Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
  • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
  • G02B26/10—Scanning systems
  • G02B26/12—Scanning systems using multifaceted mirrors
  • G02B26/125—Details of the optical system between the polygonal mirror and the image plane
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
  • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
  • G02B26/10—Scanning systems
  • G02B26/105—Scanning systems with one or more pivoting mirrors or galvano-mirrors
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
  • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
  • G02B26/10—Scanning systems
  • G02B26/108—Scanning systems having one or more prisms as scanning elements
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
  • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
  • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
  • G09G3/3433—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices
  • G09G3/346—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices based on modulation of the reflection angle, e.g. micromirrors

Definitions

• the present invention relates to a two-dimensional optical scanning apparatus and an image display apparatus using the same, and more particularly to a two-dimensional optical scanning apparatus and an image display apparatus using the same in which a prism block for correction is employed.
• wide-screen image display apparatuses have been popular. It is possible to classify the wide-screen image display apparatuses as a direct view type such as a CRT device, a projection type such as an LCD device, and an optical scanning type.
• the CRT device of the direct view type produces color images when its phosphorescent surface is struck by red/green/blue electron beams.
• the CRT device is required to have a large traveling distance of electron beams between electron guns and the phosphorescent surface, resulting in huge dimensions and a heavy weight thereof. Therefore, the CRT device is not suitable for a wide-screen image display apparatus.
• the LCD projector of the projection type has an advantage of a slim size, but it has a drawback in that it is required to employ a polarizer which may incur light loss.
• image display apparatuses of the optical scanning type have been suggested in Korean Patent No.
• the prior art optical scanning apparatus generally has a curved image surface since it is designed on the basis of an optical axis of the optical elements.
• a general screen is a plane for image display apparatus, so the image quality and resolution power is degraded according to the distance from the optical axis.
• a scanning unit 30 rotates at a constant angular velocity, a scanning length per unit time is increased on a plane screen 50 as the distance from the optical axis increases ( ⁇ d1 ⁇ ⁇ d2 ⁇ ⁇ d3).
• an object of a present invention is to provide a two-dimensional optical scanning apparatus and an image display apparatus using the same that has a uniform image quality and resolution power over a screen by changing emitting time at a scanning position over the screen. It is another object of a present invention is to provide a two-dimensional optical scanning apparatus and an image display apparatus using the same that has a uniform image quality and resolution power over a screen by placing a prism block between a scanning unit and the screen.
• a two-dimensional optical scanning apparatus includes a linear light source unit elongated in a predetermined direction for emitting light that is modulated according to an image to be displayed, and a scanning unit elongated parallel to the linear light source unit for scanning the light emitted from the light source unit.
• the apparatus preferably employs a prism block with an incident surface and an exit surface which are comprised of a plurality of faces whose slopes are changed discontinuously according to a resolution power and a scanning angle.
• the linear light source unit preferably has a plurality of lighting elements which are arranged in a row, and a collimator lens for converting light from each lighting element into a substantially collimated light beam.
• the linear light source unit has at least one lighting element, and a second scanning unit for scanning light from the lighting element along the predetermined direction of the light source unit.
• a two-dimensional optical scanning apparatus has a linear light source unit elongated in a predetermined direction, a scanning unit elongated parallel to the linear light source unit, and a prism block having an incident surface into which the light from the scanning unit enters and an exit surface from which the light exits.
• the incident surface and the exit surface comprise a plurality of faces whose slopes are changed discontinuously according to a resolution power and a scanning angle.
• - ⁇ +a') + qtan( ⁇ r ⁇ - ⁇ i+ ⁇ i'+ ⁇ ), and ⁇ (i) - ⁇ (i+1) L tan( ⁇ max ) /k, and ⁇ max is a maximum scanning angle; L is a distance between the scanning unit and the image plane; (2k+1) is a maximum line number of pixels; ⁇ j' is a resultant scanning
• an image display apparatus uses a two-dimensional optical scanning apparatus described above.
• Fig. 1 shows a schematic perspective view of an exemplary two- dimensional optical scanning apparatus according to a first embodiment of the present invention
• Fig. 2 shows a schematic perspective view of another example of the apparatus according to the first embodiment of the present invention
• Fig. 3 shows a view illustrating a change of scanning time of the two- dimensional optical scanning apparatus according to the first embodiment
• Fig. 4 shows a schematic view of a two dimensional optical scanning apparatus according to a second embodiment of the present invention
• Fig. 5 shows a view illustrating a prism block in the optical scanning apparatus according to the second embodiment
• Fig. 1 shows a schematic perspective view of an exemplary two- dimensional optical scanning apparatus according to a first embodiment of the present invention
• Fig. 2 shows a schematic perspective view of another example of the apparatus according to the first embodiment of the present invention
• Fig. 3 shows a view illustrating a change of scanning time of the two- dimensional optical scanning apparatus according to
• a two-dimensional optical scanning apparatus according to a first embodiment of the present invention has a linear light source unit 100 and a rotatory polygon mirror 300 which is elongated along a direction parallel to the linear light source unit 100.
• the linear light source unit 100 is a one-dimensional light source that has a specific dimension in a direction perpendicular to the optical axis.
• the linear light source unit 100 emits red, green, and blue light that are modulated according to an image to be displayed.
• the linear light source unit 100 preferably has a plurality of lighting elements arranged in a row and collimator lenses 200. Each collimator lens converts light from a lighting element into a substantially collimated light beam.
• a magnification lens may be placed to form an enlarged image that is larger than the dimension of the linear light source unit 100. It is also possible to implement a linear light source unit 100 as shown in Fig. 2.
• the linear light source unit 100 has a point source 101 for emitting modulated light, and a scanning unit such as a rotatory polygon mirror 102 which is flat along its rotating axis.
• a scanning unit such as a rotatory polygon mirror 102 which is flat along its rotating axis.
• light that enters into the polygon mirror 300 from the point light source 101 is reflected from the rotatory polygon mirror 102 to be scanned one-dimensionally.
• Fig. 2 shows that a polygon mirror 102 is employed as a scanning unit, it is possible to employ a Galvano-mirror or an acoustic-optic modulator (AO modulator), etc.
• AO modulator acoustic-optic modulator
• the linear light source unit 100 emits modulated light according to a control signal from a control unit (not shown) during a variable emitting time interval that depends on a scanning angle.
• the polygon mirror 300 has a rotating axis 310 which is parallel with the linear light source unit 100.
• the polygon mirror 300 is elongated in a direction of the rotating axis and is rotated at a constant angular velocity ⁇ by a motor (not shown).
• a polygon mirror is employed as a scanning unit in the first embodiment, the scanning unit is not limited to the polygon mirror. It is possible to use a suitable scanning unit such as a Galvano-mirror or an acoustic modulator.
• the mirror surface When a rotatory polygon mirror is employed, the mirror surface may be deviated somewhat from the optical axis according to its rotating angle. However, a radius from the rotating axis of the polygon mirror is less than a scanning distance, so the off-axis deviation may be less than the scanning distance such that it can be ignored in this consideration.
• a radius from the rotating axis of the polygon mirror is less than a scanning distance, so the off-axis deviation may be less than the scanning distance such that it can be ignored in this consideration.
• the emitting time depending on the scanning angle will be described. First, let assume that the optical axis of the scanning unit is a z-axis, and the screen 500 lies parallel to an x-axis as shown in Fig. 3.
• L is a scanning distance
• ⁇ max is a maximum scanning angle
• (2k+1) is a maximum line number of the pixels.
• the scanning time interval ⁇ t between the i-th line and (i+1)-th line may be obtained from conditions (3) and (4).
• the two-dimensional apparatus according to the first embodiment of the present invention operates as follows. The modulated light emitted from the linear light source 100 is scanned by the rotatory polygon mirror 300 two-dimensionally to display an image on the screen
• a two-dimensional optical scanning apparatus has a linear light source unit 100, a prism block 600, and a rotatory polygon mirror 300.
• the linear light source unit 100 is a one-dimensional light source that has a specific a dimension in a direction perpendicular to the optical axis, and emits red, green, and blue light that are modulated according to an image to be displayed.
• the light source unit 100 preferably has a plurality of lighting elements arranged in a row and collimator lenses for converting light into substantially collimated light beams. A magnification lens may be placed to form an enlarged image. It is also possible to implement a linear light source unit 100 having a point source and flat rotatory polygon mirror 300 to scan light one-dimensionally as described in reference to Fig. 2.
• the linear light source unit 100 emits modulated light according to a control signal from a control unit (not shown).
• the polygon mirror 300 has a rotating axis 310 which is parallel with the linear light source unit 100.
• the polygon mirror 300 is elongated in a direction of the rotating axis and is rotated at a constant angular velocity ⁇ by a motor (not shown).
• a polygon mirror is employed as a scanning unit in the first embodiment, the scanning unit is not limited to the polygon mirror. It is possible to use a suitable scanning unit such as a Galvano-mirror or an acoustic modulator.
• the prism block has an incident surface 601 and an exit surface 602.
• the incident surface 601 and the exit surface 602 have a plurality of faces whose slopes are changed discontinuously according to a resolution power (average pixel size) and a scanning angle of the optical scanning apparatus.
• a specific application may be possible in which an incident surface 601 or an exit surface 602 is a continuous plane or curved surface. It should be noted that the surface 601 or 602 may also be a continuous surface in a high resolution application.
• the prism block 600 may be formed as a single element or by forming pieces corresponding to individual faces and then cementing them to one another. Referring to Fig. 5, the incident surface 601 and the exit surface 602 will be described. As shown in Fig.
• the screen 500 lies parallel to an x-axis, and the optical axis of the scanning unit is a z-axis.
• L represents a scanning distance
• a represents a distance between the scanning unit 300 and a prism block 600
• a ray scanning a point Xj on the screen enters a face Ai of the incident surface 601 and exits from a face B
• the light reflected by the scanning unit 300 is scanned on a point Xi on the screen, and then point x i+ ⁇ in the next line.
• the two-dimensional apparatus operates as follows.
• the modulated light emitted from the linear light source 100 is two-dimensionally scanned by the rotatory polygon mirror 300, and then passes through the prism block 600 to display an image on the screen 500.
• the prism block 600 has an incident surface 601 and an exit surface 602.
• the incident surface 601 and the exit surface 602 have a plurality of faces and Bi with slopes ⁇ j and ⁇ ', respectively, which are obtained from the above conditions (5) to (8).
• Fig. 6 shows a shape of a prism block according to Table 1.
• the lower half of the prism block is not shown, but is symmetric to the upper half part.
• Fig. 7 shows a shape of a prism block 600 according to Table 2, of which the incident surface 601 is a continuous plane. It is possible for the first and second embodiments to be merged into another embodiment, although this is not shown in drawings. Therefore, a two- dimensional optical scanning apparatus may be implemented in which a prism block as well as variable scanning times are used to maintain the uniform resolution power. In this type of apparatus, it is possible to easily reduce the distortion due to the difference of the magnification change as well as the distortion due to a magnification difference on the screen. Further, when two scanning units are used as shown in Fig. 2, they are independent from each other in scanning direction.
• any compensation for image quality or resolution power in which a prism block as well as variable scanning times are used are applicable in both units independently, resulting in a uniform image quality and resolution power.
• Some suitable optical elements may be placed between the light source unit and the scanning unit, and/or between the scanning unit and the screen to compensate for aberration.
• a magnification optical element may be placed between the light source unit and the scanning unit to display an image with desired magnification.
• the two-dimensional optical scanning apparatus has an advantage in that it has a uniform image quality and resolution power over a screen by changing emitting time at a scanning position over the screen. It is also possible to construct the two-dimensional optical scanning apparatus and image display apparatus with the high image quality by placing a prism block between a scanning unit and the screen.
• a two-dimensional optical scanning apparatus may be implemented in which a prism block as well as variable scanning times are used to obtain a uniform resolution power and high image quality.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Computer Hardware Design (AREA)
• Theoretical Computer Science (AREA)
• Mechanical Optical Scanning Systems (AREA)
• Facsimile Scanning Arrangements (AREA)

Applications Claiming Priority (2)

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Citations (2)

• 2003
  • 2003-10-15 KR KR20030071919A patent/KR100607643B1/ko not_active IP Right Cessation
• 2004
  • 2004-10-14 WO PCT/KR2004/002628 patent/WO2005038504A1/en active Application Filing

Patent Citations (2)

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