JP2010237536A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanning type image display device capable of shortening a time required until the start of image display by performing start-up processing of a low-speed scanning element and a high-speed scanning element at high speed. <P>SOLUTION: The image display device is configured to execute first processing to move a scanning position by the low-speed scanning element to an invalid scanning area where a projection object is not irradiated with laser light, second processing to oscillate the reflection mirror of the high-speed scanning element, third processing to detect the oscillating state of the reflection mirror of the high-speed scanning element and resonant oscillate, fourth processing to generate an image display driving signal for driving the low-speed scanning element based on the oscillating state of the reflection mirror of the high-speed scanning element. During the execution of the processing whose processing time is longer than that of the other between the first processing and the second processing, the other processing is executed, thereafter, during the execution of the processing whose processing time is longer than that of the other between the third processing and the fourth processing, the other processing is executed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image display device. More specifically, the present invention relates to an image display device that displays an image by two-dimensionally scanning a laser beam having an intensity corresponding to an image signal emitted from a light source unit by driving an optical scanning element.

  Conventionally, a laser beam generated based on image information is generated on the screen based on image information on a retinal scanning image display device that displays an image by scanning and projecting on at least one retina of a user. An image display device such as a screen scanning image display device that displays an image by scanning a laser beam is known.

  For example, in the image display device described in Patent Document 1 below, the reflection mirror of an optical scanning element (hereinafter also referred to as “high-speed scanning element”) that can swing the reflection mirror at a relatively high speed is driven in a resonance mode. Thus, the reflection mirror of the optical scanning element (hereinafter also referred to as “low-speed scanning element”) that can reciprocate the laser beam in the horizontal direction and oscillate the reflection mirror at a relatively low speed is sawtooth in a non-resonant mode. By driving, the laser beam is scanned in the vertical direction to display an image.

JP 2006-276399 A

  By the way, when the laser beam is scanned in the horizontal direction by swinging the reflection mirror of the high-speed scanning element by utilizing the resonance characteristic unique to the high-speed scanning element as in the image display device described in Patent Document 1 above, The horizontal scanning frequency changes according to the resonance characteristics of the high-speed scanning element.

  Therefore, it is necessary to change the waveform of the drive signal for driving the low-speed scanning element in accordance with the horizontal scanning frequency.

  The horizontal scanning frequency can be detected based on the swinging state of the high-speed scanning element. The swinging state of the high-speed scanning element is obtained by, for example, scanning the inspection laser light emitted from the light source unit with the high-speed scanning element. The scanning inspection laser light can be detected by a photodetector. At this time, the inspection laser beam must be emitted from the light source unit to the high-speed scanning element after the low-speed scanning element is moved to the invalid scanning area so that unnecessary light is not emitted within the effective scanning area.

  Therefore, conventionally, after the low-speed scanning element is moved to the invalid scanning region, the high-speed scanning element is driven to detect its swinging state, and a drive signal for driving the low-speed scanning element according to the swinging state. Then, the low-speed scanning element is driven based on the generated drive signal. For this reason, it takes time from the start of driving the image display apparatus to the display of the image.

  The present invention has been made in view of the above-described problems, and is an optical scanning type image which can shorten the time required to start image display by performing start-up processing of a low-speed scanning element and a high-speed scanning element at high speed. An object is to provide a display device.

  In order to achieve the above object, an invention according to claim 1 is directed to a light source section that emits laser light having an intensity corresponding to an image signal, and to scan the laser light at a relatively high speed in a first direction by a reflection mirror. A high-speed scanning element, a low-speed scanning element that scans the laser light in a second direction orthogonal to the first direction by a reflection mirror, and a laser having an intensity corresponding to the image signal by controlling the light source unit A control unit that emits light and drives the high-speed scanning element and the low-speed scanning element to two-dimensionally scan the laser light emitted from the light source unit, and projects the two-dimensionally scanned laser light And a projection unit configured to project an image onto the target and display an image. The control unit moves the scanning position of the low-speed scanning element to an invalid scanning region where laser light is not emitted to the projection target. 1 treatment , A second process for swinging the reflection mirror of the high-speed scanning element, a third process for detecting a swinging state of the reflection mirror of the high-speed scanning element and resonantly swinging, and a swing of the reflection mirror of the high-speed scanning element. A fourth process for generating an image display driving signal for driving the low-speed scanning element based on a moving state; a fifth process for driving the low-speed scanning element by the generated image display driving signal; After the process is executed and the laser beam can be scanned by the low-speed scanning element and the high-speed scanning element, a sixth process of emitting a laser beam having an intensity corresponding to the image signal from the light source unit can be performed. One of the first process and the second process having the longer processing time is executed while the other process is executed, and then the third process and the fourth process having the longer processing time. Real processing Perform other processed during, then, and executes the 5 process and the sixth process.

  According to a second aspect of the present invention, in the image display device according to the first aspect of the present invention, the image display device further includes a detection unit that detects a shift in a scanning line interval caused by a natural resonance of the low-speed scanning element, and the control unit After the execution of the fifth process is started, the sixth process is executed when the deviation of the scanning line interval detected by the detection unit becomes a predetermined value or less.

  According to a third aspect of the present invention, in the image display device according to the first or second aspect, when the processing having the longer processing time of the first processing and the second processing is completed, the other processing is performed. The timing of the first process and the second process is set so that the process ends.

  According to a fourth aspect of the present invention, in the image display device according to any one of the first to third aspects, the processing having the longer processing time out of the third processing and the fourth processing is completed. In this case, the timing of the third process and the fourth process is set so that the other process ends.

  According to a fifth aspect of the present invention, in the image display device according to any one of the first to fourth aspects of the present invention, the third process is performed by changing the oscillation frequency of the reflection mirror of the high-speed scanning element to the high-speed scanning. And adjusting the oscillation amplitude of the reflection mirror of the high-speed scanning element after adjusting to the natural resonance frequency of the element, and the control unit performs the fourth process after adjusting to the natural resonance frequency of the high-speed scanning element. It is something to execute.

  According to a sixth aspect of the present invention, in the image display device according to any one of the first to fifth aspects of the present invention, the scanning position by the high-speed scanning element is in an invalid scanning area where no laser beam is emitted to the projection target. There is a light detection unit at a position where laser light emitted from the light source unit is scanned and incident by the high-speed scanning element, and the control unit has a scanning position by the high-speed scanning element in the invalid scanning region. At a certain time, laser light having a predetermined intensity is emitted from the light source unit, and the oscillation state of the high-speed scanning element is detected according to the detection result of the light detection unit with respect to the laser light.

  According to a seventh aspect of the present invention, in the image display device according to any one of the first to sixth aspects, the projection unit emits laser light scanned by the high-speed scanning element and the low-speed scanning element. It is an eyepiece optical system that is incident on a user's eye and projects an image corresponding to the image signal onto the retina of the user.

  According to the present invention, it is possible to shorten the time until the image display starts by performing the start-up process of the low-speed scanning element and the high-speed scanning element at high speed.

1 is a diagram illustrating an overall configuration of an image display device (retinal scanning display) according to an embodiment of the present invention. It is a figure which shows the structure of the vertical drive signal generator of FIG. It is operation | movement explanatory drawing of the scanning part of FIG. It is a figure which shows the ringing waveform which generate | occur | produces by the resonance intrinsic | native to a low-speed scanning element. It is a figure which shows the flow of a process at the time of the drive start of an image display apparatus. It is a figure which shows the flow of a process at the time of the drive start of an image display apparatus.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, an example of a retinal scanning type image display device that scans a laser beam according to a drive signal based on image information, projects an image on at least one retina of a user, and displays the image is taken as an example. However, the present invention is not limited to this example. For example, the scanning unit scans a laser beam having an intensity corresponding to a drive signal based on image information, so that the image is projected on a screen to be projected. The present invention can be applied to other image display apparatuses that display an image by scanning a laser beam, such as a screen scanning image display apparatus that projects and displays an image.

  Hereinafter, the image display apparatus 1 according to the present embodiment will be specifically described with reference to FIGS. 1 and 2.

[1. Specific configuration including electrical configuration and optical configuration of image display apparatus 1]
As shown in FIG. 1, the image display device 1 includes a control unit 10, a light source unit 20, a scanning unit 30, an operation unit 40, an optical fiber cable 50, and a half mirror 31.

  The control unit 10 includes a main control unit 11, a horizontal drive signal generator 12 that generates a horizontal drive signal 61 that is an image display drive signal, a vertical drive signal generator 13 that generates a vertical drive signal 62, and an image signal. And a drive signal supply circuit 18 for generating a signal or the like as an element for synthesizing an image based on S.

  The main control unit 11 includes a CPU (Central Processing Unit), a flash memory (ROM) as a ROM (Read Only Memory), a RAM (Random Access Memory), a VRAM (Video Random Access Memory), and an input interface (I / F). The horizontal drive signal generator 12, the vertical drive signal generator 13, the drive signal supply circuit 18 and the like are controlled according to a control program stored in the flash memory.

  The horizontal drive signal generator 12 has a function of generating and outputting a horizontal drive signal 61 for swinging a reflection mirror 82 of a high-speed scanning element 81 of the horizontal scanning unit 80 described later. The frequency of the horizontal drive signal 61 is adjusted based on the first photodetection signal 97 output from the first photodetector 96 so that the signal has a frequency corresponding to the inherent resonance frequency. Further, the amplitude of the horizontal drive signal 61 is adjusted based on the second light detection signal 99 output from the second light detector 98 so that the reflection mirror 82 of the high speed scanning element 81 has a preset swing amplitude.

  The first and second light detection signals 97 and 99 are generated when the scanning position of the laser light of the reflection mirror 82 by the high-speed scanning element 81 is the position where the first and second light detectors 96 and 98 are disposed. It is a signal output from the first and second photodetectors 96 and 98, and in the present embodiment, the first photodetector 96 is substantially at the center in the horizontal scanning direction (substantially at the center in the horizontal effective scanning region X1 described later). The second photodetector 98 is disposed on the end side in the horizontal scanning direction (outside the horizontal effective scanning region X1 described later).

  The horizontal drive signal generator 12 compares the horizontal drive signal 61 with the output timing of the first light detection signal 97 from the first light detector 96, and compares the waveform of the horizontal drive signal 61 with the reflection mirror of the high-speed scanning element 81. A phase difference from the phase of the oscillating waveform 82 is detected, and the frequency of the horizontal drive signal 61 is adjusted so that this phase difference is approximately 90 degrees.

  Further, the horizontal drive signal generator 12 has a preset swing amplitude of the reflection mirror 82 of the high-speed scanning element 81 according to the presence / absence and timing of the second light detection signal 99 output from the second light detector 98. Thus, the amplitude of the horizontal drive signal 61 is adjusted.

  The vertical drive signal generator 13 has a function of generating a vertical drive signal 62 for oscillating a reflection mirror 92 of a low-speed scanning element 91 of the vertical scanning unit 90 described later. A vertical drive signal 62 having a drive waveform corresponding to the frequency is generated and output.

  As shown in FIG. 2, the vertical drive signal generator 13 includes a first storage unit 130 storing sawtooth waveform data (hereinafter referred to as “saw waveform”), notch filter processing, and bandpass. A filter 131 that performs filter processing, a second storage unit 132 that stores data of a signal subjected to filtering processing by the filter 131, a DA converter 133 that reads data from the second storage unit 132, performs analog conversion, and outputs the converted data , A drive control unit 134 is provided. The drive control unit 134 reads the sawtooth waveform data (here, one cycle) from the first storage unit 130 at a timing corresponding to the resonance frequency unique to the high-speed scanning element 81, and a sawtooth waveform signal corresponding to the horizontal scanning frequency. Is input to the filter 131, subjected to filtering processing and stored in the second storage unit 132, thereby generating the basic waveform data of the vertical drive signal 62. Thereafter, the drive control unit 134 reads out the basic waveform data stored in the second storage unit 132 at a timing according to the resonance frequency unique to the high-speed scanning element 81, and inputs the analog waveform to the DA converter 133 to perform vertical drive. A signal 62 is generated and output.

  Based on the image signal S, the drive signal supply circuit 18 generates each signal, which is an element for forming an image, in units of pixels. That is, the drive signal supply circuit 18 generates and outputs an R (red) drive signal 60r, a G (green) drive signal 60g, and a B (blue) drive signal 60b. The drive signal supply circuit 18 outputs a horizontal drive signal 61 used by the horizontal scanning unit 80 and a vertical drive signal 62 used by the vertical scanning unit 90, respectively.

  The light source unit 20 is intensity-modulated according to the drive signals 60r, 60g, and 60b of the R drive signal 60r, the G drive signal 60g, and the B drive signal 60b output from the drive signal supply circuit 18 in units of pixels. An R laser driver 66, a G laser driver 67, and a B laser driver 68 for driving the R laser 63, the G laser 64, and the B laser 65, respectively, are provided so as to emit laser light (also referred to as “light beam”). ing. Each laser 63, 64, 65 can be configured as, for example, a semiconductor laser or a solid-state laser with a harmonic generation mechanism. If a semiconductor laser is used, the drive current can be directly modulated to modulate the intensity of the laser beam. However, if a solid-state laser is used, each laser is equipped with an external modulator, and the intensity of the laser beam is modulated. Need to do.

  Further, the light source unit 20 multiplexes the collimated laser light and collimated optical systems 71, 72, 73 provided so as to collimate the laser light emitted from the lasers 63, 64, 65 into parallel light. There are provided dichroic mirrors 74, 75, and 76, and a coupling optical system 77 that guides the combined laser light to the optical fiber cable 50.

  Therefore, the laser beams emitted from the lasers 63, 64, 65 are collimated by the collimating optical systems 71, 72, 73, respectively, and then enter the dichroic mirrors 74, 75, 76. Thereafter, each of the laser beams is selectively reflected and transmitted with respect to the wavelength by these dichroic mirrors 74, 75, and 76. The three primary color laser beams incident on these three dichroic mirrors 74, 75, and 76 are reflected or transmitted in a wavelength selective manner, reach the coupling optical system 77, and are collected and output to the optical fiber cable 50. The

  The scanning unit 30 located between the light source unit 20 and the user's eye 101 includes a collimating optical system 79 that collimates the laser light generated by the light source unit 20 and emitted through the optical fiber cable 50; A horizontal scanning unit 80 that reciprocally scans the laser beam collimated by the collimating optical system 79 in the horizontal direction (first direction) for image display, and the laser beam scanned in the horizontal direction by the horizontal scanning unit 80 The vertical scanning unit 90 that scans in the vertical direction (second direction) orthogonal to the horizontal direction, the first relay optical system 85 provided between the horizontal scanning unit 80 and the vertical scanning unit 90, and thus the horizontal direction And a second relay optical system 95 for emitting laser light scanned in the vertical direction to the pupil 101a.

  The horizontal scanning unit 80 and the vertical scanning unit 90 scan in the horizontal direction and the vertical direction in order to make the laser beam incident from the optical fiber cable 50 projectable on the user's retina 101b as an image. The horizontal scanning unit 80 includes a resonance type optical scanning element (hereinafter referred to as “high-speed scanning element”) 81 having a reflection mirror 82 for scanning the laser beam in the horizontal direction at a relatively high speed. A horizontal scanning drive circuit 83 that generates a drive signal for causing the high-speed scanning element 81 to resonate and to swing the reflection mirror 82 of the high-speed scanning element 81 based on the horizontal drive signal 61 is provided.

  On the other hand, the vertical scanning unit 90 includes a non-resonant optical scanning element (hereinafter referred to as “low-speed scanning element”) 91 having a reflection mirror 92 for scanning laser light in the vertical direction at a relatively low speed, and this low-speed. And a vertical scanning drive circuit 93 that amplifies the vertical drive signal 62 to generate a drive signal for swinging the reflection mirror 92 of the scanning element 91 in a non-resonant state, and forms an image for each frame of an image to be displayed. The laser beam for scanning is vertically scanned from the first horizontal scanning line toward the last horizontal scanning line. Here, the “horizontal scanning line” means one scanning in the horizontal direction by the horizontal scanning unit 80.

  In addition, the vertical scanning unit 90 includes a vertical fluctuation detection circuit 94. The vertical oscillation detection circuit 94 acquires the oscillation waveform of the reflection mirror 92 of the low-speed scanning element 91, extracts the ringing waveform (see FIG. 4) included in the oscillation waveform by band-pass filter processing, etc. The ringing amplitude (hereinafter referred to as “ringing amplitude”) is detected and output to the control unit 10. For example, as described in Japanese Patent Application Laid-Open No. 2006-276634, the displacement of the beam member that drives the reflection mirror 92 is detected by a piezoelectric element or the like. This can be done by detecting the voltage to be generated by the vertical oscillation detection circuit 94. Note that the configuration is not limited to this configuration as long as the ringing amplitude can be acquired. For example, the reflection mirror 92 is attached by attaching an electrode to the bottom of the reflection mirror 92 and the like, and attaching the electrode to the main body of the low-speed scanning element 91 facing the electrode, thereby detecting the capacitance generated between these electrodes. And the ringing amplitude included in the oscillation waveform can be detected.

  Here, the high-speed scanning element 81 and the low-speed scanning element 91 use galvanometer mirrors, but if the reflection mirror (reflection surface) can be swung or rotated so as to scan the laser beam, Any driving method such as piezoelectric driving, electromagnetic driving, or electrostatic driving may be used.

  The first relay optical system 85 that relays the laser light between the horizontal scanning unit 80 and the vertical scanning unit 90 converts the laser light scanned in the horizontal direction by the reflection mirror 82 of the high-speed scanning element 81 to the low-speed scanning element 91. To the reflecting mirror 92. Then, the laser beam is scanned in the vertical direction by the reflection mirror 92 of the low-speed scanning element 91, and the eye 101 passes through the second relay optical system 95 in which two lenses 95a and 95b having positive refractive power are arranged in series. Is reflected by the half mirror 31 positioned in front of the lens and enters the user's pupil 101a, and an image corresponding to the image signal S is projected onto the retina 101b. Thereby, the user recognizes the laser light incident on the pupil 101a as an image. Further, the half mirror 31 transmits the external light 200 so as to enter the user's pupil 101a, so that the user can visually recognize an image in which the image based on the laser light is superimposed on the external scene based on the external light. .

  In the second relay optical system 95, the respective scanning lights are made substantially parallel to each other and converted into convergent laser lights by the lens 95a. That is, the lens 95a is a telecentric optical system. The laser beams are converted into substantially parallel laser beams by the lens 95b, and the center lines of these laser beams are converted so as to converge on the user's pupil 101a. The lens 95b functions as an eyepiece optical system that projects the image according to the image signal S onto the user's retina 101b by causing the laser light scanned by the scanning unit 30 to enter the user's eye 101 as a projection unit. .

  3 shows the maximum scanning region W (the range formed by the maximum horizontal scanning region Xa and the maximum vertical scanning region Ya shown in FIG. 3) by the high-speed scanning element 81 and the low-speed scanning element 91 of the horizontal scanning unit 80 and the vertical scanning unit 90. ) And the effective scanning area Z (range formed by the horizontal effective scanning area X1 and the vertical effective scanning area Y1 shown in FIG. 3). Here, the “maximum scanning region” means the maximum range in which laser light can be scanned by the high speed scanning element 81 and the low speed scanning element 91. FIG. 3 virtually shows a locus γ of the laser light scanned by the high speed scanning element 81 and the low speed scanning element 91 when it is assumed that the laser light is always emitted from the light source unit 20. However, the number of scans in the horizontal direction by the high-speed scanning element 81 is about several hundred to thousands per frame, and the locus γ of the laser beam is simply shown in FIG.

  The horizontal scanning drive circuit 83 amplifies the horizontal drive signal 61 output from the drive signal supply circuit 18 and applies it to the high-speed scanning element 81 to drive the reflection mirror 82 of the high-speed scanning element 81. The vertical scanning drive circuit 93 amplifies the vertical drive signal 62 output from the drive signal supply circuit 18 and applies it to the low speed scanning element 91 to drive the reflection mirror 82 of the low speed scanning element 91. In accordance with the image signal S from the light source unit 20 at the timing when the scanning positions of the high-speed scanning element 81 and the low-speed scanning element 91 are in the effective scanning area Z among the maximum scanning areas W of the high-speed scanning element 81 and the low-speed scanning element 91. An intensity-modulated laser beam is emitted. As a result, the laser beam is scanned in the effective scanning area Z by the high-speed scanning element 81 and the low-speed scanning element 91, and one frame of laser light is scanned in the effective scanning area Z. This scanning is repeated for each frame image.

  Further, in the image display device 1, the first photodetector 96 is disposed in the vertical invalid scanning area Y2 substantially at the center of the horizontal effective scanning area X1, and outside the horizontal effective scanning area X1 and in the vertical invalid scanning area Y2. A second photodetector 98 is arranged. The first and second light detectors 96 and 98 detect laser light having a predetermined intensity emitted from the light source unit 20 (hereinafter referred to as “inspection laser light”), and detect the first and second light. The signals 97 and 99 are output. As described above, in the image display device 1 according to the present embodiment, the laser beam emitted from the light source unit 20 when the scanning position by the high-speed scanning element 81 is in the invalid scanning region where the laser light is not emitted to the projection target is the high-speed scanning element. First and second light detectors 96 and 98 as light detection units are provided at the positions where the light is scanned by 81.

[2. Operation at the start of driving of the image display apparatus 1]
In the image display device 1 configured as described above, the operation from the state where the operations of the light source unit 20 and the scanning unit 30 are stopped to the start of image display by the light source unit 20 and the scanning unit 30 is as follows. It can be made faster by doing this. The operation will be specifically described below with reference to FIGS.

  When the operation unit 40 is operated or the image signal S is input, the control unit 10 of the image display device 1 firstly reflects the reflecting mirror 92 of the low-speed scanning element 91 as shown in FIGS. The low-speed scanning element 91 starts to be driven so that the scanning direction is moved to the vertical invalid scanning region Y2 where the laser beam is not emitted toward the eye 101 that is the projection target (step S10).

  Specifically, the drive control unit 134 of the vertical drive signal generator 13 reads the drive signal data for the initial operation stored in the second storage unit 132 and inputs it to the DA converter 133 for analog conversion. Then, a vertical drive signal 62 for moving the reflecting mirror 92 of the low speed scanning element 91 to the vertical invalid scanning region Y2 is generated and output. The low-speed scanning element 91 starts swinging of the reflection mirror 92 based on the vertical drive signal 62 input from the vertical drive signal generator 13 in this way.

  Next, the control unit 10 outputs the horizontal drive signal 61 to the vertical scanning drive circuit 93 to start driving the reflection mirror 82 of the high speed scanning element 81 (step S11).

  Specifically, the horizontal drive signal generator 12 outputs a horizontal drive signal 61 having a frequency and amplitude set by default to the high-speed scanning element 81, thereby driving the reflection mirror 82 of the high-speed scanning element 81. Start. The horizontal drive signal generator 12 stores the frequency and amplitude information used for driving the reflection mirror 82 of the high-speed scanning element 81 in the internal storage means when the previous image was displayed. The horizontal drive signal 61 may be generated and output based on the stored frequency and amplitude information.

  Next, the control unit 10 moves the reflection mirror 92 of the low-speed scanning element 91 to the vertical invalid scanning region Y <b> 2 (hereinafter also referred to as “first process”) and drives the reflection mirror 82 of the high-speed scanning element 81. It is determined whether or not (hereinafter also referred to as “second processing”) has ended (step S12).

  The vertical drive signal generator 13 is configured to output a movement end signal to the control unit 10 when the reflecting mirror 92 of the low-speed scanning element 91 is moved to the vertical invalid scanning region Y2, whereby the control unit 10 The end of the movement of the reflection mirror 92 to the vertical invalid scanning area Y2 is determined. The vertical drive signal generator 13 or the control unit 10 stores in advance a sufficient time necessary for moving the reflecting mirror 92 of the low-speed scanning element 91 to the vertical invalid scanning area Y2 in the internal storage means, and performs control. The unit 10 may determine the end of the movement of the reflecting mirror 92 to the vertical invalid scanning area Y2 based on the time thus stored.

  When the horizontal drive signal generator 12 determines that the reflection mirror 82 of the high-speed scanning element 81 is driven at the frequency of the horizontal drive signal 61 based on the first light detection signal 97 output from the first light detector 96. The driving end signal is configured to be output to the control unit 10, whereby the control unit 10 determines the end of the driving process of the reflecting mirror 82. Note that when the first light detection signal 97 is output at a period that is ½ times the period of the horizontal drive signal 61 (= 1 / frequency of the horizontal drive signal 61), the reflection mirror 82 has the frequency of the horizontal drive signal 61. Is determined to have been driven.

  In this way, the processes of steps S10 to S12 are executed, and the other second process is executed while the first process having a longer processing time is being executed among the first process and the second process.

  By executing the processing in this way, it is possible to shorten the processing time compared to the case where the first processing and the second processing are executed while being shifted in time.

  If the processing time of the second process is longer than the first process, the processing order of step S10 and step S11 is reversed. By doing in this way, the processing time can be shortened by executing the other first processing while executing the second processing having the longer processing time of the first processing and the second processing.

  In particular, if the process with the longer processing time of the first process and the second process is completed, the other process is terminated, so that the start of the other process can be delayed to the maximum. Electric power can be reduced. For example, when the driving process (second process) of the reflection mirror 82 of the high-speed scanning element 81 is completed, if the reflection mirror 92 of the low-speed scanning element 91 has not yet moved to the vertical invalid scanning region Y2, the reflection mirror 92 is Although it is necessary to continue to swing the reflecting mirror 82 of the high-speed scanning element 81 until it moves to the vertical invalid scanning area Y2, this process can suppress wasteful power consumption. Further, when the processing time of the second process is long, the position of the reflecting mirror 92 is determined when the second process is not completed when the movement process (first process) of the reflecting mirror 92 to the vertical invalid scanning region Y2 is completed. However, useless power consumption can be suppressed by such processing.

  If it is determined in step S12 that both the first process and the second process have been completed (step S12: YES), the control unit 10 sets the oscillation frequency of the reflection mirror 82 of the high-speed scanning element 81 to the high-speed scanning element 81. A process of adjusting to a specific resonance frequency is performed (step S13). The reflection mirror 82 of the high-speed scanning element 81 is swung in a resonance state when the phase of the oscillation waveform of the reflection mirror 82 of the high-speed scanning element 81 is shifted by about 90 degrees with respect to the drive signal input to the high-speed scanning element 81. It will be moved. Therefore, the control unit 10 adjusts the oscillation frequency of the reflection mirror 82 of the high-speed scanning element 81 using the characteristics as follows.

  First, the control unit 10 outputs driving signals 60r, 60g, and 60b for inspection to the light source unit 20, and emits laser light (inspection laser light) having a predetermined luminance from the lasers 63, 64, and 65. The horizontal drive signal generator 12 compares the output horizontal drive signal 61 with the output timing of the first light detection signal 97 from the first light detector 96, and compares the waveform of the horizontal drive signal 61 with the high-speed scanning element. The phase difference with the swing waveform of the reflection mirror 82 of 81 is detected, and the frequency of the horizontal drive signal 61 is changed so that this phase difference becomes approximately 90 degrees, and this phase difference becomes approximately 90 degrees. Sometimes, the adjustment of the oscillation frequency of the reflection mirror 82 is finished. In this way, the process of adjusting the oscillation frequency of the reflection mirror 82 of the high-speed scanning element 81 to the resonance frequency unique to the high-speed scanning element 81 is performed.

  In the horizontal drive signal generator 12 or the control unit 10, a necessary and sufficient time for adjusting the oscillation frequency of the reflection mirror 82 of the high-speed scanning element 81 is stored in advance in the internal storage means. It may be determined that the adjustment of the oscillation frequency of the reflection mirror 82 has been completed based on the time stored in the above.

  When the adjustment of the oscillation frequency of the reflection mirror 82 of the high-speed scanning element 81 is completed in step S13, the control unit 10 starts a process of adjusting the oscillation amplitude of the reflection mirror 82 of the high-speed scanning element 81 (step S14).

  Specifically, the control unit 10 outputs driving signals 60r, 60g, and 60b for inspection to the light source unit 20, and emits laser light (inspection laser light) having a predetermined luminance from the lasers 63, 64, and 65. . The horizontal drive signal generator 12 of the control unit 10 detects the swing amplitude of the reflection mirror 82 based on the presence and timing of the second light detection signal 99 output from the second light detector 98. That is, when the light detection signal 99 is not output from the second photodetector 98, the horizontal drive signal generator 12 determines that the swinging amplitude of the reflection mirror 82 is small and increases the amplitude of the horizontal drive signal 61. Further, when the light detection signal 99 is output from the second light detector 98, the horizontal drive signal generator 12 determines that the swinging amplitude of the reflection mirror 82 is equal to or greater than a predetermined value, and the light detection signal 99. The swing amplitude of the reflection mirror 82 is determined according to the interval, and the amplitude of the horizontal drive signal 61 is adjusted according to the swing amplitude. Note that when the period of the second light detection signal 99 output from the second photodetector 98 is the same as the period of oscillation of the reflection mirror 82, the horizontal drive signal generator 12 has an oscillation amplitude of the reflection mirror 82 of the second. It is determined that the amplitude is up to the position of the photodetector 98, and the amplitude of the horizontal drive signal 61 is increased.

  The second photodetector 98 is composed of a plurality of photosensors, and these photosensors are arranged in the vertical invalid scanning region Y2 from the center of the horizontal effective scanning region X1 to the end of the maximum horizontal scanning region Xa. Thus, the swing amplitude of the reflection mirror 82 may be detected. Further, for example, as described in JP-A-2006-276634, the displacement of the beam member that drives the reflection mirror 82 may be detected by a piezoelectric element or the like.

  As described above, the control unit 10 causes the light source unit 20 to emit laser light having a predetermined intensity when the scanning position by the high-speed scanning element 81 is in the invalid scanning region in steps S13 and S14. The swing state (swing frequency and swing amplitude) of the high speed scanning element 81 is detected in accordance with the detection results of the second photodetectors 96 and 98, and thereby the high speed scanning element 81 is resonantly swung. A resonance oscillation process is performed.

  Further, after starting the adjustment of the swing amplitude of the reflection mirror 82 of the high speed scanning element 81 in step S14, the control unit 10 starts generating a drive signal waveform of the low speed scanning element 91 (step S15).

  Specifically, the drive control unit 134 generates a sawtooth waveform (in this case, from the first storage unit 130 at a timing corresponding to the oscillation frequency of the high-speed scanning element 81 adjusted to the resonance frequency unique to the high-speed scanning element 81 in step S13. Data for one cycle) is read out and a sawtooth waveform signal corresponding to the horizontal scanning frequency is generated. This sawtooth waveform signal is input to the filter 131 and subjected to filtering processing. The drive control unit 134 stores the signal subjected to the filtering process in the second storage unit 132 as basic waveform data of the vertical drive signal 62. This completes the drive signal waveform generation process.

  Next, the resonance oscillation process (hereinafter also referred to as “third process”) of the reflection mirror 82 of the high-speed scanning element 81 and the drive signal waveform generation process (hereinafter referred to as “fourth process”) of the low-speed scanning element 91 are also referred to. ) Is determined (step S16). Note that the resonance oscillation process of the reflection mirror 82 of the high-speed scanning element 81 is a process in which the reflection mirror 82 is in the oscillation state of a predetermined amplitude in the resonance state so that the laser beam can be scanned by the high-speed scanning element 81. Specifically, after adjusting the oscillation frequency of the reflection mirror of the high-speed scanning element 81 to the natural resonance frequency of the high-speed scanning element 81, the process adjusts the oscillation amplitude of the reflection mirror 82 of the high-speed scanning element 81. is there.

  In this way, the processes in steps S14 to S16 are executed, and the other fourth process is executed while the third process having a longer processing time is being executed among the third process and the fourth process.

  By executing the processing in this way, it is possible to shorten the processing time as compared with the case where the third processing and the fourth processing are executed while being shifted in time.

  When the processing time of the fourth process is longer than the swing amplitude adjustment process in the third process, the processing order of steps S14 and S15 is reversed. By doing so, it is possible to reduce the processing time by executing the other third process while executing the fourth process having the long processing time among the third process and the fourth process.

  In particular, if the process with the longer processing time of the third process and the fourth process is completed when the other process ends, the start of the other process can be delayed as much as possible. Electric power can be reduced. For example, if the vertical drive signal generator 13 detects the swinging state of the reflection mirror 82 of the high-speed scanning element 81 by the time the generation process of the drive signal waveform is finished, the resonance swing is performed with a predetermined swing amplitude. Although the resonance oscillation of the reflection mirror 82 until the drive signal waveform processing of the low-speed scanning element 91 is completed is wasted, the power consumption that is wasted can be reduced by terminating these processes at the same time. it can.

  If it is determined in the process of step S16 that both the third process and the fourth process have been completed (step S16: YES), the control unit 10 performs the vertical drive signal of the drive signal waveform generated in step S15 as the fifth process. 62 is output to the low-speed scanning element 91, and the reflection mirror 92 of the low-speed scanning element 91 is swung in a sawtooth shape (step S17).

  Specifically, the drive control unit 134 reads out data from the second storage unit 132 at a timing corresponding to the resonance frequency unique to the high-speed scanning element 81, inputs the data to the DA converter 133, and converts the data into an analog drive signal. 62 is generated and output. By repeating this process, a vertical drive signal 62, which is a periodic saw-shaped drive signal, is generated and output to the low-speed scanning element 91, and the reflection mirror 92 of the low-speed scanning element 91 is continuously swung in a sawtooth shape. Move.

  Next, the control unit 10 determines whether or not the swing of the reflection mirror 92 of the low-speed scanning element 91 is stable (step S18). That is, the control unit 10 detects the shift of the scanning line interval caused by the natural resonance of the low-speed scanning element 91, and when the shift of the scanning line interval becomes a predetermined value or less, the swing of the reflection mirror 92 is stable. It is determined that

  Specifically, the control unit 10 determines the deviation of the scanning line interval based on the fluctuation detection signal 78 output from the vertical fluctuation detection circuit 94, and the deviation of the scanning line interval becomes a predetermined value or less. It is determined that the swinging of the reflecting mirror 92 is stable. That is, when the amplitude of ringing generated by the natural resonance of the low-speed scanning element 91 is large, the deviation of the scanning line interval becomes large. The swing detection signal 78 is amplitude information of a high-frequency component (ringing) generated in the swing of the reflecting mirror due to the resonant vibration generated in the low-speed scanning element 91, and the control unit 10 has the ringing amplitude less than a predetermined value. In some cases, it is determined that the deviation of the scanning line interval is equal to or less than a predetermined value. As described above, the vertical oscillation detection circuit 94 functions as a detection unit that detects a shift in the scanning line interval caused by the natural resonance of the low-speed scanning element 91. By doing so, it is possible to prevent the laser light from being emitted and projected from the light source unit 20 in a state where the driving of the low-speed scanning element 91 is not stable, thereby projecting a low-quality image. Can be prevented.

  When it is determined that the swing of the reflection mirror 92 of the low-speed scanning element 91 is stable (step S18: YES), the control unit 10 emits laser light corresponding to the image signal from the light source unit 20 and the high-speed scanning element 81 and the low-speed scanning element 81. Two-dimensional scanning of the laser beam is started by the scanning element 91 (step S19). As a result, laser light that has been two-dimensionally scanned is projected onto the retina 101b of the user's eye 101 so that the user can visually recognize an image corresponding to the image signal S.

  As described above, in the image display device 1 according to the present embodiment, the first process and the second process are performed at the same time, and then the third process and the fourth process are performed at the same time, whereby the high-speed scanning element. 81 and the low-speed scanning element 91 are activated at high speed, and the time until the start of image display can be shortened.

  As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are merely examples, and various embodiments can be made based on the knowledge of those skilled in the art including the aspects described in the Summary of the Invention. The present invention can be implemented in other forms that have been modified or improved.

  Although the present invention has been described through the above-described embodiments, the following effects can be expected according to this embodiment.

(1) A light source unit 20 that emits a laser beam having an intensity corresponding to the image signal S, a high-speed scanning element 81 that scans the laser beam at a relatively high speed in the horizontal direction (first direction) by a reflection mirror 82, and a laser A low-speed scanning element 91 that scans light relatively slowly in a vertical direction (second direction) orthogonal to the horizontal direction by a reflection mirror 92, and a laser beam having an intensity corresponding to the image signal S by controlling the light source unit 20. The control unit 10 that two-dimensionally scans the laser light emitted and driven from the light source unit 20 by driving the high-speed scanning element 81 and the low-speed scanning element 91 and the two-dimensionally scanned laser light to be projected In the image display device provided with a lens 95b (projection unit) that projects an image on the screen, the control unit 10 makes the scanning position by the low-speed scanning element 91 a vertical position where laser light is not emitted to the eye 101 (projection target). Invalid run The first process of moving to the area Y2 (ineffective scanning area), the second process of swinging the reflection mirror 82 of the high-speed scanning element 81, and the swinging state of the reflection mirror 82 of the high-speed scanning element 81 are detected, and the resonance fluctuation is detected. And a fourth process for generating a vertical drive signal 62 (image display drive signal) for driving the low-speed scanning element 91 based on the swinging state of the reflection mirror 82 of the high-speed scanning element 81. The fifth process of driving the low-speed scanning element 91 by the vertical drive signal 62 and the fifth process are executed, and after the laser beam can be scanned by the low-speed scanning element 91 and the high-speed scanning element 81, the light source unit 20 A sixth process for emitting a laser beam having an intensity corresponding to the image signal S can be executed, and the other process is executed while the process with the longer processing time is being executed among the first process and the second process. ,afterwards The other process is executed while the process having the longer processing time of the third process and the fourth process is executed, and then the fifth process and the sixth process are executed. Therefore, the high-speed scanning element 81 and the low-speed scanning element 91 It is possible to shorten the time until the image display starts by performing the startup process at high speed.

(2) In addition, a vertical fluctuation detection circuit 94 (detection unit) that detects a shift in the scanning line interval caused by the natural resonance of the low-speed scanning element 91 is provided, and the control unit 10 starts executing the fifth process. Since the sixth process is executed when the deviation of the horizontal scanning line interval detected by the vertical oscillation detection circuit 94 becomes equal to or less than a predetermined value, the light source unit is driven in a state where the driving of the low-speed scanning element 91 is not stable. Thus, it is possible to prevent the laser beam from being projected from the laser beam 20, thereby preventing a low-quality image from being projected.

(3) Also, by setting the timing of the first process and the second process so that the other process ends when the process with the longer processing time of the first process and the second process ends. Unnecessary processing can be avoided and power consumption can be reduced.

(4) Also, by setting the timing of the third process and the fourth process so that the other process ends when the process with the longer processing time of the third process and the fourth process ends, Unnecessary processing can be avoided and power consumption can be reduced.

(5) The third process is a process of adjusting the oscillation amplitude of the reflection mirror 82 of the high-speed scanning element 81 after adjusting the oscillation frequency of the reflection mirror 82 of the high-speed scanning element 81 to the natural resonance frequency of the high-speed scanning element. Yes, the control unit 10 executes the fourth process after adjusting to the natural resonance frequency of the high-speed scanning element 81. Therefore, before adjusting the oscillation frequency of the reflection mirror 82 of the high-speed scanning element 81, the control unit 10 Since the swing amplitude is adjusted, the fourth process can be performed quickly.

(6) Laser light emitted from the light source unit 20 when the scanning position by the high-speed scanning element 81 is in the vertical invalid scanning region Y2 (invalid scanning region) where the laser light is not emitted to the user's eye 101 (projection target). Has first and second photodetectors 96 and 98 (light detection units) at positions where they are scanned by the high-speed scanning element 81 and the control unit 10 determines that the scanning position by the high-speed scanning element 81 is a vertical invalid scanning region. A laser beam with a predetermined intensity is emitted from the light source unit 20 when it is in Y2 (invalid scanning region), and the high-speed scanning element 81 fluctuates according to the detection results of the first and second photodetectors 96 and 98 with respect to the laser beam. Since the moving state is detected, it is possible to detect the swinging state of the high-speed scanning element 81 with high accuracy.

DESCRIPTION OF SYMBOLS 1 Image display apparatus 10 Control part 20 Light source part 30 Scanning part 80 Horizontal scanning part 81 High speed scanning element 82 Reflection mirror 90 of a high speed scanning element Vertical scanning part 91 Low speed scanning element 92 Reflection mirror 95b of a low speed scanning element Lens 96 1st light detection 98 Second Photodetector

Claims (7)

A light source unit that emits laser light having an intensity corresponding to an image signal, a high-speed scanning element that scans the laser light in a first direction with a reflection mirror at a relatively high speed, and a laser beam that emits the laser light in a first direction with a reflection mirror. A low-speed scanning element that scans at a relatively low speed in a second direction orthogonal to each other and a laser beam having an intensity corresponding to the image signal by controlling the light source unit to drive the high-speed scanning element and the low-speed scanning element And a control unit that two-dimensionally scans the laser light emitted from the light source unit, and a projection unit that projects the two-dimensionally scanned laser light onto a projection target and displays an image. In an image display device,
The controller is
A first process of moving a scanning position by the low-speed scanning element to an invalid scanning area where laser light is not emitted to the projection target;
A second process of swinging the reflection mirror of the high-speed scanning element;
A third process for detecting a swinging state of the reflection mirror of the high-speed scanning element and causing the swinging of the reflection mirror;
A fourth process of generating an image display drive signal for driving the low-speed scanning element based on the swinging state of the reflection mirror of the high-speed scanning element;
A fifth process of driving the low-speed scanning element by the generated image display drive signal;
A sixth process of emitting laser light having an intensity corresponding to the image signal from the light source unit after the fifth process is performed and laser light can be scanned by the low-speed scanning element and the high-speed scanning element; Is executable,
The other process is executed while the process having the longer processing time of the first process and the second process is being executed, and then the process having the longer process time of the third process and the fourth process is performed. An image display device, wherein the other process is executed during execution, and then the fifth process and the sixth process are executed. A detection unit that detects a shift in the scanning line interval caused by the natural resonance of the low-speed scanning element;
The control unit executes the sixth process when the deviation of the scanning line interval detected by the detection unit becomes equal to or less than a predetermined value after the execution of the fifth process is started. The image display device according to claim 1.   The timing of the first process and the second process is set so that the process with the longer processing time of the first process and the second process ends when the other process ends. The image display device according to claim 1 or 2.   The timing of the third process and the fourth process is set so that the process with the longer processing time of the third process and the fourth process ends when the other process ends. The image display device according to claim 1. The third process is a process of adjusting the oscillation amplitude of the reflection mirror of the high-speed scanning element after adjusting the oscillation frequency of the reflection mirror of the high-speed scanning element to the natural resonance frequency of the high-speed scanning element;
5. The image display device according to claim 1, wherein the control unit performs the fourth process after adjusting to a natural resonance frequency of the high-speed scanning element. 6. When the scanning position by the high-speed scanning element is in an invalid scanning area where laser light is not emitted to the projection target, a light detection unit is provided at a position where the laser light emitted from the light source unit is scanned and incident by the high-speed scanning element. Have
The control unit emits a laser beam with a predetermined intensity from the light source unit when the scanning position by the high-speed scanning element is in the invalid scanning region, and the high-speed scanning unit according to a detection result of the light detection unit with respect to the laser beam The image display apparatus according to claim 1, wherein a swinging state of the scanning element is detected.   The projection unit is an eyepiece optical system that projects laser light scanned by the high-speed scanning element and the low-speed scanning element to a user's eye and projects an image corresponding to the image signal on the user's retina. The image display device according to claim 1, wherein:

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