JP4374954B2 - Image display device - Google Patents

Description

  The present invention relates to an image display device that displays an image to be displayed on an image display surface by scanning a light beam by using an optical means, and particularly relates to a technique for cleaning the optical means.

An image display apparatus that displays an image to be displayed on an image display surface by scanning with a light beam by using optical means is already known (see, for example, Patent Document 1).
Japanese Patent No. 2874208

  When this type of image display apparatus is used, foreign substances such as dirt and dust may adhere to the optical means. When foreign matter adheres to the optical means, the amount of light transmitted in the optical system including the optical means is lost, and the brightness of the image displayed by the light is reduced, or an unexpected pattern is displayed on the image. Image quality may be degraded.

  In order to eliminate such inconveniences in image display, it is conceivable that the user who uses the image display device or a contractor handling the image display device manually cleans the optical means. However, the work requires special skills. Problems such as complicated work and long time can be easily considered.

  An object of the present invention is to clean an optical means without bothering a human hand in an image display apparatus that displays an image to be displayed on an image display surface by scanning a light beam by using an optical means. It is a thing.

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

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

According to one aspect of the present invention, there is provided an image display device that displays an image to be displayed on an image display surface by scanning a light beam, the wavefront modulation mechanism for modulating the wavefront of the light beam, and the wavefront by the wavefront modulation mechanism. Is a first optical unit on which a modulated light beam is incident, and is coated with a photocatalyst for cleaning the first optical unit by the incident light beam. Wavefront modulation mechanism control means for controlling the wavefront modulation mechanism so that the area of the incident light beam is larger than the area at the time of displaying the image, and the light beam emitted from the wavefront modulation mechanism is configured to display the image and the An image display device used for cleaning is provided.
The following aspects are obtained by the present invention. Each aspect is divided into sections, each section is given a number, and is described in a form that cites other section numbers as necessary. This is to facilitate understanding of some of the technical features that the present invention can employ and combinations thereof, and the technical features that can be employed by the present invention and combinations thereof are limited to the following embodiments. Should not be interpreted. That is, although not described in the following embodiments, it should be construed that it is not impeded to appropriately extract and employ the technical features described in the present specification as the technical features of the present invention.

  According to this apparatus, when the optical means to be cleaned is irradiated with a light beam, the optical means is cleaned by the action of the photocatalyst coated on the optical means.

  Therefore, according to this apparatus, it is not indispensable for a human to clean the optical means directly by hand, so that labor saving of the cleaning work can be easily achieved.

(2) The optical means constitutes a plurality of optical means including other optical means,
At least one of the plurality of optical means is a selection optical means selected as an object to be cleaned, and the selection optical means is coated with the photocatalyst,
The plurality of optical means includes a light source that outputs the luminous flux,
The image display device according to item (1), wherein a light beam output from the light source is used for displaying the image and for cleaning.

  According to this apparatus, it is not necessary to add a dedicated light source for cleaning in order to add a function of performing cleaning to the optical means. Therefore, it is possible to suppress an increase in apparatus cost accompanying the addition of the cleaning function. It becomes easy.

(3) The plurality of optical means includes a condensing unit that condenses the light flux,
The image display device according to (2), wherein the selection optical unit includes an optical unit on which a light beam collected by the light collecting unit is incident.

  The larger the foreign matter attached to the optical means, the larger the area of the portion of the light flux incident on the optical means where the disturbance of light due to the foreign matter occurs. On the other hand, even if the size of the foreign matter adhering to the optical means is the same, the smaller the area of the light beam incident on the optical means, the smaller the area occupied by the portion where the light disturbance due to the foreign matter occurs in the cross section of the light flux The proportion of increases. This means that the smaller the area of the incident light beam on the optical means to which the foreign matter is attached, the larger the proportion of the area occupied by the portion of the display image where the disturbance of the light is caused by the foreign matter.

  Therefore, when there are optical means having a small incident light beam area and optical means having a large incident light beam area, the cleaning of the former optical means is more necessary than the cleaning of the latter optical means. Moreover, the area of the display image that is improved by cleaning is wider than the area of the cleaning area of each optical means.

  Based on the above knowledge, in the apparatus according to this section, cleaning is performed on the optical means on which the luminous flux is condensed and incident. Therefore, according to this apparatus, it becomes easy to improve the cleaning effect.

(4) The plurality of optical means scan the light beam output from the light source in the main scanning direction at the main scanning position, and the light beam scanned in the main scanning direction intersects the main scanning direction at the sub scanning position. Including a scanning unit that scans in the scanning direction;
The image display apparatus according to (2) or (3), wherein the selection optical unit includes an optical unit on which a light beam scanned in the main scanning direction is incident between the main scanning position and the sub-scanning position.

  When the light beam output from the light source is scanned in the main scanning direction and then in the sub scanning direction, the optical means between the sub scanning position and the image display surface is turned on. If a foreign material adheres to the optical means between the main scanning position and the sub-scanning position, it will appear as a dotted pattern on the display image. The dot-like foreign matter appears as a dot-like black noise image on the sub-scanning position, but the dot-like black noise image is enlarged to a linear black noise image extending in the sub-scanning direction by sub-scanning. It is projected on the image display surface.

  Therefore, the cleaning of the optical means between the main scanning position and the sub-scanning position is more necessary than the cleaning of the optical means between the sub-scanning position and the image display surface, and among the display images, The area of the region that is improved by cleaning is larger than the area of the cleaning region of each optical means.

  Based on the knowledge described above, in the apparatus according to this section, the optical unit that receives the light beam scanned in the main scanning direction is cleaned between the main scanning position and the sub-scanning position. Therefore, according to this apparatus, it becomes easy to improve the cleaning effect.

(5) The image display device according to (4), wherein the cleaning is performed using the light source and the scanning unit during an image display period in which an image is displayed by the image display device.

  According to this apparatus, since the optical unit is cleaned in parallel with the image display, it is not indispensable to set the cleaning period independently from the image display period.

  Furthermore, this apparatus can perform cleaning in an image display period without waiting for a command from the user of the apparatus, and in this case, cleaning can be performed regardless of user error. It will be implemented reliably.

(6) The image display device according to item (5), wherein the photocatalyst is a photocatalyst for visible light.

  The light beam for image display is visible light, while the photocatalyst in the above item (5) needs to perform a cleaning action with the light beam for image display. Therefore, the photocatalyst is desirably sensitized so as to have high sensitivity at the wavelength of the light beam used for image display.

  Based on such knowledge, in the apparatus according to this section, the photocatalyst is configured as a visible light photocatalyst. Therefore, according to this apparatus, it is easy to satisfactorily perform both the function of displaying an image and the function of cleaning while having the same luminous flux.

(7) Further, in any one of the items (4) to (6), the image display device further includes a cleaning control unit that performs the cleaning using the light source and the scanning unit during a non-image display period in which no image is displayed. The image display device described.

  According to this apparatus, since the period for cleaning is set independently from the image display period, for example, cleaning is performed prior to image display, cleaning is performed over a longer time than the image display period, Cleaning can be performed more times than the frequency of image display by the apparatus.

  As a result, according to this apparatus, the degree of freedom in setting the cleaning execution time, the length of the execution period, or the number of executions is improved, and it becomes easy to respond to various needs of the user of the apparatus.

(8) The image display device according to item (7), wherein the cleaning control unit performs the cleaning over a time required to display an image for one frame on the image display surface.

According to this device, cleaning, the non-image display period, image on image display period is performed without leakage for the entire region to be a child that is displayed, incomplete portion of the cleaning after performing the completion of cleaning not occur You do n’t have to.

(9) The plurality of optical means includes a wavefront modulation mechanism that modulates the wavefront of the light beam,
The selection optical means includes optical means on which a light beam whose wavefront is modulated by the wavefront modulation mechanism is incident,
The image display device according to any one of (2) to (8), wherein a light beam emitted from the wavefront modulation mechanism is used for displaying the image and for cleaning.

  If the wavefront of the light beam incident on the optical means to be cleaned is changed, the area of the light beam incident on the optical means, that is, the beam diameter or spot diameter of the light beam also changes. Specifically, for example, if the radius of curvature of the wavefront of the incident light beam is increased, the beam diameter of the incident light beam is also increased.

  On the other hand, among the optical means to be cleaned, the cleaning area, which is a two-dimensional area cleaned by the incident light beam, is defined by the scanning of the incident light beam, so that the beam diameter of the incident light beam changes. As a result, the area of the cleaning region also changes.

  Therefore, according to the apparatus according to the present section, it is possible to change the area of the cleaning region in the optical means to be cleaned.

(10) The apparatus further includes a wavefront modulation mechanism control unit that controls the wavefront modulation mechanism so that, during the cleaning, the area of the light beam incident on the selection optical unit is larger than the area when the image is displayed. The image display device described in 1.

  Among the optical means to be cleaned, the intensity of the light beam irradiated for cleaning, that is, the intensity of the light beam at each position of the cleaning area is weaker in the peripheral portion of the cleaning area than in the interior thereof. The cleaning effect tends to be small.

  Therefore, when the cleaning area is set so as to coincide with the area of the light beam irradiated at the time of image display, that is, the image display area, the cleaning effect tends to be insufficient at the peripheral portion of the image display area. .

  On the other hand, in the apparatus according to this section, the wavefront incident on the optical unit is larger at the time of cleaning so that the area of the light beam incident on the optical unit to be cleaned is larger than the area at the time of image display. Modulated.

  Therefore, according to this apparatus, the cleaning area is set as an area wider than the image display area, and as a result, the entire image display area can be easily cleaned with a light beam having a strength suitable for good cleaning. Become.

(11) The image display device according to any one of (1) to (10), wherein the image display surface is a retinal scanning display device that is an image formation surface of an eye retina.

(12) The image display device according to any one of (1) to (10), wherein the image display surface is a projection display device having a screen.

(13) The optical means constitutes a plurality of optical means including other optical means,
At least one of the plurality of optical means is a selection optical means selected as an object to be cleaned, and the selection optical means is coated with the photocatalyst,
The plurality of optical means includes:
A light source that outputs a luminous flux;
A scanning unit that scans the light beam output by the light source in the main scanning direction;
A latent image forming member that forms a latent image while being sent in the sub-scanning direction intersecting the main scanning direction by the scanned light flux, and reveals the latent image formed on the latent image forming member The image display device according to any one of (1) to (10), wherein the image display device is a laser printer that prints an image on a surface of a print medium as the image display surface.

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

  FIG. 1 systematically represents a retinal scanning display device according to the first embodiment of the present invention. This retinal scanning display device (hereinafter abbreviated as “RSD”) modulates the wavefront and intensity of a laser beam as appropriate, passes through the pupil 12 of the observer's eye 10, and the image plane of the retina 14. The apparatus projects the image directly onto the retina 14 by two-dimensionally scanning the laser beam on the imaging plane.

  That is, in the present embodiment, RSD is an example of the “image display device” according to the item (1), the laser beam is an example of the “light beam” in the item, and the imaging plane of the retina 14 is the same item. This is an example of the “image display surface”.

  The RSD includes a light source unit 20 and includes a wavefront modulation optical system 22 and a scanning device 24 arranged in that order between the light source unit 20 and the eye 10 of the observer.

  The light source unit 20 includes an R laser 30 that emits red laser light and a green laser for focusing three laser lights having three primary colors (RGB) into one laser light to generate laser light of an arbitrary color. A G laser 32 that emits light and a B laser 34 that emits blue laser light are provided. Each of the lasers 30, 32, and 34 can be configured as a semiconductor laser, for example.

  The laser beams emitted from the lasers 30, 32, 34 are collimated by the collimating optical systems 40, 42, 44 in order to synthesize them, and then each dichroic mirror 50, 52, having wavelength dependency. 54, so that each laser beam is selectively reflected and transmitted with respect to the wavelength.

  Specifically, red laser light emitted from the R laser 30 is collimated by the collimating optical system 40 and then incident on the dichroic mirror 50. The green laser light emitted from the G laser 32 is incident on the dichroic mirror 52 through the collimating optical system 42. The blue laser light emitted from the B laser 34 is incident on the dichroic mirror 54 via the collimating optical system 44.

  The laser beams of the three primary colors incident on the three dichroic mirrors 50, 52, 54 are finally incident on one dichroic mirror 54 representing the three dichroic mirrors 50, 52, 54, and then converged. The light is collected by the coupling optical system 80.

  Although the optical part of the light source unit 20 has been described above, the electrical part will be described below.

  The light source unit 20 includes a signal processing circuit 60 mainly composed of a computer. The signal processing circuit 60 performs signal processing for driving the lasers 30, 32, and 34 based on video signals supplied from the outside, signal processing for modulating the wavefront of the laser beam, which will be described later, It is designed to perform signal processing for scanning with a laser beam.

  In order to drive each laser 30, 32, 34, the signal processing circuit 60 determines the color necessary for the laser light for each pixel on the image to be projected on the retina 14 based on the video signal supplied from the outside. A drive signal necessary for realizing the intensity is supplied to each laser 30, 32, 34 via each laser driver 70, 72, 74.

  The light source unit 20 described above causes the coupling optical system 80 to emit a laser beam. The laser beam emitted therefrom passes through an optical fiber 82 serving as an optical transmission medium and a collimating optical system 84 that collimates the laser beam emitted from the rear end of the optical fiber 82 in this order, and thereby a wavefront modulation optical system. 22 is incident.

  The wavefront modulation optical system 22 is an optical system that modulates the wavefront (wavefront curvature) of the laser beam emitted from the light source unit 20 according to each pixel on the image to be projected onto the retina 14.

  Specifically, the wavefront modulation optical system 22 is mainly composed of a combination of a condensing lens and a movable mirror that can be displaced on its optical axis. More specifically, the wavefront modulation optical system 22 includes a half mirror 90 on which the laser beam emitted from the collimating optical system 84 is incident, and a condenser lens 92 that condenses the laser beam reflected and emitted therefrom, Furthermore, a movable mirror 94 that reflects the laser beam emitted from the condenser lens 92 with a plane mirror, and an actuator 96 that changes the position of the movable mirror 94 on the optical axis are provided. An example of the actuator 96 is a type using a piezoelectric element. In the wavefront modulation optical system 22, the laser beam reflected by the movable mirror 94 passes through the condenser lens 92 and the half mirror 90 and enters the scanning device 24 described above.

  In addition, it is possible to adopt another method for modulating the wavefront of the laser beam in the wavefront modulation optical system 22. For example, it is possible to employ a system in which a variable focus mirror whose focal length is changed by an actuator is used, and the wavefront of the laser beam is modulated by changing the curvature of the reflecting surface that reflects the incident laser beam.

  Meanwhile, the signal processing circuit 60 described above generates a wavefront modulation signal that needs to be supplied to the actuator 96 in order to modulate the wavefront of the laser beam, based on the video signal supplied from the outside, and supplies it to the actuator 96. Designed to supply. This is the above-described signal processing for modulating the wavefront of the laser beam. The actuator 96 modulates the wavefront of the laser beam emitted from the wavefront modulation optical system 22 based on the wavefront modulation signal supplied thereto.

  The laser beam emitted from the wavefront modulation optical system 22 configured as described above is incident on the scanning device 24 described above. The scanning device 24 includes a horizontal scanning system 100 and a vertical scanning system 102.

  The horizontal scanning system 100 is an optical system that performs horizontal scanning (this is an example of main scanning) in which a laser beam is raster-scanned horizontally along a plurality of horizontal scanning lines for each frame of an image to be displayed. is there. On the other hand, the vertical scanning system 102 performs vertical scanning in which a laser beam is scanned vertically from the first scanning line toward the last scanning line for each frame of an image to be displayed (this is an example of sub scanning). ).

  Specifically, in the present embodiment, the horizontal scanning system 100 includes a polygon mirror 104 as a unidirectional rotating mirror that performs mechanical deflection. The polygon mirror 104 is rotated at a high speed by a motor (not shown) around a rotation axis intersecting the optical axis of the laser beam incident thereon. The rotation speed of the polygon mirror 104 is controlled based on a horizontal synchronization signal supplied from the signal processing circuit 60.

  The polygon mirror 104 includes a plurality of reflecting surfaces 106 arranged around the rotation axis, and is deflected once each time the incident laser beam passes through one reflecting surface 106. The deflected laser beam is transmitted to the vertical scanning system 102 by the relay optical system 110. In the present embodiment, the relay optical system 110 includes a plurality of lenses 112 and 114 arranged side by side on the optical path.

  This RSD has a beam detector 120 in place. The beam detector 120 is provided to detect the position of the laser beam in the main scanning direction by detecting the laser beam deflected by the polygon mirror 104 (that is, the laser beam scanned in the main scanning direction). Yes. An example of the beam detector 120 is a photodiode.

  Although the horizontal scanning system 100 has been described above, the vertical scanning system 102 includes a galvanometer mirror 130 as a swinging mirror that performs mechanical deflection. A laser beam emitted from the horizontal scanning system 100 is collected by the relay optical system 110 and enters the galvanometer mirror 130. The galvanometer mirror 130 is swung around a rotation axis that intersects the optical axis of the laser beam incident thereon. The activation timing and rotation speed of the galvanometer mirror 130 are controlled based on the vertical synchronization signal supplied from the signal processing circuit 60.

  In cooperation with the horizontal scanning system 100 and the vertical scanning system 102 described above, the laser beam is scanned two-dimensionally, and an image represented by the scanned laser beam passes through the relay optical system 140 to the eyes of the observer. 10 is irradiated. In the present embodiment, the relay optical system 140 includes a plurality of lenses 142 and 144 arranged side by side on the optical path.

  As shown in FIG. 1, in this embodiment, a visible light reaction type photocatalyst is coated on the reflection surfaces 150, 106, 152 of the mirrors 94, 104, 130 used in the wavefront modulation optical system 22 and the scanning device 24. Has been. The photocatalyst is a substance that is activated by irradiating light to itself, and removes or decomposes the dirt attached to the photocatalyst. Specifically, the mirrors coated with the photocatalyst are the movable mirror 94 of the wavefront modulation optical system 22, the polygon mirror 104 of the horizontal scanning system 100, and the galvanometer mirror 130 of the vertical scanning system 102.

  Here, the self-cleaning action by the photocatalyst will be described. In the RSD, inorganic molecules such as dust or organic molecules such as oil stains are floating, and if they adhere to the optical means, the amount of light emitted from the optical component may be reduced. In particular, since the light is focused on a minute region of the reflecting surfaces 150, 106, and 152 on the mirrors 94, 104, and 130 that scan the laser beam, the amount of light is greatly reduced due to dirt adhering to the region.

  In contrast, when the reflection surfaces 150, 106, and 152 of the mirrors 94, 104, and 130 are coated with a photocatalyst to form a coating surface, dirt, oil, and other contaminants in the RSD adhere to the coating surface. When the coating surface is irradiated with light, the photocatalyst is activated by the light, and the attached dirt is detached or decomposed. That is, the mirrors 94, 104, and 130 are self-cleaned by the cooperative action of light and photocatalyst.

  Here, taking the case where this photocatalyst is titanium oxide, which is the most common material, as an example, the mechanism of the self-cleaning action of the photocatalyst is to remove the dirt of inorganic substances such as dust and to decompose the dirt of organic substances such as oil. This will be explained separately.

  First, the removal of inorganic dirt will be described. When light is irradiated onto the surface coated with the photocatalyst, the photocatalyst is thereby activated and reacts with moisture in the air to generate hydroxyl radicals. Since the hydroxyl radical has a strong hydrophilicity, it has a function of forming a thin water film on the coating surface to make it difficult to generate static electricity.

  On the other hand, inorganic dirt is often adsorbed to the target surface by static electricity. Therefore, if the target surface is coated with a photocatalyst and the coating surface is irradiated with light to suppress the generation of static electricity, the contamination of inorganic matter is less likely to adhere to the coating surface. Furthermore, dirt that has already adhered to the coating surface before the light irradiation is likely to be detached because a thin water film is formed between the coating surface and the dirt when the light is irradiated.

  Next, decomposition of organic matter such as oil will be described. Organic dirt has the property of easily adhering to the target surface even when static electricity is not generated, and further has the property of easily attaching inorganic dirt such as dust on the dirt. As described above, radicals of hydroxyl groups are generated on the surface coated with the photocatalyst when irradiated with light, but at the same time, active oxygen is also generated. This active oxygen has an action of decomposing organic substances.

  The active oxygen generated on the coating surface by light decomposes the adhering organic matter into gas (for example, oxygen dioxide) and moisture. Along with this, the inorganic dirt adhered on the organic matter is also released.

  Thereby, it is possible to remove inorganic dirt such as dust and organic dirt such as oil adhering to the surface coated with the photocatalyst only by irradiating the coating surface with light.

  By the way, a photocatalyst generally used is a photocatalyst that reacts with ultraviolet light (for example, anatase type titanium oxide) and reacts with ultraviolet light having a wavelength of 350 nm or less. The wavelength of the laser light normally used for displaying an image by the RSD according to the present embodiment is about 435 nm to 480 nm even for the blue laser light having the shortest wavelength, and is longer than 350 nm. If a reaction type photocatalyst is used, the reaction is slow.

  On the other hand, in recent years, a visible light responsive photocatalyst (for example, brookite type titanium oxide) has been developed. This reacts not only with ultraviolet light but also with visible light having a wavelength longer than 350 nm.

  In this embodiment, by using the visible light responsive photocatalyst, the photocatalyst reacts with laser light in the entire wavelength range that is normally used for the RSD to display an image. Accordingly, the mirrors 94, 104, and 130 are cleaned by all the laser beams used.

  Therefore, in this embodiment, if a laser beam is irradiated on the reflecting surfaces 150, 106, and 152 of the mirrors 94, 104, and 130 coated with the photocatalyst, dirt and the like are less likely to adhere to the mirrors, and The dirt that has been removed is easily removed or decomposed. That is, the reflecting surfaces 150, 106, and 152 of the mirrors 94, 104, and 130 are cleaned by the cooperative action of the laser beam and the photocatalyst, thereby preventing a decrease in the amount of light due to dirt.

Furthermore, according to the present embodiment, when the image is displayed by RSD, the mirror coated with the photocatalyst is cleaned by the same laser beam in parallel with the image display, so that a special process for cleaning is unnecessary. Cleaning is performed automatically during the normal process.

  As is clear from the above description, in the present embodiment, the movable mirror 94, the polygon mirror 104, and the galvanometer mirror 130 constitute an example of the “optical means” in the above item (1), and the visible light response type This photocatalyst constitutes an example of the “photocatalyst” in the same term and an example of the “photocatalyst for visible light” in the item (6).

  Further, in the present embodiment, the movable mirror 94, the polygon mirror 104, and the galvanometer mirror 130 each constitute an example of the “selection optical means” in the item (2), and the light source unit 20 corresponds to the “light source” in the same term. It constitutes an example.

  Further, in the present embodiment, the collimating optical system 84, the condensing lens 92, and the lenses 112 and 114 constitute an example of the “condensing unit” in the above (3), and the movable mirror 94 and the polygon mirror 104 are included. And the galvanometer mirror 130 constitute an example of the “selection optical means” in the item (9), and the wavefront modulation optical system 22 constitutes an example of the “wavefront modulation mechanism” in the item (9). is there.

  Next, a second embodiment of the present invention will be described. However, since this embodiment has many elements in common with the first embodiment, and different elements are only related to the optical means coated with the photocatalyst, only the different elements will be described in detail, and the common elements are the same. The detailed description is omitted by quoting using the symbol or name.

  In the first embodiment, the photocatalyst is coated on each reflecting surface of the movable mirror 94, the polygon mirror 104, and the galvanometer mirror 130 that collects light.

  On the other hand, in the present embodiment, as shown in FIG. 2, the visible light responsive photocatalyst is converted into the polygon mirror 104 of the horizontal scanning system 100 and the galvanometer mirror 130 of the vertical scanning system 102 as in the first embodiment. The incident surface 170 and the exit surface 172 of the lens 112 of the relay optical system 110 and the entrance surface 174 and the exit surface 176 of the lens 114 are coated.

  The lenses 112, 114, 142, and 144 of the relay optical system 110 and 114 are used for condensing and transmitting the laser beam. When dirt such as dust adheres to these lenses 112, 114, 142, and 144, the retina 14, a clear image cannot be obtained. In particular, if dirt is attached to a plurality of lenses 112 and 114 installed between the polygon mirror 104 that performs scanning in the main scanning direction and the galvanometer mirror 130 that performs scanning in the sub-scanning direction, One point of dirt appears as a black spot on the reflecting surface 152 of the galvanometer mirror 130. The black spot appears on the reflective surface 152 of the galvano mirror 130 at substantially the same position from the first horizontal scanning line to the last horizontal scanning line, and thus a two-dimensional image is displayed by repeating horizontal scanning and vertical scanning. Sometimes, the black spot appears as a black line on the retina 14.

  Accordingly, in the present embodiment, the lenses 112 and 114 of the relay optical system 110 are selected as optical means for coating the photocatalyst, and dirt such as dust adheres by irradiating the lenses 112 and 114 with a laser beam. It becomes difficult to remove or decompose the attached dirt. That is, the lenses 112 and 114 are cleaned by the cooperative action of the laser beam and the photocatalyst, and black lines due to dirt on the retina 14 are prevented.

  As is apparent from the above description, in this embodiment, the lenses 112 and 114 of the relay optical system 110 constitute an example of the “selection optical means” in the above (2) or (4), respectively, and the scanning device 24 constitutes an example of the “scanning section” in the above item (4).

  Next, a third embodiment of the present invention will be described. However, since this embodiment has many elements in common with the first embodiment or the second embodiment, and different elements are only related to the optical means on which the photocatalyst is coated, only the different elements will be described in detail. By quoting common elements using the same reference numerals or names, detailed description will be omitted.

  In the first embodiment, the photocatalyst is coated on each reflecting surface 150, 106, 152 of the movable mirror 94, the polygon mirror 104, and the galvanometer mirror 130. In the second embodiment, the polygon mirror 104 and the galvanometer mirror 130 are coated. Is coated on the relay optical system 110.

  On the other hand, in this embodiment, as shown in FIG. 3, the photocatalyst further includes the entrance surface 190 and the exit surface 192 of the lens 142 of the relay optical system 140 on the downstream side of the galvanometer mirror 130, and the lens 144. The entrance surface 194 and the exit surface 196 are also coated.

  In the present embodiment, the photocatalyst is coated on both the entrance surfaces 190 and 194 and the exit surfaces 192 and 196 of the lenses 142 and 144 of the relay optical system 140 in the same manner as the lenses 112 and 114 of the relay optical system 110. Yes.

  The lenses 142 and 144 of the relay optical system 140 are the optical means closest to the observer's eye 10 among the optical means of the RSD, and are easily contacted with the skin or hair of the observer. Easy to adhere. When such dirt adheres to the lenses 142 and 144 in the form of dots, one spot on the lenses 142 and 144 appears as a black spot on the retina 14.

  Therefore, in this embodiment, the photocatalyst is coated on the movable mirror 94 and all the optical means 94, 104, 112, 114, 130, 142, 144 including the scanning device 24 and disposed downstream thereof, As a result, the reduction of the brightness of the image on the retina 14 and the generation of black lines and black spots are prevented.

  As is apparent from the above description, in the present embodiment, the movable mirror 94, the polygon mirror 104, the lenses 112 and 114 of the relay optical system 110, the galvano mirror 130, and the lenses 142 of the relay optical system 140. , 144 constitute an example of the “selecting optical means” in the item (2), and the scanning device 24 constitutes an example of the “scanning unit” in the item (4).

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

  In the first to third embodiments, cleaning is performed in parallel with image display during the image display period. In contrast, in the present embodiment, cleaning is also performed during a period other than the image display period.

  Specifically, during the preparation period from when the RSD is turned on until the start of the image display period, and after the end of the image display period, the mode is shifted to a cleaning mode dedicated to cleaning, and cleaning is performed in the cleaning mode. Is called. However, cleaning is always performed in the preparation period without waiting for an instruction from the user, whereas after the end of the image display period, the cleaning is selectively performed after the instruction from the user.

  Furthermore, in the present embodiment, in the cleaning mode, the diameter of the laser beam incident on the optical means to be cleaned (hereinafter simply referred to as “beam diameter”) is expanded from the image display period. Yes. That is, cleaning is performed by irradiating the optical means with a laser beam in an area wider than the image display period.

  The cleaning mode in this embodiment is an area where the beam diameter of the laser beam irradiated to each optical means coated with the photocatalyst is expanded by using the RSD wavefront modulation optical system 22 and cleaned from the image display period. It is set as a mode to enlarge the area. Specifically, in the cleaning mode, a method of enlarging the beam diameter by bringing the position of the movable mirror 94 of the wavefront modulation optical system 22 closer to the condenser lens 92 from the image display period is adopted.

  Here, the control of the movable mirror 94 in the cleaning mode and the control of the wavefront of the laser beam in the image display period will be described with reference to FIGS. 4A and 4B and FIG.

  As shown in FIGS. 4A and 4B, during the image display period, the movable mirror 94 and the position where the condenser lens 92 is closer to the condenser lens 92 by a distance d than the focal position of the condenser lens 92. Moved between. The focal position of the condensing lens 92 is the initial position of the movable mirror 94, and the position closer to the condensing lens 92 by a distance d from that position is the maximum moving position of the movable mirror 94. Therefore, the distance d means the maximum distance that the movable mirror 94 moves during the image display period.

  4A, the focal length f of the condensing lens 92 and the distance from the principal point 210 of the condensing lens 92 to the movable mirror 94 (hereinafter abbreviated as “mirror-lens distance”). The laser beams in the case where they coincide with each other are represented by optical path diagrams. The laser beam emitted from the collimating optical system 84 in FIG. 1 is incident and reflected as a parallel beam on the half mirror 90, enters and passes through the condenser lens 92, is reflected by the movable mirror 94, and is again reflected on the condenser lens 92. Pass through. This time, since the focal length f of the condenser lens 92 and the distance between the mirror and the lens coincide with each other, the laser beam emitted from the condenser lens 92 is emitted from the half mirror 90 as parallel light and enters the polygon mirror 104. To do.

  On the other hand, in FIG. 4B, a laser beam when the distance between the mirror and the lens is shorter than the focal length f of the condenser lens 92 by the distance d is shown in an optical path diagram. Similarly to (a) of the figure, the laser beam incident from the collimating optical system 84 and emitted from the half mirror 90 enters the condensing lens 92 and passes, and then is reflected by the movable mirror 94 and condensed again. It passes through the lens 92. Since the mirror-lens distance is shorter than the focal length f of the condensing lens 92 this time, the laser beam emitted from the condensing lens 92 becomes diffused light and exits from the half mirror 90 and enters the polygon mirror 104.

  Therefore, in the image display period, the irradiation area of the laser beam incident on the polygon mirror 104 is the minimum when the focal length f of the condensing lens 92 and the mirror-lens distance coincide with each other. This is the maximum when the distance is shorter than the focal length f of the condenser lens 92 by the distance d.

  In contrast, in the cleaning mode, as shown in FIG. 5, the movable mirror 94 is moved to a position closer to the condenser lens 92 by a distance c than the position where the distance between the mirror and the lens is the maximum distance d. . At this time, since the distance between the mirror and the lens is short by the distance c in the case of FIG. 4B, the outgoing light from the movable mirror 94 is further diffused and passes through the half mirror 90 and enters the polygon mirror 104. .

  Therefore, in the cleaning mode, the irradiation area of the laser beam incident on the polygon mirror 104 is wider than the maximum area during the image display period.

  As a result, in the present embodiment, by using the wavefront modulation optical system 22, the irradiation area of the laser beam irradiated to the optical means coated with the photocatalyst is expanded, so that the optical means is cleaned. The area becomes wider than the image display period.

  Therefore, according to the present embodiment, the cleaning is sufficiently performed on the outer peripheral portion of the laser beam irradiation region of the optical means, which is insufficient only for the cleaning during the image display period.

  The optical part of the RSD according to the present embodiment has been mainly described above. Next, the electrical part will be described.

  FIG. 6 conceptually shows a hardware configuration of the signal processing circuit 60 for controlling the RSD in a block diagram. The signal processing circuit 60 is mainly configured by a computer 226 having a CPU 220, a ROM 222, and a RAM 224. Various programs including a cleaning control program described later are stored in the ROM 222 in advance, and predetermined programs are executed by executing these programs by the CPU 220 using the RAM 224.

  As shown in FIG. 6, a main switch 230, a start switch 232, and a cleaning switch 234 are connected to the signal processing circuit 60.

  The main switch 230 is a switch operated by a user to turn on the power of the RSD and the power of the computer 226. The main switch 230 is designed to be kept ON after being operated from OFF to ON unless it is operated again from ON to OFF.

  On the other hand, the start switch 232 is a switch that is operated from OFF to ON by the user after the main switch 230 is turned ON by the user and preparation for image display by RSD is completed. The start switch 232 is also designed to be kept on unless it is operated from on to off by the user.

  The cleaning switch 234 is a switch that is operated from OFF to ON when the user desires cleaning after the user operates the start switch 232 from ON to OFF. The cleaning switch 234 is designed to be automatically restored from ON to OFF when one cleaning is completed by a cleaning control program described later.

  FIG. 7 conceptually shows the contents of the cleaning control program in a flowchart.

  This cleaning control program is repeatedly executed by the computer 226 after the user operates the main switch 230 from OFF to ON. At the time of each execution, it is first determined in step S1 (hereinafter simply represented by “S1”, the same applies to other steps) whether or not the RSD is in the preparation period.

  This time, immediately after the RSD is turned on and the RSD is in the preparation period, the determination in S1 is YES. In the present embodiment, when the preparation period starts, the polygon mirror 104 that performs main scanning starts rotating, and the galvano mirror 130 that performs sub-scanning is further swung a set number of times.

  If the determination in S1 is YES because the RSD is in the preparation period, it is determined in S2 whether or not the flag is ON. This flag indicates that the cleaning has not been completed during the RSD preparation period in the OFF state, while the cleaning has been completed in the ON state. This flag is initialized to the OFF state as the computer 226 is turned on.

  Since this time is immediately after the computer 226 is turned on, the flag is OFF. Therefore, the determination in S2 is NO, and then the process proceeds to S3.

  In S3, the cleaning mode is started. Subsequently, in S4, the beam diameter is expanded. Specifically, the movable mirror 94 is moved by a distance (fdc) from the initial position in a direction toward the condenser lens 92. Thereafter, in S5, a laser beam is emitted by at least one of the R laser 30, the G laser 32, and the B laser 34, thereby starting cleaning.

  Thereafter, in S6, it is determined whether or not the cleaning should be terminated. In the present embodiment, during the preparation period, when scanning is performed for at least one set number of screens by the polygon mirror 104 and the galvanometer mirror 130 in the laser beam emission state, one cleaning is finished. Designed. The determination as to whether or not scanning for the set number of screens has been performed is, for example, a determination as to whether or not the elapsed time from the start of the preparation period has reached the reference time, or the main scan from the start of the preparation period. It is possible to make a determination as to whether the number of scans or sub-scans has reached the reference number.

  If it is assumed that the current cleaning has been completed because scanning has been performed for the set number of screens in the laser beam emission state, the determination in S6 is YES, and then in S7, the emission of the laser beam is terminated, and in S8. The position of the movable mirror 94 is restored to the initial position so that the beam diameter is returned to the initial value. Thereafter, in S9, the flag is turned on, which indicates that the current cleaning is completed.

  This completes one execution of the cleaning control program.

  After that, if this cleaning control program is executed again during the same preparation period, the determination of S1 is YES as in the previous case, but since the flag is turned on this time, the determination of S2 is YES, and the current execution of this cleaning control program ends immediately.

  If the preparation period ends after the execution of this cleaning control program is repeated several times, the determination in S1 is NO and the process proceeds to S10. In S10, it is determined whether an image is displayed in response to the start switch 232 being turned ON by the user. That is, it is determined whether the image display period is currently in progress.

  If it is assumed that it is not during the image display period this time, the determination in S10 is NO, and it is determined in S11 whether or not the cleaning switch 234 has been turned ON by the user. If it is assumed that the operation is not turned ON this time, this determination is also NO, and the current execution of this cleaning control program is immediately terminated.

  On the other hand, if it is assumed that this time is during the image display period, the determination in S10 is YES, and the current execution of this cleaning control program is immediately terminated. During the image display period, the cleaning is automatically performed in parallel with the image display, that is, without special processing.

  On the other hand, if it is assumed that the current image display period ends because the start switch 232 is turned OFF by the user, the determination in S10 is NO. Thereafter, assuming that the user has operated the cleaning switch 234 to be ON, the determination in S11 is YES, and the process proceeds to S3. Thereby, the cleaning mode is started according to the user's intention.

  Specifically, similarly to the cleaning during the preparation period, the beam diameter is expanded in S4, and light emission is performed in S5. Thereafter, in S6, the cleaning is waited for to end, and if completed, the light emission is ended in S7, and the beam diameter is returned to the initial value in S8. Further, in S9, the flag is turned ON, but this flag functions only during the preparation period and does not function during other periods.

  Here, an example of execution of this cleaning control program will be specifically described.

  FIG. 8 shows an example of execution of this cleaning control program in a time chart. In this time chart, a time axis t is taken on the horizontal axis, and several times t1 to t7 are set in that order on the time axis t.

  First, at time t1, when the main switch 230 is turned on by the user, the preparation period starts and the scanning device 24 is activated. Along with this, the mode is shifted to the cleaning mode and the cleaning is performed without any instruction from the user. The cleaning mode and the cleaning are finished at time t2.

  When the preparation period ends at time t3, the start switch 232 is turned ON by the user at time t4. Along with this, image display is started. In parallel with this image display, cleaning is also performed.

  Thereafter, when the user operates the start switch 232 to turn off at time t5, the image display ends, and accordingly, the cleaning in parallel with the image display ends. Subsequently, when the user operates the cleaning switch 234 to be turned on at time t6, the cleaning mode is again started and cleaning is started, and the cleaning mode and cleaning are ended at time t7.

  In this embodiment, since cleaning is performed in parallel with image display, the cleaning of the corresponding optical means is maintained better than when such cleaning is never performed, but the number of times of image display That is, when the frequency of use of RSD is low, the cleaning frequency is also reduced accordingly.

  On the other hand, in the present embodiment, cleaning is automatically performed not only in the image display period but also in the preparation period that precedes it, so that the cleaning of the corresponding optical means is excellent for the frequency of use of the RSD. Will be maintained.

  Further, in the present embodiment, since the user can perform cleaning by operating the cleaning switch 234, the cleaning is performed at an appropriate time according to the circumstances of each RSD and the user's request. Can be done. Therefore, according to this embodiment, it is easy to improve the usability of RSD with respect to cleaning.

  As is apparent from the above description, in this embodiment, the portion of the computer 226 that executes the cleaning control program of FIG. The portion of the computer 226 that executes S4 and S8 in FIG. 7 constitutes an example of the “wavefront modulation mechanism control means” in section (10).

  Next, a fifth embodiment of the present invention will be described.

  Each of the first to fourth embodiments is an embodiment when the present invention is applied to a retinal scanning display device, but this embodiment is an embodiment when the present invention is applied to a laser printer. It is a form.

  FIG. 9 is a perspective view of the optical system 252 of the laser printer 250 according to the present embodiment. In the laser printer 250, the laser beam emitted from the semiconductor laser 254 is scanned one-dimensionally in the main scanning direction by the polygon mirror 256, so that a latent image is formed on the photosensitive drum 258. An image corresponding to the latent image is formed and transferred to a print medium (not shown).

  Laser light emitted from the semiconductor laser 254 is collimated by the collimator lens 260 and then incident on the polygon mirror 256. The polygon mirror 256 includes a plurality of reflection surfaces 262 arranged around the rotation axis thereof, and is deflected once each time the reflection surface passes through the incident laser beam. The deflected laser beam is incident on the f-θ lens 264 and its traveling direction is corrected, and a latent image is formed on the photosensitive drum 258 by the laser beam whose traveling direction is corrected in this way.

  The photosensitive drum 258 is rotated in one direction, and the laser beam is scanned two-dimensionally on the photosensitive drum 258 in cooperation with the rotation of the photosensitive drum 258 and the rotation of the polygon mirror 256. By the scanning, a latent image is formed on the photosensitive drum 258, and the formed latent image is transferred to a printing medium by a transfer mechanism (not shown).

  As shown in FIG. 9, in this embodiment, a visible light responsive photocatalyst is coated on the surface of the optical means through which the laser beam passes or reflects. Specifically, the optical means coated with the photocatalyst includes the entrance surface 270 and the exit surface 272 of the collimate lens 260, the reflection surface 262 of the polygon mirror 256, and the entrance surface 274 and the exit surface of the f-θ lens 264. 276.

  Therefore, in the present embodiment, the optical means 260, 256, 264 coated with the photocatalyst is cleaned by the laser beam irradiation without bothering human hands.

  Furthermore, according to the present embodiment, when the image is displayed by the laser printer 250, the optical means 260, 256, 264 coated with the photocatalyst is cleaned in parallel with the image display. Cleaning is performed automatically during normal operation without any steps.

  As is clear from the above description, in this embodiment, the semiconductor laser 254 constitutes an example of the “light source” in the item (13), the laser beam constitutes an example of the “light beam” in the term, and the polygon The mirror 256 constitutes an example of the “scanning unit” in the same term, the photosensitive drum 258 constitutes an example of the “latent image forming member” in the same term, the collimator lens 260, the polygon mirror 256, the f-θ lens 264 However, each constitutes an example of “selective optical means” in the same section.

  As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are merely examples, and those skilled in the art including the aspects described in the above-mentioned section of [Means for Solving the Problems] will be described. It is possible to implement the present invention in other forms in which various modifications and improvements are made based on the knowledge.

1 is a system diagram showing a retinal scanning display device according to a first embodiment of the present invention. It is a systematic diagram showing a retinal scanning display device according to a second embodiment of the present invention. It is a systematic diagram showing a retinal scanning display device according to a third embodiment of the present invention. It is an optical path figure for demonstrating the wavefront modulation | alteration of the laser beam during the image display period in the retinal scanning display apparatus according to 4th Embodiment of this invention. FIG. 5 is an optical path diagram for explaining wavefront modulation during the cleaning mode in the retinal scanning display device of FIG. 4. FIG. 5 is a block diagram showing a hardware configuration of a signal processing circuit 60 in the retinal scanning display device of FIG. 4. 7 is a flowchart conceptually showing the contents of a cleaning control program executed by a computer 226 in FIG. 6. It is a time chart for demonstrating one execution example of the cleaning control program of FIG. It is a perspective view which shows the optical system 252 in the laser printer 250 according to 5th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 14 Retina 20 Light source unit 22 Wavefront modulation optical system 24 Scanning device 84 Collimating optical system 92 Condensing lens 94 Movable mirror 104,256 Polygon mirror 110,140 Relay optical system 112,114,142,144 Lens 130 Galvanomirror 254 Semiconductor laser 258 Photosensitive drum 260 Collimating lens 264 f-θ lens

Claims (8)

An image display apparatus for displaying on the image display plane by the scanning of the light beam an image to be displayed,
A wavefront modulation mechanism for modulating the wavefront of the luminous flux;
A first optical means on which a light flux whose wavefront is modulated by the wavefront modulation mechanism is incident, and a photocatalyst for cleaning the first optical means is coated with the incident light flux;
Wavefront modulation mechanism control means for controlling the wavefront modulation mechanism so that the area of the light beam incident on the first optical means is larger than the area at the time of displaying the image during the cleaning;
An image display device in which a light beam emitted from the wavefront modulation mechanism is used for displaying the image and for cleaning . further,
Including a light source that outputs the luminous flux;
The image display device according to claim 1, wherein a light beam output from the light source is used for displaying the image and for cleaning. further,
And the condensing unit for focusing the optical flux,
A second optical means for the light beam condensed by the condensing unit is incident to claim 2 comprising as photocatalyst for cleaning the second optical means by means of the optical beam to the incident have been coated The image display device described. further,
A scanning unit for scanning in a sub-scanning direction is scanned in the main scanning direction, which intersects the main scanning direction a light beam scanned in the main scanning direction in the sub-scanning position in the main scanning position of light flux outputted from the light source,
A third optical means in which a light beam scanned in the main scanning direction is incident between the main scanning position and the sub-scanning position, and a photocatalyst for cleaning the third optical means by the incident light beam is coated. the image display apparatus according to claim 2 or 3 and a those.   The image display apparatus according to claim 4, wherein the cleaning is performed using the light source and the scanning unit during an image display period in which an image is displayed by the image display apparatus.   The image display device according to claim 5, wherein the photocatalyst is a photocatalyst for visible light.   The image display apparatus according to claim 4, further comprising a cleaning control unit that performs the cleaning using the light source and the scanning unit during a non-image display period in which no image is displayed by the image display apparatus. The cleaning control unit displays the light source and the scanning unit during the non-image display period, and displays an image for one frame on the image display surface during an image display period during which an image is displayed by the image display device. The image display apparatus according to claim 7, wherein the cleaning is performed by operating for a time equal to or longer than a required length of time.

Images