JP4830653B2 - Image display device - Google Patents

Description

  The present invention relates to an image display device that displays an image by guiding light modulated in accordance with information such as an image to a human eye (observer's eye) through an optical element, and more particularly to a head-mounted display or a head. The present invention relates to an image display device that can have a small and light eyeglass-type configuration such as an up display.

  2. Description of the Related Art Conventionally, various image display devices such as a personal portable terminal display (PDA) direct-view small liquid crystal display, a head-up display (HUD), and a head-mounted display (HMD) have been proposed as portable displays. A conventional HMD has been proposed that enlarges and projects an image of a display element such as an LCD (Liquid Crystal Display) to the eye. However, if the HMD is made to have an appropriate size, the angle of view cannot be increased. However, there is a problem that the entire apparatus becomes too large to be a practical apparatus configuration.

On the other hand, as a smaller scanner, a micro electro mechanical system (MEMS) formed on a semiconductor substrate such as silicon in recent years by applying semiconductor manufacturing technology, for example, a mirror formed by etching or the like in a required pattern. The mirror unit is supported on a substrate so as to be swingable by a swing shaft having a suspension function, a so-called torsion bar (torsion bar), and an electrostatic force is generated by an electrode pair provided on the mirror unit and its peripheral part. An electrostatic drive type two-dimensional scanning element that swings the lens is proposed (for example, see Patent Document 1).
This electrostatic drive type two-dimensional scanning element is driven by an electrostatic force, and can change the reflected light path of incident light by rotating about the oscillation axis as a rotation axis, and can switch and scan laser light. The effect can be obtained. However, the driving speed is much lower than that of the polygon mirror scanner.

On the other hand, it has a mirror part that is swingably supported by a swinging shaft and a magnetic field generating means for generating a parallel magnetic field in two directions orthogonal to the periphery of the mirror part, and a current is supplied to the coil part provided in the mirror part. There has also been proposed an electromagnetically driven two-dimensional scanning element that generates an electromagnetic force by applying it to swing the mirror portion. This electromagnetically driven two-dimensional scanning element has an advantage that it is easy to improve the deflection angle and the operating frequency because the electromagnetic force is relatively large.
As an optical apparatus that displays a two-dimensional image using such a two-dimensional scanning element, for example, a retinal scanning display apparatus that scans and displays a two-dimensional image on the retina has been proposed (for example, see Patent Document 2). ).
A MEMS type two-dimensional scanning element that supports such a minute mirror part on a substrate so as to be able to oscillate on an oscillating shaft is much easier to miniaturize than a polygon mirror scanner, and the optical system is miniaturized. Therefore, the structure can be simplified, and there are few problems due to dust generation due to the absence of a rotating body. Furthermore, various advantages such as power saving, noise reduction, low vibration, and shortened start-up time can be obtained.

JP 2002-31376 A JP 2004-145367 A

  However, in the retinal scanning display device described in Patent Document 2, the light scanned by the MEMS type two-dimensional scanning element as described above is temporarily passed through the objective lens, prism, eyepiece, and beam splitter to the human eye. Because of the guiding structure, when it is desired to obtain a desired wide angle of view, it is necessary to increase the size of the beam splitter, which is the optical element immediately in front of the eyes, leading to an increase in the size and weight of the entire apparatus. .

  In view of the above problems, an object of the present invention is to provide an image display device that can maintain a small and lightweight device configuration and can achieve a desired wide angle of view.

In order to solve the above problems, the present invention provides a light source that emits light modulated in accordance with information, a scanning element that scans incident light in at least one direction, and guides light emitted from the light source to the scanning element. And an optical system. The light reflected by the scanning element is directly incident on the observer's eye and an image is displayed.
Further, the present invention is configured by using a two-dimensional scanning element as a scanning element in the above-described image display apparatus.
Furthermore, according to the present invention, in the above-described image display apparatus, the scan mirror of the scanning element is divided into a plurality of scan mirrors.

As described above, in the image display device of the present invention, light from a light source modulated in accordance with information such as an image or video is directly transmitted to the observer's eye from the scanning element. In this configuration, light is incident to display an image.
As described above, in the present invention, the image light is directly observed from the scanning element, that is, without any optical element, or without receiving an optical action when the optical element is interposed. It is set as the structure made to inject into. By doing so, it is possible to suppress an increase in the size and weight of the entire apparatus when widening the angle of view.
Further, by using a two-dimensional scanning element as the scanning element, it is possible to provide an image display apparatus having a smaller and simpler device configuration.
Furthermore, by dividing the scan mirror of the scanning element into a plurality of scan mirrors, for example, by dividing the scan mirror in the horizontal direction, it becomes possible to perform display with a wide angle of view in the horizontal direction, In addition, since the individual scan mirrors do not increase in size, scanning can be performed with a sufficiently high frequency, and display can be performed with good resolution.

  According to the present invention, it is possible to provide an image display device capable of displaying with a relatively wide angle of view while maintaining a small and lightweight device configuration.

Examples of the best mode for carrying out the present invention will be described below, but the present invention is not limited to the following examples.
FIG. 1 is a schematic schematic configuration diagram of an example of an image display apparatus according to an embodiment of the present invention. The image display device 100 includes a light source 1 that can emit light after being modulated in accordance with video information or the like, such as a semiconductor laser diode (LD) or a semiconductor light emitting diode (LED). And an optical system 2 composed of a collimator lens and the like, and the scanning element 10 such as the MEMS type structure described above. In the present invention, the scanning element 10 is disposed immediately in front of the observer's eye, and the light reflected by the scanning mirror 18 of the scanning element 10 is directly, that is, without passing through the optical element, or optically received by this light. It is configured to enter the pupil of the observer's eye through an optical element that has little function. As the scanning element 10, for example, a MEMS type two-dimensional scanning element that can vibrate (swing) at high speed in two orthogonal directions can be used.
In such a configuration, the light emitted from the light source 1 is converted into, for example, parallel light or divergent light having a certain focal length by the optical system 2 such as a collimator lens, and the scanning element 10 is indicated by an arrow Li. Is incident on the scan mirror 18. The light reflected by the scan mirror 18 is directly incident on the observer eye 200 as indicated by an arrow Lo. In FIG. 1, how the scan mirror 18 vibrates is indicated by a broken line 18a, a solid line 18b, and a broken line 18c. Due to this vibration, an image is recognized from the observer's eye 200 with a wide angle of view indicated by θp.

  In this case, as described above, the light emitted from the light source 1 is converted into parallel light or divergent light having a certain focal length by the collimator lens, so that the focal length virtually set at infinity or the collimator is obtained. An image display device 100 having an original image can be configured. Since this apparatus 100 does not use an optical element such as a lens other than the optical system 2 that collimates light from the light source 1, for example, it can be extremely miniaturized.

  When the light from the light source 1 is directly scanned by the scanning element 10 with respect to the observer's eye 200 to display an image, the size of the scan mirror 18 of the scanning element 10 is displayed as shown in FIG. That is, the angle that can be displayed, that is, the angle of view changes depending on the width and height. In order to increase the angle of view, it is necessary to increase the mirror or to reduce the distance from the scanning element 10 to the observer's eye 200 as much as possible. On the other hand, since it is necessary to increase the scanning frequency of the scanning element 10 in order to increase the resolution of the image to be displayed, it is necessary to reduce the weight of the movable part by making the scan mirror 18 as small as possible. When two one-dimensional scanning elements, that is, two mirrors that scan in one direction are used, the second mirror that scans needs to be very large, which is not suitable for downsizing the apparatus. Therefore, in order to reduce the size and weight and display a good image, it is desirable to use a two-dimensional scanning element as the scanning element and to reduce the size thereof as much as possible.

In the image display apparatus shown in FIG. 1, the position where an image is displayed is determined by the focal position of a lens that collimates the light source 1 by the optical system 2. For this reason, if it is desired to move the position of the image in near vision or the like, the position of the collimating lens of the optical system 2 can be adjusted so that the position of the image can be adjusted and diopter correction can be performed.
The distance from the scanning element 10 to the observer's eye 200 is desirably 20 mm or less. With such a configuration, the above-described diopter correction is facilitated.

  Further, since the display by the scanning element 10 can be performed only for one observer's eye 200, it is necessary to provide two systems of the apparatus shown in FIG. 1 independently for both eyes. Appropriate display becomes possible by adjusting the distance between the two optical systems. Also, stereoscopic viewing is possible by appropriately shifting the position of the image signal to be displayed.

  Next, a configuration example of the MEMS type two-dimensional scanning element 10 will be described with reference to FIG. FIG. 2 is a schematic perspective view of a two-dimensional scanning element 10 suitable for use in the image display apparatus of the present invention. The scanning element 10 includes a scan mirror 18 that reflects incident light such as a laser, a square inner frame portion 19 that supports the scan mirror 18, and a square outer frame portion that supports the inner frame portion 19. 20 is provided. The scan mirror 18 is supported on the inner frame portion 19 by main shaft torsion bars 16a and 16b made of a pair of torsion bars. The inner frame portion 19 is supported on the outer frame portion 20 by sub-shaft torsion bars 12a and 12b made of a pair of torsion bars whose vibration axes are in a direction substantially perpendicular to the vibration axes of the main shaft torsion bars 16a and 16b. With such a configuration, the scan mirror 18 and the inner frame portion 19 vibrate with respect to directions orthogonal to each other. In this example, the axis that vibrates the scan mirror 18 is the main axis, and the axis that vibrates the inner frame portion 19 is the sub-axis. Further, in this example, the main shaft torsion bars 16a and 16b are driven by electrostatic force, and the sub shaft torsion bars 12a and 12b are driven by electromagnetic force. The direction orthogonal to the direction in which the sub shaft torsion bars 12a and 12b oppose ( An example is shown in which electromagnetic drive magnets 11a and 11b are arranged so as to sandwich an outer frame portion 20 in the direction in which the main shaft extends.

  The main shaft torsion bars 16a and 16b and the sub shaft torsion bars 12a and 12b are members having a predetermined elastic force so that the members held inside can be twisted to the left and right by a predetermined angle, respectively. The inner frame portion 19 and the outer frame portion 20 may be integrally formed.

Near the corners on the diagonal line of the outer frame part 20, the auxiliary shaft electrodes 14 a and 14 b are provided. The wiring portion led out from the auxiliary shaft electrode 14a is laid on the outer edge portion of the inner frame portion 19 via the auxiliary shaft torsion bar 12a, and is patterned into a coil shape of several turns along the edge, and the auxiliary shaft electromagnetic drive The coil 13 is configured. The terminal end of the coil 13 is connected to the auxiliary shaft electrode 14b via the auxiliary shaft torsion bar 12b.
In such a configuration, for example, when an AC voltage with a driving frequency of 60 Hz is applied to the auxiliary shaft electrodes 14a and 14b, an electromagnetic force is generated and vibrates in the direction indicated by the arrow rs by the twisting action of the auxiliary shaft torsion bars 12a and 12b. To do. In this case, the vibration method of the countershaft torsion bar 12a12b is a non-resonant type, and the vibration waveform is a sawtooth waveform.

On the other hand, the main shaft electrodes 15a and 15b are provided in the vicinity of the corners on the other diagonal lines that intersect with the diagonal lines on which the sub-axis electrodes 14a and 14b of the outer frame 20 are provided. From the main shaft electrodes 15a and 15b, for example, a wiring portion is formed through the back side of the outer frame portion 20 shown in FIG. 2, and for example, the main shaft torsion bar 16a of the inner frame portion 19 and the auxiliary shaft torsion bars 16a and 12b are interposed. 16b is connected to, for example, comb-like electrostatic driving electrodes 17a and 17b facing each other through a minute gap. Comb-like protrusions having the same pitch as those of the electrostatic drive electrodes 17a and 17b are provided on both sides of the main shaft torsion bars 16a and 16b. The capacity can be increased.
In such a configuration, electrostatic driving is performed by applying, for example, an alternating voltage of about 18 kHz, which substantially matches the resonance frequency of the scan mirror 18, between the main shaft electrodes 15a and 15b. At this time, the main shaft torsion bars 16a and 16b vibrate at high speed in the direction indicated by the arrow rm by the twisting action. The drive system of the main shafts 16a and 16b is an electrostatic system, the vibration system is a resonance system, and the vibration waveform is a sine wave.

Setting the resonance frequency of the scan mirror 18 outside the human audible band range prevents the resonance from being transmitted to the outside during operation, that is, during image display, and being heard by the observer as an unpleasant sound. Has the advantage of not feeling.
The human audible band is generally set to 20 Hz or more and 20 kHz or less. However, when the resonance frequency of the scan mirror 18 is within this range, particularly a frequency that can be heard by the majority of human ears of less than 18 kHz, scanning is performed. The resonance of the mirror 18 is transmitted to the outside and may be heard by the user as an annoying sound.
Even if the design of the mechanical mechanism part of the two-dimensional scanning element 10 is devised so that this vibration is not transmitted to the outside as much as possible, the vibration is transmitted to the outside in principle and a resonance sound is generated. Therefore, it is desirable to set the resonance frequency outside the human audible range in order to make it fundamentally inaudible. This frequency may be 18 kHz or more so that it cannot be heard by the majority of humans, and even if it is heard, it will not be harsh.
In this way, by setting the resonance frequency of the scan mirror 18 to 18 kHz or more, most users (observers) cannot hear the resonance sound, and even if it is heard, the influence can be reduced, which is substantially unpleasant. Can be sufficiently suppressed or avoided.
Note that, for example, in addition to image display, music playback or the like is possible, and in the case of viewing a music program including a relatively high-frequency sound source, the resonance frequency of the scan mirror may be higher, about 20 kHz or more. desirable.

The material of the scan mirror 18 is, for example, from an SOI (Silicon On Insulator) substrate in which an oxide layer such as silicon dioxide (SiO ₂ ) and a semiconductor film such as silicon are sequentially stacked on the surface of a holding substrate formed of silicon. It can be formed of a semiconductor film from which the holding substrate and the oxide layer are selectively removed, and the flat surface of this semiconductor film is used as the scan mirror 18 serving as a light incident surface. A reflective film such as aluminum (Al) or gold (Au) may be formed on the flat surface of the scan mirror 18 in order to increase the reflectance. In the example shown in FIG. 2, an example in which a substantially elliptical scan mirror 18 is provided is shown, but other rectangles, squares, other polygonal shapes, and the like may be used.

In such a two-dimensional scanning element 10, a schematic configuration diagram of an embodiment in which a scan mirror is divided into a plurality of scan mirrors is shown in FIG. In FIG. 3, parts corresponding to those in FIG.
In the example shown in FIG. 3, an example is shown in which six scanning mirrors 18 are arranged to face one of the left and right observer eyes 200 to configure a scanning element. As shown in FIG. 3, in this case, the comb-like electrostatic drive electrodes 21a and 21b are opposed to the comb-like electrostatic drive electrodes 17a and 17b via a small gap, and the inner frame portion 19 is arranged. An example provided in is shown.
In such a configuration, each scan mirror 18 is driven by the same drive unit for vibration in the sub-axis direction indicated by arrow rs, and is driven by an independent drive unit for vibration in the main axis direction indicated by arrow rm. You can also

  As described above, since the angle of view of the image to be displayed is determined according to the size of the scan mirror 18 of the scanning element 10, the aspect ratio of the scan mirror 18 of the two-dimensional scanning element 10 is to be displayed. It is desirable to select appropriately according to the size of the screen. When the image display apparatus of the present invention is applied to an HMD, it is desirable that the angle of view is about 90 degrees or more in the horizontal direction in order to obtain a sense of reality. In the vertical direction, there is no problem with the conventional angle of view, that is, about 22 degrees. Accordingly, a wide angle ratio such as 1: 4 or 1: 3 is required for the vertical: horizontal ratio. Therefore, the aspect ratio of the scan mirror 18 of the scanning element 10 is required to be greater than 9:16. The aspect ratio of the scan mirror 18 is desirably the same as the aspect ratio of the actual display image. However, by dividing the scan mirror 18 as shown in FIG. 3, the horizontal width of each scan mirror 18 can be made small and light. Therefore, it is possible to vibrate with a high frequency sufficient to obtain a desired resolution.

  As an example, if a display angle of view of 90 degrees is taken at a distance of 4 mm from the observer's eye 200, for example, a scan mirror having a size of 8 mm in the horizontal direction is required if the size of the pupil is ignored, and the resolution is increased. It becomes difficult. Therefore, as shown in the example shown in FIG. 3, by dividing the scan mirror into a plurality of pieces and reducing the area of one mirror, the vibration frequency of the scan mirror 18 can be increased and display with high resolution can be achieved. A wide angle of view of about 90 degrees can be displayed. Thereby, the aspect ratio of the entire scan mirror 18 can be made wider than 9:16.

  As a scanning method on the screen, for example, one side is one scan with a frame, and the other is one scan with one scan line. It is necessary to increase the vibration frequency in the scanning line scanning direction. Therefore, it is necessary that the scan mirror is divided in the horizontal direction, that is, the scan mirrors divided in the horizontal direction are arranged side by side, and each scan mirror 18 is first driven in the horizontal direction. That is, in the example shown in FIG. 3, the extension direction of the main shaft torsion bars 16a and 16b is the vertical direction, and the extension direction of the sub shaft torsion bars 12a and 12b is the horizontal direction. The horizontal vibration is performed at a high frequency, and the base to which the divided scan mirrors 18 are attached, that is, the entire inner frame portion 19 vibrates at a relatively low frequency in the vertical direction. With such a configuration, scanning on the screen can be performed.

When the scan mirror is divided in this way, the light is reflected by the different scan mirrors and enters the observer's eye. Therefore, as shown in FIG. 4, the relative angles and the incident angles of the scan mirrors 18A and 18B Depending on the case, there may be a gap 25 where no light is incident at the boundary. In FIG. 4, broken lines 18A 'and 18B' schematically show how the scan mirrors 18A and 18B vibrate, arrows LiA and LiB indicate incident light incident on the scan mirrors 18A and 18B, and broken lines LoA and solid lines LoB, respectively. The light beams reflected by the scan mirrors 18A and 18B are shown. In order to avoid the generation of such a gap, it is necessary to enter the pupil within a certain range of the light reflected at the extreme end of the effective area of the scan mirror.
That is, in the state where the boundary of the light incident on the observer's eye 200 from the adjacent scan mirrors 18A and 18B among the divided scan mirrors maximizes the scanning angle of these scan mirrors 18A and 18B in the opposite direction, FIG. Alternatively, as shown in B, the reflected light of the adjacent scan mirrors 18A and 18B can be surely made incident in the pupil by being configured to be incident from the center of the pupil of the observer's eye at half or less of the radius re. It is possible to reliably avoid the generation of a gap.

In the example shown in FIG. 5A, an example is shown in which the boundaries of light reflected by the adjacent scan mirrors 18A and 18B cross toward the observer's eye 200 and are incident without any gap.
In FIG. 5B, the boundary of the light reflected by the adjacent scan mirrors 18A and 18B is incident on the observer's eye substantially in parallel, but the interval d is less than half the radius re of the pupil of the observer's eye 200. An example is shown. In this case, it is possible to display an image satisfactorily with almost no gap recognized.
When, for example, an even number of divided scan mirrors are used for the observer's eye 200, the light reflected by the left-side scan mirror or the scan mirror group enters the left observer's eye, and the right-side scan mirror or scan The light reflected by the mirror group may be incident on the right observer's eye. In such a configuration, if an observer moves his eyes to the left side to see the left side, an image that has been difficult to see until then becomes easy to see, which is preferable as an image display form.

  Further, as described above, when the scan mirror is divided, the number of scan mirrors to be driven increases, so that it is difficult to capture the signal line through the inner frame portion and its torsion bar. Therefore, for example, as shown in a schematic plan view of one embodiment in FIG. 6, electrostatic drive electrodes 17a and 17b and electrostatic drive fixed electrodes 21a and 21b which are drive terminals of the divided scan mirror 18 are provided. May be connected in parallel, for example. In this case, there are two drive terminals as schematically shown by arrows a1 and a2, and it is possible to reduce the number of signal lines to be supplied. 6, parts corresponding to those in FIGS. 2 and 3 are given the same reference numerals, and redundant description is omitted. Similarly, signal lines can be reduced when connected in series. In-phase or reverse-phase connection is possible.

Thus, when connecting the drive terminals of the scan mirrors 18 in parallel or in series, it is desirable that the sizes of the scan mirrors 18 be equal. Moreover, as shown in FIG. 6, it is desirable that the scan mirrors 18 connected and vibrated in synchronization are aligned in a direction along the vibration direction.
Since each divided scan mirror 18 displays different pixels, each scan mirror 18 needs to be configured to be irradiated with light from different light sources 1.

Next, an incident aspect of incident light on the scanning element 10 will be described. It is desirable for light to enter the scanning element 10 from between the scanning element 10 and the observer eye 200. However, since the distance between the two is narrow and it is difficult to select the incident angle as it is when a plurality of mirrors are used, the scanning element is shown in FIG. It is desirable to use an optical component that guides light to a position between 10 and the observer eye 200, for example, the light guide plate 30. The light guide plate 30 can incorporate light deflecting means such as a hologram so that light can enter the scanning element 10. In FIG. 7, parts corresponding to those in FIG.
FIG. 7 shows an example in which three scanning mirrors 18A, 18B, and 18C are provided facing each other on one observer eye 200, for example, the right eye. Light emitted from the light sources 1A, 1B, and 1C is incident on the waveguides 30A, 30B, and 30C in the light guide plate 30, respectively. Incident-side diffraction regions 31A, 31B, and 31C are provided at the incident positions of the waveguides 30A, 30B, and 30C, where each light is diffracted and guided in the waveguides 30A, 30B, and 30C, respectively. In addition, emission side diffraction regions 32A, 32B, and 32C are provided at positions facing the scan mirrors 18A, 18B, and 18C, where each light is diffracted and incident on the scan mirrors 18A, 18B, and 18C, respectively. In FIG. 7, broken lines 18A ′, 18B ′, and 18C ′ schematically show how the scan mirrors 18A, 18B, and 18C vibrate. The light reflected by these scan mirrors 18A, 18B and 18C is directed to the observer's eye 200 as indicated by arrows LiA, LiB and LiC, respectively. By observing as indicated by the arrow W, the image is recognized.

  As described above, when a plurality of scan mirrors are provided, it is necessary to individually enter light for each scan mirror. Therefore, it is necessary to provide a plurality of optical elements, such as waveguides, that guide light to the scan mirror. It is also possible to stack and integrate the optical elements having such a waveguide configuration, and further configure the optical element as a part of the package 40 that covers the scanning element 10. Note that in the MEMS type scanning element, it is necessary to keep the inside of the housing that houses the entire scanning element 10 in a vacuum or a reduced pressure state in order to reduce the air resistance of the scan mirror 18. Thus, by integrating the light guide plate 30 with the package 40, the scanning element 10 can be easily held in a vacuum or a reduced pressure state. In addition, the distance between the scanning element 10 and the observer eye 200 can be greatly increased.

When the light guide plate 30 is used in this way, the light reflected by the scan mirrors 18A, 18B, and 18C of the scanning element 10 is reflected by the optical element, that is, the light guide plate 30 and the hologram region (exit-side diffraction region 32A, In 32B and 32C), it is desirable to pass through the optical system without receiving any optical action and directly enter the observer's eye 200.
In order to pass through the return path from the scanning element 10 without reacting to the hologram or the like, the hologram constituting the emission-side diffraction region is used as a polarization hologram, and, for example, on the side facing the scanning element 10 of the light guide plate 30, It is good also as a structure provided with wavelength plates 33, such as 1 wavelength plate. In such a configuration, the light reflected by the scanning element 10 and incident on the hologram area again is polarized by 90 degrees, so that it can be prevented from reacting with the hologram area and can pass through as it is. The observer's eye 200 can be reached.

Further, as shown in the schematic cross-sectional configuration diagram of the main part of the embodiment in FIG. 8, the fact that the hologram is highly dependent on the light incident angle makes it possible to guide the inside of the waveguide until it enters the hologram. The reflection angle θg of the light beam to be reflected (the normal direction is indicated by a one-dot chain line vg) and the emission angle θm of the light reflected from the scan mirror 18 of the scanning element toward the observer's eye 200 (the normal direction is the one-dot chain line vm). Show)
θm <θg
As a relation, the light reflected by the scan mirror 18 may be configured so that the efficiency of the hologram is substantially zero.
Further, as shown in FIG. 8, at an incident angle of the light L reflected from the scan mirror 18, diffraction at an angle θd (> θm, the normal direction is indicated by a one-dot chain line vd) that does not enter the observer's eye 200. The hologram may be designed so that light is generated.
By adopting such a configuration, even when an optical element, for example, a hologram is interposed between the scan mirror 18 and the observer's eye 200, the light substantially reflected by the scan mirror 18 is prevented. It is possible to display a good image without causing an optical action and by preventing the optical action from entering the observer's eye 200 even if the optical action occurs.

  Further, as shown in FIG. 9 which is a schematic plan view of the main part of the embodiment, the scan mirror 18 of the scanning element is divided and a mirror having the same shape as the divided mirror is provided as a dummy mirror 118. The angle of the scan mirror 18 can be detected by detecting the light reflected by the dummy mirror 118. Thus, when performing angle detection, highly accurate angle control can be performed.

  FIG. 10 shows a schematic sectional configuration diagram of an embodiment of the image display apparatus in this case. In this case, the light emitted from the light source 1 enters the light guide plate 30 through the optical system 2. The light deflected in the incident side diffraction region 31 is guided in the light guide plate 30 and is diffracted by the emission side diffraction regions 32d and 32 provided at positions facing the dummy mirror 118 and the scan mirror 18, respectively. 118 and the scan mirror 18. The light Li reflected by the scan mirror 18 enters the observer eye 200 as it is, for example, by adopting the configuration described in FIG. On the other hand, the light reflected by the dummy mirror 118 is detected by a light detection element 119 made of, for example, a photodiode attached to a part of the light guide plate 30. As schematically shown in FIG. 9, the light detection element 119 is configured such that, for example, the light receiving region is divided in half, and by extracting the difference in light detected from each region as a signal Sa, The angle information of the dummy mirror 118 can be detected.

FIG. 11 is a schematic configuration diagram showing an overall configuration of an image display apparatus according to an embodiment of the present invention. In this example, scanning elements 10R and 10L each having four scan mirrors are provided in packages 40R and 40L for the right observer eye 200 and the left observer eye 200L, respectively. The light sources 1R and 1L for the right eye and the left eye, and the optical systems 2R and 2L are accommodated in the packages 42R and 42L, respectively, and are arranged on the incident region side of the light guide plates 30R and 30L. In FIG. 11, one light source and one optical system are typically shown, but it is desirable that each of them be provided by the number of scan mirrors. Further, when the image display device 100 has an HMD configuration, for example, support bodies 43R and 43L that can be held on the head by hanging on the right and left ears may be attached to the packages 42R and 42L. . Although not shown, control units such as a drive power source and a modulation circuit for appropriately driving the light sources 1R and 1L and the scanning elements 10R and 10L are disposed in the packages 40R and 40L, 32R and 42L, respectively.
By adopting such a configuration, it is possible to realize an image display device that is extremely small and can be reduced in weight, and to set the angle of view to a desired wide angle.
In addition, as shown in FIG. 11, by providing a space adjustment unit 41 between the right light guide plate 30R and the left light guide plate 30L and making each part movable, it is adapted to the position of the observer's eye. It is possible to select the display position appropriately.
Further, when different light sources and optical systems are used for the right eye and the left eye as in the example shown in FIG. 11, stereoscopic viewing is performed by causing an appropriate shift in image information incident on each eye. Is also possible.

As described above, according to the present invention, it is possible to provide an image display device having an extremely small and lightweight HMD type configuration.
In addition, according to the present invention, it is possible to provide an image display device that can easily correct the diopter and has a wide adjustment range without being affected by the aberration of the optical system, and to realize a wide viewing angle.
In particular, by dividing the scan mirror of the scanning element and using a plurality of scan mirrors, it is possible to display an image with a high aspect ratio with a large aspect ratio.
Further, even when a plurality of scan mirrors divided in this way are used, it is possible to drive with a small number of signal lines, and it is also possible to drive a plurality of scan mirrors synchronously. Furthermore, it is possible to drive a plurality of scanning elements with a half-phase shift, for example.

In addition to a plurality of scan mirrors, a dummy mirror is provided, and by detecting the light reflected by the dummy mirror, the angle of the scan mirror can be detected, and the angle of the scan mirror is controlled based on the angle information. Can be performed with high accuracy.
When a plurality of divided scan mirrors are used, it is possible to display a natural image in which the left image can be seen by moving the eyes to the left and the right image can be seen by moving the eyes to the right.
Furthermore, in a narrow space between the scanning element and the observer's eyes, an optical element such as a light guide plate can be used to allow light to enter the scanning element, and the distance between the scanning element and the observer's eyes. Can be maximized. When such an optical element is used, it is possible to display an image by individually entering light from a light source into a plurality of divided scan mirrors.
In addition, by appropriately selecting the incident angle of the reflected light from the scanning element to the optical element and the diffraction angle of the optical element such as a hologram, diffraction of the hologram due to the reflected light from the scanning element is prevented, and a good image is displayed. Can be done.
Furthermore, by setting the resonance frequency of the scan mirror to 18 kHz or higher, it is possible to sufficiently suppress or avoid hearing an irritating resonance sound due to vibration being transmitted to the outside, and to suppress or avoid discomfort to the observer.

The present invention is not limited to the examples described in the above embodiments, and various modifications and changes can be made without departing from the configuration of the present invention.
For example, when the scan mirror of the scanning element is configured to be sufficiently wide and can vibrate with a desired high frequency, a configuration in which an image is displayed by one scan mirror for one observer's eye It is also possible. In addition, it goes without saying that various modifications and changes can be made in the configuration and materials of each part such as the drive electrode of the two-dimensional scanning element shown in FIGS.

1 is a schematic configuration diagram of an image display device according to an embodiment of the present invention. 1 is a schematic perspective configuration diagram of an example of a scanning element used in an image display apparatus according to an embodiment of the present invention. It is a schematic plane block diagram of an example of the scanning element used for the image display apparatus which concerns on the example of embodiment of this invention. It is explanatory drawing of the incident aspect of the incident light to the pupil of the image display apparatus which concerns on the example of embodiment of this invention. A and B are explanatory diagrams of an incident mode of incident light to the pupil of the image display device according to the embodiment of the present invention. It is a schematic plane block diagram of an example of the scanning element used for the image display apparatus which concerns on the example of embodiment of this invention. 1 is a schematic cross-sectional configuration diagram of an image display device according to an embodiment of the present invention. 1 is a schematic cross-sectional configuration diagram of a main part of an image display device according to an embodiment of the present invention. It is a schematic plane block diagram of an example of the scanning element used for the image display apparatus which concerns on the example of embodiment of this invention. 1 is a schematic cross-sectional configuration diagram of an image display device according to an embodiment of the present invention. 1 is a schematic cross-sectional configuration diagram of an image display device according to an embodiment of the present invention.

Explanation of symbols

  1. 1. light source; Optical system, 10. Scanning elements 11a, 11b. Secondary shaft electromagnetic drive magnets 12a, 12b. Minor shaft torsion bar, 13. Sub-axis electromagnetic drive coils, 14a, 14b. Countershaft electrodes, 15a, 15b. Main shaft electrodes, 16a, 16b. Secondary shaft torsion bar, 17a, 17b. Electrostatic drive electrode, 18. 18. Scan mirror, Inner frame, 20. Outer frame part, 21a, 21b. Fixed side electrode for electrostatic drive, 40. Package, 100. Image display device, 200. Observer eye

Claims (14)

A light source that emits light modulated according to information;
A scanning element that includes a plurality of divided scan mirrors, scans incident light in a two-dimensional manner, and reflects reflected light directly into an observer's eye to display an image ;
An optical system for guiding the light emitted from the light source to the scanning element;
Bei to give a,
The boundary line of the effective area of the light incident on the observer's eye in the state where the scan angles adjacent to each other among the divided scan mirrors are reversed and maximized is the pupil of the observer's eye Arranged so that it is incident within half the pupil radius from the center,
An image display device characterized by that.   The image display apparatus according to claim 1, wherein the plurality of divided scan mirrors are independently driven in one direction and driven by the same driving unit in the other direction.   2. The image display device according to claim 1, wherein the divided scan mirrors are substantially equally divided and arranged in one direction.   The image display apparatus according to claim 1, wherein a light source is individually provided for each of the divided scan mirrors of the scanning element.   The image display apparatus according to claim 1, wherein the drive electrodes of the divided scan mirrors are connected in series or in parallel and driven in synchronization. A dummy mirror formed in the same shape as the scan mirror, provided at an end of the plurality of scan mirrors;
2. The image display device according to claim 1 , wherein the angle of the scan mirror is detected by detecting light reflected by the dummy mirror .   The image display device according to claim 1, wherein a light guide plate is used for an optical system that guides light emitted from the light source to the scanning element.   The image display apparatus according to claim 1, wherein a light guide plate and a hologram for guiding light emitted from the light source to the scanning element are provided independently for the divided scan mirror.   An optical system from the light source to the scanning element is provided corresponding to both the left and right observer eyes, and an interval between the optical systems can be adjusted according to the distance between the left and right observer eyes. The image display device according to claim 1, wherein: The image display apparatus according to claim 7 , wherein a hologram is used for a part of the light guide plate, and light is emitted from the light guide plate to the scanning element. The propagation angle of light of the light guide plate in the image display apparatus according to claim 7, characterized in that it is larger than the maximum irradiation angle of light incident to the observer's eye from the scanning device. The image display device according to claim 7 , wherein the light guide plate constitutes a part of a housing that covers the scanning element. 9. The image display device according to claim 8, wherein the hologram is a polarization hologram and is used together with a quarter-wave plate. The diffraction angle of the diffracted light generated when the light reflected by the scanning element passes through the hologram is made larger than the incident angle of the light incident on the observer's eye from the scanning element. 8. The image display device according to 8 .

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