JP2000075406A - Light source for projector and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact projector in which a heat is hardly generated, and capable of preventing the periphery of a screen from becoming dark even in the case of enlarging/displaying. SOLUTION: Inside the liquid crystal projector 1, a liquid crystal panel 3, a thin- shaped panel FED 4 as a light source, a heat sink 5 and a projecting lens 6 are installed. A screen is shown by figure 25. The light source is made thinner in shape, so that the light source is more compact than the conventional one. The FED 4 is provided with a solid-state phosphor layer on the anode substrate of an outer jacket. Many cone-shaped emitters are installed on the inside face of a cathode substrate. Electrons are discharged by converging the electric field on the leading end of the emitter. As for the installation density of the emitter, the density in a part corresponding to the center of a light emitting area is the lowest, the density in the intermediate rectangular ring area follows the aforesaid density, and the density in the outer rectangular ring area is the highest. Because of the optical aberration of the projecting lens 6, the center of the projected image is bright, but, the peripheral part of the image is dark. The number of emitters are more increased as the periphery area is darker so as to increase the luminance and to make the luminance of the whole projected image uniform while giving consideration to the influence of the light reduction at the periphery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projector for enlarging and projecting an image displayed on an image forming unit such as a liquid crystal panel using a light source and a projection lens. In particular, the present invention provides a panel-shaped new light source suitable for such a projector, and also provides a projector provided with such a light source.

[0002]

FIG. 8 shows a conventional liquid crystal projector 100.
Is shown. Inside the housing 101, there is a liquid crystal panel 102 as an image forming unit. Behind this, a condenser lens 103 and a light source 104 are provided. Light source 104
Is provided with a cooling fan 105. LCD panel 102
Is located in front of the projection lens 106. Light from the light source 104 is applied to the liquid crystal panel 102 through the condenser lens 103. After passing through the liquid crystal panel 102, the light reaches the screen 107 via the projection lens 106. Thus, the image displayed on the liquid crystal panel 102 is enlarged and projected on the screen 107. Cooling fan 105 is light source 1
04 is cooled.

In the above-described conventional projector, a halogen lamp, a metal halide lamp, and a short arc xenon lamp are known as light sources.

A halogen lamp is a lamp in which a halogen gas is sealed in a tungsten lamp tube, and uses a halogen regeneration cycle. Since it is relatively small, it can be easily incorporated into an optical system and exchanged, and the price is low, but the efficiency is low and the life is short.

[0005] The metal halide lamp is obtained by enclosing a metal halide as a light emitting substance in an arc tube of a mercury lamp. Various emission spectra can be obtained by selecting the halide to be enclosed. Although the arc length has been reduced for miniaturization, the blackening of the end due to the evaporation of the electrode material has a greater effect on the luminance reduction, resulting in a shorter lamp life. The safety of mercury in lamp tubes also needs to be considered.

[0006] A short arc xenon lamp utilizes light emission due to discharge in xenon gas. Although it is close to a point light source and has high brightness, its luminous efficiency is as low as about 20 to 40 lm / W. When the enclosed xenon gas reaches 20 to 30 atm during lighting, safety measures in the event of breakage are important.

[0007]

Some of the above-mentioned light sources used in conventional projectors include brightness,
No one satisfies the three conditions of compactness and long life at the same time. In conventional projection-type projectors, the lamp power is increased because the brightness of the light source, the light-collecting efficiency of the light-collecting optical system, and the transmission efficiency of the entire optical system are not sufficient. Heat was generated, causing a problem in reliability of image forming means such as a liquid crystal panel. Therefore, it is not possible to reduce the size, and it is inevitable that the arrangement of the cooling fan and the like increases the size, the power consumption, and the noise. Further, leakage light emission increases and efficiency decreases.

Further, the above-mentioned conventional projector light source has a long start-up time and cannot be immediately turned on when the switch is turned on.

In the above-mentioned conventional projector,
Since the point light source is enlarged to a large area by an optical system such as a lens, the periphery of the screen becomes dark (peripheral dimming), and it is difficult to improve the uniformity of the display screen.

Further, the above-mentioned conventional light source for a projector cannot reproduce a color screen with accurate chromaticity due to its light emission principle.

According to the present invention, the display screen is uniform because the periphery of the screen does not become dark even when the display is enlarged in a large area, and the display screen becomes uniform. It is an object of the present invention to provide a light source for a projector and a projector that can reproduce a color screen with accurate chromaticity.

[0012]

A projector light source (FED4) according to claim 1 is a panel-shaped light source, and is an image forming section (liquid crystal panels 3 and D) on which an image is formed.
A light source for a projector applied to a projector for enlarging and projecting the light applied to the MD 23) onto a display unit (screen 25) via an image enlarging means (projection lens 6) has a substantially planar light emitting area. The luminance is adjusted so as to be different depending on the position in the light emitting area so as to compensate for the peripheral dimming of the image enlarged and projected on the display unit by the image enlarging means.

According to a second aspect of the present invention, there is provided a projector light source according to the first aspect, wherein the envelope (9) is evacuated and sealed to a high vacuum state, and the inside of the envelope is provided. A cold-cathode light-emitting device having an anode (anode conductor 15) provided, a phosphor layer (16) provided on the anode, and a cathode (cathode conductor 10) provided in the envelope ( FED4).

According to a third aspect of the present invention, in the projector light source according to the second aspect, the adjustment of the luminance according to the position in the light emitting area is performed by a control signal given to the projector light source. It is characterized by being performed.

According to a fourth aspect of the invention, in the light source for a projector according to the third aspect, the control signal for adjusting luminance according to a position in the light emitting area is supplied to the anode. And a control signal supplied to the cathode.

According to a fifth aspect of the present invention, in the light source for a projector according to the second aspect, the adjustment of luminance according to a position in the light emitting area is determined by a structure of the light emitting area. It is characterized by.

According to a sixth aspect of the present invention, in the light source for a projector according to the fifth aspect, the structure of the light emitting area for adjusting the brightness according to the position in the light emitting area is the cold cathode. It is characterized by being selected from a group of items consisting of an area density of an electron source, an area density of the phosphor layer, and a resistance value of a resistor provided to the anode for each region.

According to a seventh aspect of the present invention, in the light source for a projector according to the second aspect, the cold cathode electron source emits three kinds of phosphors (R, G, and B) which emit red, green, and blue light, respectively. ), And the brightness of the light emitting surface can be adjusted differently depending on the position in the light emitting area for each color.

According to an eighth aspect of the present invention, in the light source for a projector according to the first or second or third or fourth or fifth or sixth or seventh aspect, the cold cathode electron source has at least an emitter (14) and a gate. A field emission device having (12).

According to a ninth aspect of the present invention, there is provided the projector light source according to the first aspect, further comprising an envelope sealed in a high vacuum state, and an anode provided in the envelope. A phosphor layer provided on the anode, a cathode provided in the envelope, an electron-emitting substance provided on the cathode, and the cathode and the phosphor in the envelope. A gate provided between the body layers.

According to a tenth aspect of the present invention, there is provided a projector light source according to the first or second or third or fourth or fifth or sixth or seventh aspect.
Or, in the projector light source of 8 or 9, a heat sink (heat sink 5) directly attached to the back of the light source for heat dissipation is provided.

A projector light source according to an eleventh aspect is the projector light source according to the first aspect, provided with an anode (32), a cathode (35), and between the anode and the cathode. The organic EL element (organic EL element 30) includes an organic layer (organic light emitting layer 34) that generates electroluminescence by a voltage applied between the anode and the cathode.

According to a twelfth aspect of the present invention, there is provided a projector light source according to the first aspect, wherein a large number of LEDs are arranged in a plane.

The projector (liquid crystal projector 1, DMD projector 21) according to the thirteenth aspect of the present invention uses the light from the light source (FED4, organic EL element 30) applied to the image forming section (liquid crystal panel 3, DMD 23) as an image. Display unit (screen 25) via magnifying means (projection lens 6)
In the projector, the light source has a substantially planar light-emitting area, and the luminance of the light-emitting surface is within the light-emitting area so as to compensate for peripheral dimming on a display unit by the image magnifying means. It is characterized in that it is adjusted to be different depending on the position of.

According to the above arrangement, the planar light-emitting area of the light source is brighter in the peripheral part than in the central part. Therefore, when an image is projected through the image magnifying means which is an optical system, it is displayed on the display part. In the obtained image, the brightness of the central part and the peripheral part becomes uniform, and the display quality is improved.

[0026]

FIG. 1 shows a first embodiment of the present invention.
Is a liquid crystal projector 1 which is an example of the first embodiment. Inside the main body 2, there is a liquid crystal panel 3 as an image forming unit. The image forming unit used in the projection type projector includes, in addition to the liquid crystal panel 3, a DMD (Di-gital Micromirror).
Device, an LSI in which a micromirror is arranged on a Si chip used for a projection display, and a spatial light amplifying device.

The light source of this embodiment is arranged in contact with the rear surface of the liquid crystal panel 3. The light source in this example is FED (Field Emiss
ion Display, a field emission display device). FED4
A heat sink 5 for heat dissipation is attached to the back side of the. On the front side of the FED 4, a projection lens 6 as an image enlargement unit is provided. 25 is a screen.

The liquid crystal projector 1 of this embodiment is a panel-type FED 4 having a thin light source and no cooling fan, so that the main body is smaller and more compact than the conventional one, and has almost no noise.

The structure of the FED 4 will be described with reference to FIG. The FED 4 includes a translucent and insulating anode substrate 7,
It has a thin panel-shaped envelope 9 constituted by an insulating cathode substrate 8 and a spacer member (not shown) provided between the outer peripheral portions of the substrates 7 and 8. The envelope 9 has an airtight structure. A cathode conductor 10 is provided on the inner surface of the cathode substrate 8 of the envelope 9. An insulating layer 11 is formed on the cathode conductor 10. On the insulating layer 11, a gate 12 is formed as a lead electrode. Insulating layer 11 and gate 1
A hole 13 is formed in 2, and a cone-shaped emitter 14 is formed on the cathode conductor 10 exposed in the hole 13. A light-transmitting anode conductor 15 is formed on the inner surface of the anode substrate 7 of the envelope 9, and a single type of phosphor layer 16 is formed in a solid shape thereon.

In the FED 41 having such a structure, when an appropriate voltage is applied to the gate 12 and the anode conductor 15 with respect to the cathode conductor 15, electrons are field-emitted from the tip of the emitter 14, and collides with the anode to emit phosphor. The layer 16 emits light.
Light emission of the phosphor layer 16 is observed from outside the anode substrate 7 through the translucent anode conductor 15 and the anode substrate 7.

In the FED 4, the side of the cathode substrate 8 on which the emitters 14 for emitting electrons are formed is the back side, and the heat sink is attached. The side of the anode substrate 7 on which the light emitting phosphor layer 16 is provided is the front side, and faces the projection lens 6.

FIG. 3 schematically shows the density of the emitters 14 formed on the cathode substrate 8 in the FED 4 of this embodiment. Here, the region S on the cathode substrate 8 is divided into three regions S1, S2, and S3 from the center. The emitter density is the lowest in the central region S1, the middle rectangular annular region S2 follows, and the outer rectangular annular region S3 is the highest. On the other hand, the phosphor layer 16 on the anode side is solid, and its density is constant everywhere. Emitter 14
When the density is high, the amount of emitted electrons is large, and the brightness of the display region of the anode facing such an outer region increases. Conversely, when the density of the emitter is low, the amount of emitted electrons is small, and the brightness of the display region of the anode facing such a central region is low.

Since the optical element such as the projection lens 6 used for the enlarged projection has optical aberrations, the center of the projected image is relatively bright, but the periphery of the image is dark (peripheral reduction). Light) occurs. Therefore, in this example, the projection density is increased by increasing the arrangement density of the emitters 14 in the peripheral region that becomes darker, increasing the emission luminance itself in the corresponding display region, and superimposing with the effect of the peripheral dimming. The brightness of the entire screen was made uniform.

The area, shape, and number of steps of the density distribution of the emitter 14 depend on the characteristics of the image forming means such as the liquid crystal panel 3, the DMD, and the spatial light amplifying device to be used, and the characteristics of the optical system used in combination therewith. In addition, the setting may be made so that the uniformity of the projection screen can be made as high as possible. For example, the density region of the emitter 14 has three levels in this example, but may have two levels or four or more levels.

In the first example, in order to compensate for peripheral dimming of an image enlarged and projected by the projection lens 6, the area density of the emitter 14 is changed so that the luminance varies depending on the position in the light emitting region. did. If the structure of the light source is fixedly set in accordance with the characteristics of the projection lens in this way, it is not suitable for other projection lenses having different optical characteristics. In such a case, as will be described later, the drive signal given to the light source may be adjusted so that the luminance is adjusted according to the position in the light emitting area.

A second example will be described. In the first example described above, the phosphor layer 16 is formed of a single type in a solid shape, and the light emitting region emits light of a single color. Unlike this, the FEC
In 1, the anode may be capable of performing any color display. An anode conductor is formed in a stripe shape on the inner surface of the anode substrate 7 and, as schematically shown in FIG.
Three kinds of phosphors emitting light of each color (red), G (green), and B (blue) are formed on the anode conductor in a predetermined order. Each anode conductor is insulated for each emission color of the phosphor layer, and each is driven. With such a structure capable of color display, by changing the light emitting area of each color of RGB and the voltage applied to each anode conductor, the white surface brightness of the screen projected on the display unit after passing through the liquid crystal panel 3 can be improved. , The chromaticity can be adjusted. Further, even if the luminous efficiency of each phosphor changes after a long period of use and a color tone shift occurs, this can be corrected. Note that the above-described effects can be obtained with two colors or four or more colors instead of three colors.

A third example will be described. In the first example,
The arrangement (area density) of the emitters 14 was changed in order to compensate for peripheral dimming of an image enlarged and projected by the projection lens 6. Another example in which the structure of the light source is set in accordance with the characteristics of the projection lens 6 will be described with reference to FIG. FIG.
4 schematically shows the area density of the phosphor layer 16 formed on the anode substrate 2 in the FED 4. The change in the area density can be realized, for example, by partially changing the area or pitch of the dots or stripes of the phosphor layer. Here, the light emitting area A on the anode substrate 7 is 3
Area A1, A2, A3. Phosphor layer 16
Is the lowest in the central area A1, the middle rectangular annular area A2 is connected to it, and the outer rectangular annular area A3 is the highest. On the other hand, the arrangement density of the cathode-side emitters 14 is constant. Even if the amount of electrons emitted by the emitter 14 is constant, the brightness of the outer light emitting region A3 where the density of the phosphor layer is high is high. Conversely, the luminance of the central light emitting region A1 where the density of the phosphor layer is low is low. Even with such a structure, the brightness of the entire projected screen becomes uniform.

The anode conductor is electrically divided for each area to be set so that the brightness is adjusted according to the position in the light emitting area, and a resistance is provided for each anode conductor. Alternatively, the luminance may be different for each region.

A fourth example will be described. In the first example, the structure of the light source is a diode type. That is, the cathode is formed on the inner surface of the cathode substrate of the envelope, and the electron emission material layer is formed thereon. Also, a phosphor layer is formed on the inner surface of the anode substrate of the envelope, and a metal back is provided on the surface.
By changing the density or thickness of the electron emitting material layer or the density or thickness of the phosphor layer, the effect of peripheral dimming due to the optical system can be canceled to make the brightness of the entire projected screen uniform.

A fifth example will be described. FED as a light source
The four light-emitting regions can be graphically displayed by an XY matrix electrode structure. For example, the cathode conductor and the gate are formed in a stripe shape crossing each other, and are driven in a matrix. If a display signal is applied to the anode conductor in accordance with this, a portion at an arbitrary position and shape in the display region can emit light with an arbitrary luminance. That is, light is emitted so that the portion near the center of the light emitting region is relatively dark and the periphery is relatively bright. As a result, the influence of the vignetting caused by the optical system can be canceled, and the luminance of the entire projected screen can be made uniform.

As described above, the adjustment of the luminance according to the position of the light source in the light emitting region is performed by adjusting the drive signal applied to the light source (the drive signal applied to the anode and / or the drive signal applied to the cathode).
Can also be done.

A sixth example will be described. FIG. 6 shows the DMD of this example.
The projector 21. Inside the main body 22, there is a DMD 23 as an image forming unit. Below the DMD 23, the FED 4 (or the light sources of the second to fifth examples described above) is arranged. On the back side of the FED 4, a heat sink 5 for heat radiation is attached. A condenser lens 24 is provided on the front side of the FED 4. DMD2
The light reflected by 3 is enlarged and projected on a screen 25 via a projection lens 6 as an image enlarging means.

The DMD projector 21 of this embodiment has a thin light source in a panel shape and has no cooling fan. Also, DMD
Since 23 is a reflection type, the overall size of the apparatus is smaller in the axial direction of the projection lens 6 than in the first example. Also in this example, it is possible to cancel out the effect of vignetting caused by the optical system and to make the luminance of the entire projected screen uniform.

A seventh example will be described. FIG. 7 shows an organic EL element 30 used as a light source in the projector of the present invention. Portions other than the light source are the same as in the first example. Organic EL
The element 30 has a structure in which a thin film containing a fluorescent organic compound is sandwiched between a cathode and an anode, and electrons and holes are injected into the thin film to be recombined, so that excitons (excitons) are formed.
Is generated, and display is performed by utilizing light emission (fluorescence / phosphorescence) when the exciton is deactivated.

As shown in FIG. 7, the organic EL element 30
The anode 32 on the substrate 31 is made of ITO, the hole transport layer 33 is made of Diamine, and the organic light emitting layer 34 is made of tris (8-quinolinolato) aluminum (III) (Alq ₃ ).
, And an alloy of magnesium and silver is used for the cathode 35. The thickness of each organic layer is about 50 nm.
Each layer is formed by vacuum evaporation. When a direct current of 10 V is applied to the organic EL element 30, green light emission of about 1000 cd / m ² is obtained. This light is emitted from the ITO anode 3.
Take out from two sides.

An eighth example will be described. This example is an LED light emitting element used as a light source in a projection type projector. This LED light emitting element is configured by arranging a large number of LEDs vertically and horizontally in a plane, and is configured to be able to selectively emit an LED at an arbitrary position. In this example, similarly to the above examples, it is possible to configure so that a portion having an arbitrary position and shape in the display area emits light at an arbitrary brightness. That is, the portion near the center of the light emitting region is relatively dark, and the periphery is relatively bright. For this purpose, the arrangement density of LEDs can be changed depending on the area,
The light emission time of the LED may be changed depending on the area.
As a result, it is possible to make the luminance of the entire projected screen uniform by canceling out the effect of vignetting by the optical system.

[0047]

According to the present invention, in the projector, the brightness in the planar light emitting area of the light source is adjusted according to the position so as to compensate for the peripheral dimming of the image by the image enlarging means. Even when the display is enlarged to the area, the periphery of the screen is not darkened, and the display screen becomes uniform. Also, the screen is bright.
It is compact, has a long service life, generates less heat,
The starting time is short and a color screen can be reproduced with accurate chromaticity.

[Brief description of the drawings]

FIG. 1 is a schematic structural diagram showing a first example of an embodiment of the present invention.

FIG. 2 shows an FED used as a light source in a first example.
4 is a sectional view of FIG.

FIG. 3 is a diagram showing, in the FED 4 of the first example, regions in which the area densities of the emitters are different.

FIG. 4 is a diagram schematically showing a configuration of a light emitting region of an anode in a second example.

FIG. 5 is a diagram showing, in the light source of the third example, regions where the area densities of the phosphor layers in the light emitting region of the anode are different.

FIG. 6 is a schematic structural diagram of a DMD projector as a sixth example.

FIG. 7 shows an organic E used as a light source in a seventh example.
It is sectional drawing which shows the basic structure of L element typically.

FIG. 8 is a diagram schematically showing a configuration of a conventional liquid crystal projector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal projector as a projector 3 Liquid crystal panel as an image formation part 4 FED (field emission light emitting element) as a light source 5 Heat sink 6 Projection lens as an image enlargement means 9 Envelope 10 Cathode conductor as a cathode 12 Gate 14 Emitter Reference Signs List 15 anode conductor as anode 16 phosphor layer 21 DMD projector as projector 23 DMD as image forming unit 30 organic EL element as light source 32 anode 34 organic light emitting layer as organic layer 35 cathode

Claims (13)

[Claims] 1. A light source for a projector which is applied to a projector for enlarging and projecting light irradiated on an image forming portion on which an image is formed on a display portion via an image enlarging means, wherein a substantially planar light emitting area is provided. A panel, wherein brightness is adjusted to be different depending on a position in the light emitting area so as to compensate for peripheral dimming of an image enlarged and projected on the display unit by the image enlarging means. Light source for projectors. 2. An envelope sealed and evacuated to a high vacuum state,
2. A cold cathode light emitting device comprising: an anode provided in the envelope; a phosphor layer provided on the anode; and a cold cathode electron source provided in the envelope.
The light source for a projector according to the above. 3. The light source for a projector according to claim 2, wherein the adjustment of the luminance according to the position in the light emitting region is performed by a control signal given to the light source for the projector. 4. The control signal according to claim 3, wherein the control signal for adjusting luminance according to a position in the light emitting region is selected from a control signal applied to the anode and a control signal applied to the cathode. Light source for projector. 5. The light source for a projector according to claim 2, wherein the adjustment of the luminance according to the position in the light emitting area is determined by the structure of the light emitting area. 6. The structure of the light emitting region in which the brightness is adjusted according to the position in the light emitting region, the density of the cold cathode electron source, the area density of the phosphor layer, and the 6. The light source for a projector according to claim 5, wherein the light source for a projector is selected from an item group constituted by a resistance value of a resistor provided on the anode. 7. The cold cathode electron source has three types of phosphors that emit red, green, and blue light, and adjusts the luminance of the light emitting surface for each color so as to differ depending on the position in the light emitting region. 3. The light source for a projector according to claim 2, which can be used. 8. The light source for a projector according to claim 1, wherein the cold cathode electron source is a field emission device having at least an emitter and a gate. 9. An envelope evacuated and sealed to a high vacuum state,
An anode provided in the envelope, a phosphor layer provided on the anode, a cathode provided in the envelope, and an electron-emitting substance provided on the cathode, The light source for a projector according to claim 1, further comprising a gate provided between the cathode and the phosphor layer in the envelope. 10. The light source for a projector according to claim 1, wherein the heat sink has a heat sink directly attached to the back of the light source for heat dissipation in claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9. 11. An organic EL light emitting device comprising an anode, a cathode, and an organic layer provided between the anode and the cathode and generating electroluminescence by a voltage applied between the anode and the cathode. The light source for a projector according to claim 1. 12. The light source for a projector according to claim 1, wherein a number of LEDs are arranged in a plane. 13. A projector for enlarging and projecting light from a light source applied to an image forming unit to a display unit via an image enlarging unit, wherein the light source has a substantially planar light emitting area, The brightness of the light emitting surface is adjusted so as to be different depending on a position in the light emitting area so as to compensate for vignetting on a display unit by the means.