JP2017156547A - Image display device, control method, program and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device that allows a movement of light-amount adjustment means for luminance adjustment to be pinpointly and quickly executed.SOLUTION: A light source unit 1 comprises a gradation ND filter 32, a stepping motor 33 and a solenoid 35. The gradation ND filter 32 has an upper side filter part 32U and a lower side filter part 32D, in which a direction of increase in transmittance on the upper side filter part 32U is opposite to a direction of increase in transmittance on the lower side filter part 32D. When a movement distance D1 necessary for the stepping motor 33 to move the gradation ND filter 32 is equal to or greater than 1/2 of a filter length Lf, the light source unit 1 is configured to perform switch processing by the solenoid 35.SELECTED DRAWING: Figure 6

Description

  The present invention relates to adjustment of laser light emitted from a light source.

  2. Description of the Related Art Conventionally, a technique related to brightness adjustment of a head-up display that allows an image configured based on laser light to be visually recognized as a virtual image from the position of a user's eyes is known. For example, Patent Document 1 discloses a head-up display that projects light by dimming light emitted from a laser light source with a neutral density filter (so-called ND filter).

JP 2014-197057 A

  According to the head-up display of Patent Document 1, it is possible to move the ND filter to an appropriate position while suppressing an increase in the number of parts. On the other hand, in the brightness adjustment using the ND filter, the moving time of the ND filter becomes a problem. For example, if the image is displayed at the lowest brightness at night and the power is turned off, and then the power is turned on in the daytime of the next day, it is necessary to increase the brightness of the image according to the brightness of the external light. Therefore, it is necessary to move the ND filter significantly. In this case, since it takes time to move the ND filter, it takes time to start displaying an image. Similarly, even when an image is being displayed, an ND filter is used to change the target luminance of the image according to the brightness of the external light when traveling in a place where the brightness of the external light changes abruptly, such as a tunnel entrance / exit. Need to move significantly. However, Patent Document 1 does not disclose any technique for moving the ND filter at high speed.

  Examples of the problem to be solved by the present invention are as described above. The main object of the present invention is to provide an image display device capable of accurately and rapidly moving the light amount adjusting means for adjusting the luminance.

  The invention described in claim is an image display device that displays an image configured based on a laser beam from a light source, and a light amount adjusting unit having a different transmittance depending on a position where the laser beam is incident, and A first moving unit and a second moving unit that move the light amount adjusting unit so as to change a position where the laser beam is incident. The first moving unit and the second moving unit are configured to change the light amount adjusting unit. The moving direction is different.

  Further, the invention described in the claims is executed by an image display apparatus that displays an image configured based on laser light from a light source and includes a light amount adjusting unit having different transmittance depending on a position where the laser light is incident. And a first moving step and a second moving step for moving the light amount adjusting means so as to change a position where the laser beam is incident, the first moving step and the second moving step. Is different in the direction in which the light amount adjusting means is moved.

  The invention described in the claims is a computer of an image display device that displays an image configured based on a laser beam from a light source and includes a light amount adjusting unit having a transmittance that varies depending on a position where the laser beam is incident. Is a program executed by causing the computer to function as first moving means and second moving means for moving the light amount adjusting means so as to change the position where the laser beam is incident, and the first moving means and the The second moving means is characterized in that a direction in which the light amount adjusting means is moved is different.

1 shows a schematic configuration of a head-up display according to an embodiment. The structure of a light source unit is shown. The front view of a gradation ND filter is shown. The transition of the laser incident position when the target luminance is increased in the first embodiment is shown. The transition of the laser incident position when the target luminance is lowered in the first embodiment is shown. It is a flowchart which shows the process sequence in 1st Example. The front view of the gradation ND filter which concerns on 3rd Example is shown. The perspective view of the gradation ND filter which concerns on 4th Example is shown. 10 shows transition of a laser incident position according to a fifth embodiment. The front view of the gradation ND filter which concerns on a modification is shown.

  In a preferred embodiment of the present invention, there is provided an image display device for displaying an image configured based on laser light from a light source, and a light amount adjusting means having different transmittance depending on a position where the laser light is incident, First moving means and second moving means for moving the light amount adjusting means so as to change the position where the laser light is incident are provided, wherein the first moving means and the second moving means are the light amount adjusting means. The direction of moving is different.

  The image display device includes a light amount adjusting unit, a first moving unit, and a second moving unit. The light amount adjusting means has different transmittance depending on the position where the laser light from the light source is incident. The first and second moving means move the light amount adjusting means so as to change the position where the laser light is incident. Here, the first moving means and the second moving means are different in the direction in which the light amount adjusting means is moved. In this aspect, the image display apparatus includes the first and second moving units that can move the light amount adjusting unit in different directions, so that the light amount adjusting unit having different transmittance according to the incident position of the laser beam. The incident position of the laser beam on the laser beam can be adjusted in a short time, and the light amount of the output laser light can be quickly set to the target light amount.

  In one aspect of the image display device, the first moving unit moves the light amount adjusting unit in the left-right direction, and the second moving unit moves the light amount adjusting unit in the up-down direction. According to this aspect, the image display apparatus can quickly move the incident position of the laser light to the position of the light amount adjusting means having the target transmittance.

  In another aspect of the image display device, the light amount adjustment unit includes a first adjustment area and a second adjustment area in which transmittance gradually changes according to a position where the laser beam is incident, and the first adjustment is performed. The direction in which the transmittance increases in the area is opposite to the direction in which the transmittance increases in the second adjustment area. In this aspect, the image display apparatus can adjust the light amount of the output laser light at high speed by appropriately switching the incident position of the laser light between the first adjustment area and the second adjustment area.

  In another aspect of the image display device, the first moving unit moves the light amount adjusting unit in a direction in which the transmittance gradually changes, and the second moving unit has a position where the laser beam is incident. The light amount adjusting means is moved in a direction to switch between the first adjustment area and the second adjustment area. According to this aspect, the image display apparatus finely adjusts the transmittance of the laser beam by moving the light amount adjusting unit by the first moving unit, and transmits the laser beam by moving the light amount adjusting unit by the second moving unit. The rate can be changed significantly, and the amount of laser light to be output can be adjusted at high speed.

  In another aspect of the image display device, the light amount adjusting unit may be configured such that when the moving distance of the light amount adjusting unit acquired according to the luminance of the image to be displayed is a predetermined distance or more, the first moving unit and the first moving unit. It is moved by two moving means. According to this aspect, the image display apparatus can adjust the light quantity of the output laser light at high speed by using the first moving means and the second moving means properly.

  In another aspect of the image display device, when the light amount adjusting unit is moved by the first moving unit and the second moving unit during the display of the image, the movement by the first moving unit is: It starts before the movement by the second moving means. According to this aspect, the image display device can preferably suppress a sudden change in the luminance of the image during the display of the image.

  In another aspect of the image display device, when the light amount adjusting unit is moved by the first moving unit and the second moving unit during the display of the image, the movement by the first moving unit, The movement by the second moving means is completed at the same time. According to this aspect, the image display apparatus can suitably suppress a sudden change in the luminance of the image during the display of the image while adjusting the amount of the laser beam to be output at high speed.

  In another aspect of the image display device, the light amount adjusting unit is moved by the first moving unit and the second moving unit during the display of the image, and is based on the second moving unit. When the luminance difference of the image caused by the movement is larger than a predetermined difference, the image is moved by the second moving unit after being moved by the first moving unit so that the luminance difference is not more than the predetermined difference. According to this aspect, the image display apparatus can reliably suppress a sudden change in the luminance of the image during the display of the image.

  In another aspect of the image display device, the light amount adjusting means is moved by the second moving means when the image is not being displayed and is moved by the first moving means and the second moving means. After being moved, or together with the movement by the second moving means, the first moving means is moved.

  In another embodiment of the present invention, an image display apparatus that displays an image configured based on a laser beam from a light source and includes a light amount adjusting unit having a transmittance that varies depending on a position where the laser beam enters is executed. A control method comprising a first movement step and a second movement step of moving the light amount adjusting means so as to change the position where the laser beam is incident, the first movement step and the second movement step, Then, the direction in which the light amount adjusting means is moved is different. By executing this control method, the image display device adjusts the incident position of the laser light to the light amount adjusting means by the first moving step and the second moving step, and the light amount of the laser light after passing through the light amount adjusting means. Can be suitably adjusted.

  In another embodiment of the present invention, there is provided a computer of an image display device including a light amount adjusting unit that displays an image configured based on laser light from a light source and has different transmittance depending on a position where the laser light is incident. A program to be executed, causing the computer to function as a first moving unit and a second moving unit that move the light amount adjusting unit so as to change a position where the laser beam is incident, and the first moving unit and the first moving unit The two moving means are different in the direction in which the light amount adjusting means is moved. The computer executes the above-described program, thereby adjusting the incident position of the laser beam to the light amount adjusting unit by the first moving unit and the second moving unit, and suitably adjusting the light amount of the laser light after passing through the light amount adjusting unit. Can be adjusted. Preferably, the program is stored in a storage medium.

  Hereinafter, preferred first to fifth embodiments of the present invention will be described with reference to the drawings.

<First embodiment>
[Configuration of head-up display]
FIG. 1 is a schematic configuration diagram of a head-up display 100 according to the first embodiment. As shown in FIG. 1, a head-up display 100 according to the first embodiment mainly includes a light source unit 1 and a concave mirror 10, and includes a front window 25, a ceiling portion 27, a hood 28, and a dashboard. 29 is attached to the vehicle.

  The light source unit 1 is provided in the dashboard 29 and irradiates the concave mirror 10 with light constituting a display image (also referred to as “display light”). In this case, the display light reflected by the concave mirror 10 reaches the front window 25 through the opening 89 provided in the dashboard 29 and further reflects by the front window 25 to reach the position of the driver's eyes. . In this manner, the light source unit 1 causes the display light to reach the position of the driver's eyes and causes the driver to visually recognize the virtual image “Iv”. Note that the light source unit 1 communicates with a navigation device (not shown) to generate various images necessary to generate a virtual image Iv, such as information on a route (guide route) to a destination set by the user. Information may be received. The light source unit 1 is an example of the “image display device” in the present invention.

  The concave mirror 10 reflects the display light emitted from the light source unit 1 toward the opening 89 provided in the dashboard 29 so as to reach the front window 25. In this case, the concave mirror 10 magnifies and reflects the image indicated by the display light.

  The installation position of the light source unit 1 is not limited to being inside the dashboard 29 as shown in FIG. For example, the light source unit 1 may be in an aspect (including an aspect in which the light source unit 1 is attached to a sun visor not shown) attached to the ceiling portion 27. In this case, a combiner may be provided between the light source unit 1 and the front window 25. Moreover, even if it is the aspect which has the light source unit 1 inside the dashboard 29, the combiner may be provided. In this case, for example, a configuration in which display light emitted from the light source unit 1 toward the opening 89 is received by a combiner provided on the dashboard 29 may be employed.

[Configuration of light source unit]
FIG. 2 shows a schematic configuration of the light source unit 1. The light source unit 1 mainly includes a projector unit 2, a light source unit 3, a power source 4 that supplies driving power for the light source unit 1, a video signal “S 1” necessary for displaying a virtual image Iv from the navigation device 51, and control. And an interface 5 that receives the signal “S2”. The video signal S1 is a video signal that can be handled by an image content signal, a projector, or the like, and corresponds to, for example, RGB888 or YUV444.

  The projector unit 2 is a unit that generates a control signal or the like that causes the light source unit 3 to emit display light. The projector unit 2 mainly includes a power supply block 6, a control block 7, a video signal processing block 8, a frame memory 11, and a ROM 12. A RAM 13, a timing controller 14, a MEMS control block 15, a MEMS driver 16, a laser control block 17, a laser driver 18, a motor driver 19, a vertical drive circuit 20, and an ADC (Analog to Digital Converter). 21 and 22.

  The light source unit 3 generates display light based on a control signal or the like supplied from the projector unit 2 and irradiates the concave mirror 10. The light source unit 3 mainly includes a MEMS mirror 31, a gradation ND filter 32 (32U, 32D), a stepping motor (left / right drive mechanism) 33, a left / right position detection sensor 34, a solenoid (up / down drive mechanism) 35, The laser light source unit 36, the light receiving element 37, and the vertical position detection sensor 43 are included. Hereinafter, the direction in which the laser beam is incident on the gradation ND filter 32 is “X-axis direction”, the longitudinal direction (left-right direction) of the gradation ND filter 32 is “Z-axis direction”, and the short direction (vertical direction) of the gradation ND filter 32 ) Is defined as “Y-axis direction”, and each positive direction is determined as shown in FIG. In FIG. 2, the incident surface of the gradation ND filter 32 formed parallel to the YZ plane is shown for convenience of explanation.

  The power supply block 6 converts the power supplied from the power supply 4 into the power used in the projector unit 2 based on the control signal received from the control block 7, and supplies and stops the power supply to each block.

  The control block 7 controls the entire projector unit 2. The control block 7 receives a control signal S2 supplied from the navigation device 51 or the like via the interface 5, and performs an operation according to an instruction indicated by the control signal S2. For example, the control block 7 performs processing such as brightness adjustment, image lighting / light-out, color balance adjustment, image adjustment, and the like based on the control signal S2. The control block 7 has a luminance change block 70.

  The luminance change block 70 moves the gradation ND filter 32 by performing drive control of the stepping motor 33 and the solenoid 35 in accordance with the luminance change instruction indicated by the control signal S2. Accordingly, the luminance change block 70 displays the incident position of the laser light (“laser incident position”) in the gradation ND filter 32 so that the image is displayed with the luminance specified by the control signal S2 (also referred to as “target luminance”). Also called “Pin”. In this case, for example, the luminance change block 70 displays, for each assumed target luminance, a map or the like indicating the position of the gradation ND filter 32 at which the transmittance at the laser incident position Pin becomes the transmittance for realizing the target luminance. The movement of the gradation ND filter 32 is controlled with reference to the map stored in advance. The movement control of the gradation ND filter 32 by the luminance change block 70 will be described in detail in the section [Movement control of gradation ND filter]. At least one of the brightness changing block 70 and the stepping motor 33 is an example of “first moving means” in the present invention, and at least one of the brightness changing block 70 and the solenoid 35 is an example of “second moving means” in the present invention. It is. The luminance change block 70 is an example of a computer that executes a program according to the present invention.

  The navigation device 51 is electrically connected to an illuminance sensor 52 for measuring the amount of ambient light outside the vehicle (that is, outside light), and the target luminance indicated by the control signal S2 according to the amount of light measured by the illuminance sensor 52. decide. Specifically, the navigation device 51 refers to a predetermined map or the like stored in advance, and increases the target luminance as the amount of external light increases, and sets the target luminance as lower as the amount of external light decreases.

  The video signal processing block 8 controls the MEMS control block 15 and the laser control block 17 based on the video signal S1 supplied via the interface 5 from the navigation device 51 or the like. Further, the video signal processing block 8 writes the video signal S1 into the frame memory 11 and reads it as needed according to the drive timing of the MEMS mirror 31, and each of the red (R), green (G), and blue (B) colors. Control signals corresponding to the brightness of the pixels are sequentially transmitted to the laser control block 17. The video signal processing block 8 is configured as, for example, an ASIC (Application Specific Integrated Circuit).

  The ROM 12 stores a control program and data for operating the video signal processing block 8. Various data are sequentially read from and written into the RAM 13 as a work memory when the video signal processing block 8 operates.

  The timing controller 14 controls the readout timing of image data from the frame memory 11 by the video signal processing block 8. The timing controller 14 also controls the operation timing of the MEMS mirror 31 via the MEMS control block 15.

  The MEMS control block 15 outputs an output signal for actually driving the MEMS mirror 31 to the MEMS driver 16 from the control signal supplied from the video signal processing block 8 and the displacement information of the MEMS mirror 31 supplied from the MEMS mirror 31. Supply.

  The MEMS driver 16 amplifies the drive signal of the MEMS mirror 31 supplied from the MEMS control block 15 so as to become a signal for operating the actual MEMS mirror 31 and supplies the amplified signal to the MEMS mirror 31.

  The laser control block 17 generates a drive signal for driving the laser light source unit 36 based on the control signal supplied from the video signal processing block 8 and the light detection signal from the light receiving element 37, and sends it to the laser driver 18. Supply. The laser control block 17 has an APC (Auto Power Control) block 71.

  The APC block 71 acquires the output values of the respective RGB lasers detected by the light receiving element 37 when the outer region of the drawing area of the image to be displayed as the virtual image Iv is illuminated with a specific luminance, and these output values are stored in advance. To a standard value (also referred to as “APC standard value”). Specifically, the APC block 71 controls the output value of the light receiving element 37 to be the APC reference value by adjusting the gain of the laser driver 18 or adjusting the gain of the video signal S1. Thereby, the APC block 71 keeps the apparent luminance and color balance constant even when the temperature changes.

  The APC reference value is obtained when the R, G, and B lasers are lit at a specific brightness when the gain adjustment of the R, G, and B lasers is performed so that the maximum brightness and color balance are optimized. The output value of the light receiving element 37 is stored in a nonvolatile memory (not shown).

  The laser driver 18 amplifies the drive signal of the laser light source unit 36 supplied from the laser control block 17. The laser driver 18 may include a DAC (Digital-to-Analog Converter), convert the drive signal described above into an analog signal, and supply the analog signal to the laser light source unit 36.

  The motor driver 19 is a drive circuit for driving the stepping motor 33, and drives the stepping motor 33 based on the control signal supplied from the luminance change block 70 to move the gradation ND filter 32 in the left-right direction (that is, the Z-axis direction). Adjust the position of. The vertical drive circuit 20 is a drive circuit for driving the solenoid 35, and drives the solenoid 35 based on a control signal supplied from the luminance change block 70 to move the gradation ND filter 32 in the vertical direction (that is, the Y-axis direction). Adjust the position.

  The ADC 21 converts the analog signal output from the light receiving element 37 into a digital signal and supplies the digital signal to the APC block 71. The ADC 22 converts the analog signal output from the left and right position detection sensor 34 into a digital signal and supplies the digital signal to the luminance change block 70. Further, the ADC 22 converts the analog signal output by the vertical position detection sensor 43 into a digital signal and supplies the digital signal to the luminance change block 70.

  The MEMS mirror 31 reflects the laser light transmitted through the gradation ND filter 32 toward the microlens array 39. In the microlens array 39, a plurality of microlenses are arranged, and the laser beam reflected by the MEMS mirror 31 enters. An intermediate image is formed on the radiation surface of the microlens array 39. The light emitted from the microlens array 39 is incident on the concave mirror 10 via a field lens or the like (not shown). The MEMS mirror 31 is provided with piezoelectric sensors 41 and 42. The piezo sensor 41 detects the position of the MEMS mirror 31 in the horizontal direction (that is, the Z-axis direction) and supplies the detection signal to the timing controller 14. The piezo sensor 42 detects the position of the MEMS mirror 31 in the vertical direction (that is, the Y-axis direction) and supplies the detection signal to the timing controller 14.

  The gradation ND filter 32 includes an upper filter portion 32U and a lower filter portion 32D whose transmittance continuously changes in the longitudinal direction. The upper filter portion 32U and the lower filter portion 32D are arranged in the short side direction (that is, the vertical direction), and are configured to be movable in the Y-axis direction and the Z-axis direction together. In this embodiment, the transmittance of the gradation ND filter 32U continuously increases from the end on the Z-axis positive direction side to the end on the Z-axis negative direction side, and the transmittance of the gradation ND filter 32D is Z-axis negative. It continuously increases from the end on the direction side to the end on the Z axis positive direction side. Thus, the direction in which the transmittance increases in the gradation ND filter 32U (that is, the Z-axis negative direction) is opposite to the direction in which the transmittance increases in the lower filter portion 32D (that is, the Z-axis positive direction). . That is, the maximum position and the minimum position of the transmittance in the gradation ND filter 32U are positions opposite to the maximum position and the minimum position of the transmittance of the lower filter section 32D, respectively. The transmittance of the gradation ND filters 32U and 32D may change linearly or logarithmically according to the position on the Z axis of the laser incident position Pin. In the case where a large attenuation characteristic such as 10,000 to 1 is provided, it is desirable that the transmittance changes logarithmically in order to reduce the size of the gradation ND filter 32. The gradation ND filter 32 is an example of the “light quantity adjusting unit” in the present invention.

  The stepping motor 33 adjusts the position of the gradation ND filter 32 on the Z axis with high accuracy based on the drive signal supplied from the motor driver 19. The stepping motor 33 has a motor shaft 44 extending in the Z-axis direction, and moves the gradation ND filter 32 along the motor shaft 44.

  The left / right position detection sensor 34 detects the position of the gradation ND filter 32 on the Z axis and supplies the detection signal to the ADC 22. The left / right position detection sensor 34 is, for example, a linear position sensor, and detects a position on the Z-axis of the gradation ND filter 32 by reading a change in voltage due to a change in resistance value with a built-in ADC.

  The solenoid 35 is a two-contact solenoid that moves the gradation ND filter 32 at a high speed in about 30 to 100 milliseconds in the Y-axis direction. In the present embodiment, the solenoid 35 includes a position where the laser incident position Pin overlaps the upper filter portion 32U (also referred to as “point A”) and a position where the laser incident position Pin overlaps the lower filter portion 32D (“point B”). Also called).

  The laser light source unit 36 includes laser diodes LD1 to LD3 having R, G, and B wavelengths. Each of the laser diodes LD <b> 1 to LD <b> 3 emits light according to a drive signal from the laser driver 18. The laser light source unit 36 includes a collimator lens that collimates the laser beams of the laser diodes LD1 to LD3, and a reflection mirror for synthesizing the laser beams of the laser diodes LD1 to LD3. The combined laser light is incident on the polarization beam splitter 38. The laser light incident on the polarization beam splitter 38 is divided into light that passes through the polarization beam splitter 38 and enters the gradation ND filter 32, and light that reflects off the polarization beam splitter 38 and enters the light receiving element 37. .

  The light receiving element 37 has a beam splitter that decomposes the laser beam reflected by the polarization beam splitter 38 into laser beams for each of R, G, and B, and corresponds to the light amount (intensity) of each of the R, G, and B laser beams. A detection signal which is an electrical signal is generated and supplied to the ADC 21. The detection signal generated by the light receiving element 37 is used as a feedback signal for stabilizing the laser power, or used for a laser safety operation for turning off the laser diodes LD1 to LD3 when abnormal light emission is detected.

  The vertical position detection sensor 43 detects the position on the Y axis of the gradation ND filter 32 (that is, whether the solenoid 35 exists at point A or B) and supplies the detection signal to the ADC 22. Instead of providing the vertical position detection sensor 43, the luminance change block 70 may specify the position of the gradation ND filter 32 on the Y axis by software processing. For example, the luminance change block 70 transmits a control signal for switching the position of the gradation ND filter 32 on the Y axis to the vertical drive circuit 20 and when the predetermined time has elapsed, the position of the gradation ND filter 32 on the Y axis. It is also possible to store the position after switching, assuming that has been switched.

[Movement control of gradation ND filter]
Hereinafter, the movement control of the gradation ND filter 32 by the luminance change block 70 will be described.

(1) Outline First, an outline of movement control of the gradation ND filter 32 by the stepping motor 33 and the solenoid 35 will be described with reference to FIG. FIG. 3 is a view of the gradation ND filter 32 observed from the incident direction of the laser beam.

  In the example of FIG. 3, the upper filter portion 32U has a transmittance from the end on the Z-axis positive direction side where the transmittance is about 0% to the end on the Z-axis negative direction side where the transmittance is about 100%. It is gradually increasing. On the other hand, the transmittance of the lower filter portion 32D gradually increases from the end on the Z-axis negative direction side where the transmittance is about 0% to the end on the Z-axis positive direction side where the transmittance is about 100%. doing. The movable distance of the gradation ND filter 32 on the Z axis by the stepping motor 33 is the physical distance of the gradation ND filter 32, that is, the length in the longitudinal direction of the gradation ND filter 32 (also referred to as “filter length Lf”). Is approximately the same. When the solenoid 35 is present at the point A, the laser incident position Pin is present at a position overlapping the upper filter portion 32U, and when the solenoid 35 is present at the point B, the laser incident position Pin is lower than the lower filter portion 32D. It exists in the position that overlaps.

  Here, when the laser incident position Pin is present at a position on the upper filter portion 32U where the transmittance is 10%, the laser incident position Pin is moved to a position where the transmittance is 90% due to the increase in target luminance. Consider the case. In this case, when the laser incident position Pin is moved to the position “PinX” where the transmittance is 90% on the same upper filter portion 32U, the gradation ND filter 32 is moved by the stepping motor 33 by the length of the arrow 50 shown in FIG. It is necessary to move in the negative Z-axis direction. On the other hand, when the laser incident position Pin is moved to the position “PinY” at which the transmittance on the lower filter portion 32D is 90%, the solenoid 35 may be switched from point A to point B (see arrow 51). Further, as described above, the moving speed of the gradation ND filter 32 by the solenoid 35 is faster than the moving speed of the gradation ND filter 32 by the stepping motor 33. Therefore, in this case, the latter using the solenoid 35 has a shorter moving time of the gradation ND filter 32.

  In consideration of the above, in the first embodiment, the luminance changing block 70 appropriately executes the movement in the Y axis direction by the solenoid 35 in addition to or instead of the movement in the Z axis direction by the stepping motor 33. The laser incident position Pin is moved at a high speed to the position of the gradation ND filter 32 having the target transmittance.

  Thereafter, the process of switching the laser incident position Pin between the position on the upper filter portion 32U and the position on the lower filter portion 32D by switching the solenoid 35 between the point A and the point B will be described as “by the solenoid 35. Also called “switching process”. Further, the moving distance of the gradation ND filter 32 (the length of the arrow 50 in FIG. 3) required when the laser incident position Pin is moved to a position where the target transmittance is obtained by the stepping motor 33 without using the solenoid 35, Also called “necessary moving distance D1”.

(2) Determination of Necessity of Switching Process by Solenoid Next, the necessity determination of the switching process by the solenoid 35 will be described. Schematically, the luminance change block 70 performs a switching process by the solenoid 35 when the necessary moving distance D1 is 1/2 or more of the filter length Lf. Thereby, the luminance change block 70 completes the movement of the gradation ND filter 32 at high speed so that the target luminance can be obtained. 1/2 of the filter length Lf is an example of the “predetermined distance” in the present invention.

  FIG. 4A is a view of the gradation ND filter 32 observed from the incident direction of the laser light. Here, FIG. 4A shows an outline of a case where the laser incident position Pin is moved from the position “Pin0” having a transmittance of 10% on the upper filter portion 32U to a position having a transmittance of 65%.

  In the example of FIG. 4A, the brightness changing block 70 first moves the laser incident position Pin from the current position Pin0 to the position “Pin1” having a transmittance of 65% while fixing the position of the solenoid 35 at the point A. The moving distance of the gradation ND filter 32 on the assumed Z axis is calculated as the required moving distance D1. In this case, the luminance change block 70 determines that the position of the solenoid 35 should be switched from the point A to the point B because the calculated required moving distance D1 is ½ or more of the previously stored filter length Lf. .

  Therefore, in this case, the luminance change block 70 is a necessary moving distance (also referred to as “necessary moving distance D2”) of the gradation ND filter 32 on the Z axis when it is assumed that the position of the solenoid 35 is switched to the B point. .) Is calculated. That is, in this case, the luminance change block 70 specifies the position “Pin3” having a transmittance of 65% on the lower filter unit 32D, and determines the distance on the Z-axis between the specified position Pin3 and the current position Pin0. Calculated as the required moving distance D2. In the example of FIG. 4A, the luminance changing block 70 moves the gradation ND filter 32 in the positive direction of the Z axis by the stepping motor 33 by the necessary moving distance D2, thereby moving the laser incident position Pin from the position Pin0 to the position “ The laser incident position Pin is moved from the position Pin2 to the position Pin3 by moving to “Pin2” and switching the solenoid 35 from the point A to the point B. Thereby, the brightness changing block 70 uses the high-speed movement of the solenoid 35 as compared with the case where the laser incident position Pin is moved from the position Pin0 to the position Pin1 while the position of the solenoid 35 is fixed at the point A. The movement of the gradation ND filter 32 can be completed early.

  In addition, instead of the example of FIG. 4A, when the required moving distance D1 is less than ½ of the filter length Lf, the luminance change block 70 does not need to execute the switching process by the solenoid 35. The gradation ND filter 32 is moved by the required moving distance D1 by the stepping motor 33. That is, in this case, the luminance change block 70 determines that the effect of shortening the moving time of the gradation ND filter 32 is not obtained or limited even when the solenoid 35 is used, and only the stepping motor 33 is used. The gradation ND filter 32 is moved. As a result, the luminance change block 70 can suitably suppress unnecessary switching of the position of the solenoid 35.

(3) Execution Timing of Switching Process by Solenoid Next, each processing timing when it is necessary to perform both the switching process by the solenoid 35 and the movement for the necessary moving distance D2 by the stepping motor 33 will be described. In the first embodiment, the luminance change block 70 performs a switching process by the solenoid 35 after the movement in the Z-axis direction by the stepping motor 33 is executed during the display of the image in order to suppress a sudden change in the luminance of the displayed image.

  FIG. 4B is a diagram showing a moving procedure of the gradation ND filter 32 in the example of FIG. In the example of FIG. 4A, if the solenoid 35 is first driven to move the laser incident position Pin from the position Pin0 having a transmittance of 10% to the position “Pin4” having a transmittance of 90%, the image being displayed The brightness of the image changes suddenly and the observer feels dazzling. Accordingly, the luminance changing block 70 first moves the laser incident position Pin from the position Pin0 to the position Pin2 by moving the gradation ND filter 32 in the positive Z-axis direction by the necessary moving distance D2 (procedure 1), and then the solenoid. By performing the switching process by 35, the laser incident position Pin is moved from the position Pin2 to the position Pin3 (procedure 2). Thereby, the brightness change block 70 can suitably set the image to the target brightness even when the target brightness needs to be significantly changed during the display of the image.

  Note that the situation in which the target brightness is significantly changed during image display is, for example, that the vehicle passes through a place where the amount of ambient light suddenly changes, such as a tunnel, an underground passage, or an entrance / exit of a shadowed area of a traveling building. This is the case. In these cases, the amount of light detected by the illuminance sensor 52 changes greatly, and it is necessary to change the target luminance significantly according to the amount of light detected by the illuminance sensor 52.

  FIG. 5 shows an outline in the case where the laser incident position Pin is moved from the position “Pin4” having the transmittance of 80% on the upper filter portion 32U to the position having the transmittance of 35%. Even when the transmittance at the laser incident position Pin is lowered, as in the example of FIG. 4 in which the transmittance at the laser incident position Pin is increased, the luminance changing block 70 first sets the target transmittance 35% on the upper filter unit 32U. The required moving distance D1 to the position “Pin5” is calculated. Then, the luminance change block 70 determines that the solenoid 35 should be switched from the A point to the B point because the calculated necessary moving distance D1 is ½ or more of the previously stored filter length Lf. Therefore, in this case, the luminance change block 70 calculates the necessary moving distance D2 on the assumption that the solenoid 35 is switched to the B point. The brightness changing block 70 moves the gradation ND filter 32 in the negative Z-axis direction by the stepping motor 33 by the required moving distance D2 to move the laser incident position Pin from the position Pin4 to the position “Pin6”, and then the solenoid 35 By switching from point A to point B, the laser incident position Pin is moved to the position “Pin 7” where the target transmittance is 35%. Even in this case, the luminance changing block 70 first moves the gradation ND filter 32 by the necessary moving distance D2, and then performs switching processing by the solenoid 35, thereby suppressing a sudden change in luminance of the displayed image. be able to. If the switching process by the solenoid 35 is first executed, the laser incident position Pin is moved from the position Pin4 having the transmittance of 80% to the position “Pin8” having the transmittance of 20%, and the brightness is suddenly changed. It will be.

  Note that when the image is displayed after the gradation ND filter 32 is moved (for example, when the light source unit 1 is activated), the luminance change block 70 is switched by the solenoid 35 because the luminance of the image does not change suddenly. The processing may be performed before or simultaneously with the start of movement by the stepping motor 33. For example, when the image is displayed at the lowest brightness at night and the power is turned off, and then the power is turned on during the day of the next day, the target brightness needs to be significantly increased, and thus the required moving distance D1 becomes longer. In such a case, the luminance change block 70 moves the gradation ND filter 32 by performing a switching process by the solenoid 35 before displaying an image. Then, after the movement of the gradation ND filter 32 is completed, the luminance change block 70 transmits a signal instructing the video signal processing block 8 and the like to start drawing, and starts drawing an image based on the video signal S1. Even in this case, the luminance changing block 70 can start drawing an image based on the video signal S1 at an early stage after the power is turned on.

(4) Processing Flow FIG. 6 is a flowchart showing a processing procedure executed by the light source unit 1. The light source unit 1 repeatedly executes the process of the flowchart of FIG.

  First, the luminance change block 70 receives the control signal S2 via the interface 5, thereby acquiring the target luminance of the image to be drawn based on the video signal S1 (step S101). Next, the luminance change block 70 acquires information (also referred to as “left / right position information”) indicating the position of the gradation ND filter 32 on the Z axis from the left / right position detection sensor 34 via the ADC 22 (step S102). ). Further, the luminance change block 70 acquires the position information of the solenoid 35 from the vertical position detection sensor 43 via the ADC 22 (step S103).

  Next, the luminance change block 70 calculates a required moving distance D1 that is a required moving distance of the gradation ND filter 32 on the Z-axis when the position switching of the solenoid 35 is not assumed (step S104). In this case, first, the luminance change block 70 specifies the current laser incident position Pin based on the left / right position information acquired in step S102 and the position information of the solenoid 35 acquired in step S103. Further, the luminance change block 70 specifies the target position of the laser incident position Pin for realizing the target luminance when the gradation ND filter 32 is not moved in the vertical direction with reference to a predetermined map or the like. Then, the luminance change block 70 calculates the distance difference between the current laser incident position Pin and the target position of the laser incident position Pin described above as the necessary moving distance D1.

  Then, the luminance change block 70 determines whether or not the necessary moving distance D1 is not less than 1/2 of the previously stored filter length Lf (step S105). Then, the luminance change block 70, when the required moving distance D1 is not less than ½ of the filter length Lf (step S105; Yes), the required movement on the Z-axis when switching processing by the solenoid 35 is assumed. A necessary moving distance D2 that is a distance is calculated (step S106). Then, the luminance change block 70 transmits a drive signal to the motor driver 19 to drive the stepping motor 33, thereby moving the gradation ND filter 32 by the necessary moving distance D2 in the Z-axis direction (step S107). Then, the luminance change block 70 moves the gradation ND filter 32 in the vertical direction by transmitting a drive signal to the vertical drive circuit 20 and switching the position of the solenoid 35 (step S108). Then, the luminance change block 70 continuously acquires the position information and sensor position information of the solenoid 35, and confirms the completion of the movement of the gradation ND filter 32 (step S110).

  On the other hand, when the required moving distance D1 is less than ½ of the filter length Lf (step S105; No), the luminance change block 70 drives only the stepping motor 33 without performing the drive control of the solenoid 35, and gradation. The ND filter 32 is moved by the necessary moving distance D1 in the Z-axis direction (step S109). Then, the luminance change block 70 continuously acquires the position information and sensor position information of the solenoid 35, and confirms the completion of the movement of the gradation ND filter 32 (step S110). In this case, the laser incident position Pin overlaps a region having a transmittance that achieves the target luminance, so that the virtual image Iv is displayed with appropriate luminance in consideration of the amount of external light.

  As described above, in the first embodiment, the light source unit 1 includes the gradation ND filter 32, the stepping motor 33, and the solenoid 35. The gradation ND filter 32 includes an upper filter portion 32U and a lower filter portion 32D, and the increasing direction of the transmittance on the upper filter portion 32U is the increasing direction of the transmittance on the lower filter portion 32D. The reverse direction. In this case, the luminance change block 70 of the light source unit 1 performs the switching process by the solenoid 35 when the necessary moving distance D1 for moving the gradation ND filter 32 by the stepping motor 33 is 1/2 or more of the filter length Lf. The moving distance of the gradation ND filter 32 by the stepping motor 33 is shortened. Thus, even when the light source unit 1 is started up or when passing near the tunnel entrance / exit during image display, the high-speed movement by the solenoid 35 is used even when the target luminance must be changed greatly. Thus, the necessary movement of the gradation ND filter 32 can be completed at an early stage. In addition, even when there are fine changes in the surrounding brightness that change from moment to moment, especially when there is a fine change in the surrounding brightness at dawn or evening, fine brightness adjustment can be performed by driving the stepping motor 33. it can. As described above, in the first embodiment, the brightness can be adjusted in various situations in the vehicle environment.

<Second embodiment>
In the second embodiment, the luminance change block 70 is necessary for both the movement for the necessary movement distance D2 by the stepping motor 33 and the switching process by the solenoid 35 for the necessary movement distance D2 by the stepping motor 33. The stepping motor 33 and the solenoid 35 are controlled so that the completion timing of the movement and the completion timing of the switching process by the solenoid 35 are the same. Thereby, the moving time of the gradation ND filter 32 is suitably shortened while suitably suppressing the sudden change in luminance during image display.

Specifically, first, the luminance change block 70 calculates the necessary moving distance D2 in step S106 of the process of the flowchart of FIG. 6 and then drives the stepping motor 33 before the solenoid 35 to thereby move the Z axis of the gradation ND filter 32. Start moving in the direction first. Thereafter, the luminance change block 70, based on the left / right position information output by the left / right position detection sensor 34, moves the movement distance on the Z axis from the movement start position of the gradation ND filter 32 (also referred to as “movement distance D3”). The required time “T1” (seconds) until the moving distance D3 becomes the required moving distance D2 is specified in real time. Specifically, the luminance change block 70 is expressed by the following equation when the pulse frequency of the stepping motor 33 is “F” (pps: Pulse Per Second), and the movement distance for one pulse is the step width “Sp” (mm). To calculate the required time T1.
T1 = (D2-D3) / Sp / F

  The pulse frequency F and the step width Sp are determined in advance according to the specifications of the stepping motor 33, and are stored in advance, for example, by the luminance change block 70. When the number of pulses that drive the stepping motor 33 is “N”, the moving distance D3 is represented by “N × Sp”. Therefore, the luminance change block 70 may calculate the movement distance D3 by “D3 = N × Sp” instead of obtaining the movement distance D3 from the left and right position information output by the left and right position detection sensor 34.

  Next, the luminance change block 70 compares the above-described required time T1 with the pre-stored expected required time “T2” of the switching process by the solenoid 35, and drives the solenoid 35 when “T1 ≦ T2” is satisfied. To start.

  As described in the example of FIGS. 4B and 5, when the switching process by the solenoid 35 is executed at a timing when the movement in the Z-axis direction is not sufficiently completed, the luminance difference due to the switching is large. , It makes it easier for the observer to feel uncomfortable. On the other hand, when the movement by the stepping motor 33 and the switching process by the solenoid 35 are sequentially performed, the movement time of the gradation ND filter 32 becomes longer. In consideration of the above, in the second embodiment, the brightness changing block 70 is configured so that the stepping motor 33 completes the movement completion timing for the required movement distance D2 and the switching processing completion timing by the solenoid 35 at the same time. 33 and the solenoid 35 are controlled. Thereby, the luminance change block 70 can suitably reduce the sudden change in luminance caused by the position switching of the solenoid 35 while shortening the moving time of the gradation ND filter 32.

<Third embodiment>
FIG. 7 shows a front view of the gradation ND filter 32A according to the third embodiment observed from the incident direction of the laser beam. The gradation ND filter 32A shown in FIG. 7 is a single filter, and includes an upper filter region 32Ua corresponding to the upper filter portion 32U of the first embodiment and a lower filter portion 32D corresponding to the lower filter portion 32D of the first embodiment. The side filter region 32Da is coated. The upper filter region 32Ua has a configuration in which the transmittance increases as it is positioned in the negative Z-axis direction, like the upper filter portion 32U of FIG. Further, the lower filter region 32Da has a configuration in which the transmittance increases as it is positioned in the positive direction of the Z-axis, like the lower filter portion 32D of FIG. Also in this configuration, the luminance change block 70 can adjust the luminance of the image suitably by moving the gradation ND filter 32A in the same manner as in the first or second embodiment.

<Fourth embodiment>
FIG. 8 is a perspective view of the gradation ND filter 32B according to the fourth embodiment. As shown in FIG. 8, the gradation ND filter 32B according to the fourth embodiment is a rectangular parallelepiped that is rotatable about the Z-axis direction, which is the direction in which the transmittance increases or decreases, and is provided in the upper filter portion 32U of the first embodiment. A corresponding filter region 32Ub and a filter region 32Db corresponding to the lower filter portion 32D of the first embodiment are provided on the side surfaces. The gradation ND filter 32B is rotatable about the Z axis by a rotation mechanism 35B such as a motor.

  In the fourth embodiment, the brightness changing block 70 is configured so that the filter region 32Ub is perpendicular to the laser beam and the filter region is switched instead of switching the solenoid 35 between point A and point B in step S108 of FIG. The rotation mechanism 35B is driven to rotate the gradation ND filter 32B by about 90 ° so that the state in which 32Db is perpendicular to the laser beam is switched. By doing in this way, the brightness | luminance change block 70 can adjust the brightness | luminance of an image suitably also in 4th Example similarly to 1st Example or 2nd Example.

<Fifth embodiment>
In the fifth embodiment, during the image display, the luminance change block 70 determines that the luminance difference before and after the switching process by the solenoid 35 (also referred to as “switching luminance difference dL”) is a predetermined threshold (also referred to as “threshold dLth”). As will be described below, the position of the gradation ND filter 32 is adjusted by the stepping motor 33 before the switching process by the solenoid 35. The switching luminance difference dLth is set in advance to a luminance difference that can be accepted by the observer based on experiments or the like. Thereby, the brightness change block 70 suitably reduces the driver's uncomfortable feeling due to the sudden change in brightness during image display.

  Specifically, after calculating the required moving distance D2 in step S106 of the flowchart of FIG. 6, the luminance change block 70 moves the gradation ND filter 32 in the Z-axis direction by the required moving distance D2 and performs switching processing by the solenoid 35. The switching luminance difference dL when it is assumed to be performed is estimated. In this case, for example, the luminance change block 70 refers to a switching luminance difference by referring to a map or the like that stores in advance the switching luminance difference dL that occurs when the solenoid 35 performs switching processing at each position on the gradation ND filter 32. Estimate dL. When the estimated switching luminance difference dL is larger than the previously stored switching luminance difference dLth, the luminance change block 70 refers again to the above-described map and the like, and changes the gradation ND filter in the Z-axis direction by the necessary moving distance D2 from the current position. A position (hereinafter also referred to as “target switching position”) at which the switching luminance difference dL is equal to or smaller than the switching luminance difference dLth at a position closest to the position where the position 32 has been moved is specified, and the moving distance D2 necessary to reach the target switching position In addition to the above, a distance (also referred to as “buffering distance D4”) that requires further movement is calculated. The luminance change block 70 moves the gradation ND filter 32 in the Z-axis direction by the stepping motor 33 by the distance from the current position to the target switching position (that is, the sum of the required moving distance D2 and the buffering distance D4), After switching the position 35, the gradation ND filter 32 is moved again in the direction opposite to the moving direction before the switching by the buffering distance D4. Thereby, it is possible to suitably prevent a luminance difference greater than or equal to the switching luminance difference dLth due to the switching process by the solenoid 35 during image display.

  FIG. 9 shows the transition of the laser incident position Pin when the movement control of the gradation ND filter 32 based on the fifth embodiment is performed. In the example of FIG. 9, the luminance change block 70 calculates the necessary moving distance D2 in step S106 of FIG. 6 and then moves to the position “Pin10” moved by the necessary moving distance D2 from the current position “Pin9” of the laser incident position Pin. The switching luminance difference dL when the position of the solenoid 35 is switched is estimated, and it is determined that the switching luminance difference dL is larger than the switching luminance difference dLth. Therefore, in this case, the luminance change block 70 specifies the switching position “Pin11” where the switching luminance difference dL is equal to or smaller than the switching luminance difference dLth at the closest position from the position Pin10, and sets the distance between the position Pin10 and the switching position Pin11. A corresponding buffering distance D4 is calculated. Then, the luminance change block 70 moves the laser incident position Pin to the switching position Pin11 by moving the gradation ND filter 32 by the distance “D2 + D4” by the stepping motor 33, and then performs switching processing by the solenoid 35 to perform laser switching. The incident position Pin is changed to the position “Pin12”. Thereafter, the luminance change block 70 moves the laser incident position Pin by the buffering distance D4 in the negative Z-axis direction, which is the direction opposite to the moving direction before the switching process by the solenoid 35, thereby transmitting the target luminance. The laser incident position Pin is moved to a position “Pin 13” having a rate of 20%.

  In this way, in the fifth embodiment, the luminance change block 70 suitably reduces the driver's feeling of glare due to the sudden change in luminance even when the target luminance changes significantly during image display. can do.

  If the luminance changing block 70 determines that the image is not being displayed, the gradation ND filter 32 may be moved by the necessary moving distance D2 without calculating the buffering distance D4. In this case, as described in the first embodiment, the luminance change block 70 may start the switching process by the solenoid 35 prior to the movement by the stepping motor 33 or simultaneously with the movement by the stepping motor 33.

<Modification>
Next, modified examples suitable for each embodiment will be described. The following modifications may be applied in any combination to the above-described embodiments.

[Modification 1]
In the configuration example of FIG. 2, the light source unit 1 moves the gradation ND filter 32 in the horizontal direction by the stepping motor 33 and moves the gradation ND filter 32 in the vertical direction by the solenoid 35. However, the configuration to which the present invention is applicable is not limited to this.

  For example, the light source unit 1 may move the gradation ND filter 32 in the vertical direction by a driving source (for example, a motor) other than the solenoid 35. Similarly, the light source unit 1 may move the gradation ND filter 32 in the left-right direction by a driving source other than the stepping motor 33.

  In another example, the light source unit 1 may move the gradation ND filter 32 in the up-down direction and the left-right direction, respectively, using a single drive source. In this case, the drive source is configured to be switchable between a state in which the gradation ND filter 32 is connected to a mechanism for moving the gradation ND filter 32 in a vertical direction and a state in which the gradation ND filter 32 is connected to a mechanism for moving the gradation ND filter 32 in a horizontal direction. . Then, the luminance change block 70 sequentially moves the gradation ND filter 32 in the vertical direction and the horizontal direction based on the first example and the like by performing switching control of the clutch and the like described above. According to this configuration, the number of drive sources can be reduced and cost reduction can be realized.

[Modification 2]
The navigation device 51 may determine the target luminance of the image based on the current position information and the map data instead of or in addition to the output of the illuminance sensor 52.

  For example, the navigation device 51 refers to the current position information and map data measured by the GPS receiver, and determines whether the vehicle passes through a point where the brightness of ambient light changes abruptly, such as the entrance of a tunnel or underground passage. Judge whether or not. When the navigation device 51 determines that the vehicle passes through a point where the brightness of the ambient light changes suddenly, the navigation device 51 sets a target luminance necessary after the passage. In this case, information on target luminance to be set may be incorporated in the map data. And the navigation apparatus 51 notifies the target brightness | luminance to the light source unit 1, and the light source unit 1 performs movement control of the gradation ND filter 32 based on either of the 1st-5th Example, and laser incident position Pin Make adjustments.

[Modification 3]
In the configuration example of FIG. 2, the navigation device 51 sets the target luminance and transmits a control signal S <b> 2 instructing the target luminance to the luminance change block 70. Instead, the luminance change block 70 of the light source unit 1 may receive the output signal from the illuminance sensor 52 instead of the navigation device 51 and set the target luminance itself. Similarly, when [Modification 2] is applied, the luminance change block 70 passes through a point where the brightness of the ambient light changes abruptly based on the map data and the current position information instead of the navigation device 51. It may be determined whether or not the target luminance is set.

[Modification 4]
The use of the light source unit 1 shown in FIG. 2 is not limited to the head-up display 100. For example, the light source unit 1 is suitably applied to a display device having a laser light source such as a projector device or a head mounted display.

[Modification 5]
The transmittance of the upper filter portion 32U and the lower filter portion 32D in FIGS. 2 and 3 continuously changed in the Z-axis direction. Alternatively, when there is a predetermined transmittance that is used more frequently than other transmittances, a region corresponding to a predetermined width corresponding to the transmittance may be provided in the upper filter portion 32U and the lower filter portion 32D. Good.

  FIG. 10 shows a gradation ND filter 32C according to a modification. As shown in FIG. 10, each of the upper filter portion 32Uc and the lower filter portion 32Dc constituting the gradation ND filter 32C is provided with a predetermined width at the end portion where the region having a transmittance of about 100% is the counter electrode. . According to this configuration, the luminance changing block 70 can suitably adjust the laser incident position Pin to a region with a transmittance of about 100% without adjusting the position of the high-precision gradation ND filter 32C.

[Modification 6]
In the description of the flowchart of FIG. 6, the luminance change block 70 determines in step S105 that the switching process by the solenoid 35 is necessary when the required moving distance D1 is ½ or more of the filter length Lf. Instead, the luminance change block 70 determines that the movement of the gradation ND filter 32 is completed earlier by driving the solenoid 35 even if the required moving distance D1 is less than ½ of the filter length Lf. In that case, the solenoid 35 may be used in combination.

  In this case, for example, the luminance change block 70 stores in advance information on the time required for the switching process by the solenoid 35 and the moving speed of the gradation ND filter 32 driven by the stepping motor 33. The time required to move the respective gradation ND filters 32 when the stepping motor 33 is driven and when only the stepping motor 33 is driven is predicted. Then, the luminance change block 70 has a shorter time required for moving the gradation ND filter 32 when the stepping motor 33 and the solenoid 35 are used together than a time required for moving the gradation ND filter 32 when only the stepping motor 33 is driven. Is predicted, the switching process by the solenoid 35 is performed. Thereby, the luminance change block 70 can appropriately determine whether or not the switching process by the solenoid 35 is necessary, and can complete the movement of the gradation ND filter 32 earlier.

DESCRIPTION OF SYMBOLS 1 Light source unit 2 Projector unit 3 Light source part 4 Power supply 5 Interface 6 Power supply block 8 Video signal processing block 11 Frame memory 12 ROM
13 RAM
DESCRIPTION OF SYMBOLS 14 Timing controller 15 MEMS control block 16 MEMS driver 17 Laser control block 18 Laser driver 19 Motor driver 20 Vertical drive circuit 31 MEMS mirror 32 Gradation ND filter 33 Stepping motor 34 Left-right position detection sensor 35 Solenoid 36 Laser diode 100 Head-up display

Claims (13)

An image display device that displays an image configured based on laser light from a light source,
A light amount adjusting means having a different transmittance depending on a position where the laser beam is incident;
First moving means and second moving means for moving the light amount adjusting means so as to change the position where the laser beam is incident;
The image display apparatus according to claim 1, wherein the first moving unit and the second moving unit have different directions in which the light amount adjusting unit is moved. The first moving means moves the light amount adjusting means in the left-right direction,
The image display apparatus according to claim 1, wherein the second moving unit moves the light amount adjusting unit in a vertical direction. The light amount adjusting means has a first adjustment area and a second adjustment area where the transmittance gradually changes according to the position where the laser beam is incident,
The image display apparatus according to claim 1, wherein a direction in which the transmittance increases in the first adjustment area is opposite to a direction in which the transmittance increases in the second adjustment area. The first moving means moves the light amount adjusting means in a direction in which the transmittance gradually changes,
4. The image according to claim 3, wherein the second moving unit moves the light amount adjusting unit in a direction in which a position where the laser beam enters is switched between the first adjustment area and the second adjustment area. 5. Display device.   The light amount adjusting unit is moved by the first moving unit and the second moving unit when the moving distance of the light amount adjusting unit acquired according to the luminance of the image to be displayed is a predetermined distance or more. The image display device according to any one of claims 1 to 4.   When the light amount adjusting means is moved by the first moving means and the second moving means during the display of the image, the movement by the first moving means precedes the movement by the second moving means. The image display device according to claim 5, wherein the image display device is started.   When the light amount adjusting means is moved by the first moving means and the second moving means during the display of the image, the movement by the first moving means and the movement by the second moving means are completed simultaneously. The image display device according to claim 6.   The light amount adjusting means is moved by the first moving means and the second moving means during the display of the image, and the brightness difference of the image caused by the movement by the second moving means is a predetermined difference. If larger, the brightness difference is moved by the second moving means after being moved by the first moving means so that the luminance difference is equal to or less than the predetermined difference. The image display device according to item.   The light amount adjusting means is moved by the second moving means or after being moved by the second moving means when moved by the first moving means and the second moving means when the image is not being displayed. The image display apparatus according to claim 1, wherein the image display apparatus is moved by the first moving unit.   The image display device according to claim 1, wherein the image display device is a head-up display that allows an observer to visually recognize the image as a virtual image. A control method executed by an image display device that displays an image configured based on a laser beam from a light source and includes a light amount adjusting unit having a transmittance that varies depending on a position where the laser beam is incident.
A first moving step and a second moving step of moving the light amount adjusting means so as to change the position where the laser beam is incident;
The control method characterized in that the first moving step and the second moving step are different in the direction in which the light amount adjusting means is moved. A program executed by a computer of an image display device that displays an image configured based on a laser beam from a light source and includes a light amount adjusting unit having a different transmittance depending on a position where the laser beam is incident,
Causing the computer to function as first moving means and second moving means for moving the light amount adjusting means so as to change the position where the laser beam is incident;
The program according to claim 1, wherein the first moving unit and the second moving unit have different directions in which the light amount adjusting unit is moved.   A storage medium storing the program according to claim 12.