JP2942155B2 - Projection type image display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for displaying an image by transmitting light from a light source to transmission type display means such as a transmission type display element and forming an image of the transmitted light on a screen. The present invention relates to a projection type image display device applied to a projection type TV system and an information display system.

[0002]

2. Description of the Related Art A transmissive display panel does not emit light by itself, but displays images and characters by modulating the intensity of light from a light source by changing the light transmittance by a drive signal. Examples of the transmissive display panel include a liquid crystal display panel, an electrochromic display, and a PLZ.
There are displays and the like using translucent ceramics such as T (Lead Zirco-Titanate doped with lanthanum). Among them, liquid crystal display panels are widely used for pocketable TVs, word processors and the like.

In such a liquid crystal display panel, the smallest display units called picture elements are regularly arranged, and the optical characteristics of the liquid crystal are changed by applying independent driving voltages to these picture elements. , Thereby displaying images and characters. Methods for applying an independent drive voltage to each picture element include a simple matrix method and an active matrix method.

In the active matrix system, each picture element is provided with an element such as a thin film transistor (TFT) or a thin film diode (MIM), and a line for supplying a drive signal to these elements is provided in each picture element. It must be wired in the gap. For this reason, the ratio (opening ratio) occupied by the picture element region on the screen is reduced.

[0005] In the light applied to the liquid crystal display panel, light incident on an area other than the picture element area is not modulated by the display signal. Furthermore, in a liquid crystal display panel in which the display operation mode is a normally black mode, that is, an operation mode in which light is not transmitted when an electric field is not applied to the liquid crystal layer, light incident on an area other than the picture element area impinges on the display panel. Does not transmit. On the other hand, in a liquid crystal display panel in which the display operation mode is a normally white mode, that is, an operation mode in which light is transmitted when no electric field is applied to the liquid crystal layer, light incident on an area other than the picture element area causes the display panel to emit light. When transmitted, the black level of the display screen rises, thus lowering the contrast. To prevent this, if necessary, light-shielding masks (hereinafter, referred to as
"BM") to absorb or reflect light that does not contribute to display.

[0006] However, when the liquid crystal display panel having the above configuration is projected, stripes due to the BM are conspicuous on the screen, and the image quality is reduced.

Therefore, as a technique for preventing the image quality from deteriorating due to the BM, for example, JP-A-59-21
No. 4,825, JP-A-63-114475, and U.S. Pat. No. 5046827.

In the technique disclosed in the above publications, a diffraction grating is inserted into an optical path on the light emission side of a liquid crystal display panel, and the light emitted from the liquid crystal display panel is diffracted by the diffraction grating, and the BM is originally displayed on a screen. A method is adopted in which light passing through the picture element opening of the liquid crystal display panel is made incident on the position where an image is formed to make the BM inconspicuous.

Japanese Unexamined Patent Publications Nos. 6-130356 and 6-130378 disclose a method of forming a virtual image by using a refraction effect of a micro prism and also making a BM inconspicuous. . In another method, as disclosed in JP-A-6-123868,
Using a plurality of projection-type image display devices, an image is superimposed and projected such that the picture element opening of one liquid crystal display panel overlaps the BM of the picture element of another liquid crystal display panel. At this time, there is a method in which a parallel plate element is inserted into the entire optical path near the projection lens, and a plurality of fine adjustments on the screen, that is, picture element alignment are performed by changing the inclination angle.
However, this method is effective only when the images of a plurality of projection image display devices are projected onto the screen at one time because all the light projected from one projection image display device to the screen is shifted.

[0010]

However, the above-mentioned conventional projection-type image display devices have the following problems. Hereinafter, a description will be given by optical path analysis.

First, in a method using a diffraction grating,
The light diffraction angle is as shown in equation (1).

Sin θ _m −sin α = mλ / D (1) where m is the order of the diffracted light, and θ _m and α are the m-th order diffracted light and the incident light with respect to the optical axis, respectively. At an angle,
λ represents the wavelength of the incident light. In this method, as shown in FIG. 9, the BM on the screen 72 is made inconspicuous by using low-order diffracted lights of the 0th order and ± 1st order. The second-order and ± first-order diffracted lights are not 100%, but second- or higher-order diffracted lights are also present. The diffracted light of the second or higher order causes diffraction loss and not only decreases the brightness contributing to the display, but also causes the display quality to deteriorate because the light spreads in a funnel shape. further,
Since the diffraction grating 71 has wavelength dependency and the diffraction angle differs for each color, there is a problem that the shift amount of the picture element differs for each color, as is clear from the equation (1).

In the method using the above-mentioned micro prism,
As shown in FIG. 10, a micro prism array 81 having a vertex angle γ and a refractive index n ₃ is used.
1a, that is, a configuration in which a parallel light beam is incident from a surface on which a micro prism is not formed. In this case, the deflection angle β of the outgoing light with respect to the light beam perpendicularly incident on the micro prism array 81 is as follows: β = | γ−cos ⁻¹ (n ₃ cosγ) | (2)

Here, the thickness of the glass substrate on the light emission side of the liquid crystal display panel 82 is t ₁ , the distance between the liquid crystal display panel 82 and the micro prism array 81 is t ₂ , the substrate thickness of the micro prism array 81 is t ₃ , Assuming that the refractive index of the glass substrate in the display panel 82 is n ₁ and the refractive index between the liquid crystal display panel 82 and the micro prism array 81 is n ₂ , when the liquid crystal display panel 82 is observed from the prism forming surface, the virtual image P is compared with the real image P. '· P "can be two, each virtual image P' · P" in each picture element opposite _{direction, d = (t 1 / n} 1 + t 2 / n 2 + t 3 / n 3) × tanβ ......... ( 3) It looks as if it has shifted by the shift amount d represented by. Therefore, the mountain-shaped one-dimensional micro prism array 81
If the shift amount d is 1/4 of the pixel pitch in the case of
The stripes due to M become inconspicuous, and the image quality is improved.

Since the method using the micro prism is not a diffraction but a multiple image formation by refraction, if a material having a small refractive index wavelength dependence is used for the prism member, the shift amount for each color is smaller than that of the diffraction grating 71. The difference can be reduced. In addition, there is no need to manufacture a different minute prism for each different liquid crystal display panel 82, and the feature is that adjustment can be made by adjusting the distance t ₂ between the liquid crystal display panel 82 and the minute prism 81.

However, for example, a micro prism array 81 having a vertical angle of 60 °, a refractive index of 1.53, and a substrate thickness of 0.1 mm.
Assuming that the liquid crystal display panel 82 having a glass substrate thickness of 1.1 mm is used, the minimum shift amount is d = 284 μm when t ₂ = 0 from the equations (2) and (3). When this shift amount is 1/4 of the pixel pitch, the liquid crystal display panel 8 having a pixel pitch of 1136 μm or more is calculated backward.
However, there is a problem that only the second method can be dealt with.

In order to address the above problem and apply to a high-definition panel with a finer pixel pitch, a method of reducing the thickness t ₁ of the glass substrate and the thickness of the prism substrate of the liquid crystal display panel 82 or the top of the micro prism array 81 A method of increasing the angle γ is conceivable. For example, when a liquid crystal display panel 82 having a pixel pitch of 60 × 60 μm and a pixel opening size of 30 × 30 μm is used, a method of reducing the substrate thickness of the liquid crystal display panel 82 and the micro prism array 81 is as follows. It is necessary to make the sum of the thicknesses of the substrate and the micro prism array 81 63.4 μm, but it is very difficult to use a glass substrate of about several tens μm as the liquid crystal display panel 82. In the method of increasing the vertex angle γ, the pixel pitch is also 60 × 60 μm, and the pixel opening is 30 × 30 μm.
If the substrate thickness of the liquid crystal display panel 82 having a glass substrate thickness of 1.1 mm and the micro prism array 81 is 0.1 mm, the apex angle γ is 88 °. In other words, it is a small prism with almost no irregularities, making it difficult to manufacture, and even if it can be manufactured, the accuracy of the prism becomes a problem, and raising the accuracy will cause an increase in cost. have.

On the other hand, the method of superimposing and projecting the images of a plurality of projection type image display devices on a screen not only increases the cost significantly but also increases the size of the devices themselves.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to realize a bright, smooth, natural image at low cost without losing the definition of a liquid crystal display panel. It is an object of the present invention to provide a projection-type image display device which can be used.

[0020]

According to a first aspect of the present invention, there is provided a projection type image display apparatus comprising: a plurality of picture elements arranged in a matrix and a matrix other than these picture elements; a transmissive matrix type display panel in which the Jo having a light shielding mask, a micro-prism array formed by arranging a large number of micro-prisms on the light emission side of the matrix display panel and a projection screen disposed on the light exit side in the projection type image display device provided with the above
In the micro prism array, the shape of each micro prism is one-dimensional
The micro prisms are formed and arranged
Intersect and different from the refractive index of the micro prism
Composed of two sheets joined via a leveling layer having a refractive index
It is characterized by being done.

[0021]

The operation of the projection type image display apparatus according to the first aspect will be described with reference to FIGS.

First, as shown in FIG. 3, using a micro prism array having a vertex angle γ and a refractive index n ₃ , a refractive index n is formed on the surface of the micro prism array (the surface on which the micro prisms are formed).
The leveling layer of No. ₄ is formed. Then, a parallel light beam is made incident from the back surface of the micro prism array (the surface on which the micro prism is not formed), and observation is performed from the light emission side of the micro prism array. At this time, as shown in FIG. 1, two virtual images P ′ · P ″ are generated with respect to the real image P due to the effect of refraction.

For the sake of simplicity, let us consider normal incident light on a matrix type display panel. As shown in FIG. 3, the deflection angle α of the emitted light at the prism interface
Is α = | γ−cos ⁻¹ ((n ₃ / n ₄ ) cos γ) | (4), and the final contact angle 出 射 of the emitted light is ζ = sin ⁻¹ (n ₄ sin α) ……… (5)

Here, the thickness of the glass substrate on the light emission side of the matrix type display panel is t ₁ , the distance between the matrix type display panel and the micro prism array is t ₂ , the substrate thickness of the micro prism array is t ₃ , and the leveling layer is Observing the matrix-type display panel from the prism-forming surface with the thickness t ₄ , the refractive index of the glass substrate of the matrix-type display panel as n ₁ , and the refractive index between the matrix-type display panel and the micro prism array as n ₂ , As described above, the real image P of the picture element
(See FIG. 1), and d = (t ₁ / n ₁ + t ₂ / n ₂ + t ₃ / n ₃ + t ₄ / n ₄ ) × tanζ in the opposite direction. ... it seems shifted by the shift amount d of the formula (6). However, t ₄ is considerably smaller than the t ₁ ~t _3,
Often negligible.

Here, if the shift amount d is preferably adjusted to be about one-fourth of the pixel pitch of the matrix type display panel, the pixel becomes a double image on the projection screen. The stripes formed by the light-shielding masks arranged in a matrix in the region (1) become inconspicuous and a smooth image can be obtained.

On the other hand, in the present invention, a leveling layer having a refractive index different from that of the micro prism and having a smooth surface opposite to the prism forming surface is laminated on the prism forming surface of the micro prism array. (4),
(5) and (6) as shown in the expression can be changed freely shift amount d by changing the ratio between the refractive index n ₄ of the refractive index n ₃ and the leveling layer of the micro prism array.

As a result, a single type of micro prism array can cope with all of the different matrix type display panels, so that a significant cost reduction can be achieved.

Further, since the double image according to the present invention is due to the refraction effect of the minute prism, it is free from the diffraction loss that occurs when a diffraction grating is used, and a bright and sharp image can be obtained. Further, by using a leveling layer having a small dependence of the refractive index on the wavelength, the difference in the shift amount d for each color can be reduced as compared with the diffraction grating.

Further, since the leveling layer provided on the surface of the micro prism also functions as a protective film, the surface of the prism is not easily damaged and cleaning is easy.

Further, the micro prism array is provided for each micro projector.
When the rhythm shape is formed and arranged one-dimensionally,
The micro prisms are orthogonal to each other and the micro prisms are
A leveling layer with a different refractive index from the
It is configured by joining two sheets through the intermediary.

Here, in the case where two micro prism arrays arranged and arranged one-dimensionally, such as a V-shaped cross section or a trapezoidal cross section, are used as the shape of each micro prism, a cross section is used. Two one-dimensional minute prism arrays having a pointed V-shape are equivalent to a two-dimensional small prism array having a quadrangular pyramid, and two one-dimensional minute prism arrays having a trapezoidal cross section are equivalent to a two-dimensional minute prism array having a truncated pyramid. .

When the shape of the light exit surface of each micro prism in the micro prism array is formed in a polygonal pyramid or a truncated polygonal pyramid, if the aspect ratio of the picture element pitch changes, the ratio depends on the ratio. It is necessary to use such a micro prism array or to perform a procedure such as leveling each micro prism surface with a leveling layer having a different refractive index. However, when two one-dimensional micro-prism arrays are used, it is possible to perform leveling for each one-dimensional micro-prism array using a leveling layer having a different refractive index. As a result, even if the same micro prism array is used, it is possible to cope with a change in the pixel pitch.

Further, when the micro prism faces are joined face to face, the prism faces can be protected more robustly than the protection by leveling.

[0034]

[Embodiment 1] An embodiment of the present invention is described below with reference to FIGS. Note that the projection type image display device of the present embodiment displays an image by inputting light from a light source to transmission type display means such as a transmission type display element and forming an image of the transmitted light on a screen. Large screen projection TV
It is applied to systems and information display systems.

As shown in FIG. 2, the projection type image display device 1 has a liquid crystal display panel 2 as a transmission type matrix display panel. On one side of the liquid crystal display panel 2, a light source 3 having a parabolic mirror 4 is provided.
Light is emitted from the light source 3 toward the liquid crystal display panel 2.

As the light source 3, a metal halide lamp is used. Alternatively, for example, a xenon lamp or a halogen lamp can be used.

The parabolic mirror 4 directs the light emitted from the light source 3 to the liquid crystal display panel 2. The condensing system is not limited to the parabolic mirror 4, and a method using a spherical mirror and a condensing lens, a method using a spheroidal mirror and an integrator, and the like can also be used.

In the liquid crystal display panel 2, the smallest display units called picture elements (not shown) are regularly arranged in a matrix, and the drive voltage applied to each of these picture elements is independent of each other. The optical properties change,
As a result, images and characters are displayed. In this embodiment, the liquid crystal display panel 2 is used as a transmissive matrix display panel. However, the present invention is not limited to this. For example, an electrochromic display, a PLZT (L
A transmissive display device provided with a non-luminous BM, such as a display using a translucent ceramic such as ead Zirco-Titanate doped with lanthanum, can also be used.

As a method for applying an independent drive voltage to each of the picture elements, there are a simple matrix method and an active matrix method, and both methods can be used in the present invention. In this embodiment, an active matrix system is adopted, and a thin film transistor (T
FT) or a thin film diode (MIM).
Lines for supplying drive signals to these elements are arranged in the gaps between the picture elements.

The pixel pitch of the liquid crystal display panel 2 is, for example, 80 μm × 80 μm, and the pixel region is, for example, 50 μm × 50 μm. The glass substrate thickness of the liquid crystal display panel 2 is, for example, 1.1 mm, and the refractive index of the glass substrate is, for example, 1.53. The operation mode of the liquid crystal uses twisted nematic, but other modes can be used. The liquid crystal display panel 2 has a normally white mode, that is, an operation mode in which light is transmitted when no electric field is applied to the liquid crystal layer. In the normally white mode liquid crystal display panel 2, when light incident on an area other than the picture element area passes through the display panel, the black level of the display screen rises, so that the contrast is reduced. Therefore, in order to prevent this, a BM (not shown) is provided in a matrix shape in a region other than the picture element so as to absorb or reflect light that does not contribute to display.

In the projection type image display device 1, an infrared and ultraviolet cut filter 5 is provided on the light source 3 side of the liquid crystal display panel 2, while a micro prism array 6 and a field A lens 7, a projection lens 8, and a projection screen 9 are provided in this order.
The light emitted from the light source 1 is collimated by the parabolic mirror 4 and then converted to infrared and ultraviolet cut filters 5.
Through the microscopic prism array 6, the field lens 7, and the projection lens 8, and projected on the projection screen 9.

Incidentally, the above-mentioned micro prism array 6
As shown in FIG. 1, a large number of micro prisms for bending the direction of light emitted from a picture element are arranged. This micro prism array 6 has a refractive index of 1.53 and a thickness of 0.6 mm.
A substrate having a refractive index of 1.53 and an apex angle γ of 6
It is an aggregate of one-dimensional micro prisms in which a large number of micro prisms each having a mountain shape having a V-shaped section with a point of 0 ° are assembled at a pitch of 100 μm.

On the light emitting side of the micro prism array 6, a leveling layer 20 which is fitted in the above-mentioned continuous mountain shape and has a smooth surface on the projection screen 9 side is laminated.
The refractive index of the leveling layer 20 is 1.50, which is different from the refractive index of the micro prism array 6.

The relative positional relationship between the liquid crystal display panel 2 and the micro prism array 6 is based on
Are arranged so that the vertical direction of the screen and the prism grooves of the micro prism array 6 are parallel to each other.

The micro prism array 6 having the above configuration
Will be described. The light incident on the micro prism array 6 through the liquid crystal display panel 2 forms two virtual images P ′ · P ″ with respect to the real image P due to the refraction effect of the micro prism array 6 as shown in FIG. When observed from the light exit side of the micro prism array 6, it looks as if the picture elements on the liquid crystal display panel 2 have moved left and right by the shift amount d from the position of the original real image P. Therefore, on the projection screen 9, The two virtual images P ′ and P ″ are projected such that the images of the liquid crystal display panel 2 shifted left and right from the original position by the shift amount d are superimposed.

The above will be described in detail. That is, as shown in FIG. 3, as a generalized one, the apex angle of each micro prism in the micro prism array 6 is γ, and the refractive index is n _3.
It is assumed that a leveling layer 20 having a refractive index of n ₄ is formed on the surface of each micro prism in the micro prism array 6. When a parallel light beam is incident from the back surface of the micro prism array 6, that is, the surface on which the micro prism is not formed, when the parallel light beam is observed from the light emission side of the micro prism array 6, as shown in FIG. Due to the effect, two virtual images P ′ · P ″ are generated.

For simplicity of description, the liquid crystal display panel 2
Let's consider the normal incident light on. As shown in FIG. 3, the deflection angle α of the outgoing light at the prism interface is as follows: α = | γ−cos ⁻¹ ((n ₃ / n ₄ ) cosγ) | The contact angle of the emitted light is as follows: ζ = sin ⁻¹ (n ₄ sinα) (5)

Here, the substrate thickness of the glass substrate 2a on the light emission side in the liquid crystal display panel 2 is t ₁ ,
T ₂ , the substrate thickness of the micro prism array 6 is t ₃ , and the thickness of the leveling layer 20 is t
₄ , the refractive index of the glass substrate 2a in the liquid crystal display panel 2 is n ₁ , and the liquid crystal display panel 2 and the micro prism array 6
When the liquid crystal display panel 2 is observed from the prism-formed surface with the refractive index between n ₂ and n ₂ , _two virtual images P ′ · P ″ are formed for the picture element of the real image P as described above (see FIG. 1). ),
It is apparent that the shift is performed by the shift amount d represented by the following equation: d = (t ₁ / n ₁ + t ₂ / n ₂ + t ₃ / n ₃ + t ₄ / n ₄ ) × tanζ (6) Looks like. However, the thickness t ₄ of the leveling layer 20 is t ₁ ~t ₃
It is considerably smaller than that and can often be ignored.

Here, preferably, when the shift amount d is adjusted so as to be about ４ of the pixel pitch of the liquid crystal display panel 2, the pixel becomes a double image on the projection screen 9 and the BM
Stripes are not conspicuous and a smooth image is obtained.

Therefore, in the present embodiment, the shift amount d is set to about one-fourth of the pixel pitch, that is, about 20 μm.
The leveling layer 2 is made of a substance having a refractive index of 1.50 on the surface of the micro prism array 6 so that the prism peaks are just hidden.
0 is formed on the light emitting surface of the liquid crystal display panel 2 via an adhesive layer controlled to 60 μm by a spacer (not shown) so that the prism forming surface is on the projection screen 9 side with the micro prism array 6 and the leveling layer 20. Are pasted together.

As a result, as shown in FIG.
A virtual image (indicated by a solid-line square in the figure) of the picture element opening is superimposed on a position (indicated by a dashed line in the figure) where only the image 10 is formed, and an image is formed. Image is obtained.

As described above, in the projection type image display apparatus 1 of the present embodiment, the prism forming surface of the micro prism array 6 has a refractive index n ₄ different from the refractive index n _{3 of the} micro prism, and The light emitting surface is formed by laminating a leveling layer 20 having a smooth surface.

Therefore, on the projection screen 9, a virtual image P ′ · P ″ shifted by the shift amount d with respect to the picture element of the real image P is formed. If the pitch is adjusted to be about a quarter of the pitch, the picture element becomes a double image on the projection screen 9, so that the stripes due to the BM are not conspicuous and a smooth image is obtained.

On the other hand, in this embodiment, a leveling layer 20 having a refractive index n ₄ different from the refractive index n ₃ of the micro prism and having a smooth light exit surface is laminated on the prism forming surface of the micro prism array 6. and for that, the (4), (5) and (6) as shown in equation freely by changing the ratio between the refractive index n ₄ of the refractive index n ₃ and the leveling layer 20 of the micro prism array 6 The shift amount d can be changed.
As a result, as will be described later, since one type of micro prism array 6 can cope with all of the different liquid crystal display panels 2, it is possible to significantly reduce costs.

Further, since the double image in the present embodiment is due to the refraction effect of the minute prism, it has no relation to the diffraction loss that occurs when a diffraction grating is used, and a bright and sharp image can be obtained. it can. Further, by using the leveling layer 20 having a small dependence of the refractive index on the wavelength, the difference in the shift amount d for each color can be reduced as compared with the diffraction grating.

Further, since the leveling layer 20 provided on the surface of the micro prism also functions as a protective film, the surface of the prism is hardly damaged and cleaning is easy.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, in the above embodiment, the liquid crystal display panel 2
Is 55 × 55 μm, and the pixel opening is 28
It can be changed to a size of × 28 μm.

Thus, the substrate thickness t ₁ of the glass substrate 2a on the emission side of the liquid crystal display panel 2, the distance t ₂ between the liquid crystal display panel 2 and the micro prism array 6, the substrate thickness t ₃ of the micro prism array 6, the leveling layer 20 thickness t ₄ ,
The refractive index n ₁ of the glass substrate 2a of the liquid crystal display panel 2 and the refractive index n ₂ between the liquid crystal display panel 2 and the micro prism array 6 are not changed at all, and the refractive index of the leveling layer 20 of the micro prism array 6 is 1 .51, the stripes due to the BM can be made inconspicuous and a smooth image can be obtained.

In this embodiment, the formation surface of the micro prisms in the micro prism array 6 is on the projection screen 9 side, and the leveling layer 20 has a smooth surface on the projection screen 9 side, but is not necessarily limited to this. Instead, the formation surface of the micro prism can be arranged on the liquid crystal display panel 2 side, and the smooth surface of the leveling layer 20 can be formed on the liquid crystal display panel 2 side, and the effect is the same.

Further, in this embodiment, the liquid crystal display panel 2
The relative positional relationship between the liquid crystal display panel 2 and the micro prism array 6 is set such that the vertical direction of the screen of the liquid crystal display panel 2 and the prism groove of the micro prism array 6 are parallel to each other. The one-dimensional micro prism array 6 having a trapezoidal cross section may be inserted in parallel with the vertical direction or the diagonal direction of the display surface of the liquid crystal display panel 2. It is also possible to use other one-dimensional micro prism arrays 6.

Further, in this embodiment, an example in which the shift amount d of the image is set to 1/4 of the pixel pitch is shown. However, the shift amount d may be any value as long as the resolution does not decrease. Pixels may partially overlap.

Embodiment 2 The following will describe another embodiment of the present invention with reference to FIGS. 5 and 6. For the sake of convenience, members having the same functions as those shown in the drawings of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, as shown in FIG. 5, a two-dimensional micro prism array 16 having a quadrangular pyramid at the top is used. The optical system has the same configuration as that of the first embodiment. The liquid crystal display panel 2 has a pixel pitch of 80 μm × 80 μm, a pixel region of 40 μm × 40 μm, a glass substrate 2a having a thickness of 1.1 mm ^t , The glass substrate 2a having a refractive index of 1.53 is used. The two-dimensional micro prism array 16
On a substrate having a refractive index of 1.53 and a thickness of 0.6 mm, a material having the same refractive index of 1.53 and a vertical angle γ of 60
The four-sided pyramid micro-prisms are formed at a pitch of 100 μm both vertically and horizontally, and the four-sided pyramids of the prisms are just covered by a substance having a refractive index of 1.50.
Used as The relative positional relationship between the liquid crystal display panel 2 and the two-dimensional micro prism array 16 is such that the vertical and horizontal directions of the screen of the liquid crystal display panel 2 and the vertical and horizontal directions of the two-dimensional micro prism array 16 are parallel to each other. Then, the two-dimensional micro prism array 16 is bonded to the light emitting surface of the liquid crystal display panel 2 via an adhesive layer adjusted to, for example, 60 μm by a spacer (not shown) so that the prism forming surface is on the projection lens side.

With the above configuration, the virtual image of the picture element on the projection screen 9 becomes a solid line as shown in FIG. 6, and a two-dimensionally inconspicuous smooth image of the BM is obtained.

The two-dimensional micro prism array 16 is not limited to the quadrangular pyramid two-dimensional micro prism array 16 shown in the above embodiment. For example, a two-dimensional micro prism having a polygonal pyramid or a truncated pyramid micro prism is formed. The prism array 16 can also be used, and similarly, a large number of virtual images are formed two-dimensionally, so that the BM can be further made inconspicuous.

As described above, in the projection type image display apparatus 1 according to the present embodiment, since the shape of each micro prism in the micro prism array 16 is formed as a polygonal pyramid or a truncated polygonal pyramid,
A multiple image can be formed, and stripes due to the BM can be made more inconspicuous than when a one-dimensional minute prism in which the shape of each minute prism is mountain-shaped or the like, whereby a smoother image can be obtained.

Embodiment 3 Still another embodiment of the present invention will be described below with reference to FIGS. 7 and 8. For convenience of explanation, members having the same functions as those shown in the drawings of the first and second embodiments are denoted by the same reference numerals, and description thereof will be omitted.

In the second embodiment, the liquid crystal display panel 2
Is 80 μm × 55 μm, the pixel area is 40 μm × 30 μm, and the thickness of the glass substrate 2a is 1.
When the above-described two-dimensional micro prism array 16 was bonded to the light emitting surface of the liquid crystal display panel 2 with 1 mm and the refractive index of the glass substrate 2a set to 1.53, the BM became inconspicuous in the vertical direction of the liquid crystal panel. The horizontal direction overlaps with another different picture element, and the resolution is reduced.

Therefore, the projection type image display device 1 of this embodiment
As shown in FIG. 7, two one-dimensional micro prism arrays having a mountain shape or a trapezoidal cross section used in the first embodiment are prepared, and a one-dimensional micro prism array 61 having a refractive index of 1.50 has a refractive index of 1.50. A leveling layer 62 is formed by leveling with a substance of 50, and a one-dimensional micro prism array 6 having a refractive index of 1.50.
3 are formed with a substance having a refractive index of 1.51 to form a leveling layer 64, these are made to face each other with the small prism faces, and the prism grooves 61a and 63a are formed.
Are bonded so as to be orthogonal. Then, the one-dimensional micro prism array 61 leveled with a substance having a small refractive index of 1.50 is placed on the liquid crystal display panel 2 side, and the liquid crystal display panel 2
Are bonded to each other through a bonding layer adjusted to 60 μm by a spacer on the light emitting surface of each of the above so that the prism forming surface is on the projection lens side. However, the relative positional relationship between the liquid crystal display panel 2 and the one-dimensional micro prism arrays 61 and 63 is determined by the grooves 61a of the one-dimensional micro prism array 61 leveled with a substance having a refractive index of 1.50 and the liquid crystal display panel 2. Are arranged so that the horizontal direction of the screen is parallel.

As described above, the projection type image display apparatus 1 of the present embodiment has a structure in which the leveling layers 62 and 64 are laminated on the one-dimensional micro prism arrays 61 and 63 in which the shape of each micro prism is formed in a mountain shape. Two sheets are stuck.

With the above configuration, as shown in FIGS. 8A and 8B, two one-dimensional micro prism arrays 61 and 63 formed in the shape of a mountain are equivalent to the two-dimensional micro prism array 16 of a pyramid. Become. Similarly, the two trapezoidal 1
The two-dimensional micro prism arrays 61 and 62 are equivalent to the two-dimensional micro prism array 16 of a truncated pyramid.

[0072] As a result, the two-dimensional micro-prism or using an array 16 micro-prism array having different apical angle γ in or had been in need of treatment, such as applying special leveling, in this embodiment, each of the one-dimensional By simply changing the refractive index of the substance used for leveling the prism array, a two-dimensional and inconspicuous smooth image of the BM can be obtained, and the small prism arrays 6 and 2 used in the first and second embodiments can be obtained.
The effect of protecting the prism surface is higher than that of the two-dimensional micro prism array 16.

On the other hand, the two-dimensional micro prism array 16
When the aspect ratio of the picture element pitch changes when the shape of the light exit surface of each micro prism is formed in a polygonal pyramid or a truncated polygonal pyramid, a two-dimensional micro prism array 16 corresponding to the ratio is used. It is necessary to take measures such as performing leveling with a leveling layer having a different refractive index on the surface of each micro prism. However, when two one-dimensional micro prism arrays 61 and 63 formed in a chevron are used, the leveling layers 6 having different refractive indices are provided for the one-dimensional micro prism arrays 61 and 63 formed in a chevron.
Leveling can be performed at 2.64.

As a result, even when the one-dimensional micro prism arrays 61 and 63 having the same refractive index n ₃ are used, it is possible to cope with a change in the pixel pitch. Further, when the micro prism surfaces are faced to each other and bonded to each other, the prism surfaces can be protected more robustly than the protection by leveling.

In this embodiment, the relative positional relationship between the two one-dimensional micro prism arrays 61 and 63 is as follows.
The grooves 61a are arranged so as to be orthogonal to each other. However, as long as the BM is inconspicuous in two dimensions, the grooves are not limited to orthogonal.

As for the bonding direction, it is most effective to protect the prism surface from external shocks and the like when bonded face-to-face. However, the bonding may be performed so that the prism surfaces face the same direction.

[0077]

As described above, according to the projection type image display device of the first aspect of the present invention, the minute prism array is provided with
While the shape of the mechanism is formed and arranged one-dimensionally,
The micro prisms are orthogonal to each other and the micro prisms
Through a leveling layer with a refractive index different from that of
And two sheets are joined.

As a result, two picture elements appear on the projection screen.
Since the image is a superimposed image, stripes due to the light-shielding mask become inconspicuous and a smooth image can be obtained.

The shift amount can be freely changed by changing the ratio between the refractive index of the micro prism and the refractive index of the leveling layer. As a result, one type of micro prism array can cope with all of the different matrix type display panels, so that a significant cost reduction can be achieved.

Further, since the double image according to the present invention is due to the refraction effect of the minute prism, it is free from the diffraction loss that occurs when a diffraction grating is used, and a bright and sharp image can be obtained. When a leveling layer having a small wavelength dependence of the refractive index is used, the color shift is smaller than that of the diffraction grating. Furthermore, since the leveling layer provided on the surface of the micro prism also functions as a protective film, there is an effect that the surface of the prism is not easily damaged and cleaning is easy.

Further , it is possible to perform leveling with a leveling layer having a different refractive index on a micro prism array formed and arranged one-dimensionally. As a result, even if the same micro prism array is used, it is possible to cope with a change in the pixel pitch.

When the micro prism surfaces are joined to face each other, there is an effect that the prism surface can be protected more robustly than the protection by leveling.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing optical characteristics in a projection type image display device according to an embodiment of the present invention.

FIG. 2 is an overall structural diagram showing the projection type image display device.

FIG. 3 is an optical path diagram of light vertically incident on a micro prism array in the projection type image display device.

FIG. 4 is an explanatory view showing a projected image on a projection screen in the projection-type image display device, wherein a broken line shows a state where no minute prism array is arranged, and a solid line shows a state where a minute prism array is arranged.

FIG. 5 is a perspective view showing a projection type image display device according to another embodiment of the present invention, showing a micro prism array formed in a polygonal pyramid.

FIG. 6 is an explanatory view showing a projected image of a projection screen in the projection type image display device, wherein a broken line shows a state where no minute prism array is arranged, and a solid line shows a state where a minute prism array is arranged.

FIG. 7 shows a projection type image display apparatus according to still another embodiment of the present invention, and is a structural diagram showing a state where two mountain-shaped one-dimensional micro prism arrays are stacked.

FIGS. 8A and 8B are explanatory diagrams showing that it is equivalent to bond two quadrangular pyramid two-dimensional microprisms and two mountain-shaped one-dimensional microprisms, and FIG. FIG. 3B shows the formation of a virtual image when two mountain-shaped one-dimensional micro prisms are bonded together.

FIG. 9 is a diagram illustrating a conventional projection image display device, and is an explanatory diagram illustrating optical characteristics of a diffraction grating.

FIG. 10 is an explanatory diagram showing optical characteristics of the projection image display device.

[Explanation of symbols]

 2 Liquid crystal display panel (matrix type display panel) 2a Glass substrate 3 Light source 6 Micro prism array 9 Projection screen 20 Leveling layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-40245 (JP, A) JP-A-1-81687 (JP, U) JP-A-1-81688 (JP, U) JP-A-1 85781 (JP, U) (58) Fields surveyed (Int. Cl. ⁶ , DB name) G02F 1/1335 G02F 1/13 505

Claims (1)

(57) [Claims] 1. A plurality of picture elements and matrix-type display panel of a transmission type having a light-shielding mask in a matrix in regions other than those picture elements arranged in a matrix, small on the light emitting side of the matrix display panel A micro prism array with a large number of prisms arranged on the light exit side
In the projection type image display device provided with the projection screen arranged , the micro prism array has a shape of each micro prism.
The micro prisms are formed and arranged in a three-dimensional manner.
Are perpendicular to each other and different from the refractive index of the micro prism.
Two layers through a leveling layer having a different refractive index
Projection type image display apparatus characterized by being configured.