KR100851071B1 - Display method using diffractive optical modulator for controlling scanning period and Apparatus thereof - Google Patents

Abstract

An image input unit configured to receive an image signal from a mobile terminal; An image data processor converting the format of the image signal into a format of an image signal suitable for an optical modulator; A scanning period control unit controlling an optical scanning period to make the interval of the light spots arranged on the screen constant by scanning processing means for reflecting and scanning the light incident from the optical modulator; And the light emitted from the optical modulator by using the light scanning period received from the scanning period control unit and the converted image signal received from the image data processing unit so that the light emitted from the optical modulator can be reflected in a predetermined area of the scanning processing unit. A display apparatus using an optical modulator including a modulator and a drive signal controller for controlling the scan processing means is provided. The mobile display method and the device using the optical modulator according to the present invention has the effect of maintaining a constant interval of the light spot corresponding to the image signal without using a costly F-theta lens.

Light modulator, polygon mirror, mobile, scanning cycle.

Description

Display method using diffractive optical modulator for controlling scanning period and Apparatus

Figure 1a is a schematic diagram showing a display device using a light modulator and a polygon mirror according to the prior art.

1b and 1c show the spacing and linear velocity of light spots arranged on a screen according to the prior art;

2 is a perspective view of a diffractive optical modulator module using a piezoelectric body applicable to the present invention.

Figure 3 is a schematic diagram showing a mobile display device using an optical modulator and a polygon mirror according to a preferred embodiment of the present invention.

4 is a functional block diagram of a processing unit for controlling an optical scanning cycle according to a preferred embodiment of the present invention.

5 shows a controlled light scanning period in accordance with a preferred embodiment of the present invention.

6 is a flowchart for controlling an optical scan period according to a preferred embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

410: mobile terminal platform

420: image input unit

430: image data processing unit

440: drive signal controller

450: diffraction type optical modulator

460: Scanning Driver

470: scanning cycle control unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display apparatus and a method thereof, and more particularly to a mobile display method and apparatus using an optical modulator for controlling a scanning period.

In general, optical signal processing has advantages of high speed, parallel processing capability, and large-capacity information processing, unlike conventional digital information processing, which cannot process a large amount of data and real-time processing, and design a binary phase filter using spatial light modulation theory. Research on fabrication, optical logic gates, optical amplifiers, image processing techniques, optical devices, optical modulators, etc. Dual optical modulators are used in the fields of optical memory, optical display, printer, optical interconnection, hologram, etc., and research and development of light beam scanning apparatus using them have been in progress.

Such a light beam scanning device scans a light beam in an image forming apparatus such as a laser printer, an LED printer, an electrophotographic copying machine, a word processor, and a projector to form an image image by spotting the light beam on a photosensitive medium.

Recently, with the development of projection television and the like, a light beam scanning device has been used as a means for scanning a beam on an image display.

FIG. 1A is a schematic diagram illustrating a display apparatus for projecting an image onto a screen using an optical modulator and a polygon mirror according to the related art. Referring to FIG. 1, a light source 110, a controller 120, a lens 130, a polygon mirror 140, and a screen 150 are illustrated. Here, although it is not necessary to use an optical modulator in the mobile projector, the following description will focus on the mobile projector using the optical modulator.

The light source 110 is a device for generating a laser beam reflected and diffracted by an optical modulator. Here, the light source 110 simultaneously generates a laser beam in a vertical direction, and the laser beam implements a 2D image by the rotating polygon mirror 140. According to another embodiment, the light source 110 may be implemented by a laser or a laser diode, and the light source 110 is turned on / off according to a driving control of the controller 120 to generate a laser beam. .

The controller 120 controls on / off of the light source 110 and driving of the polygon mirror 140.

The lens 130 focuses the laser beam generated from the light source 110 in the rotation axis direction of the polygon mirror 140.

The polygon mirror 140 is turned on / off according to the driving control of the controller 120, and rotates at a predetermined rotational speed during driving. The polygon mirror 140 is implemented as a polygon to reflect the beam incident through each surface during rotation.

The polygon mirror 140 includes a motor (not shown) capable of rotating at a constant angular speed, and reflects a beam scanned through the lens 130 in the direction of the screen 150 while rotating by the motor.

Here, by using an F-theta lens (not shown) between the polygon mirror 140 and the screen 150, the light spot spacing can be kept constant. That is, the F-theta lens scans the beam 150 reflected by the polygon mirror 140 to the screen 150, but scans between the current reflective surface of the polygon mirror 140 and the scanning surface of the screen 150. By keeping the distance constant to keep the scanning linear velocity on the screen 150 constant, the arrangement interval of the light spots is adjusted to be constant. According to the presence or absence of the F-theta lens, the arrangement interval of the beam spots formed on the piececanning object 180 is changed. However, the F-theta lens, which can maintain a constant distance of the light spot, has a problem in that it takes a lot of development time and high manufacturing cost due to difficulty in processing and design.

1B and 1C are diagrams showing the spacing and linear velocity of light spots arranged on a screen when there is no device for controlling the light spot spacing, such as an F-theta lens according to the prior art. Referring to FIG. 1B, the x axis is a scanning axis and the y axis is a vertical axis. Since the polygon mirror 140 has the smallest distance from the screen 150 at the center of the screen 150, the light spot is dense at the center of the screen 150 when the same light scanning period is performed. Also, referring to FIG. 1C, the x axis is the scanning axis and the y axis is the linear velocity on the screen 150. As described above, the linear velocity on the screen 150 which is the distance between the light spots for the same light scanning period for the same reason is the smallest at the center of the screen 150.

For this reason, there is a problem in that the image emitted from the mobile projector is output as a distorted image on the screen 150. Therefore, in the mobile projector, when the optical modulator and the polygon mirror 140 are used, the light spots scanned on the screen 150 are constantly arranged to scan a predetermined beam on the screen 150 in order not to distort the projected image. There is a need to do so.

The present invention provides a display method and apparatus using an optical modulator capable of maintaining a constant distance between light spots corresponding to an image signal without using an expensive F-theta lens.

In addition, the present invention provides a display method using an optical modulator that can reduce the overall size by maintaining a constant interval of the light spot corresponding to the image signal without using an F-theta lens in a small mobile display and Provide the device.

In addition, the present invention provides a display method and apparatus using an optical modulator for controlling the scanning period so as to maintain a constant interval of the light spot corresponding to the image signal scanned on the screen by controlling the light scanning period.

Technical problems other than the present invention will be easily understood through the following description.

According to an aspect of the invention, the image input unit for receiving an image signal from the mobile terminal; An image data processor converting the format of the image signal into a format of an image signal suitable for an optical modulator; A scanning period control unit controlling an optical scanning period to make the interval of the light spots arranged on the screen constant by scanning processing means for reflecting and scanning the light incident from the optical modulator; And the light emitted from the optical modulator by using the light scanning period received from the scanning period control unit and the converted image signal received from the image data processing unit so that the light emitted from the optical modulator can be reflected in a predetermined area of the scanning processing unit. A display device using an optical modulator including a modulator and a driving signal controller for controlling the scan processing means may be provided.

Here, the scanning processing means may be a rotating mirror that reflects the light diffracted and modulated by the optical modulator at a constant speed.

Here, the rotating mirror may be a polygon mirror that rotates at a constant angular velocity by a rotating motor.

The driving signal controller may control the driving period of each pixel of the optical modulator in correspondence to the optical scanning period.

In addition, the display apparatus using the optical modulator according to the present invention may further include a scanning driver for receiving a control signal of the scan processing means from the drive signal controller to control the rotation of the scan processing means.

Here, the scanning period control unit may determine the optical scanning period by the following equation.

Where Δt is the light scan period, Δx is the spacing of the light spots arranged on the screen, Ω is the angular velocity of the polygon mirror, and V is the linear speed of the light spot on the screen.

According to another aspect of the invention, (a) receiving a video signal from a mobile terminal; converting the format of the video signal into a format of a video signal suitable for an optical modulator; (c) controlling a light scanning period to uniformly space the light spots arranged on the screen by the rotating mirror for reflecting and scanning the light incident from the light modulator; And (d) controlling the optical modulator and the scanning processing means such that the light emitted from the optical modulator using the optical scanning period and the image signal can be reflected in a predetermined area of the scanning processing means. A display method using a modulator can be provided.

In addition, the display method using the optical modulator according to the present invention may further comprise the step of (e) receiving a pulse having a specific period in the scanning driver to control the rotation of the scanning processing means.

Here, the scanning processing means may be a rotating mirror that reflects the light diffracted and modulated by the optical modulator at a constant speed.

Here, the rotating mirror may be a polygon mirror that rotates at a constant angular velocity by a rotating motor.

In the step (d), the optical modulator may be controlled by determining a driving period of each pixel of the optical modulator in correspondence to the optical scanning period.

Here, in the step (c), the optical scan period can be determined by the following equation.

Where Δt is the light scan period, Δx is the spacing of the light spots arranged on the screen, Ω is the angular velocity of the polygon mirror, and V is the linear speed of the light spot on the screen.

Hereinafter, a preferred embodiment of a display method and a device using the optical modulator according to the present invention will be described in detail with reference to the accompanying drawings, in the description with reference to the accompanying drawings, the same components regardless of reference numerals are the same. Reference numerals will be omitted and duplicate description thereof will be omitted. In addition, the optical modulator applied to the present invention will be described first before describing the preferred embodiments of the present invention in detail.

The optical modulator element is largely divided into a direct method of directly controlling the on / off of light and an indirect method using reflection and diffraction, and the indirect method may be divided into an electrostatic method and a piezoelectric method. Herein, the optical modulator device may be applied to the present invention regardless of the method of driving or the product name of the manufacturing company (for example, a Grating Light Valve (GLV) device which is an optical modulator of Silicon Light Machine Co., Ltd.).

The electrostatic grating light modulator disclosed in US Pat. No. 5,311,360 includes a plurality of uniformly spaced deformable reflective ribbons having reflective surface portions and suspended above a substrate. An insulating layer is deposited on the silicon substrate. Next, the deposition process of the sacrificial silicon dioxide film and the silicon nitride film is followed.

The nitride film is patterned from the ribbon and a portion of the silicon dioxide layer is etched so that the ribbon is held on the oxide spacer layer by the nitride frame. To modulate light with a single wavelength [lambda] 0, the modulator is designed such that the thickness of the ribbon and the thickness of the oxide spacers are [lambda] 0/4.

The lattice amplitude of this modulator, defined by the vertical distance d between the reflective surface on the ribbon and the reflective surface of the substrate, is the conduction of the ribbon (reflective surface of the ribbon serving as the first electrode) and the substrate (substrate serving as the second electrode). Film).

2 is a perspective view of a diffractive light modulator module using a piezoelectric element among indirect light modulators applicable to the present invention. Referring to FIG. 2, an optical modulator including a substrate 211, an insulating layer 212, a sacrificial layer 213, a ribbon structure 214, and a piezoelectric body 215 is illustrated.

The substrate 211 is a commonly used semiconductor substrate, and the insulating layer 212 is deposited as an etch stop layer, and an etchant for etching a material used as a sacrificial layer, where the etchant is an etching gas or an etching Solution). Here, the insulating layer 212 may be coated with a reflective layer (not shown) to reflect incident light.

The sacrificial layer 213 supports the ribbon structure 214 on both sides so that the ribbon structure can be spaced apart from the insulating layer 212 at regular intervals, and forms a space at the center.

The ribbon structure 214 serves to light modulate the signal by causing diffraction and interference of incident light as described above. The shape of the ribbon structure 214 may be configured in a plurality of ribbon shapes according to the electrostatic method, or may be provided with a plurality of open holes in the center of the ribbon according to the piezoelectric method. In addition, the piezoelectric member 215 controls the ribbon structure 214 to move up and down in a piezoelectric manner.

When the wavelength of light is λ, the distance between the ribbon structure 214 and the insulating layer 212 on which the lower reflective layer is formed is equal to λ / 2 in the state where the optical modulator is not deformed (no voltage is applied). Thus, the total path difference between the light reflected from the ribbon structure 214 and the insulating layer 212 is equal to λ so that light interferes constructively.

In addition, when an appropriate voltage is applied to the piezoelectric material 215, the distance between the ribbon structure 214 and the insulating layer 212 on which the lower reflective layer is formed is equal to λ / 4. Thus, the total path difference between the light reflected from the ribbon structure 214 and the insulating layer 212 is equal to [lambda] / 2 so that light interferes with each other. As a result of such interference, the optical modulator may load a signal on the light by adjusting the amount of incident light. The optical modulator elements may be classified into recesses and protrusions according to the shape of the ribbon structure 214.

3 is a schematic diagram showing a mobile display device using an optical modulator and a polygon mirror according to a preferred embodiment of the present invention. Hereinafter, the piezoelectric diffraction type optical modulator will be described. Referring to FIG. 3, a diffractive optical modulator 310, a drive signal controller 320, a scan processing unit 330, and a screen 340 are shown. Here, the scanning processing means 330 is a device for reflecting and scanning the light incident from the optical modulator, and includes a rotating mirror, a rotating bar, a polygon mirror, and the like. Hereinafter, the case where the scanning processing means 330 is a polygon mirror will be described.

The diffractive light modulator 310 is a device that reflects and diffracts a laser beam in response to an image signal. Here, the diffractive light modulator 310 simultaneously generates a laser beam in a vertical direction, and the laser beam implements a two-dimensional image by the rotating polygon mirror 330. In the diffraction type optical modulator 310 according to the present invention, the number of ribbons is determined according to projection pixels, and in general, 480 ribbons are arranged in the case of VGA 640 * 480 resolution to reflect and diffract a laser beam for a vertical pixel. Can be injected into the screen 340.

The driving signal control unit 320 uses the light scanning period received from the scanning period control unit (not shown) and the converted image signal received from the image data processing unit to convert the light emitted from the diffraction type optical modulator 310 into the polygon mirror 330. The driving of the diffractive light modulator 310 and the polygon mirror 330 is controlled so as to be reflected in a predetermined region. Here, the scanning period control unit controls the scanning period of the light emitted from the light source to make the interval of the light spots arranged on the screen constant by the polygon mirror 330 for reflecting and scanning the light incident from the optical modulator. Herein, the light source corresponds to a light modulator when the optical modulator directly controls the on / off of light, and when the light modulator follows an indirect method using reflection and diffraction, the light is irradiated to the diffractive light modulator. Refers to a light source (for example, a laser diode LD).

The driving signal controller 320 synchronizes an image signal based on a polygon mirror reference signal or a position profile signal related to the position and rotation of the polygon mirror 330, so that the light emitted from the diffractive optical modulator 310 is converted into a polygon mirror. A polygon mirror control signal and an optical modulator control signal are generated to be reflected in the preset area of 330. The image signal may be synchronized by delaying a predetermined time with respect to the polygon mirror reference signal. Here, the lens (not shown) focuses the laser beam generated from the diffractive light modulator 310 in the rotation axis direction of the polygon mirror 330. Here, the position profile signal is generally composed of an analog signal, and the position of the polygon mirror 330 may be preset by an initial value of the position profile signal. The polygon mirror reference signal or the position profile signal represents data related to the current position of the polygon mirror 330, the rotational speed, and the position where the polygon mirror 330 is set to reflect light emitted from the diffractive optical modulator 310. .

Here, the video signal generally consists of a video synchronization signal and video data. That is, the image synchronization signal is a signal for notifying the start of a new frame and the start of a new scan line in a frame. The new frame start is controlled by the vertical sync signal and the new scan line start by the horizontal sync signal. Since the diffraction type optical modulator 310 according to the present invention has a constant ribbon formed in the vertical direction, it needs to be synchronized in the horizontal direction. According to the present invention, the light emitted from the diffractive light modulator 310 may be controlled to be reflected in a predetermined area of the polygon mirror using the image synchronization signal. That is, by using the polygon mirror reference signal or the position profile signal of the polygon mirror 330 synchronized with the image synchronization signal, light corresponding to the image signal may be reflected on the preset effective plane of the polygon mirror 330 to reach the screen. Can be controlled.

The polygon mirror 330 is turned on / off according to the driving control of the driving signal controller 320 and rotates at a predetermined rotational speed during driving. The polygon mirror 330 is implemented as a polygon to reflect the beam incident through each surface during rotation. At this time, the beam reflected from one surface of the polygon mirror 330 forms a spot array at a predetermined interval by scanning, and is scanned on the screen 340, which spot arrays one screen of the screen 340. Create For example, in the case of VGA 640 * 480 resolution, 640 modulations are performed on one surface of the polygon mirror 330 for 480 vertical pixels, thereby generating one frame per screen of the polygon mirror 330.

The polygon mirror 330 includes a motor (not shown) capable of rotating at a constant angular speed, and reflects a beam scanned through the lens 130 in the direction of the screen 340 while rotating by the motor. Here, the polygon mirror 330 may be replaced by a rotating bar or a galvano mirror.

4 is a functional block diagram of a processing unit for synchronizing an image signal with a polygon mirror according to an exemplary embodiment of the present invention. Referring to FIG. 4, the mobile terminal platform 410, the image input unit 420, the image data processor 430, the drive signal controller 440, the diffractive optical modulator 450, the scanning driver 460, and the scan period controller 470 is shown.

The mobile terminal platform 410 is a platform mounted on a mobile device such as a pocket PC, a mobile phone, or a smartphone. When an image signal is generated by a user's setting or default operation, the image signal is transmitted to the image input unit 420, and the image input unit 420 transmits the received signal to the image data processor 430. The video signal includes a video synchronization signal and video data.

The image data processor 430 converts the format of the input image signal into a format of an image signal suitable for an optical modulator.

The driving signal controller 440 may be configured to generate light emitted from the optical modulator by using the optical scan period received from the scan period controller and the converted image signal received from the image data processor in a predetermined area of the polygon mirror 330. The light modulator and the polygon mirror 330 are controlled to be reflected. Here, the driving signal controller 440 may generate a polygon mirror reference signal or a position profile signal for specifying the position of the polygon mirror 330. That is, a position profile signal capable of controlling the rotation and / or the position of the polygon mirror 330 is generated so that light corresponding to the image data may be projected onto a predetermined effective surface on one surface of the polygon mirror 330. Since the position profile signal can be corrected in position by a calibration procedure in the scanning driver, the initial value can be set to an arbitrary value.

The diffractive light modulator 450 is operated by controlling the driving period of each pixel corresponding to the light scanning period transmitted from the driving signal controller 440. Here, the pixel of the diffractive light modulator 450 is a unit in which an image signal is implemented corresponding to each ribbon. According to another exemplary embodiment, an optical modulator controller for receiving the optical modulator control signal from the driving signal controller 440 to control the diffractive optical modulator 450 may be further provided to control the diffractive optical modulator 450.

The scanning driver 460 receives the control signal of the polygon mirror 330 from the driving signal controller 440 to control the rotation of the polygon mirror 330. For example, the scanning driver 460 receives a pulse having a specific period from the driving signal controller 440 and controls the rotation of the polygon mirror 330. Here, the driving signal controller 440 may directly control the position and rotation speed of the polygon mirror 330 by replacing the scanning driver 460.

The scanning period control unit 470 controls the scanning period of the light scanned from the light source so that the polygon mirror 330 for reflecting and scanning the light incident from the light modulator is uniformly spaced between the light spots arranged on the screen. Here, the light scan period may be determined by the following equation.

The spacing of the light spots arranged on the screen is set to a constant as follows.

(1)

(One)

는 폴리곤 미러의 회전 각이며, V는 스크린 상의 광 스팟의 선속도이다. 또한, 폴리곤 미러의 각속도는 다음과 같이 정의된다. here,

Is the rotation angle of the polygon mirror, and V is the linear velocity of the light spot on the screen. In addition, the angular velocity of the polygon mirror is defined as follows.

(2)

(2)

Therefore, in summary, the scan period of light can be determined as follows.

(3)

(3)

Where? T is the scan period of light,? X is the spacing of the light spots arranged on the screen,? Is the angular velocity of the polygon mirror, and V is the linear velocity of the light spot on the screen. Δx is a constant since it is a desired constant interval, and Ω is a constant because of the angular velocity of the polygon mirror. Δt is therefore inversely proportional to V. That is, in the case of the center of the screen having a small linear velocity on the screen, Δt, which is a light scanning period, becomes large in inverse proportion to V, so that the number of light scanned per unit time in the light source is small. The opposite is true for both sides of the screen where the linear velocity on the screen is large.

5 is a diagram illustrating a light scanning period controlled in correspondence with the linear velocity of the light spot on the screen according to the preferred embodiment of the present invention. Referring to FIG. 5, the x-axis is the scanning axis and the y-axis is the axis representing the light scanning period. Comparing FIG. 1C with FIG. 5, it can be seen that the light scanning period shown in FIG. 5 is shown in inverse proportion to the scanning linear velocity.

6 is a flowchart for controlling an optical scan period according to a preferred embodiment of the present invention.

In operation S610, the image input unit receives an image signal from the mobile terminal. Here, other initial values, for example, a position profile signal or a polygon mirror reference signal, which is a reference value for adjusting the position of the polygon mirror, are set.

In operation S620, the image data processor converts the format of the image signal into a format suitable for the optical modulator. Here, the video signal includes a video synchronization signal and video data.

In step S630, the scanning period control unit controls the light scanning period to make the interval of the light spots arranged on the screen constant by the rotating mirror for reflecting and scanning the light incident from the optical modulator. The optical scanning period may be calculated using the linear velocity of the light spot formed on the screen as described above.

In step S640, the drive signal controller controls the light modulator and the rotation mirror so that the light emitted from the light modulator can be reflected in a predetermined area of the rotation mirror (polygon mirror) using the light scanning period and the image signal. In step S650, the scanning driver receives the control signal of the rotation mirror (polygon mirror) from the drive signal controller to control the rotation of the rotation mirror to project a predetermined image irradiated from the optical modulator onto the screen.

The present invention is not limited to the above embodiments, and many variations are possible by those skilled in the art within the spirit of the present invention.

As described above, the display method and the apparatus using the optical modulator according to the present invention have the effect of maintaining a constant interval of the light spot corresponding to the image signal without using an expensive F-theta lens. have.

In addition, the display method and the device using the optical modulator according to the present invention is the overall size by maintaining a constant interval of the light spot corresponding to the video signal without using an F-theta lens in a small mobile display There is an effect to reduce.

In addition, the display method and the apparatus using the optical modulator according to the present invention has the effect of controlling the scanning period to maintain a constant interval of the light spot corresponding to the image signal scanned on the screen by controlling the light scanning period have.

Although the above has been described with reference to a preferred embodiment of the present invention, those of ordinary skill in the art to the present invention without departing from the spirit and scope of the present invention and equivalents thereof described in the claims below It will be understood that various modifications and changes can be made.

Claims (12)

An image input unit configured to receive an image signal from a mobile terminal; An image data processor converting the format of the image signal into a format of an image signal suitable for an optical modulator; A scanning period control unit controlling an optical scanning period to make the interval of the light spots arranged on the screen constant by scanning processing means for reflecting and scanning the light incident from the optical modulator; And The optical modulator to reflect light emitted from the optical modulator by using the optical scan period received from the scan period control unit and the converted image signal received from the image data processor. And a driving signal controller configured to control the scanning processing means. The method of claim 1, And the scanning processing means is a rotating mirror which moves and reflects the light diffracted and modulated by the optical modulator at a constant speed. The method of claim 2, The rotating mirror is a display device using an optical modulator, characterized in that the polygon mirror rotates at a constant angular speed by a rotating motor. The method of claim 1, And the driving signal controller controls the driving period of each pixel of the optical modulator in correspondence with the optical scanning period. The method of claim 1, And a scanning driver which receives a control signal of the scanning processing means from the driving signal control unit and controls the rotation of the scanning processing means. The method of claim 1, The scan period control unit And the optical scanning period is determined by the following equation.

Where Δt is the light scan period, Δx is the spacing of the light spots arranged on the screen, Ω is the angular velocity of the polygon mirror, and V is the linear speed of the light spot on the screen. (a) receiving an image signal from a mobile terminal; converting the format of the video signal into a format of a video signal suitable for an optical modulator; (c) controlling the light scanning period to make the interval of the light spots arranged on the screen constant by scanning processing means for reflecting and scanning the light incident from the light modulator; And (d) controlling the optical modulator and the scanning processing means such that the light emitted from the optical modulator using the optical scanning period and the image signal can be reflected in a predetermined area of the scanning processing means. Display method using a modulator. The method of claim 7, wherein and (e) controlling a rotation of the scanning processing means by receiving a pulse having a specific period in the scanning driver. The method of claim 7, wherein And the scanning processing means is a rotating mirror which moves and reflects the light diffracted and modulated by the optical modulator at a constant speed. The method of claim 9, The rotating mirror is a display method using an optical modulator, characterized in that the polygon mirror which rotates at a constant angular speed by a rotating motor. The method of claim 7, wherein And in step (d), controlling the optical modulator by determining a driving period of each pixel of the optical modulator in correspondence with the optical scanning period. The method of claim 7, wherein In step (c), A display method using an optical modulator, characterized in that the optical scanning period is determined by the following equation.

Where Δt is the light scan period, Δx is the spacing of the light spots arranged on the screen, Ω is the angular velocity of the polygon mirror, and V is the linear speed of the light spot on the screen.

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