JPH06208112A - Direct-view display device - Google Patents

Abstract

PURPOSE:To provide a direct-view display device in which a striped pattern to be caused by parallax can be eliminated, and the quality of picture images has been improved. CONSTITUTION:On the emitting side of a back-light 6, a liquid crystal panel 1 for carrying out active matrix drive is arranged. On the surface 3a of the base plate 3 of the liquid crystal panel 1, a microlens array 5 consisting of a plurality of microlenses 5a that are formed so as to correspond to the respective picture elements of the liquid crystal panel 1 is formed. Further, between the microlens array 5 and an observer 9, a field lens 7 and an eyepiece 8 are arranged in this order. Since the field lens 7 converges the principal rays parallel to the optical axis of the light emitted from the microlens array 5 to the eyepiece 8, the Moire fringes to be caused by parallax can be eliminated, and the quality of picture images can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly to a direct-view display device applied as a display means such as a viewfinder used in a video camera or a scope used in a virtual reality system.

[0002]

2. Description of the Related Art A display panel used in the present invention does not emit light by itself, but its transmittance changes according to a drive signal, and an intensity of light from a separately provided light source is modulated to display an image or a character. Is a transmissive display panel for displaying. Examples include liquid crystal display panels, electrochromic displays, and translucent ceramics such as PLZT, among which liquid crystal display panels are widely used in portable televisions, word processors, projectors, and the like.

The pixel electrodes of the liquid crystal display panel are formed by being regularly arranged in a matrix. An independent drive voltage is applied to each of these pixel electrodes, and an image or a character is displayed by changing the optical characteristics of the liquid crystal. As a method of applying an independent drive voltage to each pixel electrode, there are a simple matrix method and an active matrix method in which a nonlinear 2-terminal element or 3-terminal element is provided. Especially, the latter is a MIM (metal-insulator-metal) element or TFT.
A switching element such as a (thin film transistor) element,
Since it is necessary to provide a wiring electrode for supplying a drive voltage to the pixel electrode, the effective area of the pixel opening in the partition of the pixel, that is, the aperture ratio becomes small. Further, since the normal display voltage is not applied to the liquid crystal existing in the area where the switching elements and the wiring electrodes are formed, the original display operation is not executed, so that the area is covered by the light shielding means called a black matrix. The transmitted light is blocked. In such a liquid crystal display panel, the light-shielding portion due to the black matrix is observed as stripes.

When performing the above-mentioned active matrix driving in a direct-view type display device used for a viewfinder of a video camera, it is necessary to provide pixel electrodes, switching elements and wiring electrodes in a relatively small area with high density. However, it is difficult to form the switching element and the wiring electrode to a certain size or less due to restrictions on their electrical performance and manufacturing technology. Therefore, the smaller the pixel pitch, the smaller the aperture ratio and the darker the display, and the conspicuous stripes due to the light-shielding portion of the black matrix described above cause a problem that the image quality is significantly deteriorated.

As a method of solving the problem associated with the reduction of the aperture ratio, it is considered to provide a microlens to expand the light emitted from each pixel electrode of the display panel to the size of the pixel. For example, JP-A-64-35415
The publication introduces an example in which a telecentric optical system for expanding and converting a parallel light flux into a parallel light flux and a meniscus microlens are used as a light valve used in a projector or the like.

[0006]

In the viewfinder of the video camera, the distance between the display panel and the eyepiece lens is short, and the vertical and horizontal parallax of the display panel becomes large. Therefore, when the microlens is provided,
An optical shift occurs between the pitch of the microlens and the pixel pitch of the display panel, the light emitted from the display panel does not pass through the center of the microlens, and a striped pattern called a so-called moire fringe occurs, resulting in poor image quality. There is a problem of a significant decrease.

In the above-mentioned Japanese Patent Laid-Open No. 64-35415, a telecentric optical system is used in consideration of this problem, and a parallel light beam is used as the incident light to the display panel. However, since it is important for the viewfinder to be small in size, it is difficult to form a light flux having a uniform illuminance distribution and a high parallelism in a limited space. Therefore, there is no choice but to use a diffused light source using a cold cathode tube, and the above-mentioned JP-A-64-35415.
The effects described in the issue cannot be expected.

An object of the present invention is to provide a direct-view type display device in which the stripe pattern caused by parallax is eliminated and the image quality is improved.

[0009]

According to the present invention, there are provided a transmissive display panel in which a plurality of pixels for controlling incident light are arranged in a matrix, a light source for irradiating the display panel with light, and the display panel. A direct-view type display device comprising an eyepiece for observing a displayed image, characterized in that a microlens is formed on a surface of the display panel on the eyepiece side corresponding to each pixel of the display panel. It is a display device.

In the direct-view type display device, the distance between the plane on which the pixels of the display panel are arranged and the plane on which the microlens is formed is t, and when the eyepiece is viewed from the display panel side. The distance between the virtual image of the observer and the plane where the pixels of the display panel are arranged is L, the refractive index of the substrate of the display panel is n, the pixel pitch of the display panel is P0, and the pitch of the microlens is P
1, the pitch P1 of the microlenses is P
1 = P0 · {1-t / (n · L)}.

Further, according to the present invention, a transmissive display panel in which a plurality of pixels for controlling incident light are arranged in a matrix, a light source for irradiating the display panel with light, and an image displayed on the display panel. In a direct-view display device including an eyepiece to be observed, on the eyepiece side surface of the display panel, a microlens is formed corresponding to each pixel of the display panel, and on the eyepiece side of the microlens,
In the direct-view type display device, a field lens is arranged in which a principal ray parallel to an optical axis of light transmitted through the microlens is condensed on the eyepiece lens.

[0012]

According to the present invention, the microlenses are formed on the surface of the display panel on the eyepiece side. The display panel is
It has a plurality of pixels arranged in a matrix and controlling incident light, and selectively controls irradiation light from a light source to form an image. Further, the microlens is formed corresponding to the plurality of pixels. Therefore, the light emitted from the plurality of pixel electrodes is enlarged to the size of the pixel and is connected to each other, and the stripe pattern disappears, the image becomes brighter and the contrast becomes uniform, so that the image quality is improved.

Further, the pitch P1 of the microlenses
Is set to P1 = P0 · {1-t / (n · L)}. Here, P0 is the pixel pitch of the display panel, and t is the distance between the plane on which the pixels of the display panel are arranged and the plane on which the microlens is formed. Further, n is the refractive index of the substrate of the display panel, and L is the distance between the virtual image of the observer when looking into the eyepiece from the display panel side and the plane where the pixels of the display panel are arranged. Therefore, since the lights emitted from the plurality of pixel electrodes are connected to each other and pass through the center of the microlens, it is possible to improve the image quality by eliminating moire fringes caused by parallax between the display panel and the microlens.

Further, according to the invention, a microlens is formed on the surface of the display panel on the eyepiece side, and a field lens is arranged on the eyepiece side of the microlens. The display panel has a plurality of pixels arranged in a matrix and controlling incident light, and selectively controls irradiation light from a light source to form an image. The microlens is formed corresponding to the plurality of pixels. Further, the field lens focuses a principal ray parallel to the optical axis of the light emitted from the microlens on the eyepiece lens. Therefore, the light emitted from the plurality of pixel electrodes is enlarged to the size of the pixel and is connected to each other, and the light is bright and the contrast is uniform. Further, since the observer who observes from the eyepiece observes only the light of the substantially parallel component of the light emitted from the microlens, the above-mentioned JP-A-64-
It is not necessary to use the parallel light flux implemented in Japanese Patent No. 35415, and it is possible to obtain an image with improved image quality without moire fringes even if a diffused light source is used, for example. Further, when used as a liquid crystal display device, a good display with a uniform contrast ratio can be realized.

[0015]

1 is a side view showing a schematic configuration of a display device 10 according to a first embodiment of the present invention. In FIG. 1, hatching is shown in the light shielding area 4a by the black matrix 4 which constitutes the display device 10 in order to make it easy to understand, and similar hatching is also described in FIGS. 2 and 4 shown below. did. The display device 10 is a direct-view display device, and includes a liquid crystal panel 1, a microlens array 5, a backlight 6, a field lens 7,
The eyepiece 8 is included.

The liquid crystal panel 1 has substrates 2 and 3 having a light transmitting property.
On one of the substrates 2 and 3, the substrate surface is provided with regularly arranged pixel electrodes, a wiring electrode for supplying a voltage to the pixel electrode, and an applied voltage between the pixel electrode and the wiring electrode. A switching element such as a TFT for switching and a black matrix 4 are formed, and a counter electrode is formed on the surface of the other substrate. In the liquid crystal panel 1, so-called active matrix driving is performed. An alignment film for aligning liquid crystal molecules is formed on the surfaces of the substrates 2 and 3, and liquid crystals are interposed between the substrates 2 and 3.

The black matrix 4 blocks the transmitted light in these areas in order to eliminate display nonuniformity caused by defective alignment of liquid crystal molecules existing on the wiring electrodes and switching elements for supplying voltage to the pixel electrodes. The black matrix 4 forms a plurality of light-shielding regions 4a and a plurality of light-transmitting regions 4b, which are shaded by the black matrix 4. The diagonal length of the liquid crystal panel 1 thus configured is, for example, 2 inches (the length in the vertical direction is 30.5 m).
m, and the lateral length is 40.6 mm). The pixel pitch P0 is, for example, 48 μm in the vertical direction and 48 μm in the horizontal direction.
The pixel opening, that is, the transmissive region 4b is, for example, 24 μm in the vertical direction and 36 μm in the horizontal direction.

On the surface 2a side of the substrate 2 of the liquid crystal panel 1, a backlight 6 as a diffused light source is arranged. The backlight 6 is realized by a cold cathode tube that emits white light. Furthermore, on the surface 3a of the substrate 3 of the liquid crystal panel 1,
The microlens array 5 is formed. The microlens array 5 includes a plurality of microlenses 5a formed corresponding to a plurality of pixels and realized by planomicrolenses. Since the microlens 5a is designed to have an enlargement ratio such that the lights emitted from the plurality of transmission regions 4b are connected to each other, it is possible to eliminate the stripe pattern generated by the light shielding region 4a.

A field lens 7 is arranged on the eyepiece 8 side of the microlens array 5. The field lens 7 is designed so that the chief ray parallel to the optical axis of the light passing through the microlens array 5 is focused on the eyepiece lens 8.

The light emitted from the backlight 6 in the display device 10 enters the liquid crystal panel 1. Of the light that has entered the liquid crystal panel 1, the light that has entered the plurality of light blocking regions 4a is blocked. On the other hand, the light incident on the plurality of transmission regions 4b is controlled according to the alignment state of liquid crystal molecules existing between the substrates 2 and 3. The light emitted from the transmissive region 4b of the liquid crystal panel 1 is magnified by the microlens 5a, and the lights are connected to each other. The light passing through the microlens array 5 is refracted by the field lens 7 so that a principal ray parallel to the optical axis of the light enters the eyepiece lens 8.
Since the observer 9 observes the light through the eyepiece lens 8, of the light emitted from the microlens array 5, light that can pass through the eyepiece lens 8, that is, a component that is nearly parallel to the optical axis. Observe only the light of.

That is, the observer 9 observes one point of the transmissive region 4b of the liquid crystal panel 1 by enlarging it to the size of each microlens 5a. The observed one point may be any part of the transmission area 4b. Therefore, the light emitted from the microlens array 5 is distributed within a certain angle range with respect to the optical axis.

FIG. 2 is a diagram showing the divergence angle θ of the light emitted from the microlens array 5. If the thickness t of the substrate 3 is 600 μm and the refractive index n is 1.52, the focal length of the microlens 5a is 395 μm (= 600 / 1.5).
2), and the divergence angle θ of the pixel aperture is geometrically 2.3 ° (= 2 · tan ⁻¹ {(24/2) / 60) in the vertical direction.
0}), and the horizontal direction is 3.4 ° (= 2 · tan ⁻¹ {(36 /
2) / 600}). Further, the distance L1 between the virtual image 9a of the observer 9 when looking into the eyepiece 8 from the liquid crystal panel 1 side and the plane on which the pixels of the liquid crystal panel 1 are arranged is 110 mm, and the eyepiece 8 and the observer 9 are Distance L2
Is 20 mm, and the distance L3 between the plane on which the pixels of the liquid crystal panel 1 are arranged and the eyepiece 8 is 80 mm,
The size of the eye ring at the eye point of the viewfinder is geometrically 2.9 mm (= {20 / (110
−80)} · 2 · 110 · tan (2.3 / 2)) ×
4.4 mm (= {20 / (110-80)} ・ 2 ・ 11
0 · tan (3.4 / 2)). The eye ring is an image of a small bright circle seen behind the eyepiece when the eye is taken away from the eyepiece, that is, an exit pupil, and the position of this exit pupil is called an eye point. The size of the eye ring is a value that can be sufficiently used as a viewfinder.

As described above, according to the present embodiment, in the display device 10, the microlens array 5 and the principal ray parallel to the optical axis of the light emitted from the microlens array 5 are directed to the eyepiece lens 8. A field lens 7 for collecting light is provided. Therefore, it is possible to eliminate the striped pattern generated by the light shielding region 4a, and it is possible to make the display bright and to make the contrast uniform. Further, even when the backlight 6 which is a diffused light source is used, it is possible to eliminate the generation of moire fringes caused by parallax between the liquid crystal panel 1 and the microlens array 5, and it is possible to improve the image quality. Further, since the observer 9 magnifies and observes one point of the transmissive region 4b through the eyepiece lens 8, the substantial aperture ratio is improved and a bright display can be obtained.

The field lens 7 of the display device 10
If the eyepiece 8 and the eyepiece 8 are designed according to the purpose, the observer 9
Can observe a virtual image of any size in any place. For example, if the focal length f of the eyepiece lens 8 is 60 m
Assuming that m is the real image A, as shown in FIG.
Depending on f, from the eyepiece lens 8, the distance d2 = 240 mm
At the position of, a virtual image B having a size about three times as large as that of the real image A is observed. Here, d1 represents the distance between the eyepiece 8 and the real image A. If the field lens 7 and the eyepiece lens 8 are designed so that the distance d2 = 1 m from the eyepiece 8 to the virtual image B, the virtual image B of about 12.5 times the size is obtained.
Can be observed and can be used as a scope for a virtual reality system.

FIG. 4 is a side view showing a schematic configuration of the display device 11 according to the second embodiment of the present invention. In this embodiment, the pitch P1 of the microlenses 12a is corrected. The display device 11 has a configuration similar to that of the display device 10, and includes a liquid crystal panel 1, a backlight 6, an eyepiece 8, and a microlens array 12 having a pitch corrected.

The liquid crystal panel 1 is formed by interposing a liquid crystal between substrates 2 and 3 on which pixel electrodes and switching elements for performing active matrix driving are formed, as in the first embodiment. A black matrix 4 is formed between them. A backlight 6 as a diffused light source is arranged on the surface 2a side of the substrate 2 of the liquid crystal panel 1, and a microlens array 12 is formed on the surface 3a of the substrate 3 of the liquid crystal panel 1. The microlens array 12 is formed of a plurality of microlenses 12a formed corresponding to a plurality of pixels and realized by planomicrolenses. An eyepiece 8 is arranged on the observer 9 side of the microlens array 12. The microlenses 12a are subjected to a pitch correction, which will be described later, and are designed to have an enlargement ratio such that lights emitted from a plurality of transmission regions 4b are connected to each other.

The pixel pitch P0 of the liquid crystal panel 1 of the display device 11 is 48 μm, the thickness t of the substrate 3 is 600 μm, the refractive index n of the substrate 3 is 1.52, and the eyepiece 8 is viewed from the liquid crystal panel 1 side. Virtual image 9a of the observer 9 when
And the distance L1 from the plane on which the pixels of the liquid crystal panel 1 are arranged is 110 mm, the pitch P1 of the microlenses 12a is P1 = P0 · {1-t / (n · L)}, that is, the microlenses. 12a pitch P1 is 4
It becomes 7.8 μm, and the light emitted from the liquid crystal panel 1 is corrected so as to pass through the center of the microlens 12a.

As described above, according to this embodiment, the microlens array 12 is formed in the display device 11, and the light emitted from the liquid crystal panel 1 has a pitch P1 of the microlenses 12a of the microlens array 12. It is corrected so as to pass through the center of the lens 12a. Therefore, it is possible to eliminate the striped pattern generated by the light shielding region 4a, and it is possible to make the display bright and to make the contrast uniform. Further, even if the backlight 6 which is a diffused light source is used, it is possible to improve the image quality by eliminating the moire fringes generated by the parallax between the liquid crystal panel 1 and the microlens array 12.

In the first and second embodiments, an example in which plano microlenses are used as the microlenses 5a and 12a has been described, but a meniscus microlens or a biconvex microlens satisfying the conditions in the respective embodiments. The use of is also within the scope of the invention.

In the first and second embodiments, the example using the liquid crystal panel 1 has been described, but an example using an electrochromic panel or a display using a translucent ceramic such as PLZT is also within the scope of the present invention. Belong to.

[0031]

As described above, according to the present invention, the microlenses are formed on the surface of the display panel on the eyepiece side. Therefore, the lights emitted from the pixel electrodes formed in the plurality of pixels of the display panel are expanded and connected to each other, and the display can be bright and the contrast can be uniform. Further, the pitch of the formed microlenses is corrected so that the light emitted from the display panel passes through the centers of the microlenses. Therefore, in addition to the above effects, it is possible to improve the image quality by eliminating moire fringes caused by parallax.

Further, according to the present invention, the microlens is formed on the surface of the display panel on the eyepiece side, and the field lens is arranged on the eyepiece side of the microlens. Therefore, the emitted lights from the pixel electrodes formed in the plurality of pixels of the display panel are expanded and connected to each other, and the display can be bright and the contrast can be made uniform, and the moire fringes caused by parallax can be eliminated and the image quality can be improved. It becomes possible to improve.

[Brief description of drawings]

FIG. 1 is a side view showing a schematic configuration of a display device 10 that is a first embodiment of the present invention.

FIG. 2 is a diagram showing a divergence angle θ of light emitted from a microlens array 5.

FIG. 3 is a diagram showing a real image A and a virtual image B.

FIG. 4 is a side view showing a schematic configuration of a display device 11 which is a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal panel 2,3 Substrate 4 Black matrix 4a Light-shielding area 4b Transmission area 5,12 Micro lens array 5a, 12a Micro lens 6 Backlight 7 Field lens 8 Eyepiece 10, 11 Display device

Claims (3)

[Claims] 1. A transmissive display panel in which a plurality of pixels for controlling incident light are arranged in a matrix, a light source for irradiating the display panel with light, and an eyepiece for observing an image displayed on the display panel. A direct-view display device comprising a lens, wherein a microlens is formed on a surface of the display panel on the eyepiece side corresponding to each pixel of the display panel. 2. A virtual image of an observer when the eyepiece lens is viewed from the display panel side and a display is made with t being a distance between a plane where pixels of the display panel are arranged and a plane where microlenses are formed. When the distance from the plane on which the pixels of the panel are arranged is L, the refractive index of the substrate of the display panel is n, the pixel pitch of the display panel is P0, and the pitch of the microlenses is P1, The pitch P1 of the microlens is P1 = P0 · {1
-T / (nL)}, The direct-view display device according to claim 1. 3. A transmissive display panel in which a plurality of pixels for controlling incident light are arranged in a matrix, a light source for irradiating the display panel with light, and an eyepiece for observing an image displayed on the display panel. In a direct-view display device including a lens, a microlens is formed on the eyepiece side surface of the display panel corresponding to each pixel of the display panel, and the microlens is transmitted to the eyepiece side of the microlens. A direct-view type display device, in which a field lens for collecting a principal ray parallel to the optical axis of the above-mentioned light is focused on the eyepiece lens.