characteristic of drive power, (C) is a temperature characteristic of the light emission period. It is a figure for demonstrating the problem of the conventional HUD apparatus, (a) is a temperature characteristic of a display period ratio, (b) is a temperature characteristic of drive electric power, (c) is a temperature transition of display luminance. It is. It is a figure showing transition of the display period ratio based on temperature in the embodiment of the present invention, drive power, and display brightness, (a) is a temperature characteristic of a display period ratio, and (b) is a temperature characteristic of drive power. , (C) are temperature transitions of display luminance. It is a figure showing the modification of the transition of the display period ratio based on the temperature in the said embodiment, drive power, and display brightness, (a) is a temperature characteristic of a display period ratio, (b) is a temperature characteristic of drive power. Yes, (c) is the temperature transition of the display brightness. It is a figure showing the modification of the transition of the drive electric power based on the temperature in the said embodiment. It is a figure showing the modification of the transition of the display period ratio based on the temperature in the said embodiment, drive power, and display brightness, (a) is a temperature characteristic of a display period ratio, (b) is a temperature characteristic of drive power. Yes, (c) is the temperature transition of the display brightness. It is a figure showing the transition of the display period ratio based on the time in the said embodiment, drive power, and display brightness, (a) is a temperature characteristic of a display period ratio, (b) is a temperature characteristic of a drive power, c) is a temperature transition of the display luminance.

Hereinafter, an embodiment in which the present invention is applied to a HUD device 1 will be described with reference to the accompanying drawings.
FIG. 1 is a diagram showing an overview when a head-up display device 1 (hereinafter referred to as a HUD device 1) according to an embodiment of the present invention is mounted on a vehicle 2. The HUD device 1 is provided in the dashboard of the vehicle and reflects the display light N representing the generated display image M on the windshield 2a (transmission reflection surface in the claims), thereby causing the user 3 to receive vehicle information and the like. The virtual image V representing is visually recognized. The user 3 can visually recognize the virtual image V together with the real scene without changing the line of sight from the front.

  FIG. 2 is a configuration diagram of the HUD device 1 according to an embodiment of the present invention. The HUD device 1 includes an illumination device 10, an illumination optical system 20, a DMD 30, a temperature detection means 40, a projection optical system 50, a screen 60, a plane mirror 70, and a concave mirror 71 (relays in claims) An optical system), a housing 80 having a window 81 through which display light N is emitted to the outside, and a main controller 90. The DMD display device described in the claims will be described as being configured by the illumination device 10, the DMD 30, the temperature detection means 40, the main control unit 90, and the like in the present embodiment.

  As shown in FIG. 3, the illumination device 10 includes a light source 11, a circuit board 12 made of an aluminum substrate, on which the light source 11 is mounted, an optical axis synthesis unit 13, and luminance unevenness reducing optical means 14.

  The light source 11 is, for example. A red light source 11r that emits red light R, a green light source 11g that emits green light G, and a blue light source 11b that emits blue light B, which includes LEDs and the like.

  The optical axis synthesizing unit 13 includes a reflection mirror 13a that reflects light, and a dichroic mirror 13b and 13c that includes a mirror in which a thin film such as a dielectric multilayer film is formed on a mirror surface, and transmits and reflects light. The optical axes of the illumination lights emitted from the red light source 11r, the green light source 11g, and the blue light source 11b are aligned.

  The luminance unevenness reducing optical means 14 is composed of a mirror box, an array lens, and the like, and reduces the unevenness of light by irregularly reflecting, scattering, and refracting the illumination light C described above. Thus, the illumination device 10 emits the illumination light C in the direction of the illumination optical system 20 described later.

  The illumination optical system 20 is composed of, for example, a concave lens or the like, and adjusts the illumination light C emitted from the illumination device 10 to the size of the DMD 30 described later.

The DMD 30 includes a plurality of movable mirror elements E. By driving the electrodes provided below the mirror elements E in a very short time of microsecond order, the mirror surface of each mirror element E is supported by a hinge as a fulcrum. Tilt ± 12 degrees. When the mirror element E is on, it tilts +12 degrees with the hinge as a fulcrum, and reflects the illumination light C emitted from the illumination optical system 20 in the direction of the projection optical system 50 described later. When it is off, the hinge is tilted by −12 degrees with the fulcrum as a fulcrum, and the illumination light C is not reflected in the direction of the projection optical system 50. Accordingly, by driving each mirror element E individually based on the display image data representing the display image M, the illumination light C from the illumination device 10 is selectively projected in the direction of the projection optical system 50, so that a desired luminance is obtained. A display image M of a desired color is generated on the screen 60 described later.
Each of the mirror elements E of the DMD 30 is also subjected to intermediate control that is controlled to an intermediate point between the on-inclination and the off-inclination when the power of the HUD device 1 is turned off, in addition to the two on / off states. The inclination of the intermediate point is a 0 degree position in the present embodiment.

The temperature detection means 40 includes a temperature sensor 41 made of a thermistor or the like built in the ceramic portion of the base substrate of the DMD 30, and an A / D converter 42. The temperature sensor 41 measures the temperature of the DMD 30, The analog data output from the temperature sensor 41 is converted into temperature data, which is digital data, by the A / D converter 42, and the temperature data (hereinafter referred to as temperature T) is output to the main controller 90 described later. The A / D converter 42 may be built in the main control unit 90.
Further, the temperature sensor 41 may measure the temperature in or around the housing 80 that affects the temperature of the DMD 30 instead of the temperature of the DMD 30.
The temperature sensor 41 may be disposed on a control board (not shown) on which the main control unit 90 is mounted, and the temperature of the DMD 30 may be measured remotely from the control board.

  The projection optical system 50 is composed of, for example, a concave lens or a convex lens, and is an optical system for efficiently irradiating the screen 60 described later with the display light N of the display image M projected from the DMD 30.

  The screen 60 includes a diffusing plate, a holographic diffuser, a microlens array, and the like. The screen 60 receives the display light N from the projection optical system 50 on the lower surface and displays the display image M on the upper surface.

The flat mirror 70 reflects the display image M displayed on the screen 60 toward a concave mirror 71 described later.
The concave mirror 71 is a concave mirror or the like, and reflects the display light N reflected by the flat mirror 70 on the concave surface, thereby emitting the display light N to the outside of the HUD device 1 from a window 81 described later. As a result, the formed virtual image V has an enlarged size of the display image M displayed on the screen 60.

  The housing 80 is formed of a hard resin or the like, and is formed in a box shape having a window portion 81 having a predetermined size above. The housing 80 accommodates the illumination device 10, the illumination optical system 20, the DMD 30, the temperature detection means 40, the projection optical system 50, the screen 60, the plane mirror 70, the concave mirror 71, and the like at predetermined positions. . A main control unit 90 to be described later may be housed in the housing 80, or may be disposed outside the housing 80 and electrically connected to components inside the housing 80 by wiring or the like.

  The window 81 is formed in a curved shape from a translucent resin such as acrylic, and is attached to the opening of the housing 80 by welding or the like. The window part 81 transmits the light reflected by the concave mirror 71.

  Next, the electrical configuration of the HUD device 1 will be described with reference to FIG. FIG. 4 is an explanatory diagram of the electrical configuration of the display device of this embodiment.

  The main control unit 90 includes a processing unit 91 composed of a plurality of or single FPGAs, microcomputers, ASICs, etc., a storage unit 92 for storing programs and data for driving the processing unit 91, and CAN (Controller Area Network) bus communication. And an input / output unit 93 that exchanges signals with the vehicle ECU 4 and the like via a network (not shown). The main control unit 90 inputs an image signal from the vehicle ECU 4 via the input / output unit 93. The main control unit 90 processes the input image signal, and controls the illumination device 10 and the DMD 30 via the illumination drive unit 94 and the display drive unit 95 described later to generate a display image M based on the image signal. .

  Further, the vehicle 2 is provided with an illuminance sensor (not shown) that detects the illuminance around the user 3, and the main control unit 90 outputs an illuminance signal of the illuminance sensor to the input / output unit 93 (illuminance signal input unit). ) And reading out illumination control data, which will be described later, from the storage unit 92 based on the illuminance signal, and adjusting the brightness of the display image M by changing the output W of the light source 11 (dimming). Further, when an operation signal of the light switch of the vehicle 2 is input from the input / output unit 93 and the light switch is turned on, it is estimated that the ambient illuminance is low, and when the light switch is turned off, the ambient illuminance is high. Thus, the output W of the light source 11 may be changed.

  The storage unit 92 stores in advance illumination control data in which the illuminance signal is associated with the output W of each of the light sources 11r, 11g, and 11b. The illumination control data is provided for each display period ratio A. For example, when the display period ratio A has three patterns of 100%, 70%, and 50%, three patterns of illumination control data are required. In this way, by providing illumination control data for controlling the light sources 11r, 11g, and 11b for each display period ratio A, the balance of the light amounts of the light sources 11r, 11g, and 11b can be kept good, and the display image M Can be displayed in a desired display color. The illumination control data is generated by performing calibration at the time of manufacturing in consideration of individual differences of the LD 11.

  The illumination drive unit 94 includes a driver that drives the light source 11, and based on the illumination control data input from the main control unit 90, the light source 11 (red light source 11r, green light source 11g) having a different color for each subframe SF. , And the blue light source 11b) are sequentially switched at high speed. The illumination control data is data that defines the output W (drive power P, light emission period H) of the light source 11 in the subframe SF so that the display image M can obtain a desired display luminance and display color. The illumination driving unit 94 controls the output W based on the illumination control data, thereby causing the light source 11 to emit a desired amount of colored light for each subframe SF. The output W generally corresponds to the amount of power represented by the product of the driving power P for driving the light source 11 and the light emission period H for turning on the light source 11. Although detailed description in this embodiment is omitted, the illumination driving unit 94 can perform PWM (Pulse Width Modulation) control of the light source 11, and in this case, the output W is approximately equal to the driving power P. This corresponds to the amount of power represented by the product of the light emission period H and the duty ratio in PWM control.

  The display drive unit 95 is configured by a driver or the like that drives the DMD 30 and turns on or off each mirror element E of the DMD 30 according to the subframe SF based on display control data input from the main control unit 90. is there. The display control data is generated for each mirror element E of the DMD 30, and the subframe SF to be turned on and the period to be turned on (on) so that the mirror element E can express desired display luminance and display color. This is data that defines the period during which the data is continued. Based on this display control data, the display drive unit 95 turns on each mirror element E for a desired period of a desired subframe SF, and turns it off otherwise.

  That is, in order to construct the display image M, the illuminating device 10 outputs the illumination light C (red light R, green light G, blue light B) at a desired output W for each desired subframe SF, and outputs the DMD 30. Illuminate. Each mirror element E of the DMD 30 reflects the illumination light C toward the screen 60 at a desired timing for each mirror element E in order to generate a display image M. With such a configuration, red light R, green light G, and blue light B of the light source 11 are used as basic colors to perform color mixing by time-division additive mixing, and the display image M is expressed in color.

  As a method for generating the display image M in the HUD device 1 of the present invention, field sequential color (hereinafter referred to as FSC) control is performed. In the FSC control according to the present embodiment, the frame F, which is a cycle constituting the display image M, is set to less than 1/60 seconds (60 Hz or more), which is equal to or higher than the critical fusion frequency at which a human can visually recognize flicker. The frame F is divided into about 1/180 seconds each as a period during which the red light source 11r, the green light source 11g, and the blue light source 11b are driven. Further, the driving period (1/180 seconds) of each color is divided into sub-frames SF of unequal periods so that 8-bit time gradation is possible. In addition, description of FSC control in this embodiment shows an example, and is not limited to these descriptions.

  The specific operations of the lighting device 10 and the DMD 30 by FSC control will be described with reference to FIG. In the following description, the mirror element E for displaying the single color portion of the display image M is the single color mirror element Ea, the mirror element E for displaying the color mixture portion of the display image M is the color mixture mirror element Eb, and the non-display of the display image M is not shown. A mirror element corresponding to the display portion will be referred to as a non-display mirror element Ec, which will be described as an example. FIG. 5 relates the operation of each mirror element E (monochromatic mirror element Ea, mixed-color mirror element Eb, non-display mirror element Ec) of the DMD 30 and the operation of the light source 11 (red light source 11r, green light source 11g, blue light source 11b). It is a time chart demonstrated.

  The single-color mirror element Ea that expresses the single color of the DMD 30 is turned on in accordance with the timing (t61 to t62 and t63 to t64) when the green light source 11g emits light as shown in FIG. Reflects in the direction of.

  Further, the color mixing mirror element Eb expressing the color mixing of the DMD 30 is turned on in accordance with the timing (t60 to t61 and t61 to t62) at which the red light source 11r and the green light source 11g emit light as shown in FIG. The mixed light of the red light R and the green light G is reflected in the direction of the screen 60.

  Further, the non-display mirror element Ec that displays nothing on the DMD 30 is turned off at all timings (t60 to tx) as shown in FIG. 5, for example, so that any light is reflected in the direction of the screen 60. No display is made without it.

  The light quantity of the red light R reflected in the direction of the screen 60 during the period from t60 to t61 is the pre-switching drive power Pro that is the drive power P of the red light source 11r and the light emission period H in which the red light source 11r is caused to emit light. Is approximately proportional to the product of the light emission period Hro. Similarly, the amount of green light G reflected in the direction of the screen 60 in the period from t61 to t62 is the pre-switching driving power Pgo that is the driving power P of the green light source 11g and the light emission period H in which the green light source 11g is caused to emit light. Is substantially proportional to the product of the light emission period Hgo. Similarly, the output W of the blue light B reflected in the direction of the screen 60 in the period from t62 to t63 is a driving power Pbo that is the driving power P of the blue light source 11b and a light emission period H in which the blue light source 11b emits light. It is roughly proportional to the product of a certain light emission period Hbo.

To briefly describe the operation until the HUD device 1 having the above configuration displays the virtual image V,
(1) The main control unit 90 generates illumination control data and display control data based on an illuminance signal and an image signal from the outside.
(2) The illumination device 10 emits illumination light C toward the DMD 30 by FSC control based on the illumination control data.
(3) The DMD 30 selectively reflects the illumination light C from the illumination device 10 toward the screen 60 by turning on / off individual mirror elements E of the DMD 30 based on the display control data.
(4) The display light N representing the display image M displayed on the screen 60 is reflected by the plane mirror 70 toward the concave mirror 71.
(5) The display image M is enlarged to a predetermined size by the concave mirror 71, and the display light N representing the enlarged display image M is reflected by the windshield 2a, so that it is displayed in front of the windshield 2a. A virtual image V of the image M is displayed. Thus, the HUD device 1 enables the user 3 to visually recognize the display image M as the virtual image V.

Next, switching of the display period ratio A in the HUD device 1 of the present embodiment will be described. FIG. 6 is a temperature characteristic diagram of the display period ratio A that is the ratio of the display period Fa in the frame F stored in the storage unit 92 in advance. Incidentally, the display period ratio A shown in FIG. 6 being 1.0 (100%) indicates that the display period Fa in the frame F is 100% and the non-display period Fb is 0%. The display period ratio A of 0.5 (50%) means that the display period Fa in the frame F is 0.5 (50%) and the non-display period Fb is 0.5 (50%). Show.
When the temperature T of the DMD 30 measured by the temperature detecting means 40 is equal to or higher than the first temperature T1, the HUD device 1 in the present embodiment sets the non-display period Fb in the frame F based on the temperature characteristics shown in FIG. Approximately half (50%) is provided (display period ratio A is set to 0.5 (50%)). Further, when the temperature T is lower than the first temperature T1, the main control unit 90 does not provide the non-display period Fb in the frame F and sets only the display period Fa for generating the display image M (display period ratio A). 1.0 (100%)).

  Next, with reference to FIG. 7, an outline of operations of the mirror element E and the light source 11 in the display period Fa and the non-display period Fb will be described. FIG. 7 is a diagram for explaining the operation of the predetermined mirror element E and the light source 11 when the display period ratio A is 0.5 (50%).

In the display period Fa, the illumination driving unit 94 sequentially switches the light sources 11 (red light source 11r, green light source 11g, blue light source 11b) of different colors for each subframe SF at high speeds with the output W requested by the illumination control data. Take control.
The display driving unit 95 turns on or off each mirror element E of the DMD 30 based on the display control data. That is, the rate at which the mirror element E is turned on within the display period Fa (first on rate U1) varies depending on the display control data, and is different for each mirror element E.

In the non-display period Fb, the illumination driving unit 94 turns off all the light sources 11 (including those in which the output W is reduced to such an extent that it is not visually recognized by the user 3).
The display driving unit 95 drives each mirror element E in a protective manner. In this protection drive, each mirror element E is turned on within one frame F (display period Fa + non-display period Fb) (in-frame ON ratio U) so that the ratio is approximately 0.5 (50%). This is a drive to turn on / off the mirror element E. That is, the rate at which the mirror element E is turned on in the non-display period Fb (second on rate U2) is adjusted by the rate at which the mirror element E is turned on in the display period Fa (first on rate U1). When the first on-ratio U1 is large, the second on-ratio U2 is decreased in the non-display period Fb, and when the first on-ratio U1 is small, the second on-ratio U2 is increased in the non-display period Fb. The ratio at which the mirror element E in the frame F is turned on (the on ratio U in the frame) is adjusted to be approximately half (50%).

Specific protection driving in the non-display period Fb will be described with reference to FIG. FIG. 8 is a time chart for explaining specific operations of the mirror elements E and the light source 11 when the display period ratio A is 0.5 (50%). The main control unit 90 calculates a second on-ratio U2 that is a rate at which the mirror element E is turned on in the non-display period Fb so that the in-frame on-ratio U is 0.5 (50%). The second on-ratio U2 is obtained by Equation 1 using the intra-frame on-ratio U, the first on-ratio U1, and the display period ratio A.

The second ON ratio U2 of the monochromatic mirror element Ea in FIG. 8 will be specifically calculated. Assuming that the first ON ratio U1 is 0.4 (40%), the second ON ratio U2 is calculated as 0.6 (60%). In other words, the single-color mirror element Ea in FIG. 8 performs protection driving in which ON is 60% (OFF 40%) in the non-display period Fb.
Similarly, in the color mixing mirror element Eb of FIG. 8, assuming that the first ON ratio U1 is 0.8 (80%), the second ON ratio U2 is calculated to be 0.2 (20%). In the non-display mirror element Ec, since the first on-ratio U1 is 0 (0%), the second on-ratio U2 is calculated as 1.0 (100%).
In this way, by setting the in-frame ON ratio U of the individual mirror elements E in the frame F to approximately 0.5 (50%) (the ratio of ON to OFF is approximately equal), the individual mirror elements E The load on the hinge (the fulcrum of the mirror element E) has a uniform on-side and off-side, and it is possible to prevent the mirror element E from sticking in either the on or off state. Also, the life of the DMD 30 can be kept long.

  Next, the operation of the protection process for keeping the life of the DMD 30 in the present embodiment long will be described with reference to FIGS. FIG. 9 is a flowchart showing the operation of the protection process of the HUD device 1 when the display period ratio A is switched based on the temperature T, and FIG. 10 is the driving power for driving the light source 11 when the display period ratio A is switched. It is a figure showing transition of P and light emission period H.

(First protection treatment)
First, in step S10 of the flowchart of FIG. 9, the main control unit 90 determines a target display period ratio Ax that is a target display period ratio A based on the temperature T of the DMD 30 detected by the temperature detection means 40.

本実施形態においては、切替前表示期間割合Ａｏが１．０（１００％）であり、目標表示期間割合Ａｘが０．５（５０％）であるので、目標発光期間Ｈｘは切替前駆動期間Ｈｏの０．５倍になる。 Next, in step S11, the main control unit 90 performs a pre-switching drive period Ho (light emission period before switching Hro, light emission period before switching Hgo, light emission before switching) that is the light emission period H of the light source 11 before switching in step S14b described later. Based on the period Hbo), a target light emission period Hx (target drive period Hrx, target drive period Hgx, target drive period Hbx) that is a light emission period H of the target light source 11 when switching in step S14b described later is calculated. .
The target light emission period Hx is a display period ratio Ao before switching that is a display period ratio A before switching at step S14a described later, and a target display period ratio Ax that is a target display period A when switching at step S14a described later. From the following equation 2.

In the present embodiment, since the pre-switching display period ratio Ao is 1.0 (100%) and the target display period ratio Ax is 0.5 (50%), the target light emission period Hx is the pre-switching drive period Ho. It becomes 0.5 times.

本実施形態においては、切替前表示期間割合Ａｏが１．０（１００％）であり、目標表示期間割合Ａｘが０．５（５０％）であるので、目標駆動電力Ｐｘは切替前駆動電力Ｐｏの２倍になる。 In step S12, the main control unit 90 pre-switching drive power Po (pre-switching red LED driving power Pro, pre-switching green LED driving power Pgo, pre-switching), which is the driving power P of the light source 11 before switching in step S14b described later. Based on the blue LED driving power Pbo), the target driving power Px (target red LED driving power Prx, target green LED driving power Pgx, target) that is the driving power P of the light source 11 to be switched at step S14b to be described later. Blue LED driving power Pbx) is calculated.
The target drive power Px is a display period ratio Ao before switching, which is a display period ratio A before switching in step S14a described later, and a target display period ratio Ax, which is a target display period A when switching in step S14a described later. From the following equation 3.

In the present embodiment, since the pre-switching display period ratio Ao is 1.0 (100%) and the target display period ratio Ax is 0.5 (50%), the target drive power Px is the pre-switching drive power Po. Twice as much.

  In step S13, the main control unit 90 determines at what timing the display period ratio A and the output W are to be switched based on the data stored in the storage unit 92 in advance after the calculation of the above calculation is completed, The switching timing of the illumination driving unit 94 and the display driving unit 95 is synchronized.

At the timing adjusted in step S <b> 13, the main control unit 90 switches the display period ratio A of each mirror element E of the DMD 30 performed via the display driving unit 95 (S <b> 14 a) and the light source performed via the illumination driving unit 94. 11 outputs W (drive power P, light emission period H) are switched simultaneously (S14b) as shown below.
In step S14a, the main control unit 90 changes the display period ratio A of each mirror element E of the DMD 30 from the pre-switching display period ratio Ao (100%) to the target display period ratio Ax (50%) via the display driving unit 95. In the non-display period Fb, the second on-ratio U2 calculated in step S11 is turned on / off.
In step S14a, when the display period ratio A is switched from the pre-switching display period ratio Ao to the target display period ratio Ax, the timing of the subframe SF is also changed based thereon.

  In step S14b, the main control unit 90 matches the lighting timing of the light source 11 with the timing of the subframe SF changed in step S14a via the illumination driving unit 94. The main controller 90 further switches the output W (drive power P and light emission period H) of the light source 11.

  With the above first protection process, the HUD device 1 of the present embodiment sets the non-display period Fb in the frame F based on the temperature characteristics of the display period ratio A when the temperature T of the DMD 30 becomes equal to or higher than the first temperature T1. In the non-display period Fb, each mirror element E of the DMD 30 is turned on so that the ON / OFF ratio in the frame F is substantially equal (the ON ratio U in the frame is 0.5 (50%)). By turning off / off, the load applied to the hinge (the fulcrum of the mirror element E) of each mirror element E is made equal between the on side and the off side. With such a configuration, it is possible to suppress the mirror element E from being fixed in either the on / off state, and the life of the DMD 30 can be kept long even when used in a high temperature environment. Furthermore, since the output W of the light source 11 is switched so as to compensate for the switching of the display period ratio A of the DMD 30, it is possible to prevent a change in display luminance of the virtual image V (display image M) even if the display period ratio A is changed. It is possible to make it difficult for the user 3 to feel uncomfortable.

  Hereafter, the second protection process in the present embodiment will be described. First, a problem when the second protection process is not performed will be described with reference to FIG. FIG. 11 is a diagram for explaining the switching of the display period ratio A based on the change in the temperature T, FIG. 11A shows the transition of the display period ratio A based on the temperature T, and FIG. FIG. 11C shows the transition of the display brightness L based on the temperature T. FIG. 11C shows the transition of the driving power P based on the temperature T. FIG.

  The first protection process described above is a process for making the display luminance L substantially uniform before and after switching by changing the output W of the light source 11 simultaneously with switching of the display period ratio A. In this first protection process, for example, as shown in FIG. 11A, when the display period ratio A is lowered from 1.0 (100%) to 0.5 (50%), the display luminance L is reduced. In order to maintain uniformity, it is necessary to make the driving power P double the target driving power Px. However, the target drive power Px as a target may exceed the upper limit (upper limit power Pmax) of the specifications of the light source 11 in some cases. Since the light source 11 may be damaged if driven beyond the upper limit power Pmax, the display period ratio A is changed from the pre-switching display period ratio Ao to the target display period ratio Ax as shown in FIG. 11 (b), the light source 11 can only increase from the pre-switching drive power Po to the upper limit power Pmax. As a result, when the display period ratio A is switched, the display luminance L is increased. As shown in FIG. 11 (c), there is a fear that the user 3 may feel uncomfortable due to a large change.

  In order to solve such a problem, the HUD device 1 of the present embodiment can suppress a sudden change in the display luminance L by executing a second protection process described below.

  The second protection process in the present embodiment is executed based on the temperature characteristics of FIG. When the temperature T reaches the second temperature T2 lower than the first temperature T1 for switching the display period ratio A, the processing unit 91 drives the driving power P according to the increase in the temperature T as shown in FIG. Is gradually reduced. When the first temperature T1 is reached, the processing unit 91 decreases the display period ratio A of the DMD 30 and simultaneously increases the driving power P of the light source 11. In this way, the sudden change in the display luminance L can be suppressed by first gradually decreasing the driving power P. Then, by sufficiently reducing the drive power P before the display period ratio A is switched, the light source 11 can greatly increase the drive power P with the upper limit power Pmax as the upper limit when the display period ratio A is switched. As a result, the rapid decrease in the display luminance L due to the rapid decrease in the display period ratio A can be compensated by the rapid increase in the driving power P, and the change in the display luminance L can be suppressed to a small amount.

  In FIG. 12C, the display luminance L is shown not to change (at the first temperature T1) when the display period ratio A is switched. However, in the present invention, the display luminance L is drastically changed greatly. Therefore, when the display period ratio A is switched (at the first temperature T1), the display luminance L may slightly decrease or increase.

  In FIG. 12B, the drive power P is lower than the upper limit power Pmax at the first temperature T1 or higher, but may be increased to the vicinity of the upper limit power Pmax at which the light source 11 is not destroyed.

  In FIG. 12, the display period ratio A and the driving power P are simultaneously switched immediately after the driving power P is gradually reduced. However, as shown in FIG. 13, the driving power P is gradually decreased below the first temperature T1. The driving power P may be kept constant regardless of the change in the temperature T from the third temperature T3 to the first temperature T1 at which the display period ratio A is switched from the third temperature T3. As described above, by maintaining the driving power P constant regardless of the change in the temperature T in the vicinity of the first temperature T1 at which the display period ratio A is switched, the display period ratio A is inadvertently caused by the fluctuation of the temperature T. Can be prevented from being switched.

  Note that when the temperature T decreases after the temperature T rises, the temperature characteristic of the driving power P gradually increases the driving power P of the light source 11 as the temperature T decreases as shown in FIG. The hysteresis may be configured to return to the power Po, and further, the trajectory of the gradual decrease of the driving power P based on the increase of the temperature T and the trajectory of the gradual decrease of the driving power P based on the increase of the temperature T are made different. May be provided. With such a configuration, it is possible to prevent the display luminance L from flickering due to frequent fluctuations in the driving power P due to the fluctuation of the temperature T.

  Moreover, although the 2nd protection process at the time of reducing the display period ratio A was demonstrated until now, a 2nd protection process may be applied when raising the display period ratio A, and the process part 91 is temperature T. When the temperature reaches a second temperature T2 lower than the first temperature T1 for switching the display period ratio A, the driving power P is gradually increased as the temperature T increases as shown in FIG. When the first temperature T1 is reached, the processing unit 91 increases the display period ratio A of the DMD 30 and simultaneously decreases the driving power P of the light source 11. In this way, by suddenly increasing the driving power P first, it is possible to suppress a sudden change in the display luminance L. Then, by sufficiently increasing the drive power P before the display period ratio A is switched, the drive power P can be greatly reduced with the lower limit power Pmin of the light source 11 as the lower limit when the display period ratio A is switched. As a result, the rapid increase in the display luminance L due to the rapid increase in the display period ratio A can be compensated by the rapid decrease in the drive power P, and the change in the display luminance L can be suppressed to a small amount.

  Note that the second protection process in the above description is a process in which the driving power P is gradually changed in accordance with the change in the temperature T, but is gradually changed in accordance with the change in the time t as shown in FIG. May be. 16A shows the time transition of the display period ratio A, FIG. 16B shows the time transition of the driving power P, and FIG. 16C shows the time transition of the display luminance L. When the processing unit 91 detects that the temperature T is equal to or higher than the first temperature T1 at time t0, the processing unit 91 gradually decreases the driving power P as time elapses. The processing unit 91 decreases the display period ratio A of the DMD 30 and simultaneously increases the driving power P of the light source 11 at a time t1 when a predetermined time has elapsed from the time t0 when the temperature T equal to or higher than the first temperature T1 is detected. As described above, by gradually changing the driving power P based on the time t, the display luminance L can be gradually changed even when the temperature T changes rapidly.

In the above embodiment, the ON ratio U in the frame when the temperature T of the DMD 30 becomes equal to or higher than the first temperature T1 is set to 0.5 (50%). It is desirable that the off period is slightly longer than the on period, such as 49% for off and 51% for off.
With such a configuration, even if the mirror element E is fixed, the possibility that the mirror element E is fixed in the ON state can be extremely reduced, that is, the bright spot that reflects the illumination light C to the screen 60 side. The possibility of occurrence of defects can be drastically reduced. Therefore, what visually recognizes the head-up display device in the present embodiment can watch the bright spot defect (erroneous display) and suppress a decrease in concentration on driving.
For the same reason, it is desirable to set the non-display period Fb in the frame F longer than the display period Fa.

  In the above description, in order to facilitate the understanding of the present invention, the description of known unimportant technical matters is appropriately omitted. The present invention is not limited to the above embodiments. Changes (including deletion of components) can be made as appropriate without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Display apparatus for vehicles 2 Windshield 3 User 10 Illumination device 11 Light source 11r Red light source 11g Green light source 11b Blue light source 12 Circuit board 13 Optical axis synthetic | combination part 14 Brightness nonuniformity reduction optical means 20 Illumination optical system 30 DMD
DESCRIPTION OF SYMBOLS 40 Temperature detection means 41 Temperature sensor 42 A / D converter 50 Projection optical system 60 Screen 70 Plane mirror 71 Concave mirror (relay optical system)
80 Housing 81 Window 90 Main Control Unit (Control Unit)
91 Processing Unit 92 Storage Unit 93 Input / Output Unit 94 Illumination Drive Unit 95 Display Drive Unit

A Display period ratio Ao Display period ratio before switching Ax Target display period ratio B Blue light C Illumination light E Mirror element Ea Monochromatic mirror element Eb Mixed color mirror element Ec Non-display mirror element F Frame Fa Display period Fb Non-display period G Green illumination light H Light emission period Ho Drive period before switching Hx Target drive period L Display brightness M Display image N Display light P Drive power Po Drive power before switch Px Target drive power R Red illumination light SF Subframe T Temperature T1 First temperature T2 Second temperature T3 3rd temperature U On-ratio in frame U1 First on-ratio U2 Second on-ratio V Virtual image

Claims (5)

A light source that emits a predetermined amount of colored light for each subframe;
A plurality of mirror elements that at least turn on the color light from the light source in a predetermined direction and turn off the color light in a direction different from the on, and frame the display image in the predetermined direction; DMD generated every time,
A control unit for controlling the light source and the DMD;
A temperature detection unit for detecting the temperature of the DMD or the vicinity thereof,
The frame has a display period in which the light source is turned on and the DMD generates the display image, and a non-display period in which the light source is turned off and the DMD does not generate the display image ,
When the control unit satisfies a predetermined condition including that the temperature detected by the temperature detection unit is equal to or higher than a predetermined temperature,
Timing that is substantially the same as gradually decreasing the output of the light source as time elapses or as the temperature rises , and then reducing the ratio of the display period in the frame to a ratio determined by the temperature. Then, a protection process is performed to increase the output of the light source so as to suppress a change in display brightness of the display image.
A DMD display device. The control unit sets the output of the light source after the protection process to be equal to or higher than the output of the light source before the protection process.
The DMD display device according to claim 1. The control unit, after gradually reducing the output of the light source in the protection process , and further when the temperature changes more than a predetermined temperature, the ratio of the display period in the protection process decreases, and the output of the light source increases Is executed at approximately the same timing ,
The DMD display device according to claim 1 , wherein the DMD display device is a display device. The control unit, after gradually reducing the output of the light source in the protection process , if the predetermined condition is further satisfied for a predetermined time or more, a decrease in the ratio of the display period in the protection process , The increase in the output of the light source is executed at substantially the same timing .
The DMD display device according to claim 1 , wherein the DMD display device is a display device. A DMD display device according to any one of claims 1 to 4 ,
A screen for displaying the display image generated by the DMD display device;
A relay optical system for enlarging display light indicating the display image displayed on the screen and directing the light to a transmission / reflection surface,
A head-up display device.

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