JP2020190617A - Virtual image display device - Google Patents

Abstract

To provide a virtual image display device that has excellent response to attitude change in displaying an image in the form of a virtual image.SOLUTION: An HUD as a virtual image display device is configured to be mounted on a vehicle, and displays an image in the form of a virtual image superimposed on a scene outside the vehicle. The HUD comprises: a light source part which emits a light beam; an optical scanning part which makes a scan with the light beam made incident from the light source part within a scanning range SR corresponding to an input voltage waveform to draw an image; and a driving control part which outputs the voltage waveform to the optical scanning part to drive the optical scanning part. The driving control part acquires information on attitude change that the vehicle has, and corrects a voltage value of a voltage waveform so as to reduce a position shift of the image from the scene due to the attitude change.SELECTED DRAWING: Figure 5

Description

The disclosure by this specification relates to a virtual image display device.

Conventionally, a virtual image display device configured to be mounted on a vehicle is known. The device disclosed in Patent Document 1 displays an image as a virtual image so as to be superimposed on the landscape outside the vehicle. The CPU acquires the posture change that occurs in the vehicle based on the captured image of the front camera or the operation information of the suspension. Further, the CPU newly calculates the display position of the first image according to the information of the posture change, and controls the projector so as to display the first image at the display position. On the other hand, the CPU does not correct the display position of the second video. Further, as the projector, a laser scanning type projector is adopted.

JP-A-2017-94882

Patent Document 1 does not show how to control the projector. In this regard, in Patent Document 1, in addition to the first image, a second image whose display position is not corrected according to the change in posture must be displayed. Therefore, a fixed scanning range is set in the laser scanning projector. It is considered that the display position of the first image relative to the scanning range is moved.

However, when the scanning range is fixed, it is necessary to set a large scanning range in advance in consideration of the movement of the display position of the first image. Therefore, although scanning is performed, the useless range in which the image is not actually drawn increases. As a result, the drawing time per frame increases. Therefore, there is concern that the responsiveness until the change in the attitude of the vehicle is reflected in the virtual image display is not good.

One of the objects of the disclosure of this specification is to provide a virtual image display device having a good response to a change in posture when displaying a virtual image of an image.

One of the embodiments disclosed herein is a virtual image display device that is configured to be mounted on a vehicle (1) and displays an image as a virtual image so as to be superimposed on a landscape outside the vehicle.
Light source units (22a, 22b, 22c) that emit light beams, and
An optical scanning unit (26) that scans an incident light beam from a light source unit and draws an image in a scanning range (SR) according to an input voltage waveform.
A drive control unit (31) that outputs a voltage waveform to the optical scanning unit and drives the optical scanning unit is provided.
The drive control unit acquires information on the attitude change that occurs in the vehicle, and corrects the voltage value in the voltage waveform so that the positional deviation of the image with respect to the landscape due to the attitude change is reduced.

According to such an aspect, the position shift assumed in the image displayed as a virtual image with respect to the landscape outside the vehicle due to the change in the posture of the vehicle is caused by the correction of the voltage value in the voltage waveform input to the optical scanning unit. It will be reduced. That is, in the optical scanning unit, the projection direction of the light beam is directly corrected by correcting the voltage value. Therefore, it is possible to eliminate or suppress the processing time such as buffering related to information processing.

Furthermore, the scanning range itself in which the light beam is scanned is changed by changing the voltage waveform. Therefore, it is possible to reduce the need to set a large scanning range in consideration of the movement of the display position of the image in advance, and it is possible to suppress the occurrence of a useless range in which the image is not actually drawn although scanning is performed. .. In other words, the increase in drawing time per frame can be suppressed. As described above, it is possible to provide a virtual image display device having a good response to a change in posture.

The reference numerals in parentheses exemplify the correspondence with the parts of the embodiments described later, and are not intended to limit the technical scope.

It is a figure which shows the mounting state of the HUD of 1st Embodiment in a vehicle. It is a block diagram which shows the structure about the control of the HUD of 1st Embodiment. It is a figure for demonstrating the optical system in the laser scanning module and a screen of 1st Embodiment. It is a front view which shows the optical scanning part of 1st Embodiment in an enlarged manner. It is a figure for demonstrating the voltage waveform by the forced drive scanning driver of 1st Embodiment, and the relationship between the voltage waveform and a scanning range. It is a figure for demonstrating the misalignment of an image due to the vibration of 1st Embodiment. It is a time chart for demonstrating the relationship between the acquisition of the posture change information of 1st Embodiment and the correction of a voltage waveform. It is a figure corresponding to FIG. 2 in one example of modification 1. It is a figure corresponding to FIG. 2 in another example of the modification 1.

One embodiment will be described with reference to the drawings.

(First Embodiment)
As shown in FIG. 1, the virtual image display device according to the first embodiment of the present disclosure is a head-up display (hereinafter, HUD) 10 configured to be mounted on the instrument panel 2 of the vehicle 1. .. The HUD 10 projects an image toward the windshield 3 of the vehicle 1. As a result, the HUD 10 displays the image as a virtual image VRI so as to be visible to the occupant of the vehicle 1 as a viewer. In particular, in the present embodiment, the occupant can visually recognize the virtual image VRI that overlaps with the scenery outside the vehicle 1 through the windshield. That is, the virtual image VRI by the HUD 10 includes an Augmented Reality (AR) display that extends the reality by displaying content superimposed on, for example, a road surface or a building.

In the following, unless otherwise specified, each direction indicated by front, rear, up, down, left and right is described with reference to vehicle 1 on the horizontal plane. Further, when the vehicle 1 is present on the horizontal plane, the direction parallel to the horizontal plane is defined as the horizontal direction HD, and the direction perpendicular to the horizontal plane is defined as the vertical direction VD.

The windshield 3 of the vehicle 1 is a transparent member formed in a translucent plate shape by, for example, glass or synthetic resin, and is arranged above the instrument panel 2. The windshield 3 is inclined so as to be separated from the instrument panel 2 from the front to the rear. The image may be projected not on the windshield 3 but on a combiner installed in the vehicle 1 separately from the vehicle 1.

As shown in FIG. 2, the vehicle 1 is equipped with an image generation ECU (Electric Control Unit) 4. The image generation ECU 4 is a so-called computer, and is mainly composed of an electronic circuit including at least one processor, a memory device, and an input / output interface. A processor is an arithmetic circuit that executes a computer program stored in a memory device. A memory device is a non-transitional substantive recording medium provided by, for example, a semiconductor memory or a magnetic disk, which stores computer programs and data readable by a processor non-temporarily.

The image generation ECU 4 acquires various information from the vehicle 1 and the like, and generates image data displayed by the HUD 10 based on the information. The image generation ECU 4 sequentially outputs the generated image data toward the HUD 10.

As shown in FIGS. 1 to 3, the HUD 10 includes a laser scanning module 21, a screen 13, a light guide unit 15, a control unit 17, and the like. As shown in FIG. 1, the laser scanning module 21, the screen 13, the light guide unit 15, and the control unit 17 are housed in a housing 11 having a hollow shape. The housing 11 has a window portion that is optically opened on the upper surface portion facing the windshield 3. The window portion may be mechanically opened, and may be covered with, for example, a dustproof sheet capable of transmitting light that contributes to displaying an image.

The laser scanning module 21 is a drawing device that constitutes an image projected on the screen 13 by scanning a laser beam as a light beam.

The screen 13 is a reflective screen formed in a micromirror array shape by depositing a metal film such as aluminum on the surface of a base material made of, for example, synthetic resin or glass. The screen 13 is formed in a plate shape in which a plurality of micromirrors having a plurality of mirror curved surfaces that reflect light are arranged in a grid pattern. When a laser beam is incident on such a screen 13, the screen 13 can project the laser beam from the screen 13 by expanding the spread angle of the laser beam while forming an image of the laser beam in the vicinity of the mirror curved surface. .. As a result, the space area in which the occupant can see the virtual image VRI in the vehicle 1, that is, the eyebox EB is expanded. As the screen 13, a transmissive screen formed in a microlens array shape or a diffuser plate may be adopted instead.

The light guide unit 15 is an optical system that guides a laser beam that contributes to the display of an image emitted from the screen 13 toward the windshield 3. As the light guide unit 15, various configurations such as a configuration composed of one concave mirror, a configuration in which one plane mirror and one concave mirror are combined, a configuration in which one convex mirror and one concave mirror are combined, and the like can be adopted. .. Here, it is preferable that the light guide unit 15 has a function of enlarging the virtual image VRI visually recognized by the occupant with respect to the image projected on the screen 13.

The control unit 17 shown in FIG. 2 is a so-called computer, and is mainly composed of an electronic circuit including at least one processor, a memory device, and an input / output interface. The electronic circuit is composed of a plurality of electronic components mounted on the HUD substrate 17a and the like. A processor is an arithmetic circuit that executes a computer program stored in a memory device. A memory device is a non-transitional substantive recording medium provided by, for example, a semiconductor memory or a magnetic disk, which non-temporarily stores a computer program readable by a processor.

The control unit 17 is electrically connected to the laser scanning module 21. Further, the control unit 17 is communicably connected to the image generation ECU 4. Examples of the communication referred to here include communication based on a communication standard such as CAN (registered trademark), and various suitable communication methods can be adopted regardless of wired communication or wireless communication.

The control unit 17 controls the operation of the laser scanning module 21. Specifically, the control unit 17 functions as a power supply unit that supplies power to the laser scanning module 21 via a power source. Further, the control unit 17 acquires image data from the image generation ECU 4, converts it into an image signal suitable for drawing by the laser scanning module 21, and outputs the image data to the laser scanning module 21.

The details of the laser scanning module 21 will be described below. The laser scanning module 21 is composed of a plurality of laser emitting units 22a, 22b, 22c, a laser guiding unit 24, an optical scanning unit 26, a drive control unit 31, and the like.

As shown in FIG. 3, the laser light emitting units 22a to 22c function as a light source unit that emits a laser beam for displaying an image. For example, three laser light emitting units 22a to 22c are provided, and each of them emits a laser beam in a pulse shape. In the present embodiment, for example, a laser diode is adopted in each of the laser emitting units 22a to 22c.

The three laser light emitting units 22a to 22c are adapted to emit laser beams having different wavelengths α, β, and γ from each other. The peak wavelength α of the laser beam emitted by the laser emitting unit 22a is, for example, a green wavelength in the range of 500 to 560 nm, preferably 540 nm. The peak wavelength β of the laser beam emitted by the laser emitting unit 22b is, for example, a blue wavelength in the range of 430 to 470 nm, preferably 450 nm. The peak wavelength γ of the laser beam emitted by the laser emitting unit 22c is, for example, a red wavelength in the range of 600 to 650 nm, preferably 640 nm.

The laser guide unit 24 guides the laser beams emitted from the laser light emitting units 22a to 22 to a common optical path so as to overlap each other. The laser guide unit 24 is composed of a plurality of condenser lenses 24a, 24b, 24c, a folded mirror 24d, a dichroic mirror 24e, 24f, and the like. The number of condenser lenses 24a to 24c is the same as that of the laser light emitting units 22a to 22c (for example, three). The number (for example, two) of the dichroic mirrors 24e and 24f is one less than that of the laser emitting units 22a to 22c.

The three condenser lenses 24a to 24c are arranged at predetermined intervals in the traveling direction of each laser beam with respect to the corresponding laser light emitting units 22a to 22c. The condensing lenses 24a to 24c are formed of, for example, synthetic resin or glass with translucency. The condensing lenses 24a to c condense the laser beams from the corresponding laser emitting units 22a to 22c by refraction so that the beam waist of each laser beam is located near the screen 13 or on the screen 13. ,adjust.

The folded mirror 24d is arranged with respect to the condenser lens 24a at a predetermined interval in the traveling direction of the laser beam, and reflects the green wavelength laser beam transmitted through the condenser lens 24a.

The two dichroic mirrors 24e and 24f are arranged at predetermined intervals in the traveling direction of each laser beam with respect to the corresponding condenser lenses 24b and 24c, respectively. The dichroic mirrors 24e and 24f reflect the laser beam having a specific wavelength among the laser beams transmitted through the condenser lenses 24a to 24c, and transmit the other laser beams. Specifically, the dichroic mirror 24e corresponding to the condenser lens 24b reflects a laser beam having a blue wavelength and transmits a laser beam having a green wavelength. The dichroic mirror 24f corresponding to the condenser lens 24c reflects a laser beam having a red wavelength and transmits a laser beam having a green wavelength and a blue wavelength.

Here, the dichroic mirrors 24e are arranged at predetermined intervals in the traveling direction of the laser beam having a green wavelength after being reflected by the folded mirror 24d. Further, the dichroic mirrors 24f are arranged at predetermined intervals in the traveling direction of the laser beam having a blue wavelength after being reflected by the dichroic mirror 24e. With these arrangements, the green wavelength laser beam reflected by the folded mirror 24d passes through the dichroic mirror 24e and is superimposed on the blue wavelength laser beam reflected by the dichroic mirror 24e. Further, the green wavelength and blue wavelength laser beams pass through the dichroic mirror 24f and are superposed on the red wavelength laser beam after reflection by the dichroic mirror 24f.

Further, as shown in FIG. 2, each laser emitting unit 22a to 22c is electrically connected to the drive control unit 31. Each of the laser light emitting units 22a to 22c emits a laser beam in a pulse shape according to an electric signal from the drive control unit 31. Then, by adding and mixing the laser beams of three colors emitted from each laser emitting unit 22a, it is possible to reproduce various colors in the image. In this way, each laser beam is incident on the optical scanning unit 26 from substantially the same direction in a state of being superposed on a common optical path.

The optical scanning unit 26 is a MEMS mirror configured to be able to scan a laser beam in time using a Micro Electro mechanical Systems (MEMS). A reflective surface 26a is formed on the surface of the optical scanning unit 26 facing the dichroic mirror 24f at a predetermined distance by metal deposition of aluminum or the like. The reflecting surface 26a can swing around two rotation axes Ax and Ay arranged substantially orthogonally along the tangent plane of the reflecting surface 26a.

As shown in detail in FIG. 4, the reflective surface 26a is supported by the inner support beam 26b. The inner support beam 26b is arranged so as to extend along the rotation axis Ay. An inner frame body 26c is formed on the outer side of the inner support beam 26b so as to surround the outer circumference of the reflecting surface 26a. The inner frame body 26c supports the inner support beam 26b and is supported by the outer support beam 26d. The outer support beam 26d is arranged so as to extend in a direction substantially orthogonal to the inner support beam 26b, that is, along the rotation axis Ax. An outer frame body 26e is formed on the outer side of the outer support beam 26d so as to surround the entire circumference of the inner frame body 26c. The outer frame body 26e supports the outer support beam 26d.

As shown in FIGS. 2 and 3, the reflective surface 26a of the optical scanning unit 26 is electrically connected to the drive control unit 31, and swings by the electric signal to change the direction. Can be done. Then, the light scanning unit 26 deflects the projection direction of the laser beam onto the screen 13 in a timely manner starting from the deflection point TP, which is the incident point of the laser beam on the reflection surface 26a, by controlling the direction. It becomes possible. In this way, the laser beam is scanned and an image can be drawn on the screen in, for example, a rectangular scanning range SR.

Here, when the reflecting surface 26a is swung around the rotation axis Ay, the laser beam is scanned in the longitudinal direction LD of the scanning range SR. The longitudinal LD of the scanning range SR corresponds to the left-right direction (or the horizontal HD of the vehicle 1) in the virtual image VRI. When the reflecting surface 26a is swung around the rotation axis Ax, the laser beam is scanned in the lateral SD of the scanning range SR. The short side SD of the scanning range SR corresponds to the vertical direction (or the vertical direction VD of the vehicle 1) in the virtual image VRI.

The drive control unit 31 shown in FIG. 2 outputs a voltage waveform to the optical scanning unit 26 and controls the driving of the optical scanning unit 26. At the same time, the drive control unit 31 controls the drive of the laser light emitting units 22a to 22c to form an image on the screen 13 according to the emission timing of the laser beam linked with the scanning. The drive control unit 31 includes a scanning controller 32, a light emitting driver 34, a resonance scanning driver 36, a forced driving scanning driver 38, a gyro sensor 40, and the like. In the drive control unit 31, various processes are performed by a clock oscillator (not shown) based on a substantially constant operating clock.

The scanning controller 32 is realized by hardware, for example, by an FPGA (Field-Programmable Gate Array). FPGA is a kind of integrated electronic circuit such as so-called PLD (Programmable logic device), and is included in a processor in a broad sense. FPGA realizes complicated processing by arranging a large number of logic gates, but it can be executed at a higher speed than processing by executing a computer program or while suppressing delay.

The scanning controller 32 is electrically connected to the control unit 17, the drivers 34, 36, 38, and the gyro sensor 40. The scanning controller 32 decomposes and converts the image signal input from the control unit 17 into a signal for controlling the light emitting driver 34, a signal for controlling the resonance scanning driver 36, and a signal for controlling the forced drive scanning driver 38, and outputs the signal. , Each driver 34, 36, 38 is controlled in cooperation with each other. At the time of signal conversion, correction is performed based on the signal input from the gyro sensor 40.

The light emitting driver 34 is a circuit that controls each laser light emitting unit 22a to 22c. Specifically, the light emitting driver 34 controls the light emitting timing and the light emitting intensity of each of the laser light emitting units 22a to 22c based on the signal from the scanning controller 32.

The resonance scanning driver 36 is a circuit that controls scanning around the rotation axis Ay among the scanning by the optical scanning unit 26. Specifically, the resonant scanning driver 36 generates and outputs a voltage waveform applied to the piezoelectric element 26f for twisting the inner support beam 26b based on the signal from the scanning controller 32.

More specifically, in scanning around the rotation axis Ay, the inner support beam 26b is twisted by controlling the voltage value applied to the piezoelectric element 26f in a relatively small cycle. Due to the twist of the support beam 26b, the reflecting surface 26a swings around the rotation axis Ay. When the support beam 26b is twisted, the elastic reaction force of the support beam 26b acts in the direction opposite to the twisting direction. Utilizing this elastic reaction force, the reflecting surface 26a can be resonated at a predetermined natural vibration frequency corresponding to the spring constant of the support beam 26b. Therefore, in the optical scanning unit 26, the drive of the vehicle 1 in the direction corresponding to the horizontal HD is a resonance drive utilizing the resonance phenomenon. The voltage waveform for resonance driving is, for example, a sine wave.

The forced drive scanning driver 38 is a circuit that controls scanning around the rotation axis Ax among the scanning by the optical scanning unit 26. Specifically, the forced drive scanning driver 38 generates and outputs a voltage waveform applied to the piezoelectric element 26g for twisting the outer support beam 26d based on the signal from the scanning controller 32.

More specifically, in scanning around the rotation axis Ax, the voltage value applied to the piezoelectric element 26g is controlled so that the outer support beam 26d is twisted and the inner frame body 26c is around the rotation axis Ax together with the reflection surface 26a. Swing to. In order to suppress the vibration due to the elastic reaction force of the support beam 26d, the voltage waveform of this vibration is assumed to have a period sufficiently larger than the natural vibration period in the resonance drive. Therefore, in the optical scanning unit 26, the drive in the direction corresponding to the vertical VD of the vehicle 1 is a forced drive in which the voltage value applied to the piezoelectric element 26 g determines the instantaneous amplitude in the swing around the rotation axis Ax. There is.

The voltage waveform for forced driving is, for example, a sawtooth wave as shown in FIG. The sawtooth wave constitutes one cycle by a set of a rapid fluctuation period PR and a slow fluctuation period PG. The sudden fluctuation period PR corresponds to the division between frames in drawing an image. While the voltage value fluctuates linearly in the sudden fluctuation period PR, the direction of the reflecting surface 26a is changed so as to return from the drawing end position of the current frame to the drawing start position of the next frame at high speed. During this period, drawing is not performed by emitting the laser beam.

The slow fluctuation period PG corresponds to the process of drawing a one-frame image. While the voltage value linearly fluctuates in the direction opposite to the sudden fluctuation period PR in the slow fluctuation period PG, the drawing of the frame ends from the drawing start position of the current frame by the combination of the resonance scanning and the forced drive scanning. To the position, the laser beam is two-dimensionally scanned on the screen. During this period, laser beams are emitted from the three laser emitting units 22a to 22c at appropriate emission timings and emission intensities according to the brightness and hue of each pixel of the image.

Then, the voltage value V0 at the start of the slow fluctuation period PG determines the position of one end (upper end in the present embodiment) of the vertical VD in the scanning range SR, and the voltage value V1 at the end of the slow fluctuation period PG is the scanning range. The position of the other end (lower end in this embodiment) of the vertical VD in the SR is determined.

By continuously repeating a plurality of cycles in the sawtooth wave, the image can be updated at a predetermined frame rate (for example, about 40 to 80 fps).

As shown in FIG. 2, the gyro sensor 40 detects a posture change that occurs in the vehicle 1. This attitude change is both a low-frequency attitude change such as a change in direction due to steering of the vehicle 1 and a change in direction of the vehicle 1 due to a slope of the road surface, and a high-frequency attitude change such as vibration of the vehicle 1 due to unevenness of the road surface. It is a concept including. However, in the present embodiment, the latter high-frequency attitude change is the main subject of correction.

The gyro sensor 40 includes a gyro detection unit 41 and a gyro processing unit 42. The gyro detection unit 41 is formed so that the angular velocity as information on the attitude change can be sequentially detected. For the detection of the angular velocity, for example, a mechanical method using a flywheel mechanism, a vibration bar mechanism, or an optical method using an optical fiber can be adopted.

The gyro processing unit 42 acquires the detection result by the gyro detection unit 41. The gyro processing unit 42 has a filter circuit that filters the detection result and outputs it to the scanning controller 32. The gyro processing unit 42 executes a time averaging process for time-averaging the angular velocities detected by the gyro detecting unit 41 at a predetermined time, a conversion process for integrating the time-averaged angular velocities and converting them into angles, and the like by using a filter circuit. .. The attitude change information filtered by the gyro processing unit 42 in this way is input to the scanning controller 32 once per cycle of the voltage waveform, that is, once per drawing of one frame of the image.

Based on the acquired attitude change information, the scanning controller 32 corrects the scanning range SR along the vertical VD so that the positional deviation of the image due to the attitude change with respect to the landscape outside the vehicle 1 is reduced. To do. As shown in FIG. 6, even if the display content of the image is accurately superimposed on the landscape outside the vehicle 1 when one frame is drawn in the image, the vehicle 1 is vertically VD due to the unevenness of the road surface. If an image is drawn with the same scanning range SR in the next frame when it vibrates, the displayed content may be displaced with respect to the landscape. Therefore, in the present embodiment, the scanning range SR of the vertical VD is changed for each frame based on the attitude change.

The scanning controller 32 calculates the displacement of the angle at the time of acquiring the information on the current attitude change with respect to the angle of the vehicle at the time of acquiring the information on the previous attitude change. This displacement corresponds to the displacement of the vertical VD with respect to the landscape of the image. The scanning controller 32 performs a correction process for correcting the voltage value in the forced drive voltage waveform so as to reduce this positional deviation.

More specifically, the scanning controller 32 calculates a voltage offset value Voff that offsets this misalignment. Then, as shown in FIG. 5, the scanning controller 32 offsets the voltage value of the slow fluctuation period PG in the voltage waveform as a whole by the offset value Voff when drawing one frame immediately after the attitude change acquisition. Since the voltage value V0 at the start of the slow fluctuation period PG and the voltage value V1 at the end are changed by the same offset value Voff, one end and the other end of the vertical VD in the scanning range SR are substantially both. Move in the same direction and by the same amount. As a result, the scanning range SR in the next frame is shifted to the vertical VD as a whole. At this time, since the scanning range SR is not extended, the pixel pitch is not changed.

By the way, as shown in FIG. 7, in the correction of the scanning range SR, it is preferable that the process from the detection of the attitude change to the drawing by the gyro sensor 40 is performed in a time shorter than one cycle of the voltage waveform.

Therefore, both processes are simplified so that the processing time of the time averaging process and the conversion process in the gyro processing unit 42 is sufficiently smaller than one cycle. Then, the posture change information is input to the scanning controller 32 by a route different from the video signal. Specifically, the attitude change information is input to the portion of the FPGA that realizes the scanning controller 32, which is close to the output side. Immediately before the scanning controller 32 outputs a signal to the forced driving scanning driver 38, the voltage waveform correction processing is performed, so that the information on the latest attitude change can be immediately reflected in the forced driving of the optical scanning unit 26. .. Therefore, in parallel with the drawing of the current frame, the time averaging process and the conversion process in the gyro processing unit 42 and the correction process by the scanning controller 32 for changing the scanning range SR of the next frame are executed.

(Action effect)
The effects of the first embodiment described above will be described again below.

According to the first embodiment, the position shift assumed in the image displayed as a virtual image with respect to the landscape outside the vehicle 1 due to the change in the posture of the vehicle 1 is the voltage value in the voltage waveform input to the optical scanning unit 26. It is reduced by the correction of. That is, in the optical scanning unit 26, the projection direction of the laser beam as the light beam is directly corrected by the correction of the voltage value. Therefore, it is possible to eliminate or suppress the processing time such as buffering related to information processing.

Furthermore, the scanning range SR itself in which the laser beam is scanned is changed by changing the voltage waveform. For this reason, it is possible to reduce the need to set a large scanning range SR in consideration of the movement of the display position of the image in advance, and to suppress the occurrence of a useless range in which the image is not actually drawn although scanning is performed. it can. In other words, the increase in drawing time per frame can be suppressed. From the above, it is possible to provide the HUD 10 as a virtual image display device having a good response to a posture change.

Further, according to the first embodiment, the optical scanning unit 26 that is forcibly driven in the direction corresponding to the vertical VD of the vehicle 1 is corrected for the voltage value in the voltage waveform of the forced drive to obtain the vertical VD. Misalignment is reduced. In the forced drive, since the voltage value determines the instantaneous amplitude, the projection direction of the laser beam can be accurately determined by the voltage value. Therefore, it is possible to realize high responsiveness and highly accurate reduction of misalignment.

Further, according to the first embodiment, an offset value Voff that offsets the misalignment of the vertical VD of the vehicle 1 is calculated for each frame of the image, and the voltage value is offset by the offset value Voff during the drawing of the one frame. Then, the scanning range SR is shifted to the vertical VD. Then, by simply correcting the voltage value, the scanning range SR can be moved while suppressing the deformation of the scanning range SR, and the positional deviation can be reduced by high responsiveness.

Further, according to the first embodiment, the correction process of the voltage waveform in the next one frame is executed in parallel with the drawing of one frame of the image. Then, the delay in drawing due to the correction process can be reduced, and the most recent posture change can be reflected in the movement of the scanning range SR.

Further, according to the first embodiment, the drive control unit 31 in the laser scanning module 21 is provided with a gyro detection unit 41 for detecting a posture change occurring in the vehicle 1. Then, since the same vibration as the vibration applied to the laser scanning module 21 can be detected, the accuracy of reducing the positional deviation can be improved, and the signal from the gyro detection unit 41 can be stably acquired, so that the operation in the correction of the voltage value can be performed. Can increase the stability of.

(Other embodiments)
Although one embodiment has been described above, the present disclosure is not construed as being limited to the embodiment, and can be applied to various embodiments without departing from the gist of the present disclosure.

Specifically, as a modification 1, the gyro sensor 40 may be arranged outside the laser scanning module 21. In the example of FIG. 8, the gyro sensor 40 is mounted on the HUD substrate 17a. The gyro sensor 40 has a gyro detection unit 41 and a gyro processing unit 42 as in the first embodiment. The gyro sensor 40 is electrically connected to the scanning controller 32 by a route different from the connection between the control unit 17 and the scanning controller 32. The drive control unit 31 acquires the information after being filtered by the gyro processing unit 42 as the information on the posture change that occurs in the vehicle 1.

Further, in the example of FIG. 9, the gyro sensor 40 is installed in the housing 11 of the HUD 10. Also in this case, the drive control unit 31 acquires the information after being filtered by the gyro processing unit 42 as the information on the posture change that occurs in the vehicle 1.

As a modification 2, the information on the posture change occurring in the vehicle 1 may be detected by using an acceleration sensor or the like other than the gyro sensor 40 if it is an inertial sensor. The accuracy of the attitude change information may be improved by combining the position information by the GPS receiver, the information of the geomagnetic sensor, and the like in addition to these inertial sensors.

The control unit and its method described in the present disclosure may be realized by a dedicated computer constituting a processor programmed to execute one or more functions embodied by a computer program. Alternatively, the apparatus and method thereof described in the present disclosure may be realized by a dedicated hardware logic circuit. Alternatively, the apparatus and method thereof described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor that executes a computer program and one or more hardware logic circuits. Further, the computer program may be stored in a computer-readable non-transitional tangible recording medium as an instruction executed by the computer.

1: Vehicle, 10: HUD (virtual image display device), 22a, 22b, 22c: Laser light emitting unit (light source unit), 26: Optical scanning unit, 31: Drive control unit, SR: Scanning range

Claims (6)

A virtual image display device that is configured to be mounted on a vehicle (1) and displays an image as a virtual image so as to be superimposed on the landscape outside the vehicle.
Light source units (22a, 22b, 22c) that emit light beams, and
An optical scanning unit (26) that scans the light beam incident from the light source unit and draws the image in a scanning range (SR) corresponding to the input voltage waveform.
A drive control unit (31) that outputs the voltage waveform to the optical scanning unit and drives the optical scanning unit is provided.
The drive control unit acquires information on a posture change that occurs in the vehicle, and corrects a voltage value in the voltage waveform so that the positional deviation of the image with respect to the landscape due to the posture change is reduced. apparatus. In the optical scanning unit, the drive in the direction (SD) corresponding to the vertical direction (VD) of the vehicle is a forced drive in which the voltage value determines the instantaneous amplitude.
The virtual image display device according to claim 1, wherein the drive control unit corrects the voltage value in the voltage waveform of the forced drive so as to reduce the positional deviation of the vehicle in the vertical direction as the posture change. .. The drive control unit calculates an offset value that offsets the vertical misalignment of the vehicle for each frame of the image, and offsets the voltage value by the offset value during the drawing of the one frame. The virtual image display device according to claim 2, wherein the scanning range is shifted in a direction corresponding to the vertical direction. The virtual image display device according to claim 3, wherein the drive control unit executes a process of correcting the voltage value in the next one frame in parallel with drawing the one frame of the image. The virtual image display device according to any one of claims 1 to 4, wherein the drive control unit includes a detection unit (41) for detecting the posture change. The detection unit (41) that detects the posture change and
A processing unit (42) for filtering the detection result by the detection unit is further provided.
The virtual image display device according to any one of claims 1 to 4, wherein the drive control unit acquires information after being filtered by the processing unit as information on the posture change.

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