Laser scan projection device, and scan control device

Abstract

To provide a laser scan projection device and scan control device that can obtain projection videos having distortion of the projection video suppressed, and having high-resolution.SOLUTION: A laser scan projection device comprises: a video data generation unit that receives video signals to generate video data; a memory that stores a non-resonance drive curve serving as a drive characteristic of non-resonance drive of an optical polarizer, and representing amplitude with respect to a drive cycle position 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 about the non-resonance drive curve of the optical polarizer. In the interpolation unit, the offset point of the non-resonance drive curve is stored that divides the drive period corresponding to the one frame to n divisions (n is an integer equal to or more than 2) and has the drive cycle position at respective divided positions associated with an amount of shift in a cycle direction with respect to the non-resonance drive curve. The interpolation unit is configured to calculate an interpolation drive curve passing through the offset point, and the video data generation unit is configured to generate the video data on the basis of a drive cycle position of the interpolation drive curve.SELECTED DRAWING: Figure 5A

Description

[Technical Field]

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

[0002] There is known an image projection device (projector) that scans laser light emitted from a light source with an optical deflector such as a MEMS (Micro Electro Mechanical Systems) to produce a high-definition image with excellent color reproducibility. Also, there is known an image 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 that copies of drive signals in the main scanning direction and sub-scanning direction are generated, and the entire waveforms of the copies are delayed, respectively, to offset the drawing interval and 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. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6364312 [Patent Document 2] Patent No. 6463507 Summary of the Invention [Problem to be solved by the invention]

[0006] When optical scanners such as MEMS are linearly driven, hysteresis in the drive of the non-resonant axis causes the control waveform and the actual behavior of the mirror to not match, which can lead to distortion in the projected image and a decrease in the resolution of the projected image.In other words, when projecting high-definition images, the hysteresis can cause problems such as double images 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. [Means for solving the problem]

[0008] A scanning control device according to one embodiment of the present invention comprises: A scanning control device for a laser scanning projection device that includes a rotating mirror, a light deflector that performs resonant driving of the rotating mirror and non-resonant driving of the rotating mirror perpendicular to the resonant driving, and that scans a laser beam using the light deflector to project an image, a video data generation unit that receives a video signal and generates video data; a memory for storing a non-resonant drive curve representing the drive characteristics of the non-resonant drive of the optical deflector, the non-resonant drive curve representing the amplitude with respect to the drive cycle position in a drive period corresponding to one frame of the video; an interpolation unit that determines an interpolated drive curve using a plurality of offset points for the non-resonant drive curve of the optical deflector; The interpolation unit divides the drive period corresponding to one frame into n divisions (n ​​is an integer of 2 or more), and stores the offset points of the non-resonant drive curve associated with the drive period position at each division position and the amount of shift in the period direction relative to the non-resonant drive curve, the interpolation unit calculates the interpolated drive curve that passes through the offset point; The video data generation unit generates the video data based on a 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 scanning control device; a semiconductor laser light source that emits the laser light; the optical deflector including the rotating mirror and scanning the laser light by non-resonantly driving the rotating mirror, The semiconductor laser light source projects the image based on the image data from the image data generating unit of the scanning control device. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram showing the configuration of a laser scanning projection device according to a first embodiment. [Figure 2] FIG. 2 is a perspective view showing a configuration of an optical deflector. [Figure 3] 10A and 10B are diagrams illustrating scanning in a non-resonant driving direction of an optical deflector performed under the control of a control device. [Figure 4] FIG. 1 is a diagram showing a plurality of observation points in the vertical direction V (non-resonant driving direction) in an image formed by scanning a laser beam. [Figure 5A] FIG. 10 is a diagram showing offset points and laser control curve signals in a scanning period (driving period) of one cycle (0.5 cycles for the forward path and 0.5 cycles for the backward path). [Figure 5B] 5B is a partially enlarged view showing a part W of FIG. 5A in an enlarged manner. [Figure 6] 10A and 10B are diagrams showing images at multiple observation points when the amplitude of non-resonant driving is optimized. [Figure 7A] FIG. 2 is a block diagram showing the configuration of a laser control curve generating unit. [Figure 7B] FIG. 10 is a diagram showing an example of a calculation formula for generating a memory address of a laser control curve. [Figure 8] 10A and 10B are diagrams showing a comparison of an image input, a projected image of a comparative example, and a projected image of the present embodiment. [Figure 9] FIG. 10 shows a first modified example of the embodiment, illustrating an offset point and a laser control curve signal during a driving period of 0.5 cycles in the forward direction. DETAILED DESCRIPTION OF THE INVENTION

[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 a video projection device of this embodiment. 1, the laser scanning projection device 5 includes 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 the 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 space, a screen, etc. to form a projected image PI. The present invention can be applied to, but is not limited to, projectors, road markings, headlights, distance measurement sensors, 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 a 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 configured to include, for example, red, green, and blue wavelength lasers so as 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 it 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.Light deflector 2 is a perspective view showing the configuration of the optical deflector 30. The optical deflector 30 is a uniaxial non-resonant / uniaxial resonant type optical deflector. Note that, in the following, a piezoelectric optical deflector will be described as an example of the optical deflector 30, but the present invention is not limited to this, and various types of optical deflectors such as an electrostatic type and an electromagnetic type can also be used. The optical deflector 30 includes a MEMS mirror 130 (rotating mirror), a first support part 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 section 135 that supports the first support section 133, and second actuators 140, 142 that rotate the first support section 133 around the X axis relative to the second support section 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, so that light is used with high 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-140D and 142A-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 in which four piezoelectric cantilevers 140A to 140D and 142A to 142D are respectively connected so as to be folded back at the end portions. 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, MEMS mirror 130 is rotated in the main scanning direction (horizontal direction) by resonant driving of actuators 134A and 134B that are compatible with high-speed operation, and is rotated in the sub-scanning direction (vertical direction) by non-resonant driving of actuators 140 and 142 that 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 can be piezoelectric sensors, sensors using the piezoresistive effect, etc. The piezoelectric sensor functions as a velocity sensor that returns a differential value of 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 resonant sensor 144 and one non-resonant sensor 146. Considering the driving stability of the MEMS mirror 130 in the main scanning direction and sub-scanning direction and the noise canceling effect of the differential signal, it is more preferable to provide one resonant sensor 144 and one non-resonant sensor 146 symmetrically with respect to the X-axis and Y-axis, as shown in FIG.

[0029] 3. Driving characteristics and interpolation of the resonant driving direction of the optical deflector (1) Driving characteristics in the resonant driving direction FIG. 3 is a diagram schematically showing scanning of the optical deflector 30 in the non-resonant driving direction, which is performed under the control of the control device 10. As shown in FIG. In the first frame F01, the laser light LB is resonantly driven in the horizontal direction H (resonance drive direction) while being scanned in the vertical direction V (non-resonance drive direction) (forward path, first scanning period). After scanning of the first frame F01 is completed, in the second frame F02, the laser light LB is scanned in the upward direction (-V direction) from the scanning end position (dashed arrow in the figure) (return path, 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 composed of 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 compose 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 backward path). The horizontal axis represents the drive period position PP, and the vertical axis represents the amplitude AMP of non-resonant drive. 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) in the non-resonant drive direction is divided into n (n is an integer greater than or equal to 2, here, it is divided into 4 equal parts), 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, curves that pass through offset points CP1 to CP5 that indicate the optimal amplitudes at observation points OP1 to OP5 and are obtained by shifting the non-resonant drive curve of the optical deflector 30 in the periodic direction are referred to as optimal control curves MC1 to MC5. Note that, as will be described later, 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, 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 the non-resonant drive curve (MC0, thin solid line in FIG. 5A) representing the amplitude AMP with respect to the drive period position PP in one period of the optical deflector 30 in the period direction (to the right in the figure), and passes through offset points CP representing the optimal amplitudes at each of the observation points OP1 to OP5. For example, the optimal control curve MC3 passes through offset point CP3 indicating 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 0.5 periods, and coincides with the section PP=0 to 0.5, the offset points CP1 and CP5 at OP1 and OP5 coincide, and the offset points CP2 and CP4 at 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 that the observation points OP5-OP1 on the return path are different from the observation points OP1-OP5 on the outward path, and that the number of observation points OP is increased.

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

[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 in which the shift amount PS in the periodic direction for the non-resonant drive curve MC0 is optimal at observation points OP1 to OP5. Image (A) shows the case in which 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 that it passes 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 that it passes through offset point CP3 at that time is the optimal control curve MC3.

[0044] (2) Interpolation of non-resonant drive curves Fig. 7A is a block diagram showing the configuration of the laser control curve generating unit 50. Fig. 7B is a diagram showing an example of a calculation formula for generating a memory address of a 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, a case is shown in which one cycle of the drive curve is divided into 4096 addresses to generate the curve. The addresses correspond to drive cycle positions PP (see FIG. 5A).

[0047] Note that the following merely shows 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 a 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] Also, 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 of the current drive period position increases by 1. The count number for one cycle is 4096, so it is divided by 512, which is eighth of that. When the current drive cycle count (addr_a) is 0 (i.e., the position where PP=0), the video signal is generated based on MC15. Therefore, the video generation count (addr_b) becomes img_offset0.

[0052] Also, at the point in time when addr_a=512 (PP=0.125), a video signal is generated based on MC24, so addr_b=img_offset1. The period between addr_a=0 and 512 (PP=0 to 0.125) is the section where the transition occurs from MC15 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, since the interval between addr_a = 512 and 1024 (PP = 0.125 to 0.25) is the interval where MC24 moves to MC3, div_offset12 is added each time addr_a increases by 1. Next, at addr_a = 1536 (PP = 0.375), a 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 shifts from MC3 to MC24.

[0054] Also, div_offset12 is the value added 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 the same manner, with addition and subtraction being switched depending on the direction in which the control curve MC moves.

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

[0056] The laser control curve generating unit 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 generating unit 15 as a non-resonant drive control signal SN.

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

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

[0059] Although an example of the laser control curve generation unit 50 and the drive curve interpolation unit 51 has been described, the present invention is not limited to this. The laser control curve generation unit 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. In addition, the calculation results described above may be stored in advance in a control curve memory separate from the drive curve memory 57, and may be read out simultaneously from the drive curve memory 57 and the control curve memory using only the current cycle count (addr_a).

[0060] 8 is a diagram showing a comparison of an image input to the laser scan projection device 5, a projected image by the laser scan projection device (CMP) of the comparative example, and a projected image by the laser scan projection device 5 (EMB) of this embodiment. The laser scan projection device (CMP) of the comparative example differs from the laser scan 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) are shown. For the image input (top), which projects a diagonal line on the screen, the laser scanning projection device (CMP) of the comparative example projects an S-shaped image, clearly showing distortion in the image. For the image input (bottom), which consists 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 reduces 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 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 of 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, with the above-described laser scanning projection device 5, distortion can be corrected while the laser is turned on in both directions of the non-resonant axis, so that it is possible to maintain a high sense of resolution while providing greater brightness.

[0064] 4. Variations (1) Variation 1 In the above embodiment, an example was described in which image projection is performed on both the forward and backward paths of non-resonant driving 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 path. FIG. 9 shows a first modification of the above embodiment, and is a diagram showing offset points and laser control curve signals when the driving period is 0.5 cycles of 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 variations 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] Although the example has been described in which the laser control curve is calculated by performing interpolation using offset points at each of the division positions obtained by dividing the drive period into n equal parts, the drive period may also be divided into n (n is an integer of 2 or more).

[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. [Explanation of symbols]

[0070] 5: Laser scanning projection device 10: Control device 11: Video data generation unit 12: Laser driver 14: Resonance drive signal generator 15: Non-resonant drive signal generator 16: Control unit 20: Laser light source 30: Optical deflector 50: Laser control curve generation unit 51: Drive curve interpolation unit 52: Drive cycle counter 53: Variable address offset section 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 cycle position PS: Shift amount in periodic direction

Claims

1. A scanning control device for a laser scanning projection device that includes a rotating mirror, a light deflector that performs resonant driving of the rotating mirror and non-resonant driving of the rotating mirror perpendicular to the resonant driving, and that scans a laser beam using the light deflector to project an image, a video data generation unit that receives a video signal and generates video data; a memory for storing a non-resonant drive curve representing the drive characteristics of the non-resonant drive of the optical deflector, the non-resonant drive curve representing the amplitude with respect to the drive cycle position in a drive period corresponding to one frame of the video; an interpolation unit that determines an interpolated drive curve using a plurality of offset points for the non-resonant drive curve of the optical deflector; the interpolation unit divides the drive period corresponding to one frame into n divisions (n ​​is an integer of 2 or more), and stores the offset points of the non-resonant drive curve, in which the drive period position at each division position is associated with a shift amount in a period direction relative to the non-resonant drive curve; the interpolation unit calculates the interpolated drive curve that passes through the offset point; The video data generating unit generates the video data based on a drive cycle position of the interpolated drive curve.

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

3. 2. 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. 2. The scanning control device according to claim 1, wherein the plurality of offset points include offset points corresponding to division positions of the amplitude center position of the non-resonant drive curve.

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

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

7. A scanning control device according to any one of claims 1 to 6; a semiconductor laser light source that emits the laser light; the optical deflector including the rotating mirror and scanning the laser light by non-resonantly driving the rotating mirror, The semiconductor laser light source projects the image based on the image data from the image data generating unit of the scanning control device.

Images