JP7018565B2 - Image display device - Google Patents

Description

The present invention relates to an image display device for displaying an image, and is suitable for mounting on a moving body such as a passenger car.

In recent years, the development of an image display device called a head-up display has been promoted, and it is mounted on a moving body such as a passenger car. In the head-up display mounted on a passenger car, light modulated by image information is projected toward a windshield (windshield), and the reflected light is applied to the driver's eyes. This allows the driver to see a virtual image of the image in front of the windshield. For example, drive assist information such as vehicle speed, various warning markers, and arrows indicating the traveling direction of a passenger car is displayed as a virtual image.

In the head-up display, a laser light source can be used as the light source. In this case, the laser beam scans the screen while being modulated according to the video signal. The laser beam is then diffused by the screen and directed to the eyebox near the driver's eyes. As a result, the driver can see the image (virtual image) in a good and stable manner even if he / she moves his / her head a little. The eyebox has, for example, a horizontally long rectangular shape.

Here, in the laser light source, the current value of the drive current is adjusted so that the target light amount corresponding to the brightness can be obtained. In the following Patent Document 1, a laser beam for adjusting an output value is output outside the range in which the display image is drawn in the range scanned by the scanning mirror unit, and the output of the laser light source is output based on the detected value. A configuration for adjusting the value is described.

Japanese Unexamined Patent Publication No. 2017-49569

The image display device usually performs a process for correcting the distortion of the displayed image. For example, when an image display device is used for an automobile, the displayed image is distorted from a predetermined shape due to the curved surface shape of the windshield or the like. The image drawing area on the screen is corrected so that this distortion is corrected. Therefore, the shape of the image drawing area on the screen changes depending on the curved surface shape of the windshield. Therefore, it is difficult to set the emission position of the laser beam for adjusting the output value in advance in the configuration in which the laser beam for adjusting the output value is output outside the range in which the display image is drawn as in Patent Document 1. Therefore, it is necessary to adjust the emission position of the laser beam for adjusting the output value for each curved surface shape of the windshield.

In view of these problems, it is an object of the present invention to provide an image display device capable of smoothly adjusting the output of a laser light source regardless of distortion correction of a displayed image.

The image display device according to the main aspect of the present invention has a light source that emits a laser beam, a screen on which an image is drawn by being scanned two-dimensionally by the laser beam, and the laser beam being scanned against the screen. It includes a scanning unit, a photodetector that detects the amount of the laser beam emitted from the light source, and a control unit. Here, the screen includes a first screen and a second screen arranged so as to line up with the first screen in a direction perpendicular to the traveling direction of the laser beam. The control unit adjusts the output value of the light source at a position at the boundary between the first screen and the second screen within the range of the display angle of view for displaying the display image of one frame. Is emitted from the light source, and the output of the light source is adjusted based on the detection signal of the light detector with respect to the laser light for adjusting the output value.

According to the image display device according to this aspect, the output value is adjusted at a position at the boundary between the first screen and the second screen within the range of the display angle of view for displaying the display image of one frame. Since the laser beam is emitted, it is not necessary to adjust the emission position of the laser beam for adjusting the output value even if the image drawing area on the screen is changed to correct the distortion of the displayed image. Therefore, the output of the laser light source can be smoothly adjusted regardless of the distortion correction of the displayed image.

As described above, according to the present invention, it is possible to provide an image display device capable of smoothly adjusting the output of a laser light source regardless of the distortion correction of the displayed image.

The effects or significance of the present invention will be further clarified by the description of the embodiments shown below. However, the embodiments shown below are merely examples for implementing the present invention, and the present invention is not limited to those described in the following embodiments.

1A and 1B are diagrams schematically showing a usage pattern of the image display device according to the embodiment, and FIG. 1C is a diagram schematically showing the configuration of the image display device according to the embodiment. Is. FIG. 2 is a diagram showing a configuration of an irradiation light generation unit and a circuit used for the irradiation light generation unit of the image display device according to the embodiment. FIG. 3A is a perspective view schematically showing the incident state of the laser beam on the screen according to the embodiment, and FIG. 3B is a diagram schematically showing the relationship between the screen and the scanning line according to the embodiment. be. FIG. 4A is a diagram showing a reference output characteristic of the laser light source according to the embodiment, and FIG. 4B is a diagram for explaining a method of setting a scale value (Iscale) according to the embodiment. FIG. 5 is a diagram showing a configuration of a look-up table for setting a threshold current value and a scale value according to an embodiment. FIG. 6A is a diagram showing the difference between the reference output characteristic of the laser light source and the output characteristic based on the actual measurement according to the embodiment, and FIG. 6B is the output based on the actual measurement of the laser light source according to the embodiment. FIG. 6 (c) is a diagram showing an output characteristic with the slope of the characteristic corrected, and FIG. 6 (c) is a diagram showing the amount of deviation of the current value of the light source threshold value between the reference output characteristic and the corrected output characteristic according to the embodiment. .. FIG. 7A is a diagram in which the set value on the low output side and the set value on the high output side are plotted on the output characteristics of each temperature at a predetermined luminance level according to the embodiment. FIG. 7B is a diagram showing a configuration of a look-up table in which the set value on the high output side and the set value on the low output side set for each environmental temperature are defined for each luminance level according to the embodiment. FIG. 8 is a flowchart showing a correction process of the current value of the laser light source according to the embodiment. 9 (a) and 9 (b) are perspective views showing the configuration of a drive unit that drives the screen according to the embodiment. FIG. 10A is a perspective view showing a configuration in which the support member and the suspension according to the embodiment are assembled. FIG. 10B is a perspective view showing the configuration of the magnetic circuit according to the embodiment. 11 (a) and 11 (b) are perspective views showing the configuration of the holder according to the embodiment, respectively. FIG. 12A is a cross-sectional view of the holder in which the two screens are installed according to the embodiment, cut in a plane parallel to the YY plane. FIG. 12B is a cross-sectional view showing the shape and action of the recess provided on the lower surface of the wall portion according to the embodiment. FIG. 12 (c) is a cross-sectional view showing the shape and action of the recess provided on the lower surface of the wall portion according to the modified example. FIG. 13 is a diagram schematically illustrating a region in which an image is drawn on the two screens according to the embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, the X, Y, and Z axes that are orthogonal to each other are appropriately added to each figure.

1A and 1B are diagrams schematically showing a usage pattern of the image display device 20. FIG. 1A is a schematic view of the inside of the passenger car 1 seen through from the side of the passenger car 1, and FIG. 1B is a view of the front of the passenger car 1 in the traveling direction.

In this embodiment, the present invention is applied to an in-vehicle head-up display. As shown in FIG. 1A, the image display device 20 is installed inside the dashboard 11 of the passenger car 1.

As shown in FIGS. 1A and 1B, the image display device 20 projects the light modulated by the video signal onto the projection area 13 near the driver's seat under the windshield 12. The projected light is reflected by the projection region 13 and irradiates a horizontally long region (eye box region) around the position of the driver 2's eyes. As a result, the predetermined image 30 is displayed as a virtual image in the field of view in front of the driver 2. The driver 2 can see the virtual image 30 superimposed on the scenery in front of the windshield 12. That is, the image display device 20 forms an image of the virtual image 30 in the space in front of the projection region 13 of the windshield 12.

FIG. 1C is a diagram schematically showing the configuration of the image display device 20.

The image display device 20 includes an irradiation light generation unit 21 and a mirror 22. The irradiation light generation unit 21 emits light modulated by a video signal. The mirror 22 has a curved reflecting surface, and reflects the light emitted from the irradiation light generation unit 21 toward the windshield 12. The light reflected by the windshield 12 is applied to the eyes 2a of the driver 2. The optical system of the irradiation light generation unit 21 and the mirror 22 are designed so that the virtual image image 30 is displayed in a predetermined size in front of the windshield 12.

The mirror 22 constitutes an optical system for generating a virtual image by the light generated from the screens 110 and 111 described later. This optical system does not necessarily have to be composed of only the mirror 22. For example, this optical system may include a plurality of mirrors, or may include a lens or the like.

FIG. 2 is a diagram showing the configuration of the irradiation light generation unit 21 of the image display device 20 and the configuration of the circuit used for the irradiation light generation unit 21.

The irradiation light generation unit 21 includes a light source 101, collimator lenses 102a to 102c, apertures 103a to 103c, mirrors 104, dichroic mirrors 105a and 105b, sampling mirrors 106, photodetectors 107, and scanning units 108. The correction lens 109 and the screens 110 and 111 are provided.

The light source 101 includes three laser light sources 101a, 101b, and 101c.

The laser light source 101a emits a laser beam having a red wavelength included in the range of 635 nm or more and 645 nm or less, the laser light source 101b emits a laser beam having a green wavelength included in the range of 510 nm or more and 530 nm or less, and the laser light source 101c emits a laser beam having a green wavelength included in the range of 510 nm or more and 530 nm or less. It emits a laser beam having a blue wavelength included in the range of 440 nm or more and 460 nm or less.

In the present embodiment, in order to display a color image as an image 30, the light source 101 includes these three laser light sources 101a, 101b, and 101c. The laser light sources 101a, 101b, and 101c are made of, for example, a semiconductor laser. When displaying a monochromatic image as the image 30, the light source 101 may include only one laser light source corresponding to the color of the image. Further, the light source 101 may be configured to include two laser light sources having different emission wavelengths.

The laser light emitted from the laser light sources 101a, 101b, and 101c is converted into parallel light by the collimator lenses 102a to 102c, respectively. The laser beam transmitted through the collimator lenses 102a to 102c is shaped into a circular beam having substantially the same size by the apertures 103a to 103c, respectively. That is, the apertures 103a to 103c form a beam shaping unit for aligning the beam size and beam shape of the laser light emitted from the laser light sources 101a, 101b, and 101c, respectively.

Instead of the collimator lenses 102a to 102c, a shaped lens that shapes the laser beam into a circular beam shape and makes it parallel light may be used. In this case, apertures 103a to 103c may be omitted.

After that, the laser light of each color emitted from the laser light sources 101a, 101b, 101c is aligned with the optical axis by the mirror 104 and the two dichroic mirrors 105a, 105b. The mirror 104 substantially totally reflects the red laser beam transmitted through the collimator lens 102a. The dichroic mirror 105a reflects the green laser light transmitted through the collimator lens 102b, and transmits the red laser light reflected by the mirror 104. The dichroic mirror 105b reflects the blue laser light transmitted through the collimator lens 102c, and transmits the red laser light and the green laser light transmitted through the dichroic mirror 105a. The mirror 104 and the two dichroic mirrors 105a and 105b are arranged so as to align the optical axes of the laser beams of the respective colors emitted from the laser light sources 101a, 101b and 101c.

The sampling mirror 106 transmits most of the red laser light, the blue laser light, and the green laser light that have passed through the dichroic mirror 105b, and a part of these laser lights (for example, about 3%) is sent to the light detector 107, respectively. Reflects. The photodetector 107 outputs a detection signal according to the amount of light received by the laser beam to the image control circuit 201.

The scanning unit 108 reflects the laser light of each color transmitted through the sampling mirror 106. The scanning unit 108 is, for example, composed of a MEMS (micro electro mechanical system) mirror, and is an axis parallel to the X-axis of the mirror 108a to which the laser light of each color transmitted through the sampling mirror 106 is incident. And rotate around an axis perpendicular to the X-axis and parallel to the reflective surface of the mirror 108a. By rotating the mirror 108a in this way, the reflection direction of the laser beam changes in the direction parallel to the XX plane and the direction parallel to the YY plane. As a result, as will be described later, the screens 110 and 111 are two-dimensionally scanned by the laser light of each color.

Here, the scanning unit 108 is configured by a two-axis drive type MEMS mirror, but the scanning unit 108 may have another configuration. For example, the scanning unit 108 may be configured by combining two mirrors that are rotated around two axes that are perpendicular to each other.

The correction lens 109 is designed so that the laser light of each color is directed in the positive direction of the Z axis regardless of the swing angle of the laser light by the scanning unit 108. The correction lens 109 is configured by, for example, combining a plurality of lenses.

The screens 110 and 111 have an effect that an image is formed by scanning the laser beam and the incident laser beam is diffused to a region (eye box region) around the position of the eye 2a of the driver 2. The screens 110 and 111 may be composed of a microlens array, a diffuser, or the like. The screens 110 and 111 may be made of a transparent resin such as PET (polyethylene terephthalate).

The screens 110 and 111 are driven by the drive unit 300 in the Z-axis direction, that is, in a direction parallel to the traveling direction of the laser beam of each color. The screen 110 is for displaying an image having a parallax in the depth direction, and the screen 111 is for displaying an image having no parallax in the depth direction. The screens 110 and 111 are arranged so as to be separated from each other in the Z-axis direction with the boundaries substantially overlapping in the Y direction. The screens 110 and 111 are integrally driven in the Z-axis direction by the drive unit 300. The drive unit 300 includes, for example, a coil and a magnetic circuit, and drives a holder that holds the screens 110 and 111 by an electromagnetic force generated in the coil. The configuration of the drive unit 300 will be described later with reference to FIGS. 9 (a) to 11 (b).

By drawing an image on the screen 110 by laser light of each color while moving the screens 110 and 111, an image having a parallax in the depth direction is displayed in front of the windshield 12. As a result, the driver 2 can see, for example, an image of an arrow indicating the traveling direction in a state of being overlapped on the road.

Further, with the screens 110 and 111 stationary at predetermined positions in the Z-axis direction, an image is drawn on the screen 111 by laser light of each color, so that an image without parallax is displayed in front of the windshield 12. To. As a result, the driver 2 can see a still image including information such as the vehicle speed and the outside air temperature slightly behind the windshield 12.

The image displayed on the entire screens 110 and 111 constitutes one frame of the image. The configuration and scanning method of the screens 110 and 111 will be described later with reference to FIGS. 3A and 3B.

The image control circuit 201 includes an arithmetic processing unit such as a CPU (Central Processing Unit) and a memory, and processes the input video signal to control the laser drive circuit 202, the mirror drive circuit 203, and the screen drive circuit 204. Further, as described later, the image control circuit 201 corrects the current value for driving the laser light sources 101a to 101c based on the amount of light detected by the photodetector 107 and the environmental temperature detected by the temperature sensor 121. do. This will be described later with reference to FIGS. 4 (a) to 7 (a).

The laser drive circuit 202 changes the emission intensity of the laser light sources 101a, 101b, and 101c according to the control signal input from the image control circuit 201. The mirror drive circuit 203 drives the mirror 108a of the scanning unit 108 in response to a control signal from the image control circuit 201. The screen drive circuit 204 drives the drive unit 300 in response to a control signal from the image control circuit 201.

As shown in FIG. 2, the laser light sources 101a, 101b, and 101c are installed on one circuit board 120. Further, the circuit board 120 is provided with a temperature sensor 121 for detecting the temperature (environmental temperature) near the installation position of the laser light sources 101a, 101b, 101c. The temperature sensor 121 is installed around the laser light source 101a that emits a laser beam having a red wavelength. That is, the temperature sensor 121 is arranged at a position closer to the laser light source 101a than the other two laser light sources 101b and 101c. A temperature sensor may be arranged for each of the laser light sources 101a, 101b, and 101c.

Further, a photodetector 130 for detecting the brightness (outside light) outside the vehicle is arranged. The detection signal from the photodetector 130 is input to the image control circuit 201. The image control circuit 201 displays an image at a high luminance level when the outside of the vehicle is bright, and displays an image at a low luminance level when the outside of the vehicle is dark, based on the detection signal input from the photodetector 130. Adjust the brightness level of the image 30. In addition, the image control circuit 201 adjusts the brightness level of the image 30 according to the setting value of the brightness level manually set.

FIG. 3A is a perspective view schematically showing the configuration of the screen 110.

As shown in FIG. 3A, on the surface of the screen 110 on the laser beam incident side, a plurality of first lens portions 110a for diverging the laser beam in the X-axis direction are provided at a constant pitch in the X-axis direction. It is formed to line up. The first lens portion 110a extends parallel to the Y-axis direction. The shape of the first lens portion 110a when viewed in the Y-axis direction is a substantially arc shape. The width of the first lens unit 110a in the X-axis direction (pitch of the first lens unit 110a) is, for example, 50 μm.

Further, on the surface of the screen 110 on the laser beam emitting side, a plurality of second lens portions 110b for diverging the laser beam in the Y-axis direction are formed so as to be arranged at a constant pitch in the Y-axis direction. The second lens portion 110b extends parallel to the X-axis direction. The shape of the second lens portion 110b when viewed in the X-axis direction is a substantially arc shape. The width of the second lens unit 110b in the Y-axis direction (pitch of the second lens unit 110b) is, for example, 70 μm. The width of the second lens unit 110b in the Y-axis direction may be the same as the width of the first lens unit 110a in the X-axis direction.

The radius of curvature Rx of the first lens portion 110a and the radius of curvature Ry of the second lens portion 110b are different from each other. The radius of curvature Rx is set smaller than the radius of curvature Ry. Therefore, the spread angle that is diverged after the laser beam is converged by the first lens unit 110a is larger than the spread angle that is diverged after the laser light is converged by the second lens unit 110b. By setting the curvatures of the first lens portion 110a and the second lens portion 110b in this way, the laser beam transmitted through the screen 110 is transmitted to a horizontally long region (eye box region) around the position of the driver 2's eye 2a. ) Can be led. The radius of curvature of the first lens portion 110a and the second lens portion 110b is determined according to the shape of the eyebox region.

The screen 111 also has the same configuration as the screen 110. However, the width of the screen 111 in the Y-axis direction is shorter than that of the screen 110.

FIG. 3B is a diagram schematically showing the relationship between the screens 110 and 111 and the scanning line.

The incident surface (the surface on the negative side of the Z axis) of the screens 110 and 111 having the above configuration is scanned by the beam B1 on which the laser beams of each color are superimposed. Scanning lines L1 to Ln through which the beam B1 passes are set in advance with respect to the incident surfaces of the screens 110 and 111 at regular intervals in the Y-axis direction. As described above, one frame of image is drawn by the scanning lines L1 to Ln.

The diameter of the beam B1 is set to be smaller than the width of the second lens portion 110b. For example, the diameter of the beam B1 is set to about 35 to 65 μm. In the present embodiment, the diameter of the beam B1 is smaller than the width of the second lens portion 110b as well as the width of the first lens portion 110a.

The scanning lines L1 to Ln set in this way are scanned by the beam B1 in order from the positive side of the Y axis. At each pixel position on the scanning lines L1 to Ln, laser light of each color is pulsed from the laser light sources 101a to 101c with a predetermined pulse width. At this time, the output value of the pulse emission is adjusted according to the gradation value (pixel value) of the brightness of the video signal at each pixel position. Specifically, the drive current applied to the laser light sources 101a, 101b, and 101c is controlled according to the video signal. The pulse width of the drive current is fixed at a predetermined value.

In this way, the screens 110 and 111 are two-dimensionally scanned by the beam B1, and an image for one frame is drawn on the screens 110 and 111. The scanning period from the scanning line L1 to the scanning line Ln is, for example, 1/60 second. As described above, an image for displaying an image having a parallax in the depth direction is drawn on the screen 110, and an image for displaying an image having no parallax in the depth direction is drawn on the screen 111. The area on which the images are drawn on the screens 110 and 111 has a distorted shape from the rectangle due to the distortion correction of the displayed image (image 30 in FIG. 1A).

The vicinity of the boundary BR1 in the Y-axis direction of the screens 110 and 111 is not used for drawing the display image because the display image is switched. That is, the video signal for image drawing is not assigned to the scanning line included in the vicinity of the boundary BR1.

In the present embodiment, the current value for driving the laser light sources 101a to 101c of each color is corrected by using the scanning line near the boundary BR1. That is, in order to correct the current value that causes the laser light sources 101a to 101c of each color to emit light at the target light amount, the laser light sources 101a to 101c of each color are pulse-emitting a plurality of times in the scanning line near the boundary BR1.

When the laser light sources 101a to 101c are emitted in the vicinity of the boundary BR1 in this way, it is preferable to provide a light shielding means in the vicinity of the boundary BR1 so that the emitted laser light of each color is not guided by the eye box. In the present embodiment, the holder that holds the screens 110 and 111 is provided with light-shielding means. The configuration of the light-shielding means will be described later with reference to FIGS. 11A and 11B.

Hereinafter, a method of correcting the current value for causing the laser light sources 101a to 101c to emit light at a target light amount will be described.

First, a method of setting the current value before correction will be described with reference to FIGS. 4A and 4B.

FIG. 4A is a diagram showing the output characteristics of the laser light source 101a that emits red laser light. In FIG. 4A, the horizontal axis is the current value of the drive current applied to the laser light source 101a, and the vertical axis is the output value of the laser light emitted from the laser light source 101a. The output value of the laser beam can be detected by the light amount detection value output from the photodetector 107 shown in FIG.

As shown in FIG. 4A, the output characteristics of the laser light source 101a change depending on the temperature of the laser light source 101a. Here, the environmental temperature around the laser light source 101a is used as the temperature of the laser light source 101a. The laser light source 101a does not emit laser light substantially in the range where the current value is from 0 to a predetermined value (emission threshold value). When the current value exceeds the emission threshold value, the output value of the laser beam increases as the current value increases. As the temperature of the laser light source 101a increases, the emission threshold value increases. Further, the slope of the characteristic graph in the range where the current value is larger than the emission threshold value becomes smaller as the temperature of the laser light source 101a becomes higher. Therefore, the higher the temperature of the laser light source 101a, the lower the light output for the same drive current.

The output characteristics of the laser light sources 101b and 101c that emit the blue laser light and the green laser light have the same tendency as in FIG. 4A. However, the output characteristics of the laser light sources 101b and 101c are different from those of the laser light sources 101a in the emission threshold value of each temperature and the inclination of the characteristic graph.

In the present embodiment, the current value of the laser light source 101a is set with the output characteristic shown in FIG. 4A as a reference output characteristic. That is, the current value I of the laser light source 101a with respect to the target light amount is set based on the following equation.

I = Ith + Iscale × (pixel value)… (1)

Here, the pixel value is a gradation value of the brightness of the video signal at each pixel position of the image drawn on the screens 110 and 111.

FIG. 4B is a diagram for explaining a method of setting the scale value (Iscale) of the above equation (1). Here, it is assumed that the temperature of the laser light source 101a is 45 ° C.

In FIG. 4B, Pm1 indicates a value of optical output (maximum optical output value) corresponding to the maximum luminance of the video signal when displaying an image at the luminance level 1. Further, Pm2 indicates an optical output value (maximum optical output value) corresponding to the maximum luminance of the video signal when the image is displayed at the luminance level 2 darker than the luminance level 1. As described above, the brightness level of the image is increased when the outside of the vehicle is bright and decreased when the outside of the vehicle is dark. The luminance level can be set to, for example, about 10 steps.

Here, at the luminance level 1, the value obtained by dividing the maximum optical output Pm1 by the number of gradations of luminance (for example, 256 gradations) is the amount of change in the optical output value per gradation. Further, at the luminance level 1, the difference ΔI1 between the current value Im1 on the output characteristic corresponding to the maximum optical output Pm1 and the current value (Ith) of the emission threshold (hereinafter referred to as “threshold current value (Ith)”) is the luminance. The value divided by the number of gradations (for example, 256 gradations) is the amount of change in the current value per gradation. The amount of change in the current value per gradation is the scale value (Iscale) of the above equation (1) at the luminance level 1 and the light source temperature of 45 ° C. That is, the scale value (Iscale) is a value that reflects the slope when the characteristic graph of the output characteristic is linearly approximated.

Similarly, at the luminance level 2, the difference ΔI2 between the current value Im2 on the output characteristic corresponding to the maximum optical output Pm2 and the current value (Ith) of the emission threshold value is divided by the number of luminance gradations (for example, 256 gradations). The value is the amount of change in the current value per gradation. The amount of change in the current value per gradation is the scale value (Iscale) of the above equation (1) at the luminance level 2 and the light source temperature of 45 ° C. Since the difference ΔI2 of the current value at the luminance level 2 is smaller than the difference ΔI1 of the current value at the luminance level 1, the scale value (Iscale) at the luminance level 2 is smaller than the scale value (Iscale) at the luminance level 1. That is, the smaller the luminance level, the smaller the scale value (Iscale).

By setting the scale value (Iscale) in this way, the current value of the laser light source 101a for causing the laser light source 101a to emit light with the target light amount corresponding to the pixel value (gradation value) by the calculation of the above equation (1). Can be obtained. As mentioned above, the scale value (Iscale) becomes smaller as the luminance level becomes lower. Further, as shown in FIG. 4A, the slope of the output characteristic changes with the temperature change of the laser light source 101a. Therefore, the scale value (Iscale) changes with the temperature change of the laser light source 101a. Further, the threshold current value (Ith) of the output characteristic also changes with the temperature change of the laser light source 101a.

In the image control circuit 201 shown in FIG. 2, in order to obtain the current value of the laser light source 101a by the calculation of the above equation (1), the threshold current value (Ith) and the scale value (Iscale) are set to the temperature of the laser light source 101a and the current value. A look-up table associated with the brightness level of the image is stored in advance.

FIG. 5 is a diagram showing a configuration of a look-up table for setting a threshold current value (Ith) and a scale value (Iscale). Also in FIG. 5, as the temperature of the laser light source 101a, the environmental temperature in the vicinity of the laser light source 101a is used.

The image control circuit 201 sets the brightness level of the image based on the detection signal (brightness outside the vehicle) from the photodetector 130, and further sets the ambient temperature of the laser light source 101a based on the detection signal from the temperature sensor 121. get. Then, the image control circuit 201 acquires and acquires the threshold current value (Ith) and the scale value (Iscale) corresponding to the set luminance level and the acquired ambient temperature from the lookup table shown in FIG. 5, respectively. The threshold current value (Ith) and the scale value (Iscale) are set in each parameter of the above equation (1). If the ambient temperature is between the temperatures specified in the lookup table, the threshold current value (Ith) and scale value (Iscale) associated with the temperature on the lookup table closest to the ambient temperature are obtained.

After that, the image control circuit 201 substitutes the pixel value (gradation value) of the video signal into the above equation (1), and acquires the current value I for each pixel by calculation. Then, the image control circuit 201 controls the laser drive circuit 202 by using the acquired current value I as the drive current value of the laser light source 101a at each pixel position.

The image control circuit 201 also holds a look-up table having the same configuration as that of FIG. 5 for the laser light sources 101b and 101c that output the blue and green laser beams, respectively. In these look-up tables, the threshold current value (Ith) and the scale value (Iscale) acquired based on the reference output characteristics of the laser light sources 101b and 101c are stored in association with the temperature and luminance level, respectively. ing.

The image control circuit 201 acquires the current value I at each pixel position of the laser light sources 101b and 101c by the same processing as described above with reference to these look-up tables, and the laser light source 101b is obtained from the acquired current value I. , 101c is driven. By driving the laser light sources 101a to 101c in this way, the image is displayed at the set luminance level.

However, due to factors such as manufacturing errors and aging deterioration of the laser light sources 101a to 101c, the actual output characteristics may deviate from the reference output characteristics corresponding to the look-up table. In this case, when the current values of the laser light sources 101a to 101c are set by the same processing as described above, a difference occurs between the amount of emitted light of the laser light sources 101a to 101c and the target amount of light corresponding to each pixel value, resulting in an image. There may be problems with the brightness and color of the laser.

Therefore, in the present embodiment, the threshold current value (Ith) and the scale value (Iscale) are corrected at any time by the following processing.

FIG. 6A is a diagram showing a deviation between the reference output characteristic of the laser light source 101a and the output characteristic based on the actual measurement.

In FIG. 6A, G0 shows a reference output characteristic (hereinafter, referred to as “reference characteristic”) of the laser light source 101a. The reference characteristic G0 in FIG. 6A shows the output characteristic of the laser light source 101a at a predetermined luminance level and a predetermined environmental temperature. In the correction, first, two optical output values (Psv1 and Psv2) and two current values (I1 and I2) are set in the reference characteristic G0. The current value (I1) is the current value on the reference characteristic G0 with respect to the optical output value (Psv1) on the low level side, and the current value (I2) is on the reference characteristic G0 with respect to the optical output value (Psv2) on the high level side. Is the current value of.

Next, the laser light source 101a is made to emit a pulse with two set current values (I1 and I2). Then, based on the detection signal output from the photodetector 107 in each pulse emission, the light output value (Ppv1, Ppv2) actually generated when the laser light source 101a is pulsed with two current values (I1 and I2) is emitted. ) Is acquired. The straight line passing through the plot consisting of the optical output values (Ppv1, Ppv2) and the two current values (I1, I2) acquired in this way is the characteristics of the laser light source 101a estimated from the actual output (hereinafter, "guessed characteristics"). It becomes G1. Here, there is a discrepancy between the guess characteristic G1 and the reference characteristic G0. Therefore, it is necessary to correct the threshold current value (Ith) and the scale value (Iscale) obtained from the look-up table so that this deviation is eliminated.

Therefore, first, in order to correct the scale value (Iscale), the ratio of the slope of the estimation characteristic G1 and the slope of the reference characteristic G0 is obtained as the correction multiplier α of the scale value (Iscale). The slope of the reference characteristic G0 and the slope of the guess characteristic can be obtained by the following equations, respectively.

Slope of reference characteristic G0 = (Psv2-Psv1) / (I2-I1) ... (2)
Guessing characteristic G1 slope = (Ppv2-Ppv1) / (I2-I1) ... (3)

Since the correction multiplier α is (slope of the reference characteristic G0) / (slope of the guessing characteristic G1), it can be obtained by the following equation.

α ＝ (Psv2-Psv1) / (Ppv2-Ppv1)… (4)

Next, in order to correct the threshold current value (Ith), the slope of the estimation characteristic G1 is matched with the slope of the reference characteristic G0 to obtain the virtual characteristic G2.

FIG. 6B is a diagram showing the virtual characteristic G2 superimposed on the graph of FIG. 6A. Here, the optical output value (Ppv1', Ppv2') is an optical output value on the virtual characteristic G2 corresponding to the current value (I1, I2). The optical output value (Ppv1', Ppv2') can be obtained by the following equation.

Ppv1'= {(Psv2-Psv1) / (Ppv2-Ppv1)} × Ppv1… (5)
Ppv2'= {(Psv2-Psv1) / (Ppv2-Ppv1)} × Ppv2… (6)

The difference between the threshold current value in the estimation characteristic G1 and the threshold current value in the reference characteristic G0 is obtained by the difference (ΔIth) between the threshold current value (Ith2) in the virtual characteristic G2 and the threshold current value (Ith0) in the reference characteristic G0. obtain. Here, the difference (ΔIth) is a value obtained by dividing the difference between the optical output value (Psv1) and the optical output value (Ppv1') by the slope of the reference characteristic G0, as shown in FIG. 6 (c). Therefore, the difference (ΔIth) can be obtained by the following equation.

ΔIth = {(I2-I1) × (Psv1-Ppv1')} / (Psv2-Psv1)… (7)

The image control circuit 201 shown in FIG. 2 multiplies the scale value (Iscale) obtained from the look-up table of FIG. 5 by the correction multiplier α obtained by the calculation of the equation (4), and the corrected scale value (Iscale). ') Get. Further, the image control circuit 201 adds the difference (ΔIth) obtained by the calculation of the equation (7) to the threshold current value (Ith) acquired from the lookup table of FIG. 5, and the corrected threshold current value (Ith). Get Ith'). Then, the image control circuit 201 applies the corrected scale value (Iscale') and the corrected threshold current value (Ith') to each parameter (Ith, Iscale) of the above equation (1) to obtain a pixel value. The current value I for outputting the corresponding target light amount is acquired. This makes it possible to set the current value I that matches the actual output characteristics of the laser light source 101a. The same processing is performed on the other laser light sources 101b and 101c.

In the above correction, the low output side optical output value (Isv1) and current value (I1) and the high output side optical output value (Isv2) and current value (I2) set in the reference characteristic G0 are the luminance levels. It is preferable to change each and every temperature.

FIG. 7A is a diagram in which the set values on the low output side (Psv1, I1) and the set values on the high output side (Psv2, I2) are plotted on the output characteristics of each temperature at a predetermined luminance level. In FIG. 7A, the setting value on the low output side is shown by the plot of black circles, and the setting value on the high output side is shown by the plot of white circles.

As shown in FIG. 7A, the reference characteristic of the laser light source 101a is a slightly curved curve in the range where the current value is larger than the threshold current value. On the other hand, the above equation (1) is an equation for obtaining the current value I by linearly approximating the reference characteristics in this range. Therefore, the set value on the low output side (Psv1, I1) and the set value on the high output side (Psv2, I2) have a linearity on the reference characteristic so as to be as close as possible to the straight line approximated in the above equation (1). It is preferably set in a high range. From this point of view, in the example of FIG. 7A, in particular, the set value on the high output side changes greatly depending on the temperature.

Further, as described with reference to FIG. 4B, the maximum value of the optical output (Pm1, Pm2) and the maximum value of the current value (Im1, Im2) are different for each luminance level. Therefore, it is preferable that the set values (Psv2, I2) on the high output side are set so as not to exceed at least the maximum value of the optical output value and the maximum value of the current value at each luminance level.

As described above, it is preferable that the set value on the low output side and the set value on the high output side in the above correction are adjusted to appropriate values according to the temperature and the luminance level. Therefore, in the present embodiment, the image control circuit 201 holds a look-up table in which the set value on the low output side and the set value on the high output side are associated with the environmental temperature and the luminance level of the laser light sources 101a to 101c. ..

FIG. 7B is a diagram showing a configuration of a look-up table in which the set value on the high output side and the set value on the low output side set for each ambient temperature are defined for each luminance level. This look-up table is for, for example, the laser light source 101a. A look-up table having the same configuration for the other laser light sources 101b and 101c is held in the image control circuit 201.

The image control circuit 201 sets the brightness level of the image based on the detection signal (brightness outside the vehicle) from the photodetector 130, and further sets the ambient temperature of the laser light source 101a based on the detection signal from the temperature sensor 121. get. Then, the image control circuit 201 acquires the set value on the low output side and the set value on the high output side corresponding to the set luminance level and the acquired ambient temperature from the look-up table shown in FIG. 7 (b), respectively. Then, the above-mentioned correction process is performed using the acquired low output side setting value and high output side setting value. If the detected ambient temperature is between the temperatures specified in the lookup table, the low and high output settings associated with the temperature on the lookup table that is closest to the ambient temperature will be. To be acquired. The same processing is performed for the other laser light sources 101b and 101c.

FIG. 8 is a flowchart showing a correction process of the current value of the laser light source 101a. The same processing is performed for the other laser light sources 101b and 101c.

The image control circuit 201 acquires the ambient temperature near the laser light source 101a based on the detection signal of the temperature sensor 121 (S101), and further, the image is based on the detection signal (brightness outside the vehicle) of the photodetector 130. The brightness level of is set (S102). Next, the image control circuit 201 acquires the set value on the low output side and the set value on the high output side corresponding to the acquired environmental temperature and luminance level from the look-up table shown in FIG. 7B (S103). ..

After that, the image control circuit 201 causes the laser light source 101a to pulse light according to the set value (I1) on the low output side at the timing when the scanning position is on the scanning line near the boundary BR1 of the screens 110 and 111 to emit light on the low output side. The measurement is performed (S104), and the laser light source 101a is pulsed to emit light by the set value (I2) on the high output side to perform the measurement on the high output side (S105). Specifically, the image control circuit 201 acquires the light output value of the laser light source 101a for each pulse light emission based on the detection signal output from the photodetector 107 during each pulse light emission.

The image control circuit 201 is a scale value by the calculation of the above equation (4) based on the optical output value acquired based on the set value on the low output side and the optical output value acquired based on the set value on the high output side. The correction multiplier α of (Iscale) is calculated (S106), and the correction value (difference ΔIth) of the threshold current value (Ith) is further calculated by the calculation of the above equation (7) (S107). Then, the image control circuit 201 corrects the scale value (Iscale) and the threshold current value (Ith) acquired from the lookup table of FIG. 5 by using the acquired correction multiplier α and the correction value (difference ΔIth) (S108). ). Specifically, the image control circuit 201 calculates the corrected scale value (Iscale) by multiplying the scale value (Iscale) by the correction multiplier α, and adds the correction value (difference ΔIth) to the threshold current value (Ith). Then, the corrected threshold current value (Ith) is calculated.

After that, the image control circuit 201 applies the corrected scale value (Iscale) and the corrected threshold current value (Ith) to the above equation (1) in order to confirm the suitability of the correction, and obtains the optical output value. The measurement is performed (S109). In this case, the image control circuit 201 acquires a current value by applying a pixel value (gradation) corresponding to the set value (Psv2) on the high output side to the above equation (1), and uses the acquired current value. , The laser light source 101a is made to emit pulse light. This pulse emission is also performed on the scanning line near the boundary BR1 of the screens 110 and 111.

Then, the image control circuit 201 acquires the optical output value of the laser light source 101a based on the detection signal output from the photodetector 107 during the pulse emission, and sets the acquired optical output value and the high output side. It is determined whether or not the difference from the value (Psv2) is within the preset allowable range (S110).

When the difference is within the permissible range (S110: YES), the image control circuit 201 terminates the correction process, assuming that the correction multiplier α and the correction value (ΔIth) obtained in steps S106 and S107 are appropriate. In this case, the correction multiplier α and the correction value (ΔIth) obtained in steps S106 and S107 are fixed, and the correction in step S108 is also fixed. After that, until the next correction, the current value is set in the laser light source 101a based on the corrected equation (1) determined in step S108.

On the other hand, when the difference is not within the permissible range (S110: NO), the image control circuit 201 returns the process to step S101, assuming that the correction multiplier α and the correction value (ΔIth) obtained in steps S106 and S107 are not appropriate. In this case, the correction multiplier α and the correction value (ΔIth) obtained in steps S106 and S107 are canceled, and the correction in step S108 is also canceled. After that, the image control circuit 201 repeats the processes of steps S101 to S109 until the determination in step S110 is YES.

In this way, when the determination in step S110 is YES, the image control circuit 201 ends the correction process. As a result, the correction multiplier α and the correction value (ΔIth) are determined, and the current value of the laser light source 101a is calculated by the calculation of the equation (1) using the corrected scale value (Iscale) and the threshold current value (Ith). Set. The same processing is performed for the other laser light sources 101b and 101c.

The correction process of FIG. 8 is performed at a preset timing. For example, the correction process of FIG. 8 may be performed every frame or every few frames.

Next, a configuration for blocking the laser light emitted in the pulse in the correction process (hereinafter, referred to as “laser light for adjusting the output value”) will be described.

In the present embodiment, the holder holding the screens 110 and 111 is provided with a configuration for blocking the laser beam for adjusting the output value. Here, the holder is driven by the drive unit 300 shown in FIG. 1 in the Z-axis direction (direction parallel to the traveling direction of the laser beam) together with the screens 110 and 111. Hereinafter, the configuration of the drive unit 300 and the configuration for blocking the laser beam for adjusting the output value will be described.

9 (a) is a perspective view showing the configuration of the drive unit 300, and FIG. 9 (b) is a perspective view showing the configuration of the drive unit 300 with the magnetic cover 308 and the holder 301 removed.

9 (a) and 9 (b) show a state in which the drive unit 300 is supported by the support base 306 and the fixed base 310. The support base 306 and the fixed base 310 are provided with openings for passing laser light of each color in the Z-axis direction. Through this aperture, the laser light of each color is applied to the screens 110 and 111 from the negative side of the Z axis.

As shown in FIG. 9A, the screens 110 and 111 are integrally supported by the holder 301 so as to be tilted in the same direction as each other. The two screens 110 and 111 are arranged in a direction (Y-axis direction) perpendicular to the traveling direction (Z-axis direction) of the laser beam, and are displaced from each other by a predetermined distance in the traveling direction (Z-axis direction) of the laser beam. It is installed in the position. Light-shielding members 302a and 302b are installed on the upper surface of the holder 301. The light-shielding members 302a and 302b are for preventing external light traveling backward in the optical system of FIG. 1C from entering the inside of the drive unit 300.

The holder 301 on which the screens 110 and 111 are installed is installed in the inner frame portion 303a of the support member 303 shown in FIG. 9B. The support member 303 is supported by two support units 305 arranged in the Y-axis direction so as to be movable in the Z-axis direction by four suspensions 304. The support unit 305 is installed on the support base 306. The support unit 305 is provided with gel covers 305a on the positive side of the X-axis and the negative side of the X-axis, respectively, and the gel covers 305a are filled with gel for damping.

In this way, the screens 110 and 111 are movably supported by the support base 306 in the Z-axis direction via the holder 301, the support member 303, the suspension 304 and the support unit 305.

A magnetic circuit 307 is further installed on the support base 306. The magnetic circuit 307 is for applying a magnetic field to the coil 311 (see FIG. 10A) mounted on the support member 303. By applying a drive signal (current) to the coil 311, an electromagnetic force in the Z-axis direction is excited to the coil 311. As a result, the support member 303 is driven in the Z-axis direction together with the coil 311. In this way, the screens 110 and 111 move in the Z-axis direction.

A magnetic cover 308 is placed on the upper surface of the magnetic circuit 307. The magnetic cover 308 is made of a magnetic material and functions as a yoke of the magnetic circuit 307. When the magnetic cover 308 is placed on the upper surface of the magnetic circuit 307, the magnetic cover 308 is attracted to the magnetic circuit 307. As a result, the magnetic cover 308 is installed in the drive unit 300. As shown in FIG. 9A, the magnetic cover 308 is provided with an opening 308a for passing the holder 301 and a slit 308b for passing the beam portion 303c of the support member 303 (see FIG. 10A). ing.

The support base 306 is installed on the fixed base 310 via the damper unit 309. The damper unit 309 supports the support base 306 in a state where the support base 306 is floated in the positive direction of the Z axis with respect to the fixed base 310. The damper unit 309 absorbs the vibration generated by driving the support member 303 before it propagates from the support base 306 to the fixed base 310.

A position detection unit 400 is further installed on the fixed base 310. The position detection unit 400 includes a printed circuit board 401 facing the side surface of the support member 303 on the positive side of the X-axis. An encoder (not shown) is arranged on the negative side of the X-axis of the printed circuit board 401. This encoder detects the position of the support member 303 in the Z-axis direction.

FIG. 10A is a perspective view showing a configuration in which the support member 303 and the suspension 304 are assembled.

As shown in FIG. 10A, the support member 303 has a frame-like shape. The support member 303 is made of a lightweight and highly rigid material. The support member 303 includes an inner frame portion 303a and an outer frame portion 303b, which are substantially rectangular in plan view, respectively. The inner frame portion 303a and the outer frame portion 303b are connected by four beam portions 303c so that the center of the inner frame portion 303a and the center of the outer frame portion 303b coincide with each other in a plan view. The inner frame portion 303a is lifted to a position shifted upward (Z-axis positive direction) with respect to the outer frame portion 303b.

The holder 301 is installed on the upper surface of the inner frame portion 303a. Further, the coil 311 is mounted on the lower surface of the outer frame portion 303b. The coil 311 orbits a rectangular shape with rounded corners along the lower surface of the outer frame portion 303b.

Connecting portions 303d extending radially are formed at the four corners of the outer frame portion 303b. These connecting portions 303d have flange portions at the upper end and the lower end, respectively. The end of the upper suspension 304 is fixed to the upper surface of the upper flange of the connecting portion 303d by the fixture 303e. Further, the end portion of the lower suspension 304 is fixed to the lower surface of the lower flange portion of the connecting portion 303d by the fixing tool 303e. In this way, the suspension 304 is attached to the support member 303.

Further, the support member 303 includes a bridge portion 303f that connects the connecting portions 303d adjacent to each other in the Y-axis direction. The bridge portion 303f has a portion extending parallel to the Y-axis direction except for both ends in the Y-axis direction, and has an installation surface 303g parallel to the YZ plane at the center of this portion. A scale is installed on the installation surface 303g of the bridge portion 303f on the positive side of the X-axis of the support member 303. This scale faces the encoder of the position detection unit 400 shown in FIGS. 9A and 9B. In this way, the encoder detects the position of the support member 303 in the Z-axis direction.

The suspension 304 has three holes 304a at the center position in the X-axis direction. Further, the suspension 304 has a crank-shaped telescopic structure 304b on both sides of the three holes 304a. The two suspensions 304 on the positive side of the Y-axis and the two suspensions 304 on the negative side of the Y-axis are connected to the support unit 305 via the three holes 304a, respectively, as shown in FIGS. 9A and 9B. It will be installed.

FIG. 10B is a perspective view showing the configuration of the magnetic circuit 307. FIG. 10B shows a state in which the magnetic circuit 307 is installed on the upper surface of the support base 306.

The magnetic circuit 307 includes two yokes 321 arranged so as to be aligned in the Y-axis direction. The shape of the yoke 321 when viewed in the X-axis direction is U-shaped. Each of the two yokes 321 has an inner wall portion 321b divided into two. A magnet 322 is installed inside the outer wall portion 321a of each yoke 321. Further, magnets 323 are installed on the outside of the two wall portions 321b inside each yoke 321 so as to face the magnet 322, respectively. Between the magnets 322 and the magnets 323 facing each other, there is a gap into which the coil 311 described above is inserted.

Further, the magnetic circuit 307 includes two yokes 324 arranged so as to be aligned in the X-axis direction. The shape of the yoke 324 when viewed in the Y-axis direction is U-shaped. In each of the two yokes 324, the outer wall portion 324a is divided into two, and the inner wall portion 324b is also divided into two. Magnets 325 are installed inside the two wall portions 324a on the outside of each yoke 324. Further, magnets 326 are installed on the outside of the two wall portions 324b inside each yoke 324 so as to face the magnet 325, respectively. Between the magnets 325 and the magnets 326 facing each other, there is a gap into which the coil 311 described above is inserted. The end portion of the magnet 326 in the Y-axis direction overlaps the side surface of the inner wall portion 321b of the adjacent yokes 321.

11 (a) and 11 (b) are perspective views showing the configuration of the holder 301, respectively. 11 (a) is a perspective view of the holder 301 as viewed from above, and FIG. 11 (b) is a perspective view of the holder 301 as viewed from below.

The holder 301 is made of a frame-shaped member. The holder 301 is made of a highly rigid and lightweight material. The holder 301 is preferably configured so that surface reflection is suppressed. As a result, it is possible to prevent the laser beam for adjusting the output value from being reflected by the holder 301 and becoming stray light. Further, the surface of the holder 301 is preferably black so as to increase the light absorption rate. In the present embodiment, the holder 301 is integrally formed of a magnesium alloy, and the surface of the holder 301 is further subjected to a black oxidation treatment. Surface reflection may be suppressed by applying grain processing to the surface of the holder 301. The holder 301 may be made of a material other than magnesium, such as aluminum. The holder 301 has a shape symmetrical in the X-axis direction.

The holder 301 has a lower frame portion 301a for supporting the screen 110 and an upper frame portion 301b for supporting the screen 111.

The lower frame portion 301a has a rectangular opening 301c in a plan view. Further, three walls 301d projecting upward are provided on the positive side edge portion of the upper surface of the lower frame portion 301a on the Y-axis side, and the wall 301d is also provided on the positive and negative side edges of the upper surface of the lower frame portion 301a on the X-axis side. Has been done. Further, a protrusion 301e projecting upward is provided between the wall 301d and the opening 301c. The protrusions 301e are continuously formed along the peripheral edge of the opening 301c. The height of the protrusion 301e is lower than the height of the wall 301d. On the upper surface of the lower frame portion 301a, four hook portions 301f protruding in the Z-axis direction are provided at positions outside the wall 301d.

The upper frame portion 301b has a rectangular opening 301g in a plan view. Further, three walls 301h projecting upward are provided on the Y-axis negative side edge portion of the upper surface of the upper frame portion 301b, and walls 301h are also provided on the X-axis positive / negative side edge portions of the upper frame portion 301b upper surface. Has been done. Further, a protrusion 301i projecting upward is provided between the wall 301h and the opening 301g. The protrusions 301i are continuously formed along the peripheral edge of the opening 301g. The height of the protrusion 301i is lower than the height of the wall 301h. On the upper surface of the upper frame portion 301b, four hook portions 301j protruding in the Z-axis direction are provided at positions outside the wall 301h.

The step between the lower frame portion 301a and the upper frame portion 301b is closed by the wall portion 301k. The upper surface of the wall portion 301k is dug downward (in the negative direction of the Z axis) to be one step lower. A recess (groove) 301k1 extending in the X-axis direction is formed on the lower surface of the wall portion 301k. The cross section of the recess 301k1 when cut in a plane parallel to the YY plane is V-shaped. The recess 301k1 is formed over the entire length of the wall portion 301k.

Further, as shown in FIG. 11B, the lower surface of the holder 301 is provided with 10 projecting pieces 301l protruding downward from the inside of the lower surface. The contour of the lower surface of the holder 301 is the same as the contour of the inner frame portion 303a of the support member 303 shown in FIG. 10 (a). When the holder 301 is placed on the inner frame portion 303a, the ten projecting pieces 301l of the holder 301 are fitted inside the inner frame portion 303a. As a result, the holder 301 is positioned on the support member 303.

The screen 110 is placed on the protrusion 301e of the lower frame portion 301a and supported by the holder 301. At this time, the end of the screen 110 on the negative side of the Y-axis enters the lower side of the wall portion 301k. The protrusions 301e are formed so as to be continuous along the three sides of the screen 110 in a state where the screen 110 is placed. In this state, the screen 110 fits inside the five walls 301d, and there is a slight gap between the outer circumference of the screen 110 and the wall 301d.

The screen 111 is placed on the protrusion 301i of the upper frame portion 301b and supported by the holder 301. At this time, the end of the screen 111 on the positive side of the Y-axis overlaps the upper side of the wall portion 301k. The protrusions 301i are formed so as to be continuous along the three sides of the screen 111 when the screen 111 is mounted. In this state, the screen 111 fits inside the five walls 301h, and there is a slight gap between the outer circumference of the screen 111 and the wall 301h.

In this way, after the screens 110 and 111 are installed in the lower frame portion 301a and the upper frame portion 301b, respectively, the light-shielding members 302a and 302b shown in FIG. 1 are installed in the lower frame portion 301a and the upper frame portion 301b, respectively. To. At this time, the four hooks 301f provided in the lower frame portion 301a are fitted into the four holes of the light-shielding member 302a, respectively, and the four hooks 301j provided in the upper frame portion 301b are the four of the light-shielding member 302b. Fit into each hole. Further, a heat-resistant member (heat-resistant packing) is inserted between the screens 110 and 111 and the light-shielding members 302a and 302b.

FIG. 12A is a cross-sectional view of the holder 301 in which the screens 110 and 111 are installed, cut in a plane parallel to the YY plane. In FIG. 12A, the light-shielding members 302a and 302b are not shown for convenience.

As described above, when adjusting the output values of the laser light sources 101a to 101b, the laser beam LT1 for adjusting the output value is emitted from the laser light sources 101a to 101b at the boundary position in the Y-axis direction of the screens 110 and 111. Will be done. In this case, as shown in FIG. 12A, since the wall portion 301k is provided at the boundary position in the Y-axis direction of the screens 110 and 111, the laser beam LT1 for adjusting the output value is the wall portion. It is shielded by 301k. That is, the wall portion 301k formed on the holder 301 serves as a light-shielding portion. As a result, it is suppressed that the laser beam for adjusting the output value advances to the mirror 22 of FIG. 1 (c) and becomes stray light.

According to the study by the inventors, when the lower surface of the wall portion 301k is designed to be a flat flat surface, a part of the laser beam for adjusting the output value incident on the lower surface of the wall portion 301k advances to the mirror 22. , It was confirmed that the displayed image was displayed slightly whitish as a whole.

In order to solve such a problem, in the present embodiment, a recess 301k1 is provided on the lower surface of the wall portion 301k. As a result, as shown in FIG. 12B, the laser beam LT1 for adjusting the output value incident on the lower surface of the wall portion 301k is taken into the recess 301k1 and returned to the correction lens 109 side as the reflected light LT2. As a result, the laser beam LT1 for adjusting the output value can be more reliably shielded from light. Therefore, a part of the laser beam for adjusting the output value advances to the mirror 22, and it is more reliably suppressed that the displayed image is displayed slightly whitish as a whole.

The shape of the recess 301k1 does not necessarily have to be V-shaped, and may be, for example, U-shaped as shown in FIG. 12 (c), or may be a rectangular recess. good. The shape of the recess 301k1 may be any shape as long as it can prevent a part of the laser beam for adjusting the output value from advancing to the mirror 22.

<Effect of embodiment>
As described above, according to the present embodiment, the following effects are achieved.

Since the laser beam for adjusting the output value is emitted at a predetermined position within the range of the display angle of view for displaying the display image of one frame (the boundary position of the screens 110 and 111 in this embodiment), the display image is displayed. Even if the image drawing area on the screen changes due to the distortion correction, it is not necessary to adjust the emission position of the laser beam for adjusting the output value. Therefore, the outputs of the laser light sources 101a to 101c can be smoothly adjusted regardless of the distortion correction of the displayed image.

Here, the "display angle of view" is the swing angle of the laser beam for displaying an image for one frame. That is, the laser light of each color can be oscillated in the two-dimensional direction within the movable range of the mirror 108a in the scanning unit 108 shown in FIG. On the other hand, the image for one frame is displayed in a swing angle range narrower than the movable range of the mirror 108a. That is, the laser light sources 101a to 101c are driven based on the video signal in a range of a predetermined swing angle narrower than the movable range of the mirror 108a, and the screens 110 and 111 are scanned by the laser light of each color. Such a swing angle in the two-dimensional direction of the laser beam for displaying an image for one frame is referred to as a "display angle of view".

In the present embodiment, drawing on the screen 110 and drawing on the screen 111 are performed within the range of the display angle of view. That is, within the range of the display angle of view, the two images are displayed on the screens 110 and 111, respectively. Further, within the range of the display angle of view, there is a range in which the image is not drawn between these two images. This range corresponds to the range of the boundary BR1 shown in FIG. 3 (b). In FIG. 13, A11 and A12 schematically show a region in which an image is drawn on the screens 110 and 111.

In the present embodiment, the laser beam for adjusting the output value is emitted at the position that becomes the boundary of the drawing range of these two images within the range of the display angle of view, that is, the boundary BR1 of the screens 110 and 111. Will be done. Therefore, the output values of the laser light sources 101a to 101c can be adjusted by the laser beam for adjusting the output value while displaying the two images having different viewing distances on the screens 110 and 111. Further, since the laser beam for adjusting the output value is emitted within the range of the display angle of view, the output of the laser light sources 101a to 101c can be smoothly adjusted regardless of the distortion correction of the displayed image as described above. can.

Further, in the present embodiment, as shown in FIG. 12A, a wall portion 301k (light-shielding portion) is provided at the boundary between the two screens 110 and 111, and the laser beam for adjusting the output value is the wall portion. It is irradiated to the position of 301k (light-shielding part). Therefore, it is possible to prevent the laser beam LT1 for output adjustment from being mixed into the display image, and the quality of the display image can be maintained high.

Further, as shown in FIGS. 12A and 12B, since the recess 301k1 is provided on the lower surface of the wall portion 301k (light-shielding portion), the laser beam LT1 for output adjustment may be mixed into the display image. It can be suppressed more reliably. As a result, the quality of the displayed image can be maintained higher.

Further, in the present embodiment, since the wall portion 301k and the recess 301k1 are integrally formed in the holder 301, it is not necessary to separately arrange a member for blocking the laser beam for adjusting the output value. Therefore, the configuration of the image display device 20 can be simplified.

In the present embodiment, the recess 301k1 is provided over the entire length of the wall portion 301k, but the recess 301k1 may be provided at least at a position where the laser beam for adjusting the output value is irradiated.

<Change example>
In the above embodiment, two screens 110 and 111 are arranged, but the number of screens is not limited to this, and only one screen may be arranged. In this case, two images may be drawn on one screen, and the laser light for adjusting the output value may be emitted at the boundary between the two images to adjust the outputs of the laser light sources 101a to 101c. The emission position of the laser beam for adjusting the output value may be set within a range in which the image within the display angle of view is not displayed.

Further, the method for adjusting the output of the laser light sources 101a to 101c is not necessarily limited to the method described in the above embodiment, and any other method may be used as long as the laser beam for adjusting the output value is used. good.

Further, in the above embodiment, the laser beam for adjusting the output value is shielded by the wall portion 301k provided on the holder 301, but the configuration for shielding the laser beam for adjusting the output value is not limited to this. do not have. For example, a mask may be provided on the screens 110 and 111 where the laser beam for output adjustment passes to block the laser beam for output adjustment. Further, when the width of the lower surface of the wall portion 301k is wide enough to substantially completely block the laser beam for adjusting the output value, it is not always necessary to provide the recess 301k1 on the lower surface of the wall portion 301k.

Further, the screen does not necessarily have to move in the Z-axis direction, and may be fixed in a predetermined position. In this case, only images with no parallax in the depth direction are displayed.

Further, in the above embodiment, the optical output values of the three laser light sources 101a to 101c are detected by one photodetector 107, but the optical output values of the three laser light sources 101a to 101c are different from each other. It may be detected by the detector 107. For example, the mirror 104 and the dichroic mirrors 105a and 105b are configured to transmit a few percent of the laser light from the laser light sources 101a to 101c, respectively, and the transmitted laser light of each color is individually detected by a photodetector. You may do it.

Further, in the above embodiment, an example in which the present invention is applied to a head-up display mounted on a passenger car 1 is shown, but the present invention can be applied not only to an in-vehicle use but also to other types of image display devices. be.

Further, the configurations of the image display device 20 and the irradiation light generation unit 21 are not limited to the configurations shown in FIGS. 1 (c) and 2 and can be appropriately changed. Further, the first lens portion 110a and the second lens portion 110b may be integrally formed with the screen 110, or a transparent sheet having these lens portions may be attached to the base material of the screen 110. May be good.

The embodiments of the present invention can be appropriately modified in various ways within the scope of the technical idea shown in the claims.

20 ... Image display device 100 ... Light source 101a, 101b, 101c ... Laser light source 107 ... Photodetector 108 ... Scanning unit 110, 111 ... Screen 201 ... Image control circuit (control unit)
300 ... Drive unit 301 ... Holder 301k ... Wall part (light-shielding part ~
301k1 ... dent

Claims (6)

A light source that emits laser light and
A screen on which an image is drawn by being scanned two-dimensionally by the laser beam, and
A scanning unit that scans the laser beam against the screen,
A photodetector that detects the amount of light emitted from the light source and the laser light.
With a control unit,
The screen is
The first screen and
A second screen arranged so as to line up with the first screen in a direction perpendicular to the traveling direction of the laser beam is provided.
The control unit adjusts the output value of the light source at a position at the boundary between the first screen and the second screen within the range of the display angle of view for displaying the display image of one frame. Is emitted from the light source, and the output of the light source is adjusted based on the detection signal of the light detector with respect to the laser light for adjusting the output value.
An image display device characterized by this. In the image display device according to claim 1,
The emission position of the laser beam for adjusting the output value is a position within the range of the display angle of view, which is a boundary between the drawing range of the first image and the drawing range of the second image.
An image display device characterized by this. In the image display device according to claim 1 or 2 .
A light-shielding portion is provided at the boundary between the first screen and the second screen.
The laser beam for adjusting the output value is applied to the position of the light-shielding portion.
An image display device characterized by this. In the image display device according to claim 3 ,
The light-shielding portion is provided with a recess at least at a position where the laser beam for adjusting the output value is irradiated.
An image display device characterized by this. In the image display device according to claim 3 or 4 .
The first screen and the second screen are held in a common holder.
The light-shielding portion is a wall portion provided on the holder.
An image display device characterized by this. In the image display device according to claim 5 ,
A drive unit for moving the holder in a direction parallel to the traveling direction of the laser beam is provided.
An image display device characterized by this.

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