JP4429656B2 - Image projection apparatus and image projection method - Google Patents

Description

  The present invention relates to an image display device and an image projection method.

  Conventionally, when displaying an image, various display methods for increasing the number of display pixels by shifting the display position of the pixels constituting the image have been proposed. Such a display method is called a pixel-shifted display method. The pixel-shifted display method is often applied to a projection display device typified by a projector, but it can also be applied to a head-mounted display or the like.

  As a method of shifting the display position of the pixel, for example, a method of displaying two or more images by shifting the display position and overlapping them at the same time, or slightly shifting the display timing and the display position of two or more images. There is a display method. The former method is often called a stacking method, and the latter method is often called a wobbling method. In the latter wobbling method, the image display position is shifted and displayed at the pixel size level.

  In the wobbling method, various methods and means for shifting the display position of an image have been proposed.

  For example, when an image displayed by a light valve is enlarged and projected onto a screen or the like, there is a method of providing an element including a liquid crystal film in a space between the light valve and the screen. In this method, by utilizing the fact that the orientation direction of the liquid crystal changes according to the direction in which the voltage is applied to the liquid crystal film, by switching the voltage direction applied to the liquid crystal film, the optical path of the light passing through the liquid crystal film is changed, The display position of the image can be shifted.

  In addition, for example, by using a reflective element including a piezoelectric element, the optical path from the light valve to the projection surface is changed by refracting the image light displayed by the light valve or changing the reflection angle, thereby changing the display position of the image. There is a way to shift. As such a refracting element, a prism is typical, and the image display position can be shifted by rotating the prism by a minute angle. Further, as the reflective element, a mirror is typical, and the image display position can be shifted by rotating the mirror by a minute angle.

  In addition to the various techniques described above, for example, there are techniques for shifting the optical axis of light from a display element (light valve) using a birefringent plate (for example, Patent Documents 1 and 2). reference).

  In addition, as a light valve, any of a transmission type / reflection type is applicable.

  By the way, when the wobbling method is used, if the moving image is seen during the moving period of the image for shifting the display position of the image, the image before the movement and the image after the movement are seen connected. That is, since the pixels cannot be seen separately, the resolution deteriorates.

  In order to avoid this deterioration, conventionally, there is an image projection apparatus that uses a piezoelectric element as a pixel shift element, in which illumination light is turned off during the pixel shift operation (for example, Patent Document 3). (Reference) This makes it possible to solve the display problem during pixel shifting as described above.

  By the way, in a standard image projection apparatus in recent years, illumination light source light is illuminated to a light valve configured by arranging a plurality of pixels that can be independently modulated in a matrix, and the pixels of the light valve are projected. The image is magnified and projected by optical means such as a lens and displayed on an image surface such as a screen.

  In such an image projector, the apparent number of pixels can be improved by shifting the projection position of the original pixel provided by the light valve at a frequency of approximately 60 Hz or more. For example, when a pixel projection position that is not shifted is used as a reference, and the shift operation is performed in the order of right, down, left, and up with respect to the reference position, the pixel position returns to the reference position by four shifts. The operation is a loop. For this reason, the position of the projected pixel image can be made constant even when the shift is repeated.

  Here, by performing the shift operation at a high speed and providing a time for the shift operation to stop at each shift position, it is possible to apparently clearly separate the images at each shift position. At this time, it is not necessary to completely stop the shift operation, but it is preferable that the shift operation is performed at a speed slower than the speed required for the shift operation as long as it corresponds to the time during which the shift operation is stopped.

Japanese Patent Laid-Open No. 4-63332 JP 7-36054 A JP 2001-356411 A

  By the way, as described above, a frame frequency of 60 Hz or more is required at least for reproducing and displaying a moving image. For example, in order to display one frame divided into two subframes in a time-divided manner, 1 The display frequency of one subframe must be 120 Hz or more.

  Similarly, in the technique described in Patent Document 3, the light source must be blinked at high speed. In the technique described in Patent Document 3, an LED is used as a light source, but a laser diode (LD) can also be used as a light source capable of high-speed blinking. In order to obtain a desired light amount using the light emitting diode LED or the laser diode (LD), a large number of LEDs are arranged and used in a two-dimensional array. When LEDs are arranged in a two-dimensional array, the temperature rises particularly at the center of the array, but it is difficult to efficiently radiate this and manage the temperature. Further, when a light emitting diode LED or a laser diode (LD) is used as a light source, the cost required for the light source is increased. Furthermore, in order to obtain a desired screen brightness with the LED or LD, it is inevitable that the output of the light source is high. For example, if it is LED, sufficient light quantity cannot be obtained unless it is two-dimensionally arrayed. However, when a two-dimensional array is formed, there is a problem of the heat dissipation efficiency described above, and the device is damaged.

  Here, for example, when a lamp is used as the light source, the cost can be reduced and the performance can be stabilized, but high-speed ON / OFF operation is difficult. Further, when a lamp is used as a light source, the light quantity loss is large because light is shielded all at once.

  Also, if the time for moving the image becomes longer than the time for displaying the image, the image of the displayed pixel becomes darker, so the shorter the moving time of the image by pixel shifting is better. However, it is extremely difficult to blink the lamp light source at this level of frequency.

  As a method of blinking the lamp light source at high speed, a means for providing a light shielding means in the illumination optical system is conceivable. In this case, basically, the chopper operation may be performed at high speed for illumination / shading. Here, the response time of the light valve used as the light shielding means needs to respond faster than the light valve that performs image display. However, it is difficult to obtain a light valve that can respond faster than a light valve that performs image display.

  By the way, when a transmission type light valve is used, it is difficult to set the aperture ratio of the pixels constituting the light valve to 100%. For this reason, there exists a subject that a light quantity loss is accompanied.

  On the other hand, when the reflective light valve is used, the aperture efficiency can be improved as compared with the transmissive light valve, but the aperture ratio is 100% or less. Further, when a reflection type light valve is used as a light blocking means, the layout of the optical system tends to be complicated.

  Conventionally, there is no example disclosed about a method of performing light shielding using a mechanism other than a light valve regarding light shielding while a pixel image is moving.

  By the way, when displaying an image of a larger number of pixels than the number of pixels of the light valve by pixel shifting display, the amount of image information to be displayed needs to correspond to the number of pixels to be shifted. For example, when pixel shifting is performed once, pixel information twice as many as the number of pixels of the light valve is required.

  In order to obtain image information for pixel shifting, a high-resolution imaging device is required. For example, when a CCD is used as the imaging device, it is necessary to increase the number of pixels of the CCD. The spatial resolution of the imaging lens is also required to be capable of resolving a frequency band equivalent to the CCD pixel size or more.

  By the way, when pixel shifting is performed once (two screens are shifted and displayed), the image information of one display frame is separated into image information of two image frames, and the separated image information of the two frames is displayed on the light valve. Display alternately. At this time, the second image frame is displayed after clearing the display of the first image frame. That is, in the wobbling method, there is a period during which the first image frame is cleared between the first image frame and the second image frame. This clearing period is a dead time because display based on image data is not performed.

  Ideally, the pixel shifting described above is performed during this dead time.

  However, when the extinction ratio during the dead time is poor, the image being shifted is displayed. As a result, the two image frames are connected, and the contrast of the image is lowered.

  On the other hand, it is possible to clear the image information of one frame all at once and display the image information of the second frame all at once. However, when the number of pixels of the light valve increases, it is transmitted when rewriting all at once. On the contrary, the amount of data increases, and time is required for display control.

  As a countermeasure, there is a case where a frame of image information is divided into a plurality of channels and parallel processing is performed to shorten the rewriting time. However, parallel processing complicates the signal processing system. turn into.

  For this reason, a method of rewriting sequentially for each scanning line is also widely used.

  Further, neither of the techniques described in Patent Documents 1 and 2 describes the movement of an image during pixel shifting.

  Further, even in the recent standard image projection apparatuses as described above, the pixel images at the fixed positions are connected to each other because the images are lit and displayed during the period during which the images are shifted. In such a case, there arises a problem that the separation characteristics between the pixel images are lowered and the resolution is deteriorated.

  An object of the present invention is to suppress deterioration in image quality due to pixel shifting.

An image projection device according to the present invention includes an image display element that has a plurality of pixels and that updates and displays an image in units of subframes obtained by dividing a display frame according to a state change of each pixel, and the image display element displays An illumination optical system that illuminates an image to be projected, a projection unit that projects an image illuminated by the illumination optical system onto a projection plane, and the image display element displays a projection position of the image projected by the projection unit within the projection plane Pixel shifting means for shifting within an update period for updating the image to be updated, and projection stop means for stopping projection of the image on the projection plane during the update period for updating the image displayed by the image display element.

  Therefore, during the update period for updating the image displayed by the image display element, the projection of the image onto the projection surface is stopped, and the moving image is visually recognized by shifting the projection position of the image during the update period. Can be prevented.

The image projection apparatus according to the present invention further includes afterimage display means for displaying the image projected immediately before by the projection means as an afterimage during the update period.

  Therefore, by displaying the afterimage of the image projected immediately before the update period, it is possible to prevent the image from becoming dark before and after the image is moved even if the projection of the image is stopped during the update period. it can.

In addition, the image projection apparatus of the present invention, the projection stopping means, the said image display device during the update period for updating an image, wherein the image display device displays a black display state.

  Therefore, for example, when a light valve is used as the image display element, it is possible to prevent the movement of the image due to the operation time of each pixel constituting the light valve from being visually recognized.

In the image projection apparatus of the present invention, the projection stopping unit may display an image illuminated by the illumination optical system during an update period in which an image displayed by the image display element is updated on the illumination optical system side with respect to the projection surface. Shield from light.

  Therefore, it is possible to simultaneously prevent the movement of the image from being visually recognized due to the update of the display image on the image display element and the display image from becoming dark.

In the image projection apparatus of the present invention, the afterimage display means is a light emitting material provided on the projection surface.

  Therefore, the display as an afterimage of the image projected immediately before the stop during the update period in which the projection of the image is stopped can be realized by the light emitting material.

In the image projection apparatus of the present invention, the light emission performance of the light emitting material is set so that light can be emitted for a time equivalent to the update period after the image projection is stopped.

  Therefore, it is possible to prevent the afterimage from being displayed at the time when the update period ends and the updated image is displayed.

In the image projection apparatus of the present invention, the light emitting performance of the light emitting material is set so that light emission can be performed for a time equivalent to the renewal period after the projection of the image is stopped in the wavelength range of the projection light of 500 to 560 nm.

  Therefore, an afterimage can be made in a wavelength band with relatively high sensitivity to vision. As a result, a high afterimage effect can be obtained, and a state in which apparently bright images are continuously displayed can be generated.

In the image projection apparatus of the present invention, the afterimage display means is a fluorescent material provided on the projection surface.

  Therefore, the action of the invention according to claim 2 can be obtained by a readily available fluorescent material. This eliminates the need for new material development costs and the like, and provides an image projection apparatus that is superior in cost.

In the image projection apparatus of the present invention, the afterimage display means is a fluorescent material in which a plurality of unit afterimage display areas that can emit light of R, G, and B are arranged corresponding to each pixel of the image display element. .

  Therefore, an afterimage with good color balance can be obtained. Thereby, a change in color balance at the timing of shifting the pixel can be reduced.

In the image projection apparatus of the present invention, the image display element updates the image in units of scanning lines scanned line-sequentially, and the pixel shifting unit projects an image corresponding to the position of the scanning line being updated. The position is shifted within the projection plane, and the projection stopping unit stops the projection of the image corresponding to the position of the scanning line being updated.

  Accordingly, it is possible to reduce the integrated value of the region where the projection of the image is stopped and the projection stop time while the pixel is shifted. Thereby, it is possible to reduce a loss of light amount due to the stop of the image projection and project a brighter image.

In the image projection apparatus of the present invention, the pixel shifting means shifts the pixels within the update time in units of scanning lines.

  Accordingly, since the pixel shift is completed within the update time, it is possible to more reliably prevent the moving image from being visually recognized.

Further, in the image projection device of the present invention, an intermediate image plane that is provided between the image display element and the projection plane and forms an image displayed by the image display element is provided, and the pixel shifting unit includes The position of the image formed on the intermediate image plane is shifted within this intermediate image plane.

  Therefore, it is possible to make the region where the projection of the image stops and the region where the image is shifted coincide with each other. As a result, an image with good image quality can be projected.

In the image projection apparatus of the present invention, the pixel shifting unit shifts the projection position of the image corresponding to the update unit region configured by a plurality of adjacent scanning lines within the projection plane, and the projection stopping unit includes: The projection of the image corresponding to the update unit area constituted by a plurality of adjacent scanning lines is stopped.

Accordingly, it is possible to reduce the change in color balance at the timing of shifting the pixels without particularly increasing the accuracy of adjustment for matching the area where the image projection is stopped and the area where the image is shifted. Thereby, the manufacturing cost of the image projection apparatus can be significantly reduced.

Further, in the image projection device of the present invention, an intermediate image plane that is provided between the image display element and the projection plane and forms an image displayed by the image display element is provided, and the pixel shifting unit includes The position of the image formed on the intermediate image plane is shifted from the intermediate image plane at a position defocused along the image projection direction.

Therefore, it is possible to project a brighter image by reducing the loss of light amount due to the stop of the image projection without particularly increasing the accuracy of the tolerance adjustment of the arrangement position of the pixel shifting means. Thereby, the manufacturing cost of the image projection apparatus can be significantly reduced.

In the image projection apparatus of the present invention , the display order in one display cycle in which one display frame divided into N (N is a positive integer) subframes is sequentially displayed is the Mth cycle (M is And a display position control means for making the difference in the (M + 1) -th cycle.

  Therefore, specific noise components such as moire generated by pixel shifting can be removed. As a result, a high-quality image can be projected.

Further, in the image projection apparatus of the present invention, in one display cycle in which one display frame divided into N (N is a positive integer) sub-frames is sequentially displayed, the sub displayed at the end of the Mth cycle. Display position control means for making the display position of the frame different from the position of the sub-frame displayed at the beginning of the (M + 1) -th cycle.

  Therefore, the temporal uniformity of the brightness of the image displayed in a shifted manner can be increased. As a result, a high-quality image can be projected.

The image projection method according to the present invention includes an illumination optical system that displays an image displayed by an image display element that has a plurality of pixels and updates and displays an image in units of subframes in which a display frame is divided into a plurality according to a state change of each pixel In the image projection method in which the projection position of the image is shifted within the projection plane when the illumination image is projected onto the projection plane by the projection unit, the image display element updates the image displayed by the image display element. The projection of the image on the projection surface is stopped during the period, and the image projected immediately before by the projection unit is displayed as an afterimage during the update period.

  Therefore, during the update period for updating the image displayed by the image display element, the projection of the image onto the projection surface is stopped, and the moving image is visually recognized by shifting the projection position of the image during the update period. Can be prevented. Also, by displaying the afterimage of the image projected immediately before during the update period, it is possible to prevent the image from becoming dark before and after the image is moved even if the image projection is stopped during the update period. it can.

According to the image projection device of the present invention, the projection of the image on the projection surface is stopped during the update period in which the image displayed by the image display element is updated, and the image is being moved by shifting the projection position of the image during the update period. Can be prevented from being visually recognized.

In the image projection apparatus of the present invention, the afterimage of the image projected immediately before during the update period is displayed, so that even if the image projection is stopped during the update period, the image becomes dark before and after the movement of the image. Can be prevented.

Further, in the image projection apparatus of the present invention , for example, when a light valve is used as an image display element, it is possible to prevent the movement of the image from being visually recognized due to the operation time of each pixel constituting the light valve.

Further, in the image projection apparatus of the present invention, it is possible to simultaneously prevent the movement of the image due to the update of the display image on the image display element and the darkening of the display image.

In the image projection apparatus of the present invention, the display as an afterimage of the image projected immediately before the stop during the update period during which the image projection is stopped can be realized by the luminescent material.

Further, in the image projection apparatus of the present invention, it is possible to prevent the afterimage from being displayed at the time when the update period ends and the image after the update is displayed, so that a high quality image can be projected.

In the image projection apparatus of the present invention, an afterimage can be made in a wavelength band with relatively high sensitivity to vision, so that a high afterimage effect can be obtained and an apparently bright image is continuously displayed. Can be generated.

Further, in the image projection apparatus of the present invention , since the action of the invention according to claim 2 can be obtained by an easily obtainable fluorescent material, the cost for newly developing the material becomes unnecessary, and the image projection excellent in cost can be achieved. An apparatus can be provided.

Further, in the image projection apparatus of the present invention, an afterimage with good color balance can be obtained, so that the change in color balance at the timing of shifting the pixel can be reduced.

Further, in the image projection apparatus of the present invention , since the integrated value of the region where the projection of the image is stopped and the projection stop time can be reduced while shifting the pixel, the loss of light amount due to the stop of the image projection is reduced, A brighter image can be projected.

In the image projection apparatus of the present invention , since the pixel shift is completed within the update time, it is possible to more reliably prevent the moving image from being visually recognized.

In the image projection apparatus of the present invention, the region where the image projection is stopped and the region where the image is shifted can be matched, so that an image with good image quality can be projected.

Further, in the image projection apparatus of the present invention, the loss of light amount due to the stop of image projection is reduced without increasing the accuracy of adjustment for matching the region where the image projection is stopped and the region where the image is shifted. it is possible to project an image, the manufacturing cost of the image projection apparatus can be greatly reduced.

Further, in the image projection apparatus of the present invention, it is possible to project a brighter image by reducing the loss of light amount due to the stop of the image projection without significantly increasing the accuracy of the tolerance adjustment of the arrangement position of the pixel shifting means. The manufacturing cost of the projection apparatus can be greatly reduced.

Further, in the image projection apparatus of the present invention, it is possible to remove specific noise components such as moire generated by pixel shifting, so that a high quality image can be projected.

In the image projection apparatus of the present invention, the temporal uniformity of the brightness of the image displayed in a shifted manner can be increased, so that a high-quality image can be projected.

According to the image projection method of the present invention, during the update period for updating the image displayed by the image display element, the projection of the image on the projection surface is stopped, and the image is being moved by shifting the projection position of the image during the update period. It is possible to prevent the image of the image from being visually recognized, and by displaying the afterimage of the image projected immediately before the update period, the image can be moved even if the projection of the image is stopped during the update period. It is possible to prevent the image from becoming dark before and after.

  The best mode for carrying out the present invention will be described with reference to FIGS. This embodiment shows an application example to an image projection apparatus.

  FIG. 1 is a schematic diagram showing an optical system configuration of the entire image projection apparatus according to an embodiment of the present invention. The image projection apparatus 1 includes a lamp light source 2, an IR filter 3, an integrator optical system 6 composed of integrators 4 and 5, a mirror 7, a light blocking means 8 as a projection stop means, a wave plate 9, a polarizing beam splitter (hereinafter referred to as PBS). 10), a dichroic mirror 11, a reflective light valve 12 (12R, 12G, 12B) as an image display element, a pixel shifting unit 13, and a projection optical system 14 as a projection unit. In the present embodiment, an illumination optical system is realized by the lamp light source 2, the IR filter 3, the integrator optical system 6, the mirror 7, the wave plate 9, the PBS 10, the dichroic mirror 11, and the like.

  Reference numeral 15 in FIG. 1 denotes a screen as a projection surface onto which an image is projected by the image projection apparatus 1. The screen 15 is provided with a light emitting material that emits light in response to the irradiated light so that an afterimage is displayed in a region where the pixel shift is performed during pixel shift in image projection to be described later. Here, an afterimage display means is realized. Note that although a light emitting material is provided in this embodiment mode, the present invention is not limited to this, and a fluorescent material that emits fluorescence in accordance with irradiated light may be provided.

  In the present embodiment, the IR filter 3 is provided between the lamp light source 2 and the integrator 4. However, the present invention is not limited to this, and is illustrated between the lamp light source 2 and the integrator 4 instead of the IR filter 3. A UV cut filter may be provided. Further, an IR filter and a UV cut filter may be provided between the lamp light source 2 and the integrator 4.

  The integrator optical system 6 generates an illumination light beam in which the spatial distribution of the illuminance of the light emitted from the lamp light source 2 is made uniform. This illumination light beam is irradiated toward the light shielding means 8 at the subsequent stage.

  In this embodiment, the mirror 7 is disposed between the integrator 4 and the integrator 5 in order to return the optical path. However, the mirror 7 is not necessarily provided.

  The light shielding unit 8 has a function of appropriately shielding an illumination light beam emitted from the integrator optical system 6 when an image to be described later is projected. The light shielding unit 8 can be realized by, for example, a liquid crystal panel having a configuration similar to that of the light valve 12 described later and having a plurality of pixels corresponding to the plurality of pixels in the light valve 12. Since such a liquid crystal panel is a known technique, description thereof is omitted.

  Here, FIG. 2 is an explanatory view showing another example of the light shielding means 8. The light shielding means 8 shown in FIG. 2 includes a light transmitting region 16 and a light shielding region 17 provided periodically, and the light transmitting region 16 and the light shielding region 17 are alternately arranged on the light emission light path from the lamp light source 3. It has a configuration that can be passed. When projecting an image, the light transmitting region 16 and the light shielding region 17 can be moved in time by alternately moving the light transmitting region 16 and the light shielding region 17. The light-transmitting area 16 and the light-shielding area 17 match the position of the scanning line where the image is updated on the light valve 12 and the light-shielding area, and the moving speed of the scanning line for updating the image and the moving speed of the light-shielding area of the light-shielding means 8 Synchronize. At this time, it is preferable to add a mechanism for adjusting the synchronization between the light shielding position and the speed. In FIG. 2, the illustrated light shielding region 17 is continuous in the direction perpendicular to the paper surface, and the length thereof is set to be at least the length of the scanning line of the light valve 12. Similarly, the direction of the scanning line is the direction perpendicular to the paper surface.

  Although not specifically shown, the light shielding unit 8 may be configured to move the light shielding region 17 by rotating a spiral disk-shaped disk.

  The wave plate 9 imparts polarization to the illumination light beam emitted from the integrator optical system 6 and converts it into linearly polarized light. In this embodiment, it is assumed that the light is converted into P-polarized light for convenience of explanation.

  The PBS 10 reflects or transmits the incident light beam according to the polarization direction of the incident light beam. In this embodiment, it is assumed that P-polarized light is reflected and S-polarized light is transmitted.

  The dichroic mirror 11 separates the illumination light from the PBS 10 into three wavelengths of red, green, and blue. Although the description is omitted because it is a known technique, the dichroic mirror 11 separates the incident light from the PBS 10 side into blue or red and other colors, and the incident light from the light valve 12 side into green and red or green. And color separation into blue. In the present embodiment, the irradiation light can be separated into three wavelengths by a single dichroic mirror 11.

  Note that, as in the present embodiment, the light is not limited to a single dichroic mirror 11 that decomposes the irradiated light into three wavelengths of red, green, and blue. It is also possible to disassemble. For example, the front dichroic mirror can separate blue or red and other colors, and the rear dichroic mirror can separate the colors into green and red or green and blue.

  The light valve 12 (12R, 12G, 12B) has a configuration in which pixel openings are arranged vertically and horizontally as shown in FIG. In FIG. 3, the gap between the pixel openings is omitted. The light valve 12 according to the present embodiment has a plurality of pixels arranged in m in the vertical direction and n in the horizontal direction. As the reflective light valve 12 used in the present embodiment, LCOS (Liquid Crystal on Silicon) is suitable.

  Although not shown, the light valve 12 is connected to display control means for controlling the operation of each pixel in the light valve 12. At the time of image projection, which will be described later, this display control means can control the operation of each pixel in each light valve 12R, 12G, 12B to display an image in units of subframes. Although the description is omitted because it is a well-known technique, a sub-frame indicates each divided frame when a single display frame is divided into a plurality of frames, and has an image density lower than the image density of the display frame. Have.

  In the present embodiment, at the time of projecting an image, which will be described later, the image is updated by scanning the scanning lines in the light valve 12 line-sequentially under the control of the display control means. In the present embodiment, a scanning line is a pixel column composed of n pixels arranged in the left-right direction in FIG. 3 or a pixel column composed of m pixels arranged in the vertical direction in FIG.

  The light valve 12 is disposed in the vicinity of the dichroic mirror 11 so that the light beam color-separated by the dichroic mirror 11 can illuminate the light valve satisfactorily. The light valves 12R, 12G, and 12B corresponding to the three colors of light separated by the dichroic mirror 11 are preferably capable of shift and tilt adjustment.

  R, G, B colors reflected by PBS 10 and transmitted through dichroic mirror 11 and split into R, G, B illumination lights by dichroic mirror 11 to illuminate corresponding light valves 12R, 12G, 12B The illumination light is converted into S-polarized light when reflected by the light valves 12R, 12G, and 12B, and is incident on the PBS 10 again through the dichroic mirror 11.

  Here, since the illumination light reflected by the light valve 12 and transmitted through the dichroic mirror 11 is polarized to S-polarized light, it passes through the PBS 10 and enters the pixel shifting means 13.

  The pixel shifting unit 13 includes a plurality of pixel shifting elements (not shown) arranged corresponding to the respective pixels of the light valve 12. Each pixel shifting element has a function of shifting and outputting the optical path of incident light.

  As the pixel shifting element, for example, a pixel shifting element 18 as shown in FIG. 4 can be used. Here, FIG. 4 is a cross-sectional view schematically showing the configuration of the pixel shifting element 18. The pixel shifting element 18 includes a dielectric layer 20, a transparent electrode 21, an adhesive layer 22, and a transparent substrate 23, which are laminated so as to be vertically symmetric with a liquid crystal layer 19 therebetween. The transparent electrode 21 extends continuously in the front and back direction of the paper surface in FIG. In the pixel shifting element 18, the smaller the difference in refractive index between the transparent electrode 21 and the adhesive layer 22, the better. Since the liquid crystal layer 19 has a high response speed, a vertical alignment type ferroelectric liquid crystal is suitable for switching.

  In the pixel shifting element 18 of the present embodiment, the stripe-shaped transparent electrode 21 is arranged to face the liquid crystal layer 19 in the layer thickness direction so that a voltage is applied. If the period is configured to be shifted by a half pitch between the upper and lower sides (or front and rear) facing each other, the uniformity of the potential difference generated in the liquid crystal layer can be improved.

  In addition, the liquid crystal layer 19 has a structure sandwiched between transparent electrodes 21 having translucency. By inserting a dielectric layer 20 between the liquid crystal layer 19 and the transparent electrode 21, the in-plane uniformity of the potential difference can be improved. Can do. In the present embodiment, the opposing transparent electrodes 21 are connected to each other by dividing resistors so that an equipotential is applied in the in-plane direction.

  In such a pixel shifting element 18, the orientation direction of the liquid crystal is controlled by applying a voltage between the upper and lower transparent electrodes 21 to generate a potential difference in the liquid crystal layer 19. The alignment direction of the liquid crystal can be made to respond in a binary manner by an applied voltage. Since the birefringence effect by the one liquid crystal layer 19 generates a uniaxial optical axis shift or tilt, the birefringence directions of the two liquid crystal layers are arranged orthogonal to each other in the biaxial direction. It is possible to shift the pixels.

  An optical path shift control circuit (not shown) that drives and controls each pixel shift element 18 is connected to the pixel shift means 13. When projecting an image, which will be described later, the voltage applied to the liquid crystal layer 19 of each pixel shifting element 18 is adjusted by an optical path shift control circuit, and the pixels in a predetermined region are shifted by controlling the alignment direction of the liquid crystal.

  When light is incident on the pixel shifting element 18 with a voltage applied to the liquid crystal layer 19, the extraordinary light component is deflected by the birefringence characteristics of the liquid crystal, and the optical path is shifted to exit the liquid crystal layer. Here, FIG. 5 is an explanatory view schematically showing the optical path of the extraordinary ray of the ray incident on the liquid crystal layer. As shown in FIG. 5, the outgoing light beam from the liquid crystal layer 19 is deflected in the liquid crystal layer 19 and is shifted and emitted with respect to the incident light beam. Since this phenomenon is a known technique, description thereof is omitted.

  At the time of image projection, which will be described later, the image shifting means 13 is driven and controlled by the optical path shift control circuit and operates each pixel shifting element 18 in response to switching of the display image on the light valve 12. Thereby, the image optical path of the display image displayed on the light valve 12 can be shifted.

  The optical path shift by the pixel shift element 18 is, for example, an operation state corresponding to one shift position when the shift signal for controlling the operation of the pixel shift element 18 is low, and is shifted to the other shift position when the shift signal is high. It is controlled so as to be in a corresponding operation state. The shift amount by the optical path shift operation in the pixel shifting element 18 can be changed by a given shift signal.

  For example, when the pixel image position displayed by such pixel shifting is displayed by moving it in two axial directions, the x direction and the y direction, the pixel image positions can be present at four locations. Become.

  Note that the pixel shifting element is not limited to the pixel shifting element 18 shown in FIG. 4, and various known techniques can be used. As the pixel shifting means 13, any known pixel shifting means having various pixel shifting elements 18 can be used as long as the pixel shifting means 13 can shift the image optical path from the light valve 12. For example, pixel shifting may be performed by tilting a prism or mirror.

  The projection optical system 14 realizes a function of forming an image displayed on the light valve 12 on the projection plane. The projection optical system 14 of the present embodiment is realized by a lens. The projection optical system 14 can use a reflection optical system in addition to the lens.

  In such an image projecting apparatus 1, during the projection of an image, the display control means performs a period from when the sub-frame image on the light valve is displayed to when switching to the next sub-frame image to be displayed. The display image information of the next subframe is read from the frame buffer and updated. Further, every time the light valve displays an image of one subframe, pixel shifting is performed by the pixel shifting means so that the projection position of each pixel on the light valve is shifted on the projection plane. At this time, the image of the sub-frame displayed on the light valve can be moved to a total of four locations by shifting in two vertical and horizontal directions as described above.

  The display image is updated by the display control means in units of scanning lines on the light valve in order of scanning lines according to the scanning line number. For example, when the scanning line numbers are 1, 2, 3,..., The subframe images are updated in order from scanning line number 1. For this reason, the time at which the update of the image of scanning line number 2 is started is slightly delayed from the time at which the update of the image of scanning line number 1 is started.

  Here, FIG. 6 is an explanatory diagram showing a state in which an image is sequentially updated by scanning lines. As shown in FIG. 6, the scan line update start time T1 at which the image of a certain subframe #N is updated first is the scan line update start time T2 at which the image of the subframe #N is updated last. It will be early.

  The update of the subframe #N is completed for each scanning line, but the update end time T3 in the scanning line that is updated first is the update end in the scanning line that is last updated in the updated subframe. It is earlier than time T4.

  That is, in general terms, the time when the update of the image of the scanning line number N + 1 is started is delayed from the time when the update of the image of the scanning line number N is started.

  Note that the time required for each scan line to update the image is the same. For this reason, as for the time when the update of the image of each scanning line is completed, the completion time of scanning line number N + 1 is delayed from the completion time of scanning line number N.

  In the conventional image projection apparatus, pixel shift is performed between time T1 and time T4.

  By the way, as can be seen from FIG. 6, the scanning line where the image update is finally started still displays the image of the subframe #N at the time T1. For this reason, when the pixel shift is performed between times T1 and T2, a state in which the images are sequentially updated (hereinafter, the image is moved) is projected.

  Further, as can be seen from FIG. 6, at the time T2, the update of the display image on the scanning line where the update ends last is not completed. For this reason, nothing can be displayed at this scanning line position.

  On the other hand, in the scanning line where the image update is started first, there is no image to be displayed between times T1 and T3, and the image of the next subframe # N + 1 is displayed at time T4. If pixel shifting is performed during T4, a state in which the image moves is displayed.

  Also, if pixel shifting is performed between times T3 and T4, an image cannot be displayed between times T1 and T3 on the scanning line where the image update is first started.

  Further, if pixel shifting is performed between times T1 and T2, an image cannot be displayed between times T2 and T4 on the scanning line where image updating is finally completed.

  FIG. 7 is a graph showing a change in display luminance when the display image is updated at the timing in the conventional image projection apparatus. In FIG. 7, the vertical axis represents screen brightness and the horizontal axis represents time. FIG. 7 shows the state of the scanning line where the image update is started first. A time T5 in FIG. 7 is a time at which the display of the image of the subframe # N + 1 is started on the scanning line where the image update is first started. As shown in FIG. 7, no image is displayed between times T1 and T5. Such a state in which no image is displayed occurs in each scanning line. For this reason, the screen becomes dark during the image update period. Such a characteristic that the brightness of the screen gradually changes at the start and end of display for each subframe is due to the response speed of the light valve. In these cases, there are many places where no image is displayed, so the image becomes dark.

  On the other hand, in this embodiment, as shown in FIG. 8, the pixel shifting means is controlled so that the pixel shifting of the scanning line where the image update is started first starts at time T1 and ends at time T2. . In addition, the pixel shifting unit is controlled so that the pixel shifting of the scanning line that finally completes the image update starts at time T3 and ends at time T4. For the scan lines between the scan line where the image update is first started and the scan line where the image update is finally completed, the pixel shift start time of each scan line is time T1 and time T3 according to the scan line order. The pixel shift unit is controlled to shift the pixels so that the pixel shift end time of each scanning line is positioned on the line connecting the time T2 and the time T4.

  Specifically, in the present embodiment, the light beam that illuminates the region corresponding to subframe #N is shielded in the time zone in which the display image at the position corresponding to subframe #N is being updated. At this time, the time during which the luminous flux is shielded is set to be substantially the same as the time from the start to the end of the update of the image of subframe #N. The timing at which the light beam is shielded and the area to be shielded correspond to the timing at which image information is updated on the light valve 12 and the area to be updated.

  Alternatively, the light valve 12 may be controlled to display a black image in the time zone in which the display image at the position corresponding to the subframe #N is being updated. This solves the problem. However, in this case, since the image is not displayed during pixel shifting, the screen becomes dark during that time.

  In the present embodiment, since a light emitting material is provided on the screen 15, an afterimage is displayed in a region where pixel shifting is performed during the above-described pixel shifting. As a result, during the period when the image in the region where the pixel shifting operation is being performed is not displayed, the image in that region is not lost.

  That is, in actual light emission, the image of the subframe #N gradually darkens from the time when the display of the subframe #N is completed and is not displayed at the time T1, but the pixel is shifted during the pixel shift as in the present embodiment. By setting the afterimage to be displayed in the region to be shifted, as shown in FIG. 9, the subframe # N + 1 is displayed until the time T5 is exceeded and the subframe # N + 1 is displayed. Since the afterimage of the image of frame #N continues to emit light as shown by the broken line, the time during which no image is displayed can be eliminated. Thereby, the display screen during the update period can be brightened.

  By the way, as means for obtaining the afterglow effect, in addition to providing a light emitting material on the screen, a fluorescent material is used on the projection screen surface so that the fluorescent material emits light when blocked by light obtained by illumination light irradiation. I made it. The light emission principle by the phosphor has been used for CRT for a long time, but in the present invention, this light emission function is used as an auxiliary during the light shielding period described above to avoid display interruption.

  As is apparent from the CRT, it is most desirable that the emission color has a pixel matrix in which each pixel is composed of three primary colors of RGB. In one pixel composed of RGB light-emitting areas, the light-emitting areas of RGB can be configured by arranging color developing areas in the scanning line direction as illustrated in the figure, for example. In addition to this, the pixels may be arranged in the scanning line column direction, or one pixel region may be divided into vertical and horizontal matrices, and the RGB regions may be arranged in a checker shape. The light emitting regions of each RGB color emit light by light absorption reaction with respect to each RGB wavelength component. For example, the R emission region senses the R wavelength and emits light. In addition, a configuration in which pixels of the RGB colors are continuous between pixels is possible. However, when pixels are continuous, for example, when considering a pixel emitting R, a pixel adjacent to the pixel is Even when it is desired not to emit R, the non-irradiation region, that is, the adjacent pixel region may react to some extent to emit light because the light emitting region is continuous.

  Here, even if the pixel matrix is configured on the screen with a phosphor having a high specific vision sensitivity only in the green wavelength band, the pixel shape information may be reproduced without a sense of incompatibility depending on the displayed image. In such applications, an effect of reducing the cost of the screen can be obtained.

  In this way, in the state where the afterimage is displayed, if the pixel shift is performed while the illumination light is shielded, the pixel shifted image can be prevented from being displayed.

  The pixel shift means 13 shifts the timing of updating the display image in the light valve 12 and the area for pixel shift, and shifts the timing of shifting the pixel column on one scanning line on the light valve on the light valve. The timing to update the image displayed on the pixels on one scanning line is matched.

  In order to realize such a function of the pixel shifting means 13, it is practically necessary to spatially separate pixel information on the light valve included in the illumination light at the position where the pixel shifting means 13 is provided. .

  In the image projection apparatus 1, a relay lens 30 may be provided between the light valve 12 and the pixel shifting unit 13. For example, as shown in FIG. 10, in the case where a lens is provided between the PBS 10 and the pixel shifting element 18, the pixel shifting means 13 is a surface on which the pixels on the light valve 12 are spatially separated by the lens (hereinafter referred to as “the lens shifting unit 13”). , The intermediate image plane). In other words, this lens can be adjusted so that the focus of the intermediate image of the image displayed by the light valve is on the pixel shifting means, so that the region where the image projection is stopped and the region where the image is shifted can be matched. It is possible to project an image with good image quality.

  By the way, when the image of the pixel before the movement is not erased when the movement of the pixel is completed, both the pixel before the movement and the image of the pixel after the movement are visible. In contrast, in the present embodiment, the light-emitting performance of the light-emitting material provided on the screen 15 is adjusted, and the light shielding timing is adjusted so that the afterimage disappears at the timing when the pixel shifting operation is completed in the pixel shifting region. In addition, the movement of the image during the pixel shifting operation can be prevented, and the updated image after the pixel shifting operation can be viewed well.

  Here, if the brightness of the image of the pixel before the movement that is visible in the afterglow is attenuated and relatively dark with respect to the image after the movement, the image quality of the afterglow image is reduced. The degree of instantaneous deterioration is reduced. The brightness of the afterimage of subframe #N at the time when the image of subframe # N + 1 is displayed is preferably attenuated to 5% or less with respect to the brightness of the image of subframe # N + 1.

  As described above, according to the present embodiment, the number of display pixels can be increased by shifting the pixels, and the resolution of the display image can be increased. In addition, the moving pixels in the pixel shifting are not displayed. It is possible to prevent the phenomenon that the resolution is deteriorated due to the connection.

  In addition, since the light-blocking region is limited and moved during the movement of the pixels, the light amount loss due to the light-blocking can be reduced and the display image can be brightened compared to the case where the entire surface is shielded from light.

  When the light is shielded all at once during the image update period from subframe #N to # N + 1, the entire surface is shielded during times T1 to T4 in FIG. 6, but the afterimage is visible due to the light emitting material provided on the display screen. Therefore, the problem that the image becomes dark during the light shielding period can be solved.

  In addition, in the case of simultaneous light shielding in this way, it is not necessary to move the pixel shifting area, so that the restrictions on the arrangement of the pixel shifting means can be relaxed, and it can be arranged at positions other than the intermediate image positions of the light valve pixels. is there. In addition, since it is not necessary to shift the pixels by adjusting the timing in units of scanning lines, the configuration and operation of the element can be simplified.

  Further, at the timing when light is shielded, the image of the pixel before the movement is visible due to the function of the light emitting material, so that a brighter image can be displayed.

  By the way, in order to reduce the adjustment cost associated with matching the position and timing of the light-shielding in units of scanning lines composed of the pixel rows on the light valve 12 and matching the position and timing of the pixel to be shifted, the light valve 12 is used. It is preferable to consider a plurality of units adjacent to the scanning line formed of the upper pixel row as one region, and to synchronize the operation of shading and pixel shifting with respect to this region.

  Even in this case, the moving speed of the light shielding area is the same as that in the above case, but the light shielding area becomes wide, so that the adjustment cost of the light shielding area can be reduced. In addition, since it is not necessary to perform pixel shifting in a time-division manner in units of scanning lines, pixel shifting is performed simultaneously for regions corresponding to a plurality of scanning line groups.

  In such a case, the pixel shifting means 13 does not necessarily have to exactly coincide with the intermediate image plane position of the light valve 12. In the space defocused before and after the optical axis direction with respect to the intermediate image plane, the spatial separation performance of the light valve 12 in units of scanning lines gradually deteriorates. Since the image information at the scanning line group level considered is separated, it is possible to shift pixels in units of scanning line groups, and to allow a wide defocus shift tolerance at the position where the pixel shifting means 13 is provided. become.

  When the screen is shifted to the XY plane, the pixel shifting direction can be varied such as ± X direction, ± Y direction, combinations thereof, and diagonal directions (± 45 degrees in the X direction and ± 45 degrees in the Y direction). .

  When pixel shifting is performed in units of light valve scanning line groups, the liquid crystal layer is separated by a wall extending in the scanning line direction, and voltage application adjusting means is provided independently for each separated region.

  By the way, in the present embodiment, the positions of the images of the respective pixels can be present at four locations.

  Here, FIG. 11 shows an image display area formed by four display positions that a certain pixel can take by the above-described pixel shifting. The image display area 24 is formed on the screen 15. As shown in FIG. 11, each pixel projected on the screen 15 can be moved to a total of four locations. Here, for simplification of explanation, the movement of the image is described in units of pixels. However, the movement of the image is described by arranging a plurality of image display areas shown in FIG. 11 in the vertical direction and the horizontal direction. Since it is possible, it is omitted here.

  In the case where the pixel positions that a certain pixel can take are indicated in the form of coordinates (i, j), in this embodiment, (1, 1), (1, 2), (2, 1), (2, 2) It can be expressed as. When the order of movement of the display position by pixel shifting of a pixel in an image display area 24 is (1,1) → (1,2) → (2,2) → (2,1), The image projection apparatus 1 causes the (1,1) pixels to emit light while the display position is moved from (1,1) to (1,2), so that the (1,2) pixels can be displayed. At this time, the light emission at the pixel (1, 1) is attenuated and disappears. The same principle is applied to the movement of (1,2) → (2,2), (2,2) → (2,1), (2,1) → (1,1), and the display is moving. The afterimage of the image at the previous display position is always visible.

  As described above, in the pixel shifting unit 13 of the present embodiment that enables the positions of the pixel images to exist at four positions, the image is displayed with respect to the positions of the four movable images at the time of pixel shifting. When the positions of the pixels to be formed are sequentially moved and displayed, if they are always displayed in the same order, a specific pattern may be seen on the screen.

  In the present embodiment, there are four moving display positions of a single pixel by the pixel shifting means 13, but when the four times of moving display are considered as one period, the display order is different at least between the preceding and following periods. Like that. That is, when the Mth cycle is set so as to shift the pixels in the order of (1, 1) → (1,2) → (2,2) → (2,1), this display frame The moving order of the display frames in the (M + 1) -th cycle to be displayed next is (2, 1) → (2, 2) → (1, 2) → (1, 1). Here, the function as the display position control means is realized.

  However, if the pixel position displayed at the end of the Mth display cycle and the position displayed at the beginning of the M + 1th display cycle are the same, the brightness appears to increase locally, so that these positions are different. It is good to consider. For example, when the movement of the display position in the Mth cycle is (1,1) → (1,2) → (2,2) → (2,1), the first display position in the (M + 1) th cycle is The display position is controlled so that it is not the last display position (1, 2) in the Mth period. Here, the function as the display position control means is realized.

  In the present embodiment, the image display area 24 is divided into regions as shown in FIG. 11. However, the present invention is not limited to this. For example, the image display area 24 may be divided as shown in FIG. FIG. 12 shows an image display area 24 ′ in which the movable element area of one pixel is divided into three areas in the scanning line direction (horizontal direction in the figure). The image display area 24 ′ is formed of a light emitting material capable of coloring R, G, and B at positions corresponding to the respective areas, and R, G, and B are formed with respect to the image display area 24 ′. When the light having the three wavelength components is irradiated, the above-described light emitting section emits light for a short time with respect to the illumination light of each wavelength, and a color in which the three wavelengths are combined is displayed as afterglow.

  As a result, the image light in the region where the pixel shifting operation is performed is blocked during the pixel shifting operation. Even when the luminous flux in the area where the pixel shift operation is performed is blocked by the pixel shift operation by updating the display image at a speed higher than the speed that can be separated and recognized by the human eye, before the pixel shift The afterglow of the other pixel occurs and exists as an afterimage.

It is the schematic which shows the optical system structure of the whole image projector of one embodiment of this invention. It is explanatory drawing which shows another example of a light-shielding means. It is the schematic explaining the arrangement | sequence of the pixel in a light valve. It is the schematic explaining a pixel shift element. It is explanatory drawing which shows typically the optical path of the extraordinary ray of the light ray which injected into the liquid-crystal layer. It is explanatory drawing which shows a mode that an image is sequentially updated by a scanning line. It is a graph which shows the fluctuation | variation of the display brightness at the time of updating a display image at the timing in the conventional image projector. It is explanatory drawing which shows a mode that a scanning line is sequentially updated in the image projector of this Embodiment. It is a graph which shows the fluctuation | variation of the display brightness at the time of updating a display image at the timing in the image projection apparatus of this Embodiment. It is the schematic which shows a part of image projection apparatus of another embodiment of this invention. It is explanatory drawing which shows the image display area formed by four display positions which a certain pixel can take by pixel shifting. It is explanatory drawing which shows another image display area.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image projector 2 Illumination optical system 8 Projection stop means 12 Image display element 13 Pixel shift means 14 Projection means

Claims (13)

An image display element that has a plurality of pixels and updates and displays an image in units of subframes obtained by dividing a display frame into a plurality according to a state change of each pixel;
An illumination optical system for illuminating an image displayed by the image display element;
Projection means for projecting an image illuminated by the illumination optical system onto a projection plane;
Pixel shifting means for shifting a projection position of an image projected by the projection means within an update period for updating an image displayed by the image display element within the projection plane ;
A projection stop means for stopping projection of the image on the projection plane during an update period in which an image displayed by the image display element is updated;
Equipped with,
The image display element updates an image in units of scanning lines scanned line-sequentially,
The pixel shifting means shifts the projection position of the image corresponding to the position of the scanning line being updated within the projection plane,
The projection stopping means stops projection of an image corresponding to the position of the scanning line being updated;
Providing an intermediate image plane between the image display element and the projection plane on which an image displayed by the image display element is formed;
The image shifting device, wherein the pixel shifting means shifts the position of an image formed on the intermediate image plane within the intermediate image plane . An image display element that has a plurality of pixels and updates and displays an image in units of subframes obtained by dividing a display frame into a plurality according to a state change of each pixel;
An illumination optical system for illuminating an image displayed by the image display element;
Projection means for projecting an image illuminated by the illumination optical system onto a projection plane;
Pixel shifting means for shifting a projection position of an image projected by the projection means within an update period for updating an image displayed by the image display element in the projection plane;
A projection stop means for stopping projection of the image on the projection plane during an update period in which an image displayed by the image display element is updated;
Comprising
The image display element updates an image in units of scanning lines scanned line-sequentially,
The pixel shifting means shifts the projection position of the image corresponding to the position of the scanning line being updated within the projection plane,
The projection stop means stops projection of an image corresponding to the position of the scanning line being updated;
Providing an intermediate image plane between the image display element and the projection plane on which an image displayed by the image display element is formed;
The image shifting device that shifts the position of the image formed on the intermediate image plane at a position defocused with respect to the intermediate image plane along the image projection direction . The projection means an image projection device according to claim 1 or 2 wherein comprises an afterimage display means for displaying an image projected immediately before as an afterimage in the update period. It said projection stopping means, the image projection device according to claim 1 or 2, wherein said image display device during the update period for updating an image, wherein the image display device displays a black display state. Said projection stopping means, according to claim 1 or 2 wherein said illumination optical system in the update period for updating an image, wherein the image display device displays are shielded by the illumination optical system side with respect to the projection plane an image which illuminates Image projection device. The image projection apparatus according to claim 3 , wherein the afterimage display means is a luminescent material provided on the projection surface. The image projecting device according to claim 6, wherein the light emitting performance of the light emitting material is set so that light can be emitted for a time equivalent to the update period after image projection stops. The image projection device according to claim 6, wherein the light emission performance of the light emitting material is set so that light emission can be performed for a time equivalent to the update period after image projection is stopped in a wavelength range of projection light of 500 to 560 nm. The image projection apparatus according to claim 3 , wherein the afterimage display means is a fluorescent material provided on the projection surface. 4. The image projection apparatus according to claim 3 , wherein the afterimage display means is a fluorescent material in which a plurality of unit afterimage display areas capable of emitting light of R, G, and B are arranged in correspondence with each pixel of the image display element. The display order in one display cycle for sequentially displaying one display frame divided into N subframes (N is a positive integer) is the Mth cycle (M is a positive integer), the (M + 1) th ) claims 1 comprises a display position control means for varying the period th image projection apparatus according to any one of 10. In one display cycle for sequentially displaying one display frame divided into N (N is a positive integer) subframes, the display position of the subframe displayed at the end of the Mth cycle and the (M + 1) th the image projection apparatus according to any one of claims 1 to 10 including the display position control means to vary the position of the subframe to be displayed in the first period th. An illumination optical system illuminates an image displayed by an image display element that has a plurality of pixels and updates and displays an image in units of subframes obtained by dividing the display frame into a plurality of frames according to a change in the state of each pixel. In the image display method in which the projection position of the image is shifted within the projection plane by the pixel shifting means when projecting onto the projection plane by the projection means,
The image display element updates an image in units of scanning lines scanned line-sequentially,
The projection position of the image corresponding to the position of the scanning line being updated by the pixel shifting means is shifted within the projection plane,
By stopping the projection of the image on the projection plane during the update period for updating the image displayed by the image display element, the projection of the image corresponding to the position of the scanning line being updated is stopped,
Providing an intermediate image plane between the image display element and the projection plane on which an image displayed by the image display element is formed;
An image display method in which the position of an image formed on the intermediate image plane is shifted within the intermediate image plane by the pixel shifting means .

Images