KR100928994B1 - Display device - Google Patents

Abstract

The present invention relates to a display apparatus having a light source unit which is sequentially driven and a transmissive display panel in which a color image is expressed by a plurality of color lights emitted from the light source unit, the display device being disposed between the light source unit and the transmissive display panel from different angles. A collimating lens for focusing incident color light into parallel light; A plurality of diffraction gratings arranged side by side along a path of color light between the collimating lens and the transmissive display panel such that refraction and straightness of any one color light are alternately performed; And a sequential refractive drive unit for driving the plurality of diffraction gratings in synchronization with the light source unit. As a result, the plurality of color light paths are formed in a straight line, thereby reducing the size of the display device.

Description

Display Device {Display Device}

The present invention relates to a display device, and more particularly, to obtain a desired image by passing green light, red light, and blue light from a light source such as an LED through a transmissive liquid crystal panel, and projecting it on a screen to display a large image on the screen. It relates to a display device to make.

In the conventional display device using the LED and the transmissive liquid crystal panel, a green light source, a red light source, and a blue light source are used separately, and thus a focusing lens for focusing the light emitted from each light source is separately required, thereby synthesizing each light. At least two dichroic mirrors were needed.

In this regard, a conventional display device 10 using an LED and a transmissive liquid crystal panel will be described with reference to FIG. 1.

1 is a configuration diagram showing a conventional display apparatus 10 using an LED module and a dichroic mirror.

As shown, the conventional display apparatus 10 includes a red LED module 21, a green LED module 22, and a blue LED module 23. These are semiconductor light sources for generating light of R, G, and B, and may be blinked in real time according to a control signal applied from the image signal processor 30. Here, the red LED module 21 and the green LED module 22 are disposed in a direction substantially perpendicular to the blue LED module 23.

The image signal processor 30 receives image data from an image source, inputs an image signal to the transmissive display panel 40, and outputs the red LED module 21 and the green LED module according to the image signal input to the transmissive display panel 40. (22) and the blue LED module 23 applies a control signal.

The transmissive display panel 40 adjusts and transmits the amounts of red, green and blue light in accordance with the input R, G, and B image signals. A transmissive liquid crystal panel is used. In general, a transmissive liquid crystal panel is composed of a two-dimensional cell array and has a very small size of less than 1 inch and is composed of pixels of VGA to SXGA level, and is a transmissive type ultra-small (less than 1 inch) liquid crystal panel. No color filter array is required.

As shown in the front of each of the red LED module 21, the green LED module 22, and the blue LED module 23, the first collimating lens 61 to first focus the light emitted from each module into parallel light. 3 collimating lens 63 is installed. That is, three collimating lenses 61, 62, and 63 are required for the conventional display apparatus 10.

The conventional display apparatus 10 includes a first dichroic mirror 71 and a second dichroic mirror 72.

The first dichroic mirror 71 is inclined about 45 degrees with respect to the traveling direction of the blue light on the front of the green LED module 22 and the blue LED module 23. The first dichroic mirror 71 is optically coated to pass blue light and reflect green light. Accordingly, blue light and green light are sent to the second dichroic mirror 72.

The second dichroic mirror 72 is disposed at an angle of about 45 degrees with respect to the traveling direction of the red light on the front of the red LED module 21. The second dichroic mirror 72 is optically coated to pass red light and reflect blue light and green light. Accordingly, red light, green light and blue light from each LED module are sent to the transmissive display panel 40.

Accordingly, the transmissive display panel 40 displays an image corresponding to an image signal applied by the image signal processor 30.

The projection lens 50 is disposed in front of the transmissive display panel 40. The projection lens 50 is intended to display a large screen image by enlarging and projecting an image of the transmissive display panel 40 on a screen.

In the display device using the LED as described above, a color image can be expressed using a single micro display panel. In this case, the color synthesis is sequentially performed in the human eye by projecting monochrome images in the order of R, G, and B sequentially. Is done.

As can be seen from the above description, in the conventional display device, three collimating lenses are required, and two dichroic mirrors are required.

R, G, B color synthesis optical system and optical integrator (optical integrator) optical system is configured separately for each of the R, G, B color, there is a disadvantage that the length and size of the optical system is increased.

There is also a problem in that the manufacturing cost of the display device increases accordingly.

SUMMARY OF THE INVENTION An object of the present invention is to obtain a compact projection illumination optical system in a display device using a single panel and to realize a very small projection optical engine.

Another object of the present invention is to provide a display device in which the size of the optical system can be made smaller than the conventional one by forming the optical path in a straight line.

Still another object of the present invention is to provide a display apparatus that can reduce manufacturing cost by reducing the collimating lens, which has been conventionally applied to each of R, G, and B light sources, to only one collimating lens.

The object of the present invention is a display device having a light source unit which is sequentially driven and a transmissive display panel in which a color image is represented by three primary colors of light emitted from the light source unit, the display device being disposed between the light source unit and the transmissive display panel and mutually A collimating lens for focusing three primary color light incident from different angles into parallel light; Diffraction is arranged between the collimating lens and the transmissive display panel in parallel along the path of the three primary colors, and each of the three primary colors is refracted and straightened alternately depending on whether the voltage is applied, including the transparent electrode layer. Gratings; And a sequential refraction circuit unit for applying a voltage to at least one of the diffraction gratings in synchronization with the light source unit such that the diffraction gratings are activated or deactivated at least alternately.

Here, the diffraction gratings are preferably a first diffraction grating which becomes transparent when voltage is applied and refracts red light when no voltage is applied, and a second grating which becomes transparent when voltage is applied and refracts blue light when no voltage is applied.

It is preferable to further include a projection lens for enlarging the color image represented in the transmissive display panel.

In addition, the collimating lens is preferably one aspherical lens.

According to the present invention, it is possible to obtain a compact projection illumination optical system and to implement a compact projection optical engine.

In addition, since the optical path is formed in a straight line, the size of the display device can be reduced.

In addition, it is possible to reduce the manufacturing cost of the display apparatus by reducing the collimating lens, which has been conventionally applied to each of R, G, and B light sources, with only one collimating lens.

In addition, the optical path of each of the R, G, and B light sources may be optimized to increase light efficiency of the display device.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 2, the display apparatus 100 according to an exemplary embodiment of the present invention includes a light source unit 110, a transmissive display panel 120, a projection lens 130, and a collimating lens 140. And a plurality of diffraction gratings 150 and 160 and a sequential refraction circuit unit 170. In one embodiment of the present invention, the display device 100 is preferably an image projector.

As shown in FIG. 2, the light source unit 110 is a semiconductor light source for generating a plurality of color lights of R, G, and B, and includes a red light source 111, a green light source 112, and a blue light source 113. And a video signal processing circuit 114.

In one embodiment of the present invention, the red light source 111, the green light source 112 and the blue light source 113 is preferably provided with a light emitting diode (LED) module arranged in a line with each other, the image signal processing circuit 114 ) Can be sequentially flashed in real time according to the control signal applied from).

The red light source 111, the green light source 112, and the blue light source 113 need to be near the focal plane of the collimating lens 140, but, for optimal performance, approximately 3 to 3 focal lengths of the collimating lens 140. It is desirable to be located within 5%.

As illustrated in FIG. 2, the image signal processing circuit 114 receives image data from an image source, inputs an image signal to the transmissive display panel 120, and according to the image signal input to the transmissive display panel 120. The control signal is applied to the red light source 111, the green light source 112, and the blue light source 113 so as to sequentially drive the light.

As illustrated in FIG. 2, the transmissive display panel 120 displays a color image by a plurality of color lights emitted from the red light source 111, the green light source 112, and the blue light source 113 of the light source unit 110. In accordance with the R, G, and B image signals input from the image signal processing circuit 114 of the light source unit 110, the amount of red light, green light, and blue light is adjusted and transmitted.

In one embodiment of the present invention, the transmissive display panel 120 is preferably a transmissive ultra-small (1 inch or less) liquid crystal panel, and generally, the transmissive liquid crystal panel is composed of a two-dimensional cell array and is 1 inch or less. It is composed of VGA ~ SXGA level pixels in very small size.

As shown in FIG. 2, the projection lens 130 is disposed in front of the transmissive display panel 120 to display a large screen image by enlarging and projecting a color image represented by the transmissive display panel 120 onto a screen.

As shown in FIG. 2, the collimating lens 140 is disposed between the light source unit 110 and the transmissive display panel 120 to focus color light incident from different angles into parallel light.

In terms of the efficiency and performance of the diffraction grating, the value of 'θ' in FIGS. 3 and 5 is generally better, but the value of 'θ' is approximately 20 degrees because the smaller value of 'θ' is better in terms of performance of the optical lens. It is preferable to be within -40 degrees. Adjusting the value of [theta] can be easily carried out by a person skilled in the art by a conventional method. The value of [theta] can be changed by adjusting the distance between the light source and the collimating lens. It can be adjusted easily.

In one embodiment of the present invention, the collimating lens 140, as shown in Figure 2, R, G, respectively irradiated from the red light source 111, green light source 112 and blue light source 113, It is preferable to provide one aspherical lens so that the B color lights are commonly incident.

Accordingly, the manufacturing cost of the display apparatus can be reduced by reducing the collimating lens, which has been conventionally applied to each of R, G, and B light sources, to only one collimating lens.

As illustrated in FIG. 2, the plurality of diffraction gratings 150 and 160 may include a first diffraction grating 150 and a second diffraction grating along a path of color light between the collimating lens 140 and the transmissive display panel 120. 160 is arranged side by side so that the refraction and the straight line of any one of the R, G, B color light is alternately made.

Specifically, the diffraction grating is provided in a form in which a holographic polymer dispersed liquid crystal (PDLC) is sandwiched between two glass substrates, and a transparent electrode (ITO: Indium-Tin Oxide) layer is formed on the two glass surfaces. And the optical interference pattern is formed to operate. As an embodiment of the present invention, the diffraction grating is described as two, but as another embodiment of the present invention may be three or more diffraction gratings as necessary.

The characteristic of the diffraction grating is a device that can control the refraction of the color light passing through the diffraction grating by applying a constant voltage to both inputs, and when the voltage is applied, the diffraction grating becomes transparent and does not refract the color light. At that time, the color light is refracted at a constant refractive index.

As shown in FIG. 3, the first diffraction grating 150 is disposed between the collimating lens 140 and the second diffraction grating 160 and becomes transparent when voltage is applied and refracts red light when no voltage is applied. . That is, the first diffraction grating 150 becomes transparent when a voltage of + 24V or -24V is applied by the sequential refraction circuit unit 170 in synchronization with the image signal processing circuit 114 of the light source unit 110, and the voltage is not applied. In this state, the red light incident at the + θ angle is folded at 0 degrees.

As shown in FIG. 5, the second diffraction grating 160 is disposed between the first diffraction grating 150 and the transmissive display panel 120 and becomes transparent when voltage is applied and refracts blue light when no voltage is applied. . That is, the second diffraction grating 160 becomes transparent when a voltage of + 24V or -24V is applied by the sequential refraction circuit unit 170, and when the voltage is not applied, the second diffraction grating 160 breaks the blue light incident at the -θ angle to 0 degrees. do.

Accordingly, by arranging the positional arrangement of the light sources in a linear arrangement in a conventional right-angle arrangement, a compact projection illumination optical system can be obtained and a micro-projection optical engine can be realized through this.

As an embodiment of the present invention, the second diffraction grating 160 is described as being sequentially disposed after the first diffraction grating 150, but as another embodiment of the present invention, the first grating grating 150 is Positions of the second diffraction grating 160 may be reversed with each other.

As shown in FIG. 2, the sequential refraction circuit unit 170 drives the plurality of diffraction gratings 150 and 160 in synchronization with the image signal processing circuit 114 of the light source unit 110. That is, the sequential refraction circuit unit 170 is preferably a circuit for appropriately controlling the first diffraction grating 150 and the second diffraction grating 160 in time.

As shown in FIG. 6, the sequential refraction circuit unit 170 deactivates the first diffraction grating 150 to refract red light while the red light source 111 is activated, and while the blue light source 113 is activated. Deactivates the second diffraction grating 160 to refract the blue light. When the sequential refraction circuit unit 170 activates the first diffraction grating 150 or the second diffraction grating 160, the polarity of the active voltage is reversed every cycle to prevent the destruction of the device.

Referring to FIG. 6, the section A and the section C are sections in which the target light source ⓒ is on, and since there is no voltage at both ends of the diffraction grating, the target light source ⓒ is refracted at a constant refractive index, and in the section B and section D, the target light source ⓒ is off. As the interval between the two ends of the diffraction grating is applied alternately, the colored light passes straight through without refraction.

As shown in FIG. 6, the sequential refraction circuit unit 170 generating the control output ⓐ of the first diffraction grating 150 and the control output ⓑ of the second diffraction grating 160 according to the light source inputted from the section A to the section D. Designing a circuit of is as shown in FIG.

Referring to FIG. 7, a waveform of 1/2 frequency of the light source ⓒ is needed to derive the terminal control signals ⓐ and ⓑ of the diffraction gratings in sections A to D according to the on / off of the light source ⓒ. For this purpose, after connecting output Q 'and D using D-FlipFlop, input light source ⓒ to ⓓ clock, and output Q can get light source ⓔ with 1/2 frequency.

FIG. 8 is a detailed control state diagram of FIG. 6 including up to 1/2 light source ⓔ. Referring to FIG. 8, ⓐ and ⓑ may be expressed as logical combinations for ⓒ and ⓔ as follows.

Ⓐ = NOT ⓒ AND ⓔ

Ⓑ = NOT ⓒ AND NOT ⓔ

If we optimize the above equations to the D'Morgang's law to use one FlipFlop and two NOR to use the minimum logic circuit,

Ⓐ = NOT (ⓒ OR NOT ⓔ)

Ⓑ = NOT (ⓒ OR ⓔ)

Accordingly, the sequential refraction circuit unit 170 alternately drives the first diffraction grating 150 and the second diffraction grating 160 so that the red light and the first diffraction grating 150 and the second diffraction grating 160 are driven. By alternately performing the refraction and the straight line of the blue light, the light path is formed in a straight line, thereby miniaturizing the size of the display apparatus 100.

By such a configuration, a process of implementing a color image by the display apparatus 100 according to the present invention will be described with reference to FIGS. 2 to 8.

First, the image signal processing circuit 114 receives image data from an image source, inputs an image signal to the transmissive display panel 120, and outputs a red light source 111 and green in accordance with the image signal input to the transmissive display panel 120. The control signal is applied to the light source 112 and the blue light source 113 so as to sequentially drive the light.

Next, the color light incident from the red light source 111, the green light source 112, and the blue light source 113 into the collimating lens 140 passes through the collimating lens 140, respectively, to some degree of parallelism.

The sequential refraction circuit unit 170 alternately drives the first diffraction grating 150 and the second diffraction grating 160 in synchronization with the image signal processing circuit 114.

That is, when red light is irradiated from the red light source 111, the sequential refraction circuit unit 170 does not apply a voltage to the first diffraction grating 150, but applies a voltage only to the second diffraction grating 160 (see FIG. 3). ).

When green light is irradiated from the green light source 112, the sequential refraction circuit 170 applies a voltage to both the first diffraction grating 150 and the second diffraction grating 160, thereby applying the first diffraction grating 150 and the second diffraction grating. By making the grating 160 transparent, the green light passes straight through without being refracted to the transmissive display panel 120 (see FIG. 4).

When blue light is irradiated from the blue light source 113, the sequential refraction circuit unit 170 does not apply a voltage to the second diffraction grating 160, but applies a voltage only to the first diffraction grating 150 (see FIG. 5).

Accordingly, the light path may be optimized in a straight line, thereby increasing the light efficiency of the display apparatus 100.

The transmissive display panel 120 receives red light, green light, and blue light that have passed through the first diffraction grating 150 and the second diffraction grating 160, based on an image signal received from the image signal processing circuit 114. A predetermined color image is expressed by green light and blue light.

The color image represented by the transmissive display panel 120 is enlarged by the projection lens 130 and is projected onto an external screen to realize a large screen image.

Thus, according to the present invention, it is possible to obtain a compact projection illumination optical system through which a compact projection optical engine can be realized.

1 is a block diagram of a display device according to the prior art,

2 is a block diagram of a display device according to the present invention;

3 is a block diagram showing a path of the red light source of FIG.

4 is a block diagram showing a path of the green light source of FIG.

5 is a block diagram showing a path of the blue light source of FIG.

6 is a control state diagram of the first and second diffraction gratings according to the present invention;

7 is a circuit diagram of a sequential refraction circuit unit according to the present invention;

8 is a detailed control state diagram of FIG. 6.

* Explanation of symbols for the main parts of the drawings

100: display device 110: light source

120: transmissive display panel 130: projection lens

140: collimating lens 150: the first grating

160: second grating 170: sequential refraction circuit

Claims (4)

A display apparatus having a light source unit which is sequentially driven and a transmissive display panel in which a color image is expressed by three primary colors of light emitted from the light source unit. A collimating lens disposed between the light source unit and the transmissive display panel to focus three primary color light incident from different angles into parallel light; Diffraction is arranged between the collimating lens and the transmissive display panel in parallel along the path of the three primary colors, and each of the three primary colors is refracted and straightened alternately depending on whether the voltage is applied, including the transparent electrode layer. Gratings; And a sequential refraction circuit unit configured to apply a voltage to at least one of the diffraction gratings in synchronization with the light source unit such that the diffraction gratings are at least alternately activated or deactivated. The method of claim 1, The diffraction grating, A first diffraction grating which becomes transparent upon application of voltage and refracts red light upon application of no voltage; And a second diffraction grating which becomes transparent upon application of voltage and refracts blue light upon application of no voltage. The method of claim 2, And a projection lens for enlarging the color image represented by the transmissive display panel. The method according to any one of claims 1 to 3, And the collimating lens is one aspherical lens.

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