JP4385735B2 - Image display device - Google Patents

Description

  In the present invention, a light beam is incident on the observer's pupil, and an image is projected on the observer's retina by the incident light beam, thereby allowing the observer to recognize that a virtual image is displayed in front of the pupil. The present invention relates to an image display device.

  A retinal scanning display is already known as an example of an image display device. In this type of image display apparatus, a light beam corresponding to an image is generated and emitted by a light source, and the emitted light beam is reflected by a reflection surface of a scanning unit to be scanned in a state where it can be projected as an image. The The scanned light flux enters the observer's pupil, and an image is projected onto the observer's retina by the light flux thus incident on the pupil. Thereby, the observer can recognize that the virtual image is displayed in front of the pupil.

The scanning unit in this type of image display device usually has a reflecting surface that reflects the light beam, and the reflection surface is moved from the reflecting surface by repeating the operation of changing the direction of the reflecting surface with respect to the light beam incident on the reflecting surface. Scanning is performed so that the reflected light beam can be projected as an image.
As described above, since the light beam is scanned by repeating the operation of changing the direction of the reflecting surface of the scanning unit, the mechanism for changing the direction of the reflecting surface can operate normally due to some trouble. When it disappears, there is a possibility that the light beam enters the observer's pupil without being scanned normally.

  Since the light beam incident on the pupil in this way is not a light beam that has been normally scanned for image display, for example, there is a possibility that the viewer may feel discomfort such as glare and flicker.

Patent Document 1 describes a conventional example of this type of image display device. In this conventional example, when a mechanical trouble occurs in the image display device, for example, when the scanning of the light beam by the scanning unit is not performed normally, the light beam is completely not in the pupil. It is configured not to be incident. Specifically, when such a trouble occurs, the emission (generation) of the light beam from the light source is stopped, or the path of the light beam is deviated from the pupil.
Japanese Patent Publication No.7-112254

  According to the conventional image display apparatus described above, when the light beam scanning by the scanning unit is not performed normally, the light beam does not enter the observer's pupil, and thus the viewer is dazzled or flickers. It is possible to prevent discomfort.

  However, in this conventional image display device, when the scanning of the light beam by the scanning unit is not performed normally, the process of preventing the light beam from entering the pupil is merely performed. In other words, for the observer, the virtual image that has been visually recognized until then suddenly disappears without being given any information, which may cause anxiety to the observer. there were.

  In view of such circumstances, an object of the present invention is to provide an image display device capable of changing the display mode without giving an observer anxiety when automatically changing the display mode of a virtual image. There is.

  The following aspects are obtained by the present invention. Each aspect is divided into sections, each section is given a number, and is described in a form that cites other section numbers as necessary. This is to facilitate understanding of some of the technical features that the present invention can employ and combinations thereof, and the technical features that can be employed by the present invention and combinations thereof are limited to the following embodiments. Should not be interpreted. That is, although not described in the following embodiments, it should be construed that it is not impeded to appropriately extract and employ the technical features described in the present specification as the technical features of the present invention.

  Further, describing each section in the form of quoting the numbers of the other sections does not necessarily prevent the technical features described in each section from being separated from the technical features described in the other sections. It should not be construed as meaning, but it should be construed that the technical features described in each section can be appropriately made independent depending on their properties.

(1) An image display device that displays an image by projecting an image on the retina of an observer by scanning a light beam,
A video signal representing the image is input, and based on the input video signal, an emission unit that emits the luminous flux,
A scanning unit that scans the light beam emitted from the emission unit;
When the setting condition is satisfied during the display of the image without depending on the operation of the observer, the low output is set in advance so that the luminous flux from the emission unit is lower than the normal output level but higher than 0. and a control unit for controlling the emitting unit to emit at the level seen including,
The scanning unit
At least one reflecting surface that reflects the luminous flux;
A driving unit that drives the reflecting surface such that the reflecting surface angle, which is an angle with respect to the light beam incident on the reflecting surface, periodically changes.
Including
The image display device includes an abnormal condition that is satisfied when the actual period in which the reflection surface angle changes deviates from a setting range.

  In this image display device, the display mode of the image is automatically changed when the setting condition is satisfied without depending on the operation of the observer during the display of the image. By this change, the output level of the light beam emitted from the emission unit for displaying an image is lowered to a low output level lower than the normal output level. However, since the low output level is not 0, an image displayed with a light beam with a low output level is lower in luminance than the normal output level, but disappears from the viewer against the content of the video signal. Absent.

  Therefore, according to this image display device, when the display mode of the image is automatically changed, the image is not lost, so that it is not necessary to give the observer anxiety due to the change of the display mode. However, even if it gives anxiety, it can be alleviated.

  The “output level” in this section and the following sections can be defined to mean, for example, the intensity of the light beam emitted from the emitting section. Further, when a device whose light emission amount varies depending on power consumption, for example, a laser diode is used for the emission part, the power supplied to the emission part to emit a light beam (for example, the maximum power, average power, It can be defined to mean (effective power).

Furthermore, according to this image display apparatus, when an abnormality occurs in the actual cycle in which the reflection surface angle of the scanning unit changes, the output level of the light beam is automatically within a range that does not cause anxiety to the observer. Reduced.

( 2 ) The abnormal condition is as follows:
The first condition that is satisfied regardless of the part where the abnormality has occurred when the part where the abnormality occurs in the scanning unit is at least one of the reflecting surface and the driving unit,
A second condition that is satisfied when an abnormality occurs at least on the reflecting surface;
The image display device according to ( 1 ), including at least a third condition that is satisfied when an abnormality occurs in the drive unit.

  According to this image display apparatus, the abnormality that occurs in the scanning unit includes an abnormality related to the reflection surface of the scanning unit and an abnormality related to the drive unit (for example, a motor, an actuator, a motion transmission unit, etc.). It becomes possible to discover regardless of which it is. Furthermore, it is possible to specify an abnormality occurring in the scanning unit as either an abnormality relating to the reflecting surface or an abnormality relating to the drive unit.

( 3 ) The scanning unit is a rotating body in which a plurality of the reflecting surfaces are arranged along a circumference coaxial with the rotation axis, and the scanning unit is rotated around the rotation axis by the driving unit. Including
The control unit detects the reflection surface angle individually for the plurality of reflection surfaces,
The first condition is satisfied when there is a reflection surface angle that deviates from the first setting range among the plurality of reflection surface angles detected for the plurality of reflection surfaces, respectively.
The second condition is a case where the first condition is satisfied, and among the plurality of reflection surface angles, a reflection surface whose deviation from an average value of the plurality of reflection surface angles exceeds a second setting range. Holds if there is an angle,
The third condition is satisfied when the first condition is satisfied, and there is no reflection surface angle in which the deviation exceeds the second setting range among the plurality of reflection surface angles ( 2 ) The image display device according to item.

In the image display device according to ( 2 ) above, the scanning unit includes a plurality of reflecting surfaces, a rotating body in which the plurality of reflecting surfaces are arranged along a circumference coaxial with the rotation axis, It is possible to implement in a mode including a drive unit that rotates the rotating body around the rotation axis.

  In this aspect, when there is an abnormal reflection surface angle among the plurality of reflection surface angles detected for each of the plurality of reflection surfaces, the scanning unit is asked whether it is related to the reflection surface or the drive unit. It is possible to determine that there is an abnormality.

  Further, in this aspect, it is a case where it is determined that there is some abnormality in the scanning unit, and among the plurality of reflection surface angles, the reflection whose deviation from the average value of the plurality of reflection surface angles is abnormal When the surface angle exists, it can be determined that some of the reflecting surfaces are abnormal.

  Further, in this aspect, when it is determined that there is some abnormality in the scanning unit, and there is no reflection surface angle with the above deviation among the plurality of reflection surface angles, Rather than determining that there is the same abnormality in each of the reflective surfaces, it is appropriate to determine that there is an abnormality in the drive unit that can have the same influence on all the reflective surfaces.

  Based on the knowledge described above, according to the image display device of this section, it is possible to determine whether the abnormality that has occurred in the scanning unit is an abnormality related to a part of the reflecting surface or an abnormality related to the drive unit. It becomes.

( 4 ) Further, it includes a beam detector that detects that the light beam scanned by the scanning unit is incident on a set position, and the control unit detects the period based on an output signal of the beam detector, The image display device according to any one of ( 1 ) to ( 3 ), wherein it is determined whether or not the abnormal condition is satisfied based on the determined period.

  In general, an image display device is configured to include a beam detector that detects an angle of a reflection surface of a scanning unit using reflected light from the reflection surface in order to synchronize scanning of a light beam by the scanning unit. .

  This beam detector can detect the scanning time required for one scan of the light beam for each reflecting surface, and thus detects the actual period at which the reflecting surface angle changes for each reflecting surface. Is possible.

  Therefore, the beam detector can be used for both scanning synchronization and detection of the change period of the reflecting surface angle.

  Therefore, according to the image display device according to the present section, since the change period of the reflection surface angle is detected using the beam detector, for example, by using the same beam detector in order to suppress an increase in the number of parts, scanning is performed. It is possible to perform both synchronization and detection of the change period of the reflecting surface angle.

( 5 ) The setting condition includes a long-time display condition that is established when a continuous display time by the image display device exceeds the set time. ( 5 ) Image display device.

  In general, the longer the continuous display time by the image display device, the longer the time that the observer continues to observe the image, and the greater the fatigue that the observer feels in the eyes. On the other hand, even if the observer observes the image for the same period of time, the darker the brightness of the image, the less fatigue the observer feels for the eyes.

  Based on such knowledge, in the image display device according to this section, when the continuous display time by the image display device exceeds the set time, the output level of the luminous flux is automatically anxious to the observer. Can be reduced within a range that does not give

  Therefore, according to this image display device, it is possible to automatically reduce the feeling of fatigue of the eyes of the observer without causing discomfort to the observer.

( 6 ) The control unit detects the continuous display time based on an elapsed time from the start of the operation of the scanning unit, and is established when the long time display is performed based on the detected continuous display time. The image display device according to item ( 5 ), wherein it is determined whether or not a condition is satisfied.

( 7 ) The control unit can understand that the control unit is in the state where the output level of the light beam emitted from the emission unit is lowered to the low output level because the setting condition is satisfied. The image display device according to any one of (1) to ( 6 ), wherein the emission unit is controlled such that a predetermined message image is projected onto the retina.

  According to this image display device, when the output level of the light beam is automatically reduced, the observer can know that the phenomenon is planned by using the message image as a medium. In this way, it is not necessary to give the observer anxiety due to the automatic decrease in the output level of the luminous flux.

( 8 ) The image display device according to ( 7 ), wherein the message image is expressed by at least one of a character, a symbol, and a figure.

  According to this image display device, the meaning that the output level of the luminous flux has been reduced as planned is not due to a decrease in the actual brightness of the image visually recognized by the observer, but the communication function equivalent to the language itself or the language. It is possible to reliably communicate to the observer through the image that fulfills the above.

( 9 ) When the setting condition is not satisfied, the control unit controls the emission unit in a normal mode in which the emission unit emits a light beam at the normal output level, and when the setting condition is satisfied. The image display device according to any one of (1) to ( 8 ), wherein the emitting unit controls the emitting unit in a low output mode in which a light beam is emitted at the low output level.

(1 0 ) The low output level is a luminous flux output level at which the observer can visually recognize the image, and is a luminous flux output level that does not cause discomfort to the viewer even if the same position on the retina is continuously irradiated. The image display device according to any one of (1) to ( 9 ).

  In this image display device, the low output level of the light beam is set from the viewpoint of avoiding or reducing discomfort that can be given to the observer by continuous irradiation on the retina.

(1 1 ) An image display device that displays an image by projecting an image on the retina of an observer by scanning a light beam,
A video signal representing the image is input, and based on the input video signal, an emission unit that emits the luminous flux,
In order to scan the light beam emitted from the emission part, (a) at least one reflection surface that reflects the emitted light beam, and (b) the angle of the reflection surface with respect to the light beam incident on the reflection surface. A scanning unit having a drive unit that drives the reflective surface such that the angle of the reflective surface changes periodically;
When the actual period in which the angle of the reflecting surface changes is optically detected and the detected period deviates from the set range, the luminous flux from the emitting unit is lower than the normal output level but larger than 0. A control unit for controlling the emission unit to emit light at a preset low output level, in a state where the output level of the light beam emitted from the emission unit is lowered to the low output level, An image display device that controls the emitting unit so that a predetermined message image is projected onto the retina so that the observer can understand that the state is in the state.

  According to this image display device, when an abnormality occurs in the actual cycle in which the reflection surface angle of the scanning unit changes, the output level of the light beam is automatically lowered within a range that does not cause anxiety to the observer. It is done.

  Furthermore, according to this image display device, when the output level of the luminous flux is automatically lowered, the observer can know that the phenomenon is planned by using the message image as a medium. This also eliminates the feeling of anxiety caused by the automatic decrease in the light beam output level.

(1 2 ) An image display device that displays an image by projecting an image on the retina of an observer by scanning with a light beam,
An output unit that generates a luminous flux corresponding to the image and emits the generated luminous flux;
A scanning unit that has a reflecting surface that reflects the light beam emitted from the light emitting unit, and scans the light beam reflected by the reflecting surface by periodically changing the direction of the reflecting surface within a predetermined angle range; ,
A guiding unit that guides and enters the light beam scanned by the scanning unit into the pupil of the observer;
A period detection unit that is arranged in a region where the light beam scanned by the scanning unit reaches and detects a cycle in which the scanning unit changes the direction of the reflecting surface by receiving the light beam that has reached the region;
When the period detected by the period detection unit deviates from a predetermined range, the operation mode of the emission unit is changed from the normal mode for emitting the light beam at the first level to the emission unit. And a switching command means for commanding switching to the low output mode in which the light beam is emitted at a second level that is lower than the level and visible to the observer.

  According to this image display apparatus, when the change period of the reflection surface angle detected by the period detection unit deviates from a predetermined range, the switching unit is configured to switch the operation mode to the low output mode for the emission unit. Commanded by means.

  The period detection unit detects a repetition period when the scanning unit changes the direction of the reflection surface (the angle of the reflection surface with respect to the light beam). Therefore, if a range that can be taken by the scanning unit when the light beam is normally scanned by the scanning unit is set as a “predetermined range” that is referred to when the switching command unit commands the switching of the operation mode, When the light beam is not normally scanned, the output unit is instructed to switch the operation mode to the low output mode.

  When the operation mode of the emission unit is switched to the low output mode in response to this command, the emission unit is a second output level lower than the first level at which the luminous flux is emitted in the normal mode and visible to the observer. A light beam is emitted at a level.

  Thus, in the low output mode, the output level of the light beam incident on the observer's pupil is within a range that can be visually recognized by the observer, and is a second level lower than that in the normal mode.

  Therefore, in the image display device according to this section, when the light beam scanning by the scanning unit is not normally performed, the virtual image displayed so far does not disappear suddenly, and the virtual image The display (a state in which the observer can visually recognize the virtual image) is maintained.

  Therefore, according to the image display apparatus according to the present section, when the light beam scanning by the scanning unit is not performed normally, an anxiety caused by the sudden disappearance of the virtual image is given to the observer. You do n’t have to.

(1 3 ) The scanning unit
A first scan that scans the light beam reflected from the first reflection surface in a first direction by periodically changing the angle of the first reflection surface that reflects the light beam with respect to the light beam within a predetermined angle range. Means,
By periodically changing the angle of the second reflection surface that reflects the light beam with respect to the light beam within a predetermined angle range, the light beam reflected from the second reflection surface intersects the first direction. Second scanning means for scanning in two directions;
The image display device according to (1 2 ), including a relay optical system that relays a light beam between the first scanning unit and the second scanning unit.

(1 4 ) The scanning unit performs main scanning for scanning the light beam in the main scanning direction and sub-scanning for scanning in the sub-scanning direction intersecting the main scanning direction using a common reflecting surface. The image display device according to item (1 2 ).

(1 5 ) The image display device according to any one of (1 2 ) to (1 4 ), wherein the guide unit includes a relay optical system that guides a light beam scanned by the scanning unit to a pupil of an observer.

(1 6 ) The guide unit described in any one of (1 2 ) to (1 5 ), wherein the guide unit guides the light beam scanned by the scanning unit directly to an observer's pupil without passing through an optical element. Image display device.

(1 7 ) When the cycle detected by the cycle detection unit returns to the range from a state exceeding the predetermined range, the switching command unit The image display device according to any one of (1 2 ) to (1 6 ), which commands to switch the operation mode from the low output mode to the normal mode.

( 18 ) The low output mode is an operation mode in which the output level of the light beam emitted from the emission unit is changed from the first level to the second level immediately. (1 2 ) to (1 7 ) The image display device described in 1.

(19) the low-power mode, the a output level of the light beam emitted from the emitting unit operation mode is changed to gradually decrease to the second level from the first level to (1 2) to (1 7) of claim The image display device according to any one of the above.

  In this section, an example of the aspect of “gradually changing the output level” is an aspect of changing in stages, and another aspect is an aspect of changing continuously.

(2 0 ) Further, when the operation mode of the emission unit is switched to the low output mode, emission of a light beam corresponding to a notification image for notifying the observer that the mode has been switched to the low output mode. Including a notification command means for commanding the emission unit;
The emission unit generates a light flux corresponding to the notification image based on the detected period by the period detection unit, according to any one of (1 2) to emit a light flux that has been generated (19) section Image display device.

  According to this image display device, when the operation mode of the emission unit is switched to the low output mode, the light beam for forming the notification image is emitted from the emission unit that has received the instruction from the notification instruction unit. The notification image is an image for notifying the observer that the operation mode has been switched to the low output mode, and the notification image is recognized by the observer as a virtual image.

  Therefore, according to this image display device, the observer can know that the operation mode of the emitting unit has been switched to the low output mode through the notification image that is a virtual image.

  In this image display device, a light beam for forming a notification image is generated by the emission unit based on the repetition period detected by the period detection unit. Therefore, according to this image display device, even if the repetition period is not normal, the notification image is displayed in a state as close to normal as possible. That is, the notification image is displayed in a state in which the deformation of the image derived from the repetition cycle is abnormal.

  The “notification image” in this section is an image for notifying the observer that the operation mode of the emission unit has been switched to the low output mode. To list specific examples, it has been switched to the low output mode. Are displayed directly, a message indicating that the repetition period detected by the period detector exceeds a predetermined range, a message indicating that some trouble has occurred in the scanning unit, and the like.

(2 1 ) Further, a time detection unit that detects an elapsed time from when the scanning unit started operation,
The switching command means commands the emission unit to switch the operation mode to the low output mode when the elapsed time detected by the time detection unit exceeds a predetermined range ( 12). ) To (2 0 ).

  In this image display device, when the elapsed time from when the scanning unit starts operating exceeds a predetermined range, the operation mode of the emitting unit is switched to the low output mode.

  In this image display device, the length of the above-mentioned “predetermined time” is set to, for example, the length of time that is expected not to give the observer a great feeling of fatigue even if the observer continues to observe the virtual image. It is possible to carry out in a different manner. In this aspect, when the elapsed time from when the scanning unit starts operating exceeds a predetermined range, the output level of the light beam incident on the observer's pupil is lowered to the second level described above. While maintaining the state in which the virtual image is displayed, it is possible to suppress the feeling of fatigue given to the eyes of the observer.

(2 2 ) The second level is an output level that can be visually recognized by the observer, and is determined so as not to cause discomfort to the observer even when the scanning unit continues to enter the pupil when scanning of the light beam is stopped. The image display device according to any one of (1 2 ) to (2 1 ), which has an output level.

  In this image display device, in the low output mode, even if the output level of the light beam incident on the pupil of the observer continues to enter the pupil when scanning of the light beam by the scanning unit is stopped, no discomfort is given to the observer. The output level is reduced to the determined level.

  Therefore, according to this image display device, it is possible to prevent the viewer from feeling uncomfortable such as dazzling or flickering while maintaining the state where the virtual image is displayed.

  In this section, “the output level determined so as not to cause discomfort to the observer even if it continues to enter the pupil when scanning of the light beam by the scanning unit” is, for example, sufficiently visible to the observer A light flux of 10 nW or more and 390 nW or less, etc., which is defined as an output level of 10 nW or more and a level that does not cause any problems even if it continues to enter one point on the retina through the pupil in the JIS standard (JIS C6802) Conceivable.

(2 3 ) An image display device that displays an image by projecting an image on the retina of an observer by scanning with a light beam,
An output unit that generates image light that is a light beam corresponding to the image and emits the generated light beam;
A scanning unit that has a reflecting surface that reflects the light beam emitted from the light emitting unit and scans the light beam reflected by the reflecting surface by repeatedly performing an operation of changing the direction of the reflecting surface within a predetermined angle range. When,
A guiding unit that guides and enters the light beam reflected by the reflecting surface of the scanning unit into the pupil of the observer;
A period detection unit that is disposed in a region where a light beam scanned by the scanning unit reaches and detects a repetitive cycle when the scanning unit changes the direction of the reflecting surface by receiving the light beam reaching the region. An image display program executed by a computer to control an image display device including:
When the repetition period detected by the period detection unit exceeds a predetermined range, the light beam is emitted to the emission unit at a first level which is a predetermined output level as an operation mode of the emission unit. An image display program including a switching command step for commanding switching from a normal mode to a low output mode that emits the luminous flux at a second level that is lower than the first level and visible to an observer.

If the image display program according to this section is executed by a computer, it is possible to achieve the same effects as those of the apparatus according to the above (1 2 ) section.

(2 4 ) Further, when the operation mode of the emission unit is switched to the low output mode, the emission unit emits a light beam corresponding to a notification image for notifying that the operation mode has been switched to the low output mode. Including a notification command means for commanding to
The image display program according to item (2 3 ), wherein the emission unit generates a light beam corresponding to the notification image based on the period detected by the period detection unit, and emits the generated light beam.

If the image display program according to this section is executed by a computer, it is possible to realize the same effects as those of the apparatus according to the above (2 0 ) section.

(2 5 ) In addition, a time detection unit that detects an elapsed time from when the scanning unit started operation,
The switching command means commands the switching of the operation mode to the low output mode when the elapsed time detected by the time detection unit exceeds a predetermined range (2 3 ) or (2 4 ). The image display program described in 1.

If the image display program according to this section is executed by a computer, it is possible to achieve the same effects as those of the apparatus according to the above (2 1 ) section.

  Note that some of the above-described image display programs are directly connected to the image display device or indirectly through another device via a recording medium such as an FD, CD-ROM, or memory card, or a communication network such as the Internet. Can be provided.

  Examples of the computer that executes the image display program include a computer built in the image display device, a computer connected to the image display device through a wireless or wired communication path so as to allow data communication.

  Hereinafter, some of more specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 systematically shows an image display device 1 according to the first embodiment of the present invention. In this image display device 1, a light beam is incident on the pupil E of an observer (that is, a user of the image display device 1), and an image is projected onto the retina of the observer by the incident light beam, thereby the pupil E This is a device that allows an observer to recognize that a virtual image is displayed in front of. This is a so-called retinal scanning display.

  As shown in FIG. 1, the image display device 1 includes an emitting unit 10 that generates and emits image light that is a light beam corresponding to an image. The emitting unit 10 generates image light by appropriately modulating the intensity of the image light. That is, the emitting unit 10 is a part that generates image light in the image display device 1.

  The image display device 1 further includes an optical fiber 20 that transmits the image light emitted from the emission unit 10 and a collimating optical system 30 that converts the image light emitted from the optical fiber 20 into a parallel light beam (parallel light). ing.

  The image display apparatus 1 further includes a scanning unit 50 that scans the image light that has been collimated by the collimating optical system 30 into a state in which the image light can be projected as an image, and the image light scanned by the scanning unit 50 And a guiding section 70 that guides the light to E and makes it incident.

  The image display device 1 further includes a cycle detection unit 100 that detects a repetition cycle when the scanning unit 50 scans image light, and a control unit 110 that controls the operation of the entire image display device 1. The control device 110 is configured mainly by a computer 112, and the computer 112 is configured to include a processor 114 and a memory 116.

  The above-described emitting unit 10 includes a B laser 11 and a B laser driver 12 that drives the B laser 11 in order to generate a blue light beam, and a G laser 13 in order to generate a green light beam. A G laser driver 14 that drives the G laser 13 is provided, and an R laser 15 and an R laser driver 16 that drives the R laser 15 are provided in order to generate a red light beam.

  The emitting unit 10 further includes a dichroic mirror 17 that couples three light beams respectively generated from the three lasers 11, 13, and 15 to one image light, and one dichroic mirror 17 coupled to the dichroic mirror 17. And a coupling optical system 18 for guiding the image light to the optical fiber 20.

  The emission unit 10 corresponds to an image to be displayed to an observer by driving the lasers 11, 13, and 15 by the laser drivers 12, 14, and 16 based on the color signal output from the control unit 110. Image light is generated with necessary intensity modulation and emitted to the optical fiber 20.

  In response to a command from the control unit 110, the emission unit 10 is designed to switch the operation mode of the emission unit 10 between a normal mode and a low output mode that are different from each other with respect to the output level of the light beam emitted from the emission unit 10. Has been. In the present embodiment, the term “output level” is defined to mean the intensity of the light beam emitted from the emission unit 10.

  Here, the “normal mode” is an operation mode in which the emitting unit 10 generates and emits, as image light, a light beam having a total sum of 1 μW or less at each moment of the output levels from the lasers 11, 13, and 15. . In the present embodiment, the output level at which the emitting unit 10 emits a light beam in the normal mode is set within a range from 0 to 1 μW, for example.

  On the other hand, the “low output mode” is an operation mode in which the emission unit 10 generates and emits a light beam whose sum of output levels from the lasers 11, 13, and 15 does not exceed 200 nW as image light. It is.

  The output level of the light beam emitted from the emitting unit 10 in the low output mode is a numerical value determined according to the JIS standard (JIS C6802) as a level that causes no problem even if it continues to enter one point on the retina through the pupil. 390 nW or less. However, the output level of the light beam emitted from the emission unit 10 in the low output mode is 10 nW or more, which is an output level that is visible to the observer.

  In the present embodiment, the output level at which the emitting unit 10 emits the light beam in the low output mode is set within a range from 0 to 200 nW, for example.

  The scanning unit 50 scans the image light incident from the collimating optical system 30 so that it can be projected as an image. The scanning unit 50 scans the image light in the horizontal direction (main scanning direction or first direction), and scans the horizontally scanned image light in the vertical direction (sub-scanning direction or second direction). Perform vertical scanning.

  In order to realize horizontal scanning, as shown in FIG. 1, the scanning unit 50 includes a polygon mirror 51 that scans image light incident from the collimating optical system 30 in the horizontal direction, and horizontal scanning that rotationally drives the polygon mirror 51. Motor 52 and a horizontal scanning drive circuit 53 that drives the horizontal scanning motor 52 in response to a command (horizontal synchronization signal) from the control unit 110.

  Further, as shown in FIG. 1, the scanning unit 50 drives the galvano mirror 54 that scans and outputs the light beam scanned by the polygon mirror 51 in the vertical direction in order to realize vertical scanning, and the galvano mirror 54. The vertical scanning actuator 55 and a vertical scanning drive circuit 56 that receives the command (vertical synchronization signal) from the control unit 110 and drives the vertical scanning actuator 55 are provided.

  As shown in FIG. 1, the scanning unit 50 further includes a first relay optical system 57 that relays a light beam between the polygon mirror 51 and the galvanometer mirror 54.

  The first relay optical system 57 is arranged such that the position where the light beam incident from the collimating optical system 30 enters in the polygon mirror 51 and the center position on the reflection surface of the galvano mirror 54 are optically in a predetermined positional relationship. Optical system.

  As shown in FIG. 1, the polygon mirror 51 has a rotating body 51b in which a plurality of reflecting surfaces 51a are arranged along a circumference coaxial with the rotation axis. When the rotating body 51b is rotated around the rotation axis by the horizontal scanning motor 52, the light beam reflected from each reflecting surface 51a is periodically scanned within a predetermined angle range on a plane intersecting the rotation axis.

  In the scanning unit 50 described above, the light beam incident on the scanning unit 50 from the collimating optical system 30 is scanned in the horizontal direction by the polygon mirror 51 and then scanned in the vertical direction by the galvano mirror 54, and then the guiding unit 70. Head to.

  The guide unit 70 is a relay optical system that guides the light beam incident on the guide unit 70 from the scanning unit 50 to the pupil E of the observer. The guiding unit 70 is disposed such that the center position of the reflection surface 54a of the galvano mirror 54 and the position of the pupil E (a position corresponding to the pupil E) of the observer have a predetermined optical relationship.

  The above-described period detection unit 100 reflects image light from one reflection surface 51a on which image light is incident among the plurality of reflection surfaces 51a in the polygon mirror 51 (hereinafter referred to as “selective reflection surface 51a”). Are arranged in an angle region to be scanned, that is, a region where image light is scanned by the polygon mirror 51. The period detection unit 100 is an example of a light receiving element that outputs a signal according to incident light. Specifically, in this embodiment, the cycle detection unit 100 is configured as a beam detector that detects a light beam, which is image light scanned by the polygon mirror 51, at a specific position.

  The period detector 100, that is, the beam detector, receives image light reflected from the selective reflection surface 51a every time the direction of the selective reflection surface 51a of the polygon mirror 51 (the angle of the selective reflection surface 51a with respect to the light beam) periodically changes. To do.

  When the period detector 100 configured as a beam detector receives image light, the period detector 100 supplies a signal indicating that the light has been received to the controller 110. Based on the signal, the control unit 110 determines the timing at which the emission unit 10 emits image light (that is, the start timing of each horizontal scanning line in the rectangular area where the image is displayed) regarding horizontal scanning. Hereinafter, the signal is referred to as a beam detector (BD) signal, focusing on the fact that it is an output signal of the beam detector.

  The control unit 110 further includes an actual scanning cycle by the polygon mirror 51 (that is, for example, a horizontal scanning start time using a certain selective reflection surface 51a and a horizontal scanning start time using the next selective reflection surface 51a). It also functions to detect the time interval between. Specifically, the control unit 110 repeatedly detects when the polygon mirror 51 changes the direction of the selective projection surface 51a (the angle of the selective reflection surface 51a with respect to the image light) by detecting the interval at which the image light is received. Detect the period.

  An image display program is stored in the memory 116 of the computer 112 of the control unit 110. The image display program is executed by the processor 114, whereby the overall operation of the image display device 1 is controlled to execute image display processing.

FIG. 2 conceptually shows the contents of the image display program in a flowchart.
This image display program is repeatedly executed after the image display device 1 is activated by turning on the power, and then the image display device 1 is stopped by turning off the power.

  When the image display program is executed each time, first, in step S110, the input of an external video signal is awaited. If the input of the video signal is started, the determination in step S110 is YES, and the process proceeds to step S120.

  In step S120, the operations of the polygon mirror 51 and the galvanometer mirror 54 are started. Specifically, in step S120, the supply of the horizontal synchronization signal to the horizontal scanning drive circuit 53 is started, that is, the horizontal synchronization signal is repeatedly output from the control unit 110 to the horizontal scanning drive circuit 53. Thus, the operation of the polygon mirror 51 is started by the horizontal scanning motor 52.

  In parallel with the horizontal scanning, the supply of the vertical synchronizing signal to the vertical scanning driving circuit 56 is started, that is, the vertical synchronizing signal is repeatedly output from the control unit 110 to the vertical scanning driving circuit 56. The operation of the galvanometer mirror 54 is started by the vertical scanning actuator 55.

  As a result, the polygon mirror 51 periodically changes the angle of each reflection surface 51a with respect to the image light within a predetermined angle range, and thereby the light beam reflected by each reflection surface 51a of the polygon mirror 51 is horizontally changed. A scanning state is realized. In contrast, the galvanometer mirror 54 is configured to scan the light beam reflected by the reflecting surface 54a in the vertical direction by periodically changing the angle of the reflecting surface 54a with respect to the image light within a predetermined angle range. The

  After the execution of step S120 described above is completed, in step S130, color signals for forming an image represented by the video signal input in step S110 are generated for each of the red, green, and blue laser light beams. To begin. Further, output of the generated various color signals to the emission unit 10 is started.

  In step S130, every time a BD signal is input from the period detection unit 100, various color signals for one horizontal scanning (one horizontal scanning line) in the image are generated and output. In the emitting unit 10 to which various color signals are input, the laser drivers 12, 14, and 16 drive the lasers 11, 13, and 15 based on the various color signals, whereby the lasers 11, 13, and 15 A luminous flux of each color is generated.

  As shown in FIG. 1, the three color light fluxes generated in this way are combined into one image light by the dichroic mirror 17, and then travel to the optical fiber 20 through the coupling optical system 18.

  Since the current execution of step S130 is the first execution after the image display device 1 is activated, the emission unit 10 starts operating in the normal mode.

Thereafter, the image light emitted from the emission unit 10 is scanned in a state where it can be projected as an image by the scanning unit 50, and the scanned image light enters the pupil E of the observer through the guide unit 70.
In this way, the image light incident on the pupil E is projected on the retina as an image, so that the observer can recognize that a virtual image is displayed in front of the observer's pupil E. .

  After the execution of step S130 described above is completed, it is determined in step S140 whether or not the input of the video signal started in step S110 is continued.

  If it is assumed that the input of the video signal is not continued this time, the determination in step S140 is NO, and in step S150, the operations of the polygon mirror 51 and the galvano mirror 54 started by the execution of step S120 are stopped. .

  Specifically, in step S150, the supply of the horizontal synchronizing signal to the horizontal scanning drive circuit 53 is stopped, whereby the operation of the polygon mirror 51 by the horizontal scanning motor 52 is stopped. Further, the operation of the galvanometer mirror 54 by the vertical scanning actuator 55 is stopped by stopping the supply of the vertical synchronizing signal to the vertical scanning driving circuit 56.

  This completes one execution of the image display program.

  On the other hand, if it is assumed that the input of the video signal is continued this time, the determination in step S140 is YES, and initialization is performed in step S160.

  In the present embodiment, the same number of variables T as the number n of the reflection surfaces 51a in the polygon mirror 51 is prepared. Each variable T is prepared for temporarily storing the period detected by the control unit 110 based on the BD signal output from the period detection unit 100 with respect to each reflection surface 51a.

  The values t of the plurality of variables T are stored in the memory 116 in association with the variables T, respectively. However, there is no fixed correspondence between the plurality of variables T and the plurality of reflection surfaces 51a, and the detection is sequentially performed by the control unit 110 using the BD signal of the period detection unit 100 as described later. Among the plurality of periods, the latest number of periods n equal to the number n of the reflecting surfaces 51a are sequentially stored in the memory 116 in association with each variable T in the same order as the detected order. .

  The initialization for the variable T described above is performed in step S160. Specifically, a plurality of variables T [1] to T [n] (n: the number of reflecting surfaces 51a) are all set to zero. Hereinafter, for convenience of explanation, a value given to each variable T [i] is represented by a value t [i].

  When the execution of step S160 ends, in step S170, each time interval at which the BD signal is repeatedly output from the period detection unit 100 in response to the repeated incidence of image light from the polygon mirror 51 to the period detection unit 100 is set as each time interval. The control unit 110 detects a cycle in which the direction of the reflecting surface 51a changes. That is, the change period of the direction of each reflecting surface 51a is detected as a time interval between two adjacent BD signals among a plurality of BD signals repeatedly output from the period detector 100.

  In step S170, when the i-th cycle T is detected, the i-th variable T [i] is set to be equal to the detected value, and the (i + 1) -th cycle T is detected. Then, the (i + 1) th variable T [i + 1] is set to be equal to the detected value. When the detection of a series of n periods T, that is, one set of periods T, is completed in this way, each detection value of the next set of periods T has n detection orders in the same order as the detection order of each period T. The data are sequentially stored in the variables T [1] to T [n]. Thereby, each value t [i] of the n variables T [1] to T [n] is updated so as to be equal to the latest detected value of the n periods T and stored in the memory 116. It becomes.

  When the execution of step S170 is completed, in step S180, the variable T in which the ratio R between the value t [i] and the reference value t0 deviates from the set range among the n variables [1] to T [n]. Whether or not exists is determined. It is determined whether there is a variable T in which the ratio R is above or below the set range. Here, the “reference value t0” is determined in advance as an average scanning time per one reflecting surface 51a of the polygon mirror 51 in a normal state where the image light is normally scanned in the horizontal direction by the polygon mirror 51. It is a value representing the given time.

  In the present embodiment, the ratio R is defined as a value obtained by dividing the reference value t0 by the value t [i], that is, t0 / t. That is,

  R = t0 / t

  It is defined to be expressed by the expression Further, the setting range is defined as a range from 0.95 to 1.05, for example.

  If it is assumed that there is no variable T whose ratio R deviates from the set range this time, the determination in step S180 is NO and the process returns to step S140. On the other hand, if it is assumed that there is a variable T whose ratio R deviates from the setting range this time, the determination in step S180 is YES, and the process proceeds to step S190.

  In step S190, the emitting unit 10 is instructed to switch the operation mode to the low output mode. Upon receiving the command, the emitting unit 10 switches the operation mode of the emitting unit 10 itself from the normal mode to the low output mode, and as a result, the maximum value of the sum of the output levels of the light beams generated from the lasers 11, 13, and 15 is increased. A light beam is generated and emitted at a predetermined low output level so as to be 200 nW or less.

  Here, the “low output level” can be obtained, for example, by multiplying the normal output level in the normal mode by a fixed coefficient smaller than 1. Specifically, it can be obtained by multiplying the normal output level determined for each pixel constituting each image and for each color by the above-described fixed coefficient based on the video signal. Accordingly, even in the low output mode, similarly to the normal mode, the output level of the light beam generated from each laser 11, 13, 15 can be made different for each pixel constituting the image according to the video signal. .

  After step S190 is executed in this way, in step S200, an average value tave of n variables T [1] to T [n] is calculated. The average value tave is

  tave = (t [1] + t [2] +... + t [n]) / n

  It is calculated by the following formula.

  Thereafter, in step S210, is there a variable T whose deviation Δt from the average value calculated in step S200 is greater than or equal to a threshold value ΔtTH among the n variables T [1] to T [n]. It is determined whether or not.

  In the present embodiment, the deviation Δt of each variable T [i] is defined as a value obtained by subtracting the average value tave from the value t [i] of each variable T [i]. Therefore, the deviation Δt is

  Δt = t−tave

  It can be expressed by the following formula. Therefore, the deviation Δt increases as the value t [i] increases from the average value tave. Further, in the present embodiment, the threshold value ΔtTH is set to be equal to, for example, 0.3 × tave.

  As described above, the value t of each variable T is set to be equal to the detected value of the scanning time when the image light is scanned in the horizontal direction, and the deviation T of the variable T is greater than the threshold value ΔtTH. The presence of the value t indicates that the scanning time is abnormally long for a part of the polygon mirror 51, not for the entire reflecting surface 51a.

  Thus, in order to consider the reason why the scanning time is locally abnormally long for a part of the plurality of reflecting surfaces 51a in the polygon mirror 51, as an example, a part of the plurality of reflecting surfaces 51a It is considered that damage such as cracks has occurred and dirt such as dust has adhered. If such a cause exists, the polygon mirror 51 cannot locally reflect the image light in a normal direction on a part of the reflection surfaces 51a. Therefore, for example, the image light from the two reflection surfaces 51a adjacent to each other cannot be reflected. At the same time, the light enters the period detector 100. As a result, there is a possibility that the detection value of the period T based on the output signal of the period detection unit 100 represents the scanning time for two reflection surfaces 51a.

  Therefore, when there is a variable T having a deviation Δt larger than the threshold value ΔtTH, there is a possibility that the polygon mirror 51 cannot locally scan the image light locally on a part of the reflection surfaces 51a. .

On the other hand, when there is no variable T in which the deviation Δt is larger than the threshold value ΔtTH, the deviation Δt is distributed almost uniformly over the entire n variables T. The scan time for all of these will be unusually long or short. This means that an abnormality has occurred in the entirety of the plurality of reflecting surfaces 51a.
Considering the cause of the abnormality, the drive unit that rotationally drives the rotator 51b of the polygon mirror 51, that is, at least part of the horizontal scanning motor 52 and the horizontal drive circuit 53 has failed. It is reasonably inferred that image light cannot be normally scanned on all of the plurality of reflecting surfaces 51a.

  This time, assuming that there is a variable T having a deviation Δt larger than the threshold value ΔtTH, the determination in step S210 is YES, and the observer is informed that an abnormality has occurred in the reflecting surface 51a of the polygon mirror 51 in step S220. Image data for displaying a reflection surface abnormality notification image, which is a message screen for notification, is read from the memory 116.

  The image data is stored in the memory 116 in advance. In this embodiment, the reflection surface abnormality notification image represented by the image data is the original image in the image display area drawn by the light beam scanned during one rotation of the polygon mirror 51 in one frame of the image. It is displayed superimposed on the image.

  In the present embodiment, when an abnormality occurs locally on some of the reflective surfaces 51a of the polygon mirror 51, a plurality of reflective surfaces 51a that are adjacent to each other among the n reflective surfaces 51a. It is assumed that an abnormality occurs in only one of the combinations. Accordingly, the reflection surface abnormality notification image is drawn by (n−2) horizontal scanning lines that are horizontally scanned by the (n−2) reflection surfaces 51a adjacent to each other.

  When the execution of step S220 is completed, in step S230, various color signals (red, green, and blue light beams) for displaying the image based on the image data representing the reflection surface abnormality notification image read in step S220. And the output of the generated color signal to the emission unit 10 is started.

  Specifically, in this step S230, first, the time interval between the latest two BD signals that are temporally adjacently input from the period detector 100 (that is, by the selective reflection surface 51a of the polygon mirror 51). The scanning time of the luminous flux) is equal to the value t (hereinafter referred to as “abnormal value tab”) of the variable T for which the deviation Δt is determined to be greater than or equal to the threshold value ΔtTH in step S210. I'll be waiting for you. That is, of the n reflecting surfaces 51a, the reflected light from the two reflecting surfaces 51a that are adjacent to each other and in which an abnormality has occurred enters the beam detector that is the period detection unit 100. Is awaited.

  In step S230, when the time interval between the BD signals becomes equal to the abnormal value tab, each time a BD signal is input from the period detection unit 100, the reflection surface abnormality notification image is displayed on the original image indicated by the video signal. Various color signals for generating a composite image to be projected onto the pupil E during one rotation of the polygon mirror 51 are generated and displayed on the laser drivers 12, 14, 16. Is output.

  Thereafter, image light for forming a composite image is emitted from the emitting unit 10, and the emitted image light enters the observer's pupil E through the scanning unit 50 and the guide unit 70 in order. The incident image light projects an image on the retina, so that the observer can recognize that the reflection surface abnormality notification image is displayed as a virtual image in front of the pupil E.

  FIG. 3 shows an example of the reflection surface abnormality notification image. According to this example, the message image expressed by characters “abnormality has occurred on the scanning surface” is normal among the n reflecting surfaces 51a of the polygon mirror 51 (n−2). It is displayed using the reflecting surface 51a. As a result, as shown in FIG. 3, the reflection surface abnormality notification image includes two reflection surfaces that cannot normally scan image light among the n reflection surfaces 51a in the image display area where one frame of the image is displayed. It is displayed at a position avoiding the horizontal scanning line H corresponding to 51a.

  In addition, in the example shown in FIG. 3, the reflection surface abnormality notification image is displayed only once per frame of the image, but the reflection surface abnormality notification image is displayed every time the polygon mirror 51 rotates once. Thus, the present invention can be implemented.

  As described above, the case where the variable T having the Δt deviation equal to or larger than the threshold value ΔtTH has been described among the n variables T. If there is no variable T, the determination in step S210 in FIG. The process proceeds to S240.

  In step S240, image data representing a drive unit abnormality notification image for notifying the observer that an abnormality has occurred in the drive unit of the polygon mirror 51 is read from the memory 116. The image data representing the drive unit abnormality notification image is stored in advance in the memory 116.

  In the present embodiment, a plurality of types of image data representing the drive unit abnormality notification image are stored in the memory 116 in accordance with the ratio r between the average value tave and the reference value t0. Image data of the drive unit abnormality notification image corresponding to the current value of the ratio r is selected and read. In this embodiment, the ratio r is defined as a value obtained by dividing the reference value t0 by the average value tave, that is, t0 / tave. That is,

  r = t0 / tave

  It is defined to be expressed by the expression

  Hereinafter, the reason why a plurality of types of image data of the drive unit abnormality notification image are prepared will be described in detail with reference to FIGS. However, in FIGS. 4A and 4B, images in which four perfect circles are arranged at four vertices of a square are shown in a normal display state and an abnormal display state, respectively. . 5A to 5C show image data of three types of drive unit abnormality notification images, respectively.

  If an abnormality occurs in the driving unit of the polygon mirror 51, the image formed by the image light scanned by the scanning unit 50 is the polygon mirror unless the vertical scanning speed (operation speed) by the galvano mirror 54 is changed. When the time required for one horizontal scanning by 51, that is, the period T is long, that is, when the horizontal scanning speed is slow (as shown in FIG. 4B), the drive unit is normal (FIG. 4A ), The pitch d between the horizontal scanning lines is longer.

  Therefore, when an abnormality occurs in the driving unit of the polygon mirror 51, the image formed by the image light scanned by the scanning unit 50 is a horizontal scanning line per screen as shown in FIG. The number of images becomes smaller than normal (see FIG. 4B).

  Since the pitch d between the horizontal scanning lines is long, an image having a smaller number of horizontal scanning lines than normal is displayed in a state of being expanded in the vertical direction (vertical direction in FIG. 4) with respect to the normal image.

  Further, since the timing at which the light beam is emitted from the emitting unit 10 (for example, the timing at which the color, intensity, etc. of the image light is modulated) does not change, the image is shown in FIG. As described above, a normal image is displayed in a state compressed in the horizontal direction.

  If the image thus deformed is displayed, the content represented by the image, that is, the virtual image may not be accurately transmitted to the observer, that is, the information transmission amount of the image may be insufficient. Furthermore, when the image is displayed while being expanded in the vertical direction, there is a possibility that the lower area of the image (the area protruding downward from the rectangular frame in FIG. 4B) may not be displayed.

  By the way, the image visually recognized by the observer is elongated in the vertical direction as the number of horizontal scanning lines is small because the horizontal scanning speed of the scanning unit 50 is slow. However, even if the actual horizontal scanning speed is slow, if the temporal change of the image light incident on the scanning unit 50 is synchronized with the actual horizontal scanning speed, the image visually recognized by the observer is not changed. That's it. Specifically, the slower the horizontal scanning speed, the slower the temporal change of the image light in the horizontal direction, the lesser the number of horizontal scanning lines will be due to a decrease in the horizontal scanning speed. Regardless, it is maintained, and thus the information transmission amount of the image is also maintained.

  For this reason, in this embodiment, as shown in FIGS. 5A to 5C, image data of three types of drive unit abnormality notification images to be selected according to the horizontal scanning speed is prepared. ing. However, the image data of these three types of drive unit abnormality notification images is not shown as the same image as the image that the observer actually observes when the drive unit is abnormal, but the laser drivers 12, 14, 16 is shown as image data corresponding to the drive signal supplied to 16. That is, in FIG. 5, the image data is not shown along the time axis for the observer, but is shown along the time axis for the laser drivers 12, 14, and 16.

  Therefore, when these three types of drive unit abnormality notification images are actually displayed, each character shown in FIG. 5 is expanded in the vertical direction and horizontally in the horizontal direction according to the corresponding horizontal scanning speed. Is compressed and displayed.

  Specifically, FIG. 5A shows a drive unit abnormality of the pattern A to be selected when the ratio r is in the first range slightly smaller than 1 because the horizontal scanning speed is slightly slower than normal. The image data of the notification image is shown. This image data is based on the original image data (image data necessary for display when the same image is displayed to the observer in a state where the drive unit is normal). When the image data is reproduced in a state where the driving unit is abnormal, the image data is defined to have a relationship of extending in the horizontal direction.

  If the image data defined in this way is reproduced using the scanning unit 50 including the polygon mirror 51 whose drive unit is abnormal, each character shown in FIG. Is expanded, but is observed as a compressed drive unit abnormality notification image in the horizontal direction. In the observed drive unit abnormality notification image, the size of each character is displayed so as to have the same size both in the vertical direction and in the horizontal direction. In the present embodiment, the first range is

  0.75 <= r <1

  Is defined by the inequality

  Further, FIG. 5B shows a drive unit abnormality notification of the pattern B to be selected when the ratio r is in the second range slightly smaller than the first range because the horizontal scanning speed is slightly slower than normal. Image data of the image is shown. This image data is defined so that the same relationship as in the above case is established with the original image data. If the image data defined as described above is reproduced, the observer is notified that the characters shown in FIG. 5B are expanded in the vertical direction and compressed in the horizontal direction. As observed. In the present embodiment, the second range is

  0.5 <= r <0.75

  Is defined by the inequality

  Further, FIG. 5C shows a drive unit abnormality notification of the pattern C to be selected when the ratio r is in the third range slightly smaller than the second range because the horizontal scanning speed is considerably slower than normal. Image data of the image is shown. This image data is defined so that the same relationship as in the above case is established with the original image data. When the image data defined as described above is reproduced, the observer is notified that the characters shown in FIG. 5C are expanded in the vertical direction and compressed in the horizontal direction. As observed. In the present embodiment, the third range is

  0.25 <= r <0.5

  Is defined by the inequality

  Further, in this embodiment, since the horizontal scanning speed is much slower than normal, the drive unit abnormality notification image of pattern D is selected when the ratio r is in the fourth range that is slightly smaller than the third range. Is done. In the present embodiment, the fourth range is

  0 <= r <0.25

  Is defined by the inequality

  In the present embodiment, when the ratio r is in the fourth range, the display of the image based on the video signal is stopped as will be described later. Is set not to display any information.

  Therefore, image data for the pattern D is not stored in the memory 116. When this pattern D is selected, the computer 112 cannot read image data from the memory 116 for the drive unit abnormality notification image.

  When the execution of step S240 is completed, in step S250, it is determined whether image data of any type of drive unit abnormality notification image has been read in step S240. Specifically, since the image data of the drive unit abnormality notification image of any of patterns A to C has been read, is it necessary to execute the steps described below for displaying the drive unit abnormality notification image? It is determined whether or not.

  This time, if it is assumed that the image data has not been read in step S240, that is, the driving part abnormality notification image of pattern D has been selected this time, the determination in step S250 is NO.

  In this case, in order to stop the display of the image based on the video signal, thereafter, in step S260, the generation and output of various color signals based on the video signal, which were started in step S130, are stopped. Subsequently, in step S270, the operations of the polygon mirror 51 and the galvanometer mirror 54 that were started in step S120 are stopped.

  Thus, a series of executions of the image display program is completed, and the computer 112 waits for an image display command from the observer again.

  On the other hand, if it is assumed that the image data is read in step S240 this time, that is, if any one of the drive unit abnormality notification images of patterns A to C is selected this time, the determination in step S250 is YES. Become.

  In this case, thereafter, in step S280, various color signals (red, green, and blue light fluxes) based on the image data of the drive unit abnormality notification image read in step S240 are generated, and the generated various colors. Output of the signal to the emission unit 10 is started. In step S280, every time a normal BD signal is input from the period detection unit 100, a polygon mirror is formed to form a composite image in which the drive unit abnormality notification image is superimposed on the original image represented by the video signal. Various color signals are generated and output for one rotation of 51.

  Thereafter, image light for forming a composite image is emitted from the emitting unit 10, and the emitted image light enters the observer's pupil E through the scanning unit 50 and the guide unit 70 in order. The incident image light projects an image on the retina, so that the observer can recognize that the drive unit abnormality notification image is displayed as a virtual image in front of the pupil E.

  When the execution of step S280 is completed, the next abnormality regarding the polygon mirror 51 is performed in steps S290 to S310 in the same manner as the above-described steps S160 to S180 in the same manner as the execution of step S230 is completed. A determination is made.

  Specifically, in step S290, n variables T are initialized as in step S160. As a result, the plurality of variables T [1] to T [n] are all set to zero.

  Thereafter, in step S300, as in step S170, sequential detection of the period T using the period detection unit 100 and storage of each detected value associated with each variable T [i] are performed. Specifically, the input interval of the BD signal from the period detection unit 100 is stored in the memory 116 in association with each variable T [i] as the period T.

  Subsequently, in step S310, similarly to step S180, whether or not there is a variable T in which the ratio R deviates from the setting range in the n variables [1] to T [n]. Is determined.

  If it is assumed that there is a variable T whose ratio R deviates from the set range this time, the determination in step S310 is YES, and the process returns to step S200. Whether it is caused by the abnormality of the reflecting surface 51a or the drive part of the polygon mirror 51 is investigated.

  On the other hand, this time, if it is assumed that there is no variable T in which the ratio R deviates from the set range, the determination in step S310 is NO, and the process proceeds to step S330. In step S330, the emitting unit 10 is instructed to switch the operation mode to the normal mode. Upon receiving this command, the emitting unit 10 switches the operation mode of the emitting unit 10 from the low output mode to the normal mode. As a result, the sum of the output levels of the light beams generated from the lasers 11, 13, and 15 is 1 μW or less. Thus, a light beam is generated and emitted as image light at a predetermined normal output level.

  Thereafter, in step S340, generation and output of various color signals corresponding to the currently selected image of the reflection surface abnormality notification image and the drive unit abnormality notification image are stopped. As a result, only the generation / output of various color signals based on the video signal, which is the process started in step S130, is continued. Then, it returns to step S140.

  In the image display device 1 configured as described above, the ratio R (= t0 / t) between the value t of each variable T and the reference value t0 is set within a set range (0.95) when executing step S180 in FIG. To 1.05), when there is an outside variable T, the emitting unit 10 is instructed to switch the operation mode to the low output mode.

  Here, the reference value t0 represents the average scanning time per one reflecting surface 51a in a state where the scanning of the image light is normally performed by the polygon mirror 51 as described above, The variable T is set to a period when the polygon mirror 51 periodically changes the direction of the reflecting surface 51a.

  Therefore, in step S180, when the ratio R deviates from the set range with respect to the cycle in which the direction of the reflecting surface 51a changes (that is, one horizontal scanning time by one reflecting surface 51a), that is, the polygon When the image light is not normally scanned by the mirror 51, the emission unit 10 is instructed to switch to the low output mode.

  Upon receiving this command, the emission unit 10 whose operation mode has been switched to the low output mode has an output level lower than the output level of the image light emitted in the normal mode, that is, an output that does not exceed 200 nW and is visible to the observer The image light is emitted at an output level set to be 10 nW or more which is a level.

  As described above, in the low output mode, the output level of the image light incident on the pupil E of the observer is lower than that in the normal mode while being within the visible range. Therefore, when the light beam scanning by the scanning unit 50 is not normally performed, it is possible to maintain a state in which the virtual image can be visually recognized by the observer while suppressing the discomfort that the image light gives to the observer. .

  In other words, when the image display device is designed so that the virtual image suddenly disappears due to the abnormality of the scanning unit 50, there is a possibility that the observer may feel anxiety due to the design. According to the embodiment, such a possibility is not caused, and it is not necessary to give the observer unpleasant feeling due to the occurrence of an abnormality in the scanning unit 50.

  Further, in the present embodiment, when the emission unit 10 switches the operation mode to the low output mode in response to receiving the switching command by executing step S190 in FIG. 2, thereafter, by executing step S230 or S290. Based on the image data read from the memory 116, image light corresponding to the reflection surface abnormality notification image and the drive unit abnormality notification image is generated and emitted.

  These notification images are used to notify the observer that the operation mode of the emission unit 10 has been switched to the low output mode due to the occurrence of an abnormality in some of the reflection surfaces 51a of the polygon mirror 51 or the drive unit. It is an image. Therefore, the observer can recognize that some abnormality has occurred in the polygon mirror 51 and that the operation mode of the emitting unit 10 has been switched to the low output mode by visually recognizing these notification images.

  In particular, in step S230, various color signals for forming the reflection surface abnormality notification image are input to the emitting unit 10 after it is determined in step S210 that there is a variable T having a deviation Δt equal to or greater than the threshold value ΔtTH. Therefore, the reflection surface abnormality notification image is accurately displayed in the image display area at a position avoiding the horizontal scanning line H corresponding to the reflection surface 51a that cannot normally scan the image light. Therefore, the observer can correctly understand the contents to be transmitted to the observer by the reflection surface abnormality notification image.

  Furthermore, in the present embodiment, after the operation mode of the emitting unit 10 is switched to the low output mode by executing step S190 in FIG. It is lowered so as not to exceed 200 nW, which is a level determined that there is no problem even if it continues to be incident on one point. Therefore, according to the present embodiment, after an abnormality occurs in the scanning unit 50, the observer can maintain a state in which a virtual image can be visually recognized, and the viewer does not experience discomfort such as glare or flicker due to abnormal image light. can do.

  In other words, the present invention can be implemented in a form in which various modifications and improvements are made to the present embodiment.

  For example, in the present embodiment, the image display program shown in FIG. 2 is executed by the computer 112 built in the image display apparatus 1. On the other hand, all or part of the plurality of steps constituting the image display program is executed by an external computer connected to the image display device 1 through a wireless or wired communication path so as to be able to perform data communication. It is possible to carry out the present invention.

  Furthermore, in the present embodiment, the memory 116 of the control unit 110 is configured as a storage element (for example, ROM, RAM) that is unremovable with respect to the control unit 110, and the memory 116 shown in FIG. An image display program is stored. On the other hand, the control unit 110 is designed so that data can be input / output to / from a recording medium such as an FD, CD-ROM, or memory card (including a recording medium that is removable with respect to the control unit 110). The present invention can be implemented in such a form that the image display program is stored in such a recording medium.

  Further, in the present embodiment, the scanning unit 50 includes the polygon mirror 51, the galvano mirror 54, and the first relay optical system 57, and the horizontal scanning and the vertical scanning are performed using the reflecting surfaces 51a and 54a independent of each other. It has come to be. On the other hand, the scanning unit 50 can implement the present invention in a form in which both horizontal scanning and vertical scanning are performed on the light beam emitted from the collimating optical system 30 using the same reflecting surface. . If this form is adopted, the number of parts of the image display device 1 can be easily reduced, and the size of the image display device 1 can be easily reduced.

  Further, in the present embodiment, the image light scanned by the scanning unit 50 enters the pupil E through the guiding unit 70. On the other hand, the present invention can be implemented in a form in which the image light scanned by the scanning unit 50 is directly incident on the pupil E.

  Further, in the present embodiment, the emitting unit 10 that has received the operation mode switching command discontinuously changes the output level of the image light from 1 μW or less to 200 nW or less, or from 200 nW or less to 1 μW or less. It is configured. On the other hand, it is possible to implement the present invention in such a manner that the emitting unit 10 that has received the operation mode switching command changes the output level of the image light stepwise or continuously.

  Next, a second embodiment of the present invention will be described. However, since this embodiment has elements in common with the first embodiment, the common elements are cited using the same reference numerals or names, and detailed description is omitted, and only different elements are cited. This will be described in detail.

  In the image display device 2 according to the present embodiment, unlike the first embodiment, a long-time display notification image is displayed when the time during which images are continuously displayed by the image display device 2 exceeds a set time. Thus, the observer is notified that the display has been performed continuously for a long time.

  FIG. 6 conceptually shows the contents of an image display program executed by the computer 112 of the image display apparatus 2 according to the present embodiment in a flowchart. Hereinafter, the image display program will be described, but the steps common to the image display program in the first embodiment are omitted in the range that does not hinder the description, or the same reference numerals or names are used. Therefore, redundant explanation is omitted.

  As shown in FIG. 6, steps S510 to S570 are added to the image display program in the present embodiment, compared to the image display program in the first embodiment.

  As shown in FIG. 6, in this image display program, after the operations of the polygon mirror 51 and the galvanometer mirror 54 are started in step S130, time measurement by a timer is started in step S510. This timer is provided for measuring the elapsed time from the start of the operation of the polygon mirror 51. In the present embodiment, the elapsed time means the length of continuous operation time of the polygon mirror 51, and is reflected in the count value incremented by 1 as time elapses.

  Subsequently, in step S140, it is determined whether or not the input of the video signal is continued. If it is assumed that the input of the video signal is not continued this time, the determination in step S140 is NO, the time measurement by the timer is stopped in step S520, and the counter value is reset to zero. Thereafter, in step S150, the operations of the polygon mirror 51 and the galvanometer mirror 54 are stopped. This completes one execution of the image display program.

  On the other hand, if it is assumed that the input of the video signal is continued this time, the determination in step S140 is YES, and the process proceeds to step S530. In step S530, it is determined whether or not the current value of the count value is greater than or equal to a predetermined value. It is determined whether or not the continuous display time by the image display device 1 is equal to or longer than the allowable time. In the present embodiment, the predetermined value is preset to a value corresponding to 2 hours. If it is assumed that the current value of the count value is not equal to or greater than the predetermined value this time, the determination in step S530 is NO, the process proceeds to step S160, and thereafter, unless the count value increases beyond the predetermined value, steps S160 and S170 , S140 and S530 are repeatedly executed.

  If it is assumed that the count value has become a predetermined value or more while the execution of the loop is repeated, the determination in step S530 is YES, and the process proceeds to step S540. In step S540, the timer is stopped and the count value is reset to 0 in the same manner as in step S520.

  Thereafter, in step S550, the emission unit 10 is instructed to switch the operation mode from the normal mode to the low output mode. Subsequently, in step S560, the long display time for notifying the observer that the continuous display time by the image display device 2, that is, the elapsed time from the start of the operation of the polygon mirror 51 is equal to or longer than the allowable time. Image data representing the time display notification image is read from the memory 116.

  The long-time display notification image can be configured, for example, as a message image with characters “Image display continues for a long time. Switched to low output mode”.

  Subsequently, in step S570, various color signals (red, green, and blue luminous flux) for displaying the long-time display notification image are generated based on the image data read in step S560, and the generated various colors. Output of the signal to the emission unit 10 is started.

  In step S570, every time a BD signal is input from the period detection unit 100, a polygon mirror is displayed in order to display a composite image in which the long-time display notification image is superimposed on the original image represented by the video signal. Various color signals corresponding to one rotation of 51 are generated and output.

  Thereafter, image light for forming a composite image is emitted from the emitting unit 10, and the emitted image light enters the observer's pupil E through the scanning unit 50 and the guide unit 70 in order. The incident image light projects an image on the retina, so that the observer can recognize that the long-time display notification image is displayed as a virtual image in front of the pupil E. Subsequently, the process proceeds to step S160.

  As is clear from the above description, in the present embodiment, when the elapsed time from the start of operation of the polygon mirror 51 exceeds the allowable time (2 hours in the present embodiment), the operation of the emitting unit 10 The mode is switched to the low power mode.

  Here, if the above-mentioned predetermined value, that is, the above-described allowable time, for example, a value that is expected not to give a large fatigue to the observer even if the observer continuously recognizes the virtual image, From the time when it is expected that the feeling of fatigue will increase if the visual recognition is further continued, the output level of the light beam incident on the pupil E is lowered to 200 nW or lower, which is the lower level in the range where the visual recognition by the observer is possible. Be made.

  Therefore, according to the present embodiment, it is possible to suppress fatigue given to the observer while maintaining the state in which the observer observes the virtual image.

As is clear from the above description, in this embodiment, the scanning unit 50 constitutes an example of the “scanning unit” in the above item (1), and steps S190 and S320 in FIG. The part that executes step S550 in FIG. 5 constitutes an example of the “switching command means” in the above (1 2 ) term.

Further, in the present embodiment, the portion of the computer 112 that executes steps S230 and S280 in FIG. 2 and step S570 in FIG. 6 constitutes an example of the “notification command means” in the item (2 0 ). is there.

Further, in the present embodiment, the timer that is conceived for measuring time in step S510 in FIG. 6 in the computer 112 constitutes an example of the “time detection unit” in the above (2 1 ) term.

  Furthermore, in the present embodiment, an output level of 1 μW or less is an example of the “normal output level” in the item (1), and an output level of 10 nW or more and 200 nW or less is an example of the “low output level” in the item. is there.

  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 based on the knowledge of those skilled in the art, including the aspects described in the above [Disclosure of the Invention] section. The present invention can be implemented in other forms with various modifications and improvements.

1 is a system diagram showing an image display device according to a first embodiment of the present invention. It is a flowchart which represents notionally the content of the image display program performed by the computer of the control part in FIG. It is a front view which shows an example of the message image displayed by execution of step S220 and S230 in FIG. FIG. 2 is a front view showing some examples of images displayed when the scanning time by the polygon mirror becomes long in the image display device shown in FIG. 1. It is a front view which shows some examples of the message image displayed by execution of step S240 and S280 in FIG. It is a flowchart which represents notionally the content of the image display program performed by the computer of the control part in the image display apparatus according to 2nd Embodiment of this invention.

DESCRIPTION OF SYMBOLS 10 Output part 50 Scan part 51 Reflecting surface 52 Drive part 112 Computer

Claims (11)

An image display device that displays an image by projecting an image on the retina of an observer by scanning a light beam,
A video signal representing the image is input, and based on the input video signal, an emission unit that emits the luminous flux,
A scanning unit that scans the light beam emitted from the emission unit;
When the setting condition is satisfied during the display of the image without depending on the operation of the observer, the low output is set in advance so that the luminous flux from the emission unit is lower than the normal output level but higher than 0. and a control unit for controlling the emitting unit to emit at the level seen including,
The scanning unit
At least one reflecting surface that reflects the luminous flux;
A driving unit that drives the reflecting surface such that the reflecting surface angle, which is an angle with respect to the light beam incident on the reflecting surface, periodically changes.
Including
The image display device includes an abnormal condition that is satisfied when the actual period in which the reflection surface angle changes deviates from a setting range.   The abnormal condition is as follows:
  The first condition that is satisfied regardless of the part where the abnormality has occurred when the part where the abnormality occurs in the scanning unit is at least one of the reflecting surface and the driving unit,
  A second condition that is satisfied when an abnormality occurs at least on the reflecting surface;
  A third condition that is satisfied at least when an abnormality occurs in the drive unit;
  The image display device according to claim 1, comprising:   The scanning unit includes a plurality of the reflecting surfaces, arranged in a line along a circumference coaxial with the rotation axis, and rotated around the rotation axis by the driving unit, The control unit detects the reflection surface angle individually for the plurality of reflection surfaces,
  The first condition is satisfied when there is a reflection surface angle that deviates from the first setting range among the plurality of reflection surface angles detected for the plurality of reflection surfaces, respectively.
  The second condition is a case where the first condition is satisfied, and among the plurality of reflection surface angles, a reflection surface whose deviation from an average value of the plurality of reflection surface angles exceeds a second setting range. Holds if there is an angle,
  The third condition is satisfied when the first condition is satisfied, and when there is no reflecting surface angle in which the deviation exceeds the second setting range among the plurality of reflecting surface angles. Item 3. The image display device according to Item 2.   Furthermore, it includes a beam detector that detects that the light beam scanned by the scanning unit has entered a set position, and the control unit detects the period based on an output signal of the beam detector, and the detected period 4. The image display device according to claim 1, wherein the image display device determines whether or not the abnormal condition is satisfied based on the following.   5. The image display device according to claim 1, wherein the setting condition includes a long-time display establishment condition that is established when a continuous display time by the image display device exceeds the set time.   The control unit detects the continuous display time based on the elapsed time from the start of the operation of the scanning unit, and the long-time display time establishment condition is satisfied based on the detected continuous display time. The image display device according to claim 5, wherein it is determined whether or not it has been performed.   In order for the observer to understand that the control unit is in the state where the output level of the light beam emitted from the emission unit is lowered to the low output level because the setting condition is satisfied, so that the observer can understand that state. The image display device according to claim 1, wherein the emission unit is controlled so that a predetermined message image is projected onto the retina.   The image display device according to claim 7, wherein the message image is expressed by at least one of a character, a symbol, and a figure.   The control unit controls the emission unit in a normal mode in which the emission unit emits a light beam at the normal output level when the setting condition is not satisfied, and when the setting condition is satisfied, The image display device according to claim 1, wherein the emission unit controls the emission unit in a low output mode in which a light beam is emitted at the low output level.   The low output level is a luminous flux output level at which an observer can visually recognize the image, and is a luminous flux output level that does not cause discomfort to the viewer even if the same position on the retina is continuously irradiated. The image display device according to any one of Items 9 to 9.   An image display device that displays an image by projecting an image on the retina of an observer by scanning a light beam,
  A video signal representing the image is input, and based on the input video signal, an emission unit that emits the luminous flux,
  In order to scan the light beam emitted from the emission part, (a) at least one reflection surface that reflects the emitted light beam, and (b) the angle of the reflection surface with respect to the light beam incident on the reflection surface. A scanning unit having a drive unit that drives the reflective surface such that the angle of the reflective surface changes periodically;
  During the display of the image, an actual period in which the angle of the reflecting surface changes is optically detected, and when the detected period deviates from a setting range, the luminous flux from the emission unit is less than the normal output level. A control unit that controls the emission unit to emit light at a low output level that is preset to be low but greater than 0, and that reduces the output level of the light beam emitted from the emission unit to the low output level. The emitting unit is controlled so that a predetermined message image is projected onto the retina so that the observer can understand that the state is
  An image display device.

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