Laser scanning projection device and scanning control device

Abstract

A scanning control device and a laser scanning projection device according to the present invention comprise: a video data generation unit that receives a video signal and generates video data; a memory that stores a non-resonant drive curve being a drive characteristic of non-resonant drive of an optical deflector and representing an amplitude (AMP) with respect to a drive periodic position (PP) in a drive period corresponding to one frame of a video; and an interpolation unit that obtains an interpolation drive curve using a plurality of offset points (CP1-CP5) for the non-resonant drive curve of the optical deflector. The interpolation unit stores the offset points (CP1-CP5) of the non-resonant drive curve in which at each of division positions obtained by dividing the drive period corresponding to one frame into n (n is an integer of two or more) parts, the drive periodic position and a shift amount in the periodic direction with respect to the non-resonant drive curve are associated with each other. The interpolation unit calculates the interpolation drive curve passing through the offset points (CP1-CP5), and the video data generation unit generates the video data on the basis of the drive periodic position of the interpolation drive curve.

Description

Laser scanning projection device and scanning control device

[0001] The present invention relates to a laser scanning projection device and a scanning control device.

[0002] There is known a video projection device (projector) that scans laser light emitted from a light source with an optical deflector such as a MEMS (Micro Electro Mechanical System) to produce a high-definition image with excellent color reproducibility. Furthermore, there is known a video projection device that projects high-definition images such as head-up displays and road surface images as vehicle lighting fixtures mounted on vehicles.

[0003] For example, Patent Document 1 discloses a technique in which copies of drive signals in the main scanning direction and sub-scanning direction are generated, and the entire waveforms of the copies are delayed to offset the drawing interval using delay signals to draw an image.

[0004] Furthermore, Patent Document 2 discloses optimizing the control curve of an optical scanner so as to increase the light utilization rate.

[0005] Patent No. 6364312 Patent No. 6463507

[0006] When an optical scanner such as a MEMS is linearly driven, hysteresis in the drive of the non-resonant axis causes a mismatch between the control waveform and the actual behavior of the mirror, resulting in distortion of the projected image and a reduction in the resolution of the projected image. In other words, when projecting a high-definition image, the hysteresis can cause a double image in the projected image. For example, the image projection device described in Patent Document 1 cannot solve the image distortion caused by hysteresis during reciprocal scanning.

[0007] The present invention has been made in consideration of the above points, and aims to provide a laser scanning projection device and a scanning control device that compensate for hysteresis in non-resonant axis drive, suppress distortion of the projected image, and produce a projected image with high resolution.

[0008] a memory for storing a non-resonant drive curve representing a drive characteristic of the non-resonant drive of the optical deflector, the non-resonant drive curve representing an amplitude versus a drive cycle position in a drive period corresponding to one frame of the image; and an interpolation unit for calculating an interpolated drive curve using a plurality of offset points for the non-resonant drive curve of the optical deflector, wherein the interpolation unit divides the drive period corresponding to one frame into n (n is an integer of 2 or more) and stores the offset points of the non-resonant drive curve, each of which is associated with the drive cycle position at each divided position and a shift amount in the periodic direction relative to the non-resonant drive curve; the interpolation unit calculates the interpolated drive curve passing through the offset points; and the image data generation unit generates the image data based on the drive cycle position of the interpolated drive curve.

[0009] A laser scanning projection device according to another embodiment of the present invention comprises the above-described scanning control device and a semiconductor laser light source that emits the laser light, wherein the optical deflector performs non-resonant driving of the rotating mirror to scan the laser light, and the semiconductor laser light source projects the image based on the image data from the image data generation unit of the scanning control device.

[0010] 5A . is a block diagram showing the configuration of a laser scanning projection device of a first embodiment. FIG. 5B is a perspective view showing the configuration of an optical deflector. FIG. 5C is a diagram schematically showing scanning in a non-resonant drive direction of an optical deflector performed under the control of a control device. FIG. 5D is a diagram showing a plurality of observation points in a vertical direction V (non-resonant drive direction) in an image formed by scanning of laser light. FIG. 5E is a diagram showing offset points and a laser control curve signal in a scanning period (drive period) of one cycle (0.5 cycles for the forward path and 0.5 cycles for the return path). FIG. 5F is a partial enlarged view showing a portion W of FIG. 5A . FIG. 5G is a diagram showing an image when the amplitude of non-resonant drive is optimized at a plurality of observation points. FIG. 5H is a block diagram showing the configuration of a laser control curve generation unit. FIG. 5I is a diagram showing an example of a calculation formula for a method of generating a memory address for a laser control curve. FIG. 5I is a diagram showing a comparison of an image input, a projected image of a comparative example, and a projected image of this embodiment. FIG. 5J is a diagram showing a first modified example of the embodiment, showing offset points and a laser control curve signal in a drive period of 0.5 cycles for the forward path.

[0011] In the following, preferred embodiments of the present invention will be described, but these may be modified and combined as appropriate. In the following description and accompanying drawings, substantially the same or equivalent parts are designated by the same reference numerals.

[0012] [First Embodiment] 1. Laser Scanning Device Fig. 1 is a block diagram showing the configuration of a laser scanning projection device 5, which is an image projection device of this embodiment. As shown in Fig. 1, the laser scanning projection device 5 has a control device 10 (scanning control device), a semiconductor laser light source 20, and an optical deflector 30. The optical deflector 30 performs scanning with laser light from the semiconductor laser light source 20 in response to a control signal from the control device 10.

[0013] The scanned laser light LB is projected onto a road surface, a spatial area, a screen, or the like to form a projected image PI. The present invention can be applied to, but is not limited to, a projector, road surface painting, a headlamp, a distance measurement sensor, and the like.

[0014] The control device 10 includes a video data generator 11, a laser driver 12, a sensor signal processor 13, a resonant drive signal generator 14, a non-resonant drive signal generator 15, and a controller 16. The controller 16 includes a laser control curve generator 50.

[0015] A video input signal VI is input to the video data generation unit 11. The video input signal VI may be, but is not limited to, a video signal output from an electronic device such as a computer, an in-vehicle electronic control unit (ECU), a camera system, or a smartphone.

[0016] The video data generator 11 receives a laser control curve signal CLD indicating the laser control curve from the laser control curve generator 50 of the controller 16, and generates video data DP based on the laser control curve signal CLD. The video data DP includes, but is not limited to, light intensity data for the laser of each wavelength. It may also include on / off data indicating blanking regions in which the laser is turned off.

[0017] The laser driver 12 generates a laser drive signal VD based on the video data DP from the video data generator 11, and drives the semiconductor laser light source 20. The semiconductor laser light source 20 is provided with a drive electronic circuit (not shown). The number of semiconductor lasers provided in the semiconductor laser light source 20 is not limited to one. The semiconductor laser light source 20 may be provided with red, green, and blue wavelength lasers, for example, and configured to be able to project full-color images.

[0018] The sensor signal processing unit 13 receives a voltage signal MS corresponding to the deflection angle of the MEMS mirror 130 (see FIG. 2 ) from the optical deflector 30, generates a sensor signal SS including phase difference information and the like, and supplies the signal to the control unit 16. Based on the sensor signal SS, the control unit 16 sends an abnormality signal SA indicating an abnormality in the MEMS mirror 130 or the like to the laser driving unit 12, and performs control such as stopping the laser driving.

[0019] The resonant drive signal generating unit 14 generates a resonant drive signal VR in response to a control signal SR from the control unit 16 and supplies it to the optical deflector 30. In addition, the non-resonant drive signal generating unit 15 generates a non-resonant drive signal VN in response to a control signal SN from the control unit 16 and supplies it to the optical deflector 30.

[0020] In addition to the signals mentioned above, the control unit 16 is configured to receive various signals from each of the above-mentioned units and to transmit various signals to each of the above-mentioned units to control each of the above-mentioned units.

[0021] 2. Optical Deflector FIG. 2 is a perspective view showing the configuration of the optical deflector 30. The optical deflector 30 is a uniaxial non-resonant / uniaxial resonant optical deflector. Note that, while the following description will be given assuming that the optical deflector 30 is a piezoelectric optical deflector, various optical deflectors, such as electrostatic and electromagnetic types, can also be used. The optical deflector 30 includes a MEMS mirror 130 (rotating mirror), a first support 133 that supports the MEMS mirror 130 with a pair of torsion bars 131A and 131B, and first actuators 134A and 134B that rotate the MEMS mirror 130 around the Y axis and resonantly drive it in the main scanning direction.

[0022] The optical deflector 30 also has a second support portion 135 that supports the first support portion 133, and second actuators 140 and 142 that rotate the first support portion 133 about the X axis relative to the second support portion 135 and non-resonantly drive the MEMS mirror 130 in the sub-scanning direction. In other words, the optical deflector 30 is a one-axis non-resonant / one-axis resonant two-axis optical deflector that is capable of two-dimensional scanning.

[0023] The laser scanning projection device 5 equipped with the optical deflector 30 projects light in accordance with two-dimensional scanning of the drawing range (image projection range) and turns on the semiconductor laser light source 20, thereby achieving high light utilization efficiency.

[0024] In this embodiment, piezoelectric actuators are used as the resonantly driven actuators 134A and 134B. Furthermore, the non-resonantly driven actuators 140 and 142 are each configured by connecting four piezoelectric cantilevers. Each of the piezoelectric cantilevers 140A to 140D and 142A to 142D of the actuators 140 and 142 is made of a laminated body that includes a support, a lower electrode, a piezoelectric body, and an upper electrode.

[0025] Each of the actuators 140 and 142 is formed as a bellows-shaped (meander-type) piezoelectric actuator, with four piezoelectric cantilevers 140A to 140D and 142A to 142D, respectively, connected so that their ends are folded back. Projection of an image based on a video signal is performed by resonant scanning (high-speed scanning) in the horizontal direction H and non-resonant scanning (low-speed scanning) in the vertical direction V. That is, the MEMS mirror 130 is rotated in the main scanning direction (horizontal direction) by resonant driving of the actuators 134A and 134B, which are compatible with high-speed operation, and is rotated in the sub-scanning direction (vertical direction) by non-resonant driving of the actuators 140 and 142, which are compatible with low-speed operation.

[0026] The first support portion 133 is provided with resonant sensors 144A and 144B (resonant sensors 144) at the bases of the torsion bars 131A and 131B to detect the rotation state of the MEMS mirror 130. In addition, non-resonant sensors 146A and 146B (non-resonant sensors 146) are provided near the actuators 140 and 142.

[0027] These sensors may be piezoelectric sensors or sensors using the piezoresistive effect. The piezoelectric sensor functions as a velocity sensor that returns a differential value relative to the amount of displacement of the deflection angle of the MEMS mirror 130. The sensor using the piezoresistive effect functions as a position sensor that returns a value proportional to the amount of displacement of the deflection angle of the MEMS mirror 130. The piezoelectric actuator and the piezoelectric sensor have the advantage that they can be manufactured using the same process.

[0028] It is also preferable to provide at least one each of the resonant sensor 144 and the non-resonant sensor 146. Considering the driving stability of the MEMS mirror 130 in the main scanning direction and the sub-scanning direction and the noise canceling effect of the differential signal, it is more preferable to provide one each of the resonant sensor 144 and the non-resonant sensor 146 symmetrically with respect to the X-axis and the Y-axis, as shown in FIG.

[0029] 3. Drive Characteristics and Interpolation in the Resonant Drive Direction of the Optical Deflector (1) Drive Characteristics in the Resonant Drive Direction Figure 3 is a diagram schematically illustrating scanning in the non-resonant drive direction of the optical deflector 30, performed under the control of the control device 10. In the first frame F01, the laser light LB is resonantly driven in the horizontal direction H (resonant drive direction) while scanning in the vertical direction V (non-resonant drive direction) (forward pass, first scanning period). After scanning of the first frame F01 is completed, in the second frame F02, the laser light LB scans upward (in the -V direction) from the scan end position (indicated by the dashed arrow in the figure) (return pass, second scanning period). The laser light LB is turned on in the region inside the scanning area (i.e., the laser lighting area AR).

[0030] More specifically, one cycle of non-resonant driving is formed by bidirectional scanning in the first frame F01 and the second frame F02. Similarly, resonant driving and non-resonant driving scanning are performed in the third and fourth frames F03 and F04 to form the next cycle, and this bidirectional scanning is repeated to form the projected image PI.

[0031] 4 is a diagram showing a plurality of observation points OP1 to OP5 in the vertical direction V (non-resonant driving direction) in an image formed by scanning with laser light LB. The outer frame line (thick line) corresponds to the laser lighting area AR.

[0032] 5A is a diagram showing the offset point and laser control curve signal during one scanning period (drive period) (0.5 cycles for the forward path and 0.5 cycles for the return path). The horizontal axis represents the drive period position PP, and the vertical axis represents the amplitude AMP of non-resonant drive. Also, FIG. 5B is a partially enlarged view of a portion W of FIG. 5A.

[0033] As shown in Figure 4, when the drive period of one frame of the projected image (i.e., 0.5 period) is divided into n (n is an integer greater than or equal to 2, here, it is divided into 4 equal parts) in the non-resonant drive direction, the observation points (division positions) are OP1 to OP5.

[0034] More specifically, as shown in FIG. 5A, the drive cycle positions PP of observation points OP1 to OP5 on the outbound path are PP=0, 0.125, 0.25, 0.375, and 0.5, respectively, and the drive cycle positions PP of observation points OP4 to OP2 on the inbound path are PP=0.625, 0.75, and 0.875.

[0035] Furthermore, the curves obtained by shifting the non-resonant drive curve of the optical deflector 30 in the periodic direction and passing through offset points CP1 to CP5 that indicate the optimal amplitudes at the observation points OP1 to OP5 are referred to as optimal control curves MC1 to MC5. Note that the optimal control curves MC1 to MC5 are used to generate a laser control curve signal CLD that is used to generate a video signal, as will be described later, and are not used as a signal that drives the MEMS mirror 130.

[0036] More specifically, the optimal control curve MC is a curve obtained by shifting in the periodic direction (to the right in the figure) the non-resonant drive curve (MC0, thin solid line in FIG. 5A ) that represents the amplitude AMP with respect to the drive period position PP in one period of the optical deflector 30, and passes through offset points CP that represent the optimal amplitude at each of the observation points OP1 to OP5. For example, the optimal control curve MC3 passes through offset point CP3 that represents the optimal amplitude at observation point OP3.

[0037] Furthermore, the non-resonant drive curve MC0 of the optical deflector 30 has 180° rotational symmetry about PP=0.25 in the sections PP=0 to 0.25 and PP=0.25 to 0.5. Furthermore, for the section PP=0.5 to 1, when the curve is rotated 180° around the point PP=0.75 (amplitude=0) and shifted in the negative direction by a period of 0.5, and coincides with the section PP=0 to 0.5, the offset points CP1 and CP5 in OP1 and OP5 coincide, and the offset points CP2 and CP4 in OP2 and OP4 coincide.

[0038] In this embodiment, the optimal control curves MC1 and MC5 at the observation points OP1 and OP5 coincide and are therefore shown as MC15, and the optimal control curves MC2 and MC4 at the observation points OP2 and OP4 coincide and are therefore shown as MC24.

[0039] However, the non-resonant drive curve MC0 does not have to have rotational symmetry and may have any shape. In this case, it is preferable to set the observation points OP5-OP1 on the return path to different observation points OP6-OP10 from the observation points OP1-OP5 on the outbound path, and to increase the number of observation points OP.

[0040] In the following description, unless otherwise specified, the observation point OP, optimal control curve MC, and offset point CP will be referred to collectively.

[0041] Each offset point CP is determined in advance by checking the projected image, and the drive period position PP at each division position and the shift amount PS in the period direction relative to the non-resonant drive curve MC0 (see Figure 5B) are associated with each other and stored in the control unit 16.

[0042] 6 shows images of the case where the shift amount PS in the periodic direction relative to the non-resonant drive curve MC0 is optimal at observation points OP1 to OP5. Image (A) shows the case where the shift amount PS is optimal at observation point OP1, and the curve obtained by shifting the non-resonant drive curve MC0 in the periodic direction so that it passes through offset point CP1 at that time is the optimal control curve MC1. The same is true for observation point OP5.

[0043] Similarly, image (B) shows the case where the shift amount PS is optimal at observation points OP2 and OP4, and the curves obtained by shifting the non-resonant drive curve MC0 in the periodic direction so as to pass through offset points CP2 and CP4 at that time are the optimal control curves MC2 and MC4. Image (C) shows the case where the shift amount PS is optimal at observation point OP3, and the curve obtained by shifting the non-resonant drive curve MC0 in the periodic direction so as to pass through offset point CP3 at that time is the optimal control curve MC3.

[0044] (2) Interpolation of Non-Resonant Drive Curve Fig. 7A is a block diagram showing the configuration of the laser control curve generator 50. Fig. 7B is a diagram showing an example of a calculation formula for generating a memory address of the laser control curve.

[0045] The laser control curve generating unit 50 has a drive curve interpolating unit 51 and a drive curve memory 57. The drive curve interpolating unit 51 has a drive cycle counter 52 and a variable address offset unit 53. The variable address offset unit 53 is made up of an offset difference calculating unit 54 and a laser control curve address generating unit 55.

[0046] That is, the laser control curve generator 50 is configured as a digital circuit. Here, one cycle of the drive curve is divided into 4096 addresses to generate the drive curve. The addresses correspond to drive cycle positions PP (see FIG. 5A).

[0047] Note that the following merely illustrates one example of the circuit configuration of the laser control curve generator 50. The laser control curve generator 50 may be configured to generate the video data DP based on the laser control curve signal CLD using another equivalent circuit or a different circuit. Alternatively, the laser control curve generator 50 may be configured as an analog circuit.

[0048] The drive curve interpolation unit 51 includes an offset point memory 54M in which offset points CP are stored in advance. That is, the offset point memory 54M stores in advance the drive period position PP at each observation point OP (division position) and the shift amount PS in the period direction relative to the non-resonance drive curve MC0 in association with each other.

[0049] The drive cycle counter 52 generates a counter value (addr_a) that indicates the drive cycle position PP of non-resonant drive of the optical deflector 30. The offset difference calculation unit 54 reads img_offset0, img_offset1, and img_offset2 from the offset point memory 54M, and calculates the offset value between the offset points CP by linear interpolation between the two points.

[0050] Specifically, img_offset0 is the amount of shift in the periodic direction of MC15 relative to the non-resonant drive curve MC0, img_offset1 is the amount of shift in the periodic direction of MC24 relative to MC0, and img_offset2 is the amount of shift in the periodic direction of MC3 relative to the non-resonant drive curve MC0.

[0051] Furthermore, div_offset01 and div_offset12 are the difference in the shift amount in the periodic direction between MC15 and MC24, and the difference in the shift amount in the periodic direction between MC24 and MC3, divided by the periodic time, and are the shift amount in the periodic direction that is added each time the count at the current drive period position increases by 1. Since the count number in one period is 4096, the division is performed by 512, which is equal to 8 of that. When the current drive period count (addr_a) is 0 (i.e., the position where PP = 0), a video signal is generated based on MC15. Therefore, the video generation count (addr_b) becomes img_offset0.

[0052] Also, when addr_a = 512 (PP = 0.125), the video signal is generated based on MC24, so addr_b = img_offset1. The section between addr_a = 0 to 512 (PP = 0 to 0.125) is the section where MC15 moves to MC24. The movement is linear, so div_offset01 is added each time addr_a increases by 1. Similarly, when addr_a = 1024 (PP = 0.25), the video signal is generated based on MC3, so addr_b = img_offset2.

[0053] Also, the section between addr_a = 512 and 1024 (PP = 0.125 to 0.25) is the section where the signal moves from MC24 to MC3, so div_offset12 is added each time addr_a increases by 1. Next, at addr_a = 1536 (PP = 0.375), the video signal is generated based on MC24, so addr_b = img_offset1. Also, the section between addr_a = 1024 and 1536 (PP = 0.25 to 0.375) is the section where the signal moves from MC3 to MC24.

[0054] Furthermore, div_offset12 is an added value when moving from MC24 to MC3, so when moving from MC3 to MC24, div_offset12 is subtracted each time addr_a increases by 1. Thereafter, addr_b is calculated in a similar manner, with addition and subtraction being switched depending on the direction in which the control curve MC moves.

[0055] The laser control curve generator 50 generates an address (addr_b) representing the interpolated drive cycle position PP from the difference calculated by the offset difference calculator 54 and the counter value (addr_a) representing the drive cycle position PP.

[0056] The laser control curve generator 50 sends the counter value of the drive cycle counter 52, that is, the drive cycle address (addr_a) of the non-resonant drive, to the non-resonant drive signal generator 15 as a non-resonant drive control signal SN.

[0057] Furthermore, the laser control curve generator 50 sends the interpolated drive cycle address (addr_b) from the drive curve interpolator 51 as a laser control curve signal CLD (see FIG. 5B) to the video data generator 11. The video data generator 11 generates video data DP based on the laser control curve signal CLD.

[0058] That is, the video data generation unit 11 reads the laser control curve signal CLD (interpolated drive cycle address) obtained by interpolation, and generates video data DP in which the drive cycle position PP of the video data is changed to the interpolated value (offset address).

[0059] Although an example of the laser control curve generator 50 and the drive curve interpolator 51 has been described, the present invention is not limited to this. The laser control curve generator may be configured to calculate an interpolated drive curve that passes through the offset point CP by interpolation, and to generate video data DP based on the interpolated drive period position included in the interpolated drive curve. Alternatively, the calculation results described above may be stored in advance in a control curve memory separate from the drive curve memory 57, and the results may be simultaneously read from the drive curve memory 57 and the control curve memory using only the current period count (addr_a).

[0060] 8 is a diagram showing a comparison of an image input to the laser scanning projection device 5, a projected image by the laser scanning projection device (CMP) of the comparative example, and a projected image by the laser scanning projection device 5 (EMB) of this embodiment. The laser scanning projection device (CMP) of the comparative example differs from the laser scanning projection device 5 (EMB) of this embodiment in that it does not include a drive curve interpolation unit 51.

[0061] Projected images for two types of image input (top and bottom rows) are shown. For the image input (top row) projected as diagonal lines on the screen, the laser scanning projection device (CMP) of the comparative example projects an S-shaped image, clearly showing distortion in the image. Furthermore, for the image input (bottom row) consisting of multiple rectangular frames, the laser scanning projection device (CMP) of the comparative example projects a double horizontal image. It can be seen that the laser scanning projection device 5 (EMB) of this embodiment significantly suppresses distortion in the projected image, resulting in a projected image with high resolution.

[0062] In other words, by controlling the projection of laser light using a laser control curve that is optimized at multiple points relative to the drive curve of the optical deflector, it is possible to project a sharp image while concentrating the luminous intensity. Note that in order to concentrate the luminous intensity, the non-resonant drive curve MC0 in Figure 5A has an S-shape.

[0063] The above interpolation process compensates for hysteresis in the non-resonant axis drive of the optical deflector 30, suppresses distortion in the projected image, and provides a laser scanning projection device and a scanning control device that can obtain a projected image with high resolution. Furthermore, the above-described laser scanning projection device 5 can correct distortion while lighting the laser in both directions of the non-resonant axis, making it possible to maintain high resolution while increasing brightness.

[0064] 4. Modifications (1) Modification 1 In the above-described embodiment, an example was described in which image projection was performed on both the forward and backward paths of non-resonant drive of the optical deflector 30, but it is also possible to perform image projection on one path and turn off the laser light on the other. Figure 9 shows modification 1 of the above-described embodiment, and is a diagram illustrating the offset point and laser control curve signal when the drive period is 0.5 cycles on the forward path.

[0065] In this first modification, an image is projected during the outward movement (0 to 0.5 cycles) of the non-resonant drive, and the laser light is turned off during the return movement (0.5 to 1 cycle). That is, one frame of image data is projected during one cycle of the non-resonant axis drive of the optical deflector 30.

[0066] (2) Other Modifications In the above embodiment, the non-resonant drive curve of the optical deflector 30 has an S-shape, but the present invention can also be applied to cases where the non-resonant drive curve has any shape.

[0067] An example has been described in which the laser control curve is calculated by interpolating using offset points at each of the division positions into which the drive period is divided into n equal parts, but the drive period may also be divided into n (n is an integer greater than or equal to 2).

[0068] Furthermore, it is preferable to divide the drive period so that the amplitude center position of the non-resonant drive curve of the optical deflector 30 becomes the observation point (OP3 in the case of the above-described embodiment). Alternatively, if the non-resonant drive curve of the optical deflector 30 has an inflection point with respect to the drive period position, it is preferable to divide the drive period so that the inflection point becomes the observation point (division position).

[0069] As described above in detail, the present invention can provide a laser scanning projection device and a scanning control device that compensate for hysteresis in the non-resonant axis drive of an optical deflector, suppress distortion of the projected image, and produce a projected image with high resolution.

[0070] 5: Laser scanning projection device 10: Control device 11: Video data generation unit 12: Laser driver 14: Resonant drive signal generation unit 15: Non-resonant drive signal generation unit 16: Control unit 20: Laser light source 30: Optical deflector 50: Laser control curve generation unit 51: Drive curve interpolation unit 52: Drive period counter 53: Variable address offset unit 54: Offset difference calculation unit 55: Laser control curve address generation unit 54M: Offset point memory 130: MEMS mirror CP: Offset point OP: Observation point PP: Drive period position PS: Shift amount in periodic direction

Claims

1. A scanning control device for a laser scanning projection device that has a rotating mirror, and an optical deflector that performs resonant drive of the rotating mirror and non-resonant drive of the rotating mirror orthogonal to the resonant drive, and that projects an image by scanning a laser beam using the optical deflector, comprising: a video data generation unit that receives a video signal and generates video data; a memory that stores a non-resonant drive curve that is a drive characteristic of the non-resonant drive of the optical deflector and represents an amplitude versus a drive cycle position in a drive period corresponding to one frame of the image; and an interpolation unit that calculates an interpolated drive curve using a plurality of offset points for the non-resonant drive curve of the optical deflector, wherein the interpolation unit divides the drive period corresponding to one frame into n (n is an integer of 2 or more) and stores the offset points of the non-resonant drive curve, where the drive cycle position at each divided position is associated with an amount of shift in the periodic direction relative to the non-resonant drive curve, and the interpolation unit calculates the interpolated drive curve that passes through the offset points; and the video data generation unit generates the video data based on the drive cycle position of the interpolated drive curve.

2. The scanning control device of claim 1, wherein the optical deflector scans the laser light in the forward and return paths of the non-resonant drive, the memory stores a non-resonant drive curve representing the amplitude versus drive cycle position in one cycle of the non-resonant drive of the optical deflector, and the interpolation unit divides the one cycle into n (n is an integer of 2 or more) and stores the offset points of the non-resonant drive curve at each divided position.

3. The scanning control device according to claim 1, wherein the interpolation unit is configured as a digital circuit and determines the interpolated drive curve based on a drive cycle position address indicating the drive cycle position of the non-resonant drive curve, a video data cycle position address indicating the drive cycle position of the video data, and an offset point address indicating the offset point.

4. A scanning control device according to claim 1, wherein said plurality of offset points include offset points corresponding to division positions of the amplitude center position of said non-resonant drive curve.

5. A scanning control device according to claim 1, wherein said optical deflector is a uniaxial non-resonant / uniaxial resonant type optical deflector.

6. The scanning control device according to claim 1, wherein said optical deflector is a meander type piezoelectric actuator.

7. A laser scanning projection device comprising: a scanning control device according to any one of claims 1 to 6; and a semiconductor laser light source that emits the laser light, wherein the optical deflector performs non-resonant driving of the rotating mirror to scan the laser light, and the semiconductor laser light source projects the image based on the image data from the image data generation unit of the scanning control device.

Images