JP6350685B2 - Image display apparatus and control method thereof - Google Patents

Description

  The present invention relates to an image display apparatus and a control method thereof, and more specifically to a laser scan type image display apparatus and a control method thereof.

  There is known a laser scan type image display device that projects and displays an image by reflecting and scanning a laser beam (for example, Patent Document 1). Laser scan type image display apparatuses are used as HUDs (Head Up Displays), projectors, and the like that project and display images on windshields and combiners of automobiles.

  In a laser scan type image display device, laser light is scanned by reflecting a laser beam by an optical scanner having a mirror and reciprocatingly swinging the mirror of the optical scanner in a horizontal direction and a vertical direction.

JP 2007-025522 A

  In the conventional image display device, feedback control is performed to control the scanning operation of the laser beam by the optical scanner. For example, in Patent Document 1, light reflected by an optical scanner is detected by an optical sensor, and feedback is performed. In another conventional technique, an optical scanner is provided with a piezoelectric film, and the operation of the optical scanner is detected and fed back using this piezoelectric film. In such feedback control of the conventional image display apparatus, the start timing of the drive signal for driving the optical scanner is controlled in order to keep the scanning frequency constant.

  However, the reciprocation of the optical scanner may fluctuate due to vibrations or electrical influences, and in the conventional image display device, the image may be shifted and displayed for each scanning unit such as a horizontal line due to this fluctuation. There is a problem that there is.

  Therefore, the present invention provides a light source unit that outputs a light beam, a scanning unit that reflects the light beam and repeats a reciprocating operation in a predetermined scanning direction, and the operation of the scanning unit for each scanning unit of the forward or backward path of the reciprocating operation. A scanning detection unit for detecting a range; and when the detected operating range is smaller than a reference range, the operation of the scanning unit in the next scanning unit based on a difference between the detected operating range and the reference range Based on the image data at a timing corresponding to the determined image drawing position, and a drawing position determining unit that determines the image drawing position for each scanning unit by reducing the interval from the start to the image drawing position An image display device comprising: a light source driving unit that drives the light source unit.

  According to another aspect of the present invention, there is provided a control method for an image display device, comprising: a light source unit that outputs a light beam; and a scanning unit that reflects the light beam and repeats a reciprocating operation in a predetermined scanning direction. When the operating range of the scanning unit is detected for each scanning unit of the forward path or the backward path, and the detected operating range is smaller than the reference range, the next is based on the difference between the detected operating range and the reference range. By reducing the interval from the start of operation of the scanning unit to the image drawing position in the scanning unit, the image drawing position is determined for each scanning unit, and at a timing corresponding to the determined image drawing position, Provided is a method for controlling an image display device, wherein the light source unit is driven based on image data.

  According to the present invention, it is possible to suppress an image shift for each scanning unit.

1 is a configuration diagram illustrating a configuration example of an image display device according to a first embodiment. 2 is a configuration diagram illustrating an example of a configuration of a horizontal scanner according to Embodiment 1. FIG. FIG. 10 is a configuration diagram illustrating another example of the configuration of the horizontal scanner according to the first embodiment. 1 is a block diagram illustrating a configuration example of an FPGA according to a first embodiment. 4 is a waveform diagram illustrating an example of signals used in the image display device according to Embodiment 1. FIG. It is explanatory drawing for demonstrating the operation | movement at the time of the ideal reciprocating scanning of a reference example. It is explanatory drawing for demonstrating the operation | movement at the time of the ideal reciprocating scanning of a reference example. It is explanatory drawing for demonstrating the operation | movement at the time of the reciprocating scanning fluctuation | variation of a reference example. It is explanatory drawing for demonstrating the operation | movement at the time of the reciprocating scanning fluctuation | variation of a reference example. FIG. 6 is an explanatory diagram for explaining an operation at the time of reciprocal scanning fluctuation according to the first embodiment. FIG. 6 is an explanatory diagram for explaining an operation at the time of reciprocal scanning fluctuation according to the first embodiment. 6 is an explanatory diagram for explaining an example of setting a line reference value according to Embodiment 1. FIG. 4 is a block diagram illustrating a configuration example of a drawing position control unit according to Embodiment 1. FIG. 4 is a flowchart illustrating an operation example of a drawing position control unit according to the first embodiment.

(Embodiment 1)
Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a configuration of an image display apparatus 100 according to the present embodiment. The image display device 100 is a laser scan type image display device that displays (draws) an image on a projection surface by reflecting laser light with an optical scanner and reciprocatingly scanning in a vertical direction and a horizontal direction. For example, the image display device 100 projects and displays the projection image 300 on a projection surface that is an image display surface such as an automobile windshield or combiner.

  As shown in FIG. 1, the image display apparatus 100 includes a video input unit 101, an FPGA (Field Programmable Gate Array) 110, a microcomputer 120, flash memories 131 and 132, a DDR (Double Data Rate) memory 133, a laser driver 140, a V An axis scanner driver 150, an H axis scanner driver 160, a comparator 170, an RGB laser diode 200, a vertical scanner 210, and a horizontal scanner 220 are provided. The vertical direction (vertical direction, Y direction) of the image to be displayed is also referred to as a V (Vertical) axis direction, and the horizontal direction (lateral direction, X direction) of the image is also referred to as an H (Horizontal) axis direction.

  The video input unit 101 receives video data to be displayed on the projection plane, and the input video data is sent to the FPGA 110. This video data includes three color signals of R (red), G (green), and B (blue). For example, the video input unit 101 may receive a video generated by another device such as a car navigation device, or the video input unit 101 may generate video data.

  The FPGA 110 and the microcomputer 120 constitute a control unit 102 of the image display apparatus 100 and perform various controls necessary for image display. The operations of the RGB laser diode 200, the vertical scanner 210, and the horizontal scanner 220 are controlled by the FPGA 110 and the microcomputer 120 via the laser driver 140, the V-axis scanner driver 150, and the H-axis scanner driver 160, and the projected image 300 is drawn. Note that the control operations of the FPGA 110 and the microcomputer 120 may be realized by either hardware or software, or both.

  The FPGA 110 outputs RGB image data line by line based on the input video data, generates a V-axis drive signal for controlling the reciprocation of the vertical scanner 210, and generates the generated V-axis drive signal. Is output. As will be described later, the FPGA 110 according to the present embodiment sets and sets the image drawing position so as to suppress the image shift for each line based on the H-axis detection pulse signal of the horizontal scanner 220 obtained from the comparator 170. At this position, the laser driver 140 is driven to perform drawing.

  The microcomputer 120 generates an H-axis drive signal for controlling the reciprocation of the horizontal scanner 220, and outputs the generated H-axis drive signal. The flash memories 131 and 132 are nonvolatile storage units that store data and programs necessary for the operation of the FPGA 110 and the microcomputer 120, respectively.

  A DDR (Double Data Rate) memory 133 is a frame buffer that temporarily stores video data input to the FPGA 110. The DDR memory 133 may be DDR2, DDR3, or other SDRAM.

  The laser driver 140 drives the RGB laser diode 200 according to the image data supplied from the FPGA 110. The laser driver 140 is a light source driving unit that drives the RGB laser diode 200 based on image data at a timing corresponding to the image display position determined by the FPGA 110. The RGB laser diode 200 emits three colors of RGB laser light by driving the laser driver 140. The RGB laser diode 200 is a light source unit that outputs laser light that is a light beam.

  The V-axis scanner driver 150 reciprocates the vertical scanner 210 in accordance with the V-axis drive signal supplied from the FPGA 110. The H-axis scanner driver 160 drives the horizontal scanner 220 reciprocally according to the H-axis drive signal supplied from the microcomputer 120.

  The vertical scanner 210 or the horizontal scanner 220 is a scanning unit that repeats a reciprocating operation in the vertical or horizontal direction. The vertical scanner 210 is an optical scanner that reflects the laser light emitted from the RGB laser diode 200 and reciprocates in the vertical direction by driving the V-axis scanner driver 150. The horizontal scanner 220 is an optical scanner that reflects the laser light emitted from the RGB laser diode 200 and reciprocates in the horizontal direction by driving the H-axis scanner driver 160. The horizontal scanner 220 includes a scanning detection unit 202 that detects a horizontal reciprocation, and outputs an H-axis detection analog signal indicating the detected reciprocation. The scanning detection unit 202 detects the operating range of the horizontal scanner 220 for each scanning unit that is a forward or backward line of a reciprocating operation.

  In this example, the horizontal scanner 220 reflects the laser light from the RGB laser diode 200, and the vertical scanner 210 further reflects the reflected light from the horizontal scanner 220, thereby drawing the projection image 300 on the projection surface. Yes. It can be said that the vertical scanner 210 and the horizontal scanner 220 constitute an optical scanner 201 that reciprocates in the vertical and horizontal directions. For example, the vertical scanner 210 and the horizontal scanner 220 may be a single two-axis (two-dimensional) optical scanner.

  The comparator 170 is a signal conversion unit that converts the H-axis detection analog signal output from the horizontal scanner 220 into an H-axis detection pulse signal that can be processed by the FPGA 110.

2 and 3 are configuration examples of the horizontal scanner 220, and are front views of the horizontal scanner 220 as viewed from the mirror side. Note that the vertical scanner 210 may be configured similarly to the horizontal scanner 220.

  The optical scanner which is the horizontal scanner 220 (and the vertical scanner 210) is a MEMS element created by MEMS (Micro Electro Mechanical Systems) technology. For example, the horizontal scanner 220 is formed by etching an SOI (Silicon On Insulator) substrate including a piezoelectric film such as a PZT (lead zirconate titanate) film.

  As shown in FIGS. 2 and 3, the horizontal scanner 220 includes a frame body 221 constituting a frame of the main body, a swinging piece portion 222 supported in a state of being separated from the frame body 221 in the frame of the frame body 221, a frame Four L-shaped beam portions 223 a to 223 d that connect the inner edge of the body 221 and the swing piece 222, and a MEMS mirror 224 formed on the surface of the swing piece 222 are provided. The MEMS mirror 224 is formed by vapor-depositing a metal with high reflectivity (for example, Al or Au).

  The L-shaped beam portions 223a to 223d are connected to the swing piece 222 at a position close to the center in the horizontal direction of the swing piece 222, and the swing piece 222 and the MEMS mirror with the connecting portion as a swing axis. 224 can swing in the horizontal direction. It can be said that the L-shaped beam portions 223a to 223d constitute a torsion bar that supports the swing piece portion 222 so as to be swingable.

  Further, a plurality of piezoelectric films extending in the horizontal direction are disposed in the four L-shaped beam portions 223a to 233d. For example, the piezoelectric film has a laminated structure in which a piezoelectric film is sandwiched between a lower electrode and an upper electrode.

  In the example of FIG. 2, driving piezoelectric films 225a and 225b to which an H-axis driving signal is supplied are arranged on the L-shaped beam portions 223a and 223b, respectively, and the L-shaped beam portion 223c facing the L-shaped beam portions 223a and 223b. And 223d, detection piezoelectric films 226a and 226b for detecting the operation of the MEMS mirror 224 (the swing piece 222) are arranged, respectively.

  Further, in the example of FIG. 3, a pair of driving piezoelectric films and detecting piezoelectric films (225a and 226a, 225b and 226b, 225c and 226c, 225d and 226d) are arranged on the L-shaped beam portions 223a to 223d, respectively. Yes.

  When an H-axis drive signal is supplied to the drive piezoelectric films 225a and 225b in FIG. 2 or the drive piezoelectric films 225a to 225d in FIG. 3, the drive piezoelectric films 225a and 225b or 225a to 225d according to the H-axis drive signal. This vibration is transmitted to the swing piece portion 222 via the L-shaped beam portions 223a and 223b or 223a to 223d, and the swing piece portion 222 and the MEMS mirror 224 swing.

  Further, the detection piezoelectric films 226a and 226b in FIG. 2 or the detection piezoelectric films 226a to 226d in FIG. 3 are the scanning detection unit 202, and detect and detect vibrations of the swing piece 222 and the MEMS mirror 224. An H-axis detection analog signal corresponding to vibration is output. An H-axis drive signal having a predetermined phase difference with respect to the H-axis detection analog signal obtained from the detection piezoelectric films 226a and 226b or 226a to 226d is fed back to the drive piezoelectric films 225a and 225b or 225a to 225d. As a result, the oscillating piece 222 and the MEMS mirror 224 can be driven to resonate.

  FIG. 4 shows functional blocks of the FPGA 110 according to the present embodiment. As shown in FIG. 4, the FPGA 110 includes an input interface 111, a DDR interface 112, an image processing unit 113, a video output unit 114, a PLL (Phase Locked Loop) 115, a drawing position control unit 116, and a V-axis drive processing unit 117. ing.

  The input interface 111 is an interface with the video input unit 101, receives the video data input from the video input unit 101, and outputs the received video data to the DDR interface 112.

  The DDR interface 112 is an interface with the DDR memory 133, temporarily stores the video data received by the input interface 111 in the DDR memory 133, and further extracts the video data stored in the DDR 133 according to the internal clock.

  The DDR interface 112 writes video data (image data) to the DDR memory 133 in units of frames, and reads each line in the horizontal direction included in one frame from the DDR memory 133 in synchronization with the internal clock. In addition, in order to perform drawing in the forward path and the backward path in the reciprocating operation of the horizontal scanner 220, the DDR interface 112 reads image data in the order of forward addresses in the case of the forward path line to be drawn in the forward path, and The image data is read out in the order of the addresses in the reverse direction to rearrange the image data of the forward path and the backward path.

  The image processing unit 113 performs necessary image processing such as change of aspect ratio and bright control on the image data extracted from the DDR 133 by the DDR interface 112. The video output unit (image output unit) 114 outputs the image data processed by the image processing unit 113 to the laser driver 140. The video output unit 114 determines the drawing position using the drawing position clock (pixel clock), HSync (H axis synchronization signal), and VSync (V axis synchronization signal) generated from the H axis detection waveform and the V axis drive signal. Then, the image data is output line by line at the determined drawing position timing.

  The PLL 115 receives an external clock 180, generates an internal clock based on the external clock 180, and supplies the generated internal clock to each block.

  The drawing position control unit (clock generation unit) 116 generates a pixel clock based on the internal clock generated by the PLL 115 in order to synchronize laser drawing with the horizontal scanner 220. For example, the pixel clock is a clock synchronized with a pixel counter described later. The drawing position control unit 116 generates pixel clocks HSync and VSync that determine the drawing position based on the H-axis detection pulse signal and the V-axis drive signal. The drawing position control unit 116 starts counting of the counter from the edge position of the H-axis detection pulse signal, and determines a drawing area based on the counted counter value. The drawing position control unit 116 is a display position determination unit that determines the image display position for each line based on the deviation between the operation range of the horizontal scanner 220 detected by the scan detection unit 202 and the reference range.

  The V-axis drive processing unit 117 generates a V-axis drive signal based on HSync and VSync, and outputs the generated V-axis drive signal to the V-axis scanner driver 150. For example, when displaying with VGA (Video Graphics Array), the vertical scanning frequency is 60 Hz, and the V-axis drive signal is output so as to swing the vertical scanner 210 in the vertical direction at 60 Hz.

  FIG. 5 shows an example of the H-axis detection analog signal and the H-axis detection pulse signal according to the present embodiment. The H-axis detection analog signal is a waveform detected by one-side piezoelectric film (for example, 226a and 226b in FIG. 2 or 226a to 226d in FIG. 3) disposed in the horizontal scanner 220 that is driven on both sides in the horizontal direction. .

  As shown in FIG. 5, the H-axis detection analog signal has an analog waveform corresponding to the direction of the MEMS mirror 224 of the horizontal scanner 220. For this reason, the H-axis detection analog signal cannot be processed by the FPGA 110 as it is. Therefore, in the present embodiment, the H-axis detection analog signal is converted into a pulsed rectangular wave using the comparator 170 or the like, and is input to the FPGA 110 as the H-axis detection pulse signal.

  In this embodiment, the H-axis detection pulse signal is generated so that the edge comes to a position where the MEMS mirror 224 is swung by the maximum angle. For example, the H-axis detection pulse signal is generated so as to repeat rising / falling for every minimum value (at the minimum peak) and maximum value (at the maximum peak) of the H-axis detection analog signal. Then, a horizontal drawing area is set in an area between edges sandwiched between edges of the H-axis pulse signal.

  Next, a drawing position control method that is a main feature of the present embodiment will be described.

  In an image display apparatus of a laser scan system, when drawing is performed, an H-axis detection waveform (H-axis detection pulse signal) that is detected from the operation of the MEMS mirror 224 output from a detection circuit such as a piezoelectric film is taken into the FPGA 110 and the drawing timing is set. Used as a reference signal.

  However, when the operation of the MEMS mirror 224 is changed due to vibration or electrical influence, the H-axis detection pulse signal is similarly changed. Since the FPGA 110 counts the edge interval of the H-axis detection pulse signal, the change in the frequency of the H-axis detection pulse signal causes a shift in the drawing timing due to a shift in the count number in the FPGA 110, and the projection to be drawn. It leads to the shift | offset | difference for every line of the image 300. FIG. In the present embodiment, this problem is improved as described below.

  First, the operation of an ideal detection pulse signal when the operation of the MEMS mirror does not change will be described with reference to FIGS. 6A and 6B. For example, FIGS. 6A and 6B show the operation of the reference example, which is an example having the same configuration as FIGS. 1 to 3 and FIG.

  As shown in FIGS. 6A and 6B, ideally, the H-axis detection pulse signal always has a detection waveform with a constant period, that is, the same edge interval (interval between the rising edge and the next falling edge, the falling edge, This is a rectangular wave that repeats High / Low at an interval until the next rising edge).

  The FPGA 110 counts the edge interval of the H-axis detection pulse signal with an internal clock synchronized with the dot (pixel), and the count value of the clock counter (clk # cnt) is constant because the H-axis detection pulse signal has a constant period. It becomes the value of. Here, as an example, the edge interval is 20 counts, and the counter value = 1 to 20 is repeated. For simplification of explanation, the count is started from the counter value = 1, but the count may be started from the counter value = 0 (the same applies hereinafter).

  Here, as an example, the area between the counter values 6 to 15 is set as the drawing area. Then, HSync that sets the drawing area has a waveform that rises at the timing of the counter value 6 and repeats falling at the timing of the counter value 15 in each of the forward and return lines.

  As a result, the drawing area of the projected image 300 drawn by repeating the forward path line and the backward path line is the area A1. In FIGS. 6A and 6B, since the H-axis detection pulse signal has a constant cycle and HSync also has a constant cycle, the drawing position in the drawing area A1 is not shifted for each line, and the vertical vertical line is a straight line. Become.

  Next, an example of the detection pulse signal when the operation of the MEMS mirror changes in the reference example before application of the present embodiment will be described with reference to FIGS. 7A and 7B. For example, FIG. 7A and FIG. 7B are operations of the reference example, and are examples having the same configuration as that of FIG. 1 to FIG. 3 and FIG.

  As shown in FIGS. 7A and 7B, when the operation of the MEMS mirror 224 is not constant, the H-axis detection pulse signal has a waveform in which the frequency (edge interval) is not constant but has changed. When the H-axis detection pulse signal is taken into the FPGA 110 and the edge interval is counted, the counter value of the clock counter varies for each edge interval.

  When the deflection of the MEMS mirror 224 is less than the ideal standard, the edge interval of the H-axis detection pulse signal is narrowed, so the counter value is small, and the MEMS mirror 224 is too much deviated from the ideal standard. In this case, since the edge interval of the H-axis detection pulse signal becomes wide, the counter value becomes large. For example, the forward line 1 is 20 counts, the backward line 2 is 18 counts, the forward line 3 is 22 counts, and the backward line 4 is 20 counts.

  When the area between the counter values 6 to 15 is set as the drawing area, the HSync setting the drawing area rises at the timing of the counter value 6 for each of the forward and return lines where the edge interval (count number) varies, and the counter value 15 The waveform repeats falling at the timing.

  As a result, the drawing area of the projection image 300 drawn by repeating the forward path line and the backward path line is the area A2. In FIGS. 7A and 7B, the cycle (edge interval) of the H-axis detection pulse signal varies and the cycle of HSync also varies, so that the rendering position of the rendering area A2 is shifted for each line. Before the embodiment is applied, the timing waveform (HSync) for drawing is generated and drawn on the basis of the counter value of the H-axis detection pulse signal, and drawing is performed when the count numbers in the forward line and the backward line are different. Deviation occurs in the vertical lines of the area.

  Next, an example of a detection pulse signal when the operation of the MEMS mirror changes after application of the present embodiment will be described with reference to FIGS. 8A and 8B. 8A and 8B are operations in the configuration of the present embodiment described with reference to FIGS.

  In the present embodiment, a line reference value serving as a reference for the edge interval (one line) of the H-axis detection pulse signal is set. When the counter value is smaller than the line reference value, a value calculated from the line reference value is used as a start counter value for starting counting on the next line. If the counter value is larger than the line reference value, the extra count is continued on the next line, or the count is stopped, and the count is started from the same position as the start position of the line reference value.

  The line reference value is an ideal swing width of the MEMS mirror 224, and here, is an average value of count numbers (or counter values) obtained by counting a plurality of lines. For example, the edge interval of the H-axis detection pulse signal from the MEMS mirror 224 is counted in the blanking area before image data display, and the line reference value is set by averaging eight lines.

  For example, 1 line = 20 counts, 2 lines = 18 counts, 3 lines = 22 counts, 4 lines = 20 counts, 5 lines = 18 counts, 6 lines = 20 counts, 7 lines = 20 counts, 9 lines = 22 counts In this case, an average value of 20 counts is used as a line reference value in one frame. For the 10th and subsequent lines, the counter value is set based on this line reference value.

  8A and 8B, as in FIGS. 7A and 7B, the frequency (edge interval) of the H-axis detection pulse signal is not constant but has a changed waveform. When the edge interval of the H-axis detection pulse signal is counted according to the internal clock, the counter value of the clock counter (clk # cnt) varies for each edge interval. For this reason, in this embodiment, a line reference value is set, and the start counter value is set so that the start count when moving to the next line is the same position as the line reference value count.

  The clock that always counts the H-axis detection pulse signal from the counter value = 1 is called the clock counter (clk # cnt), and the clock that counts from the start counter value set based on the line reference value is the pixel counter (pix # cnt) Called.

  In FIG. 8A and FIG. 8B, as in FIG. 7A and FIG. 7B, for example, the forward line 1 has 20 counts (clk # cnt = 1-20), the return path 2 has 18 counts (clk # cnt = 1-18), The forward line 3 has 22 counts (clk # cnt = 1 to 22), and the backward line 4 has 20 counts (clk # cnt = 1 to 20).

  As an example in which the shake of the MEMS mirror 224 is less than the reference value, for example, the return line 2 has 18 counts, which is smaller than 20 counts of the line reference value, and the shake of the MEMS mirror 224 is insufficient. In this example, the left end in the horizontal direction is shorter than the line reference value. In this case, the difference value (20−18 = 2) is obtained by subtracting the counter value (pix # cnt = 18) of the pixel counter from 20 counts of the line reference value. In the next line, in order to shift the timing by the dot of this difference value (the amount deficient from the reference value), the value obtained by adding this difference value to the minimum counter value = 1 (1 + 2 = 3) is used as the next forward path. The start counter value of line 3 is assumed. That is, when the counter value is smaller than the line reference value, the interval from the edge of the next line to the drawing area is shortened by increasing the counter value based on the difference between the counter value and the line reference value. As a result, the counter values 6 to 15 for the return line 2 and the counter values 6 to 15 for the forward line 3 are equal in the vertical direction.

  Further, as an example in which the MEMS mirror 224 is shaken too much from the reference value, the forward line 3 has 22 counts, which is larger than the line reference value of 20 counts, and the MEMS mirror 224 is shaken too much. In this example, the right end in the horizontal direction is longer than the line reference value. In this case, a difference value (24-20 = 4) is obtained by subtracting 20 counts of the line reference value from the counter value (pix # cnt = 24) counted by the pixel counter. In the next line, in order to shift the timing by this difference value dot (exceeding the reference value), the next return line 4 starts from the next position (4 + 1 = 5th count) of the difference value count. Start counting. That is, when the counter value is larger than the line reference value, the interval from the edge of the next line to the drawing area is lengthened by delaying the start of counting based on the difference between the counter value and the line reference value. Thereby, the counter values 6 to 15 of the forward path line 3 and the counter values 6 to 15 of the backward path line 4 are equal in the vertical direction.

  For example, at this time, the counter value is not advanced during the count of the difference value, and after moving to the next line, the count value is stopped for 1 count for 4 counts of the stopped count value. Start counting from 1. Further, the counting may be continued without stopping until the counting is started on the next line.

  Under such control, HSync for setting the drawing area rises at the timing of the corrected counter value 6 for each of the forward and return lines where the edge interval (count number) fluctuates, and the timing of the corrected counter value 15 The waveform repeats falling at.

  As a result, the drawing area of the projection image 300 drawn by repeating the forward line and the backward line is the area A3. 8A and 8B, by controlling the counter based on the difference between the edge interval of the H-axis detection pulse signal and the reference value, the distance from the drawing area to the end of the previous line and the beginning of the next line The distance to the drawing area can be made equal. That is, in the present embodiment, the drawing area is controlled by controlling the count value based on the counter value as a reference and the count value from the detection pulse signal of the MEMS mirror so that the drawing areas match in the vertical line. The range can be kept constant, and vertical line shifts can be eliminated.

  Here, the set value of the line reference value will be further described. In the above, the line reference value is determined by the average value obtained by counting a plurality of lines. For example, an average value of 8 lines in one frame is set as a line reference value. However, if the line reference value is an odd number, drawing deviation of one dot occurs. Therefore, it is preferable to determine that the line reference value is always an even number.

  FIG. 9 shows an example in which the line reference value is set to an odd number. FIG. 9 shows an example in which the line reference value is 21 and the drawing area is between the counter values 6-15. In this case, the drawing area of the projection image 300 drawn by repeating the forward path line and the backward path line is the area A4.

  As shown in FIG. 9, when the line reference value is set to an odd number, the drawing position on the forward line (counter values 6 to 15) and the drawing position on the backward line (counter values 6 to 15) are shifted by 1 dot, and the forward path And the return path becomes alternate. For this reason, in this embodiment, the line reference value is always set to an even number to prevent the deviation between the forward path and the backward path. For example, when the average value is 21, the reference value is set to 20 or 22.

  Next, a configuration example for realizing the operation of the present embodiment described with reference to FIGS. 8A and 8B will be described. FIG. 10 is an example of a functional block of the drawing position control unit 116, and FIG. 11 is an example of a flowchart of the drawing position control unit 116. Note that the operations in FIGS. 8A and 8B may be realized by other configurations.

  As shown in FIG. 10, the drawing position control unit 116 includes a counter 11, a line reference value setting unit 12, a drawing position determination unit 13, a line deviation determination unit 14, and a line deviation correction unit 15.

  The counter 11 is a counter that counts the edge interval of the H-axis detection pulse signal. The counter 11 includes the clock counter and the pixel counter shown in FIGS. 8A and 8B. The line reference value setting unit 12 sets a line reference value to be a reference value for the counter of one line.

  The drawing position determination unit 13 determines a drawing position (drawing area) based on the value of the counter 11. The line deviation determination unit 14 compares the value of the counter 11 with the line reference value to determine line deviation. In order to correct the determined line shift, the line shift correction unit 15 corrects the start counter value and stops the counter as shown in FIGS. 8A and 8B.

  As shown in FIG. 11, when the input of the H-axis detection pulse signal is started to the drawing position control unit 116 (S101), the line reference value setting unit 12 first sets the line reference value. As described above, after the counter 11 counts the edge interval of the H-axis detection pulse signal a plurality of times, the line reference value setting unit 12 obtains the average value of the counter values and sets the line reference value. In particular, the line reference value setting unit 12 sets the line reference value to be an even number as described above.

  Subsequently, the counter 11 counts the scanning range of the MEMS mirror (S103). In synchronization with the internal clock, the counter 11 counts the edge interval of the H-axis detection pulse signal by a clock counter (clk # cnt) and a pixel counter (pix # cnt) as shown in FIGS. 8A and 8B.

  Subsequently, the drawing position determination unit 13 determines the drawing position based on the counter value. For example, the drawing position determination unit 13 sets between the counter values 5 to 14 as a drawing area, and generates HSync that rises at the timing of the counter value 5 and repeats the falling at the timing of the counter value 14.

  Subsequently, the line deviation determination unit 14 compares the counter value with the line reference value (S105). If the counter value is equal to the line reference value, there is no deviation in the line, so the count and the drawing position are determined as they are (S103, S104).

  When the counter value is smaller than the line reference value, the start counter value is set so as to correct the position of the drawing area based on the difference between the line reference value and the counter value as shown in FIGS. 8A and 8B (S106). . Thereafter, counting is started based on the set start counter value, and the drawing position is determined (S103, S104).

  When the counter value is larger than the line reference value, as shown in FIGS. 8A and 8B, the start of counting is waited so as to correct the position of the drawing area based on the difference between the counter value and the line reference value (S107). . Thereafter, the counting is started in accordance with the timing when there is no difference from the line reference value, and the drawing position is determined (S103, S104).

  As described above, in the present embodiment, in the laser scan type image display device, the operation of the MEMS mirror is detected by the piezoelectric film provided in the optical scanner, and based on the deviation between the detected operation range and the reference range. The drawing position was corrected. Accordingly, the drawing position shift caused by the change in the detected waveform due to the fluctuation of the operation of the MEMS mirror is corrected, and the drawing shift for each line can be prevented by always setting the drawing area at a fixed location. In particular, by setting the count value for setting the drawing position so as not to be always constant but constant with respect to the reference, it is possible to eliminate drawing position deviation for each line and prevent drawing deviation.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

11 Counter 12 Line Reference Value Setting Unit 13 Drawing Position Determination Unit 14 Line Deviation Determination Unit 15 Line Deviation Correction Unit 100 Image Display Device 101 Video Input Unit 111 Input Interface 112 DDR Interface 113 Image Processing Unit 114 Video Output Unit 116 Drawing Position Control Unit 117 V-axis drive processing unit 120 Microcomputer 131, 132 Flash memory 133 DDR memory 140 Laser driver 150 V-axis scanner driver 160 H-axis scanner driver 170 Comparator 180 External clock 200 RGB laser diode 201 Optical scanner 202 Scanning detection unit 210 Vertical scanner 220 Horizontal Scanner 221 Frame 222 Oscillating piece portions 223a to 223d L-shaped beam portion 224 MEMS mirrors 225a to 225d Driving piezoelectric films 226a to 226d Pressure for detection Film 300 projected image

Claims (5)

A light source that outputs a luminous flux;
A scanning unit that reflects the luminous flux and repeats a reciprocating motion in a predetermined scanning direction;
A scanning detection unit for detecting an operating range of the scanning unit for each scanning unit of the forward or backward movement of the reciprocating operation;
The rather smaller than the detected operating range reference range, when the end portion of the detected operating range does not reach the end of the reference range, the difference between the reference range and the detected operating range A drawing position determination unit that determines the image drawing position for each scanning unit by reducing an interval from the operation start of the scanning unit to the image drawing position in the next scanning unit;
A light source driving unit that drives the light source unit based on image data at a timing corresponding to the determined image drawing position;
An image display device comprising: A counter that counts the detected operating range based on a clock;
The drawing position determination unit increases a start count value of the counter in the next scanning unit based on a difference between a counter value obtained by the counter counting the detected operation range and a counter value corresponding to the reference range. ,
The image display device according to claim 1. The drawing position determination unit sets the reference range based on an average of the detected plurality of motion ranges;
The image display device according to claim 1. The drawing position determination unit sets the reference range to be an even number when the operation range is counted based on a clock;
The image display apparatus as described in any one of Claims 1 thru | or 3. A control method for an image display device, comprising: a light source unit that outputs a light beam; and a scanning unit that reflects the light beam and repeats reciprocation in a predetermined scanning direction,
Detecting an operating range of the scanning unit for each scanning unit of the forward or backward movement of the reciprocating operation;
The rather smaller than the detected operating range reference range, when the end portion of the detected operating range does not reach the end of the reference range, the difference between the reference range and the detected operating range Based on this, by reducing the interval from the start of operation of the scanning unit to the image drawing position in the next scanning unit, the image drawing position is determined for each scanning unit,
Driving the light source unit based on image data at a timing corresponding to the determined image drawing position;
A method for controlling an image display device.