JP3384026B2 - 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 display device which synthesizes a transmitted image and a reflected image to display.

[0002]

2. Description of the Related Art Conventionally, a mirror called a half mirror or a beam splitter has been used for synthesizing a reflected image and a transmitted image, and a display device as disclosed in, for example, JP-A-60-84573 is known. In this mirror, a dielectric layer was provided on the surface of a glass substrate to control the ratio of reflection and transmission.

[0003]

However, when the above-mentioned conventional technique is used, about half of the light incident on the half mirror is reflected and the other half is transmitted, so that the viewer sees a transmitted image and a reflected image. Only about half the light reaches each. Therefore, the display device has a low brightness.

Further, when the image forming means is a liquid crystal display element, a polarizing plate or the like is used, so that the efficiency is poor and the light is further attenuated by the half mirror. Therefore, the power of the light source may be increased, but this time a problem of heat generation occurs, which adversely affects the liquid crystal display element and impairs the image quality.

Therefore, the present invention solves such a problem, and an object thereof is to provide a display device capable of bright display.

[0006]

[0007]

A display device according to the present invention comprises a means for forming a transmitted image, a means for forming a reflected image, and a synthesizing means for synthesizing the transmitted image and the reflected image. In, the light emitted from one of the means for forming the transmission image and the means for forming the reflection image has a narrow band wavelength region in red light, green light, and blue light, and is emitted from the other. The emitted light has at least a wavelength band other than the narrow band wavelength band, and the combining unit,
When the light emitted from the means for forming the transmission image has the narrow band wavelength band, the narrow band wavelength band is transmitted and the wavelength band other than the narrow band wavelength band is reflected, or When the light emitted from the means for forming the reflected image has the narrow band wavelength band, the narrow band wavelength band is reflected and the wavelength band other than the narrow band wavelength band is transmitted. It is characterized by being composed of a single dichroic mirror.

Further, the display device of the present invention is a display device comprising means for forming a transmission image, means for forming a reflection image, and combining means for combining the transmission image and the reflection image. Means for forming
The light emitted from one of the means for forming the reflection image is
Has a narrow band wavelength range for red light, green light, and blue light,
The emitted light from the other has at least a wavelength range other than the narrow band wavelength range, the combining means, the emitted light from the means for forming the transmission image has the narrow band wavelength range. When it is present, the narrow band wavelength range is transmitted, the wavelength band other than the narrow band wavelength range is reflected, or the light emitted from the means for forming the reflected image has the narrow band wavelength range. In this case, the hologram is constituted by a hologram that reflects the narrow band wavelength band and transmits the wavelength band other than the narrow band wavelength band.

[0009]

[0010]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a display device 100 of the present invention. Liquid crystal display element 1 as transmission image forming means
Then, the three-dimensional object 2 is arranged so as to have an L shape as a reflection image forming means. As a means for combining the two images, a polarization beam splitter 3 is arranged at an angle of 45 degrees so that the images of the liquid crystal display element 1 and the three-dimensional object 2 can be combined.

The liquid crystal display element 1 is of a transmissive type and controls white light from the light source 6 to perform color display to form a transmissive image. As the mode, the most general TN type which uses a polarizing plate by utilizing the optical rotatory power of liquid crystal is used. The three-dimensional object 2 forms a reflection image only when illuminated by the illumination light 7.

From the observation window 5 of the display device 100, the image of the liquid crystal display element 1 and the image of the three-dimensional object 2 are observed by the observer 4 in an overlapping manner. For example, if the image of the liquid crystal display element 1 is a clown and the three-dimensional object 2 is a ball, it is observed that the clown is dancing on a three-dimensional ball. At this time, the distance from the viewer 4 to the liquid crystal display element 1 and the three-dimensional object 2 is almost equal.

Next, FIG. 2 shows a configuration diagram of the polarization beam splitter 3 used in the present invention.

Generally, as the polarization beam splitter 3,
The polarizing film 11 is sandwiched between the slopes of two right-angle prisms, and the slopes are bonded together. In this structure, the refractive index of the prism and the refractive index of the constituent material of the film are greatly involved, and it was difficult to cover the entire visible range with a plate-shaped material. However, if a prism is used, it becomes heavy and the price is high, so it is difficult to use.

In consideration of this point, the plate-shaped polarization beam splitter 3 as shown in FIG. 2A was used this time. The composition is
A polarizing film 11 is provided between the planes of the two prism plates 10.
Is sandwiched between. The prism plate 10 is formed by arranging a plurality of rows of prism elements having an angle of 45 degrees with a surface normal and having two surfaces orthogonal to each other.

The material of the prism plate 10 is an optical plastic having a high transmittance and can be mass-produced inexpensively by injection molding or the like. The polarizing film 11 is a dielectric multilayer film, and by adhering two prism plates 10 together, p-polarized light of visible light can be transmitted and s-polarized light can be reflected. When it is difficult to deposit directly on the prism plate 10 made of a plastic material, a method of depositing on one surface of glass and then bonding the two prism plates 3 together is adopted.

Since the polarization beam splitter 3 is a conventional prism type and is miniaturized and arranged in a plate shape, it can be handled in the same manner as the conventional one. That is, as shown in FIG. 3B, of the incident light 12 incident at 45 degrees, the p-polarized light 13 is transmitted and the s-polarized light 14 is reflected. By adjusting the polarization characteristics of the emitted light of the liquid crystal display element 1 to p-polarized light, almost 100% of the light can be transmitted. Specifically, it suffices to align the polarization axis of the polarizing plate with the optical axis of p-polarized light.

In the conventional display device 100, assuming that the brightness of the transmitted image and the brightness of the reflected image are 100, they are attenuated to about 50 by the half mirrors, respectively.
The combined light had a brightness of about 100. However, according to the present invention, by making the polarization axis of the emitted light of the liquid crystal display element 1 and the transmission axis of the polarization beam splitter the same, the brightness of the reflected image is reduced to about 50, but the brightness of the transmitted image is reduced. Can maintain almost 100, and the brightness of the combined light becomes 150.

Further, the liquid crystal display element 1 is weaker to heat than the three-dimensional object 2 and causes deterioration of image quality such as reduction of contrast ratio. Therefore, the power of the light source 6 cannot be increased in order to increase brightness. Since the illumination light 7 can be easily powered up, it is easy to balance the brightness of the transmitted image and the reflected image.

As the transmission image forming means and the reflection image forming means, the liquid crystal display element 1 and the three-dimensional object 2 may be interchanged, or both may be the liquid crystal display element 1. When the reflection image forming means is the liquid crystal display element 1, the polarization axis of the emitted light is aligned with the s-polarization axis. In FIG. 1, the direction is perpendicular to the paper surface.

When both the transmission image forming means and the reflection image forming means are the liquid crystal display element 1, the effect is further enhanced. The outgoing light of the transmitted image is p-polarized light, and the outgoing light of the reflected image is s
When polarized light is used, there is no loss of light in the polarization beam splitter 3, and the brightness of each emitted light can be maintained almost as it is, so that the brightness is about twice that of the half mirror.

In addition to this, any means may be used as a means for forming a transmission image or a reflection image as long as the emitted light is polarized, and may be a CRT or an electronic display. That is, by adjusting the outgoing light of the transmitted image to be the p-polarized light and the outgoing light of the reflected image to be the s-polarized light with respect to the polarization beam splitter 3, the light beams can be combined without lowering the brightness.

(Embodiment 2) Another embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a block diagram of the display device 100 of the present invention. A three-dimensional object 2 as a transmission image forming means and a color type liquid crystal display element 1 as a reflection image forming means are arranged in an L shape. A dichroic mirror 8 is arranged as a combining means at an angle of 45 degrees so that the images of the liquid crystal display element 1 and the three-dimensional object 2 can be combined. The image of the liquid crystal display element 1 and the image of the three-dimensional object 2 are observed by the observer 4 through the observation window 5 in an overlapping manner. As the light source 6, a three-wavelength emission type fluorescent lamp was used. Further, as the illumination light 7, a continuous emission tungsten lamp was used.

FIG. 4 is a spectral characteristic diagram of the dichroic mirror 8 (dashed line), the light source 6 (solid line), and the illumination light (dotted line). Since a three-wavelength type fluorescent lamp is used as the light source 6, it has peaks in three colors of R, G and B as shown in the figure. The spectral characteristic of the reflected image formed by the liquid crystal display element 1 also conforms to the spectral characteristic of the light source 6.

For this characteristic, the dichroic mirror 8
As can be seen from the figure, the characteristic of (3) reflects only the emission wavelength band of the light source 6 and transmits other wavelength bands. Therefore, almost 100% of the emitted light of the reflected image reaches the viewer 4.

In the transmitted image, since a halogen lamp that continuously emits light is used for the illumination light 7, the reflection band of the dichroic mirror 8 is reflected and does not reach the viewer 4. However, other than about 80% of the wavelength band, Reach all.

In the conventional display device 100, if the brightness of the transmitted image and the brightness of the reflected image are 100, they are attenuated to about 50 by the half mirrors, respectively.
The combined light had a brightness of about 100. However, according to the present invention, since the wavelength characteristic of the reflected image is set to a narrow band and the dichroic mirror 8 adapted to the narrow band is used, the brightness of the reflected image is maintained at about 100 and the brightness of the transmitted image is 80%. The combined light has a brightness of about 180.

The liquid crystal display element 1 and the three-dimensional object 2 may be replaced with each other as the transmission image forming means and the reflection image forming means. In that case, naturally dichroic mirror 8
It is necessary to change the characteristics of.

In addition to this, there are CRTs, LEDs, fluorescent display elements, plasma display elements and the like as display elements which emit light in a narrow band wavelength range. These electronic displays are used as a means for forming a transmission image and a reflection image, and the emission distribution characteristics are shifted by the emitted light of the transmission image and the reflected light, and the optimum transmission characteristics and reflection are matched to the emission distribution of the transmission image and the reflection image. If the dichroic mirror 8 having the characteristic is used, almost all the emitted light of the transmitted image and the reflected image can be made to reach the viewer 4, and bright display is possible.

(Embodiment 3) Another embodiment of the present invention will be described below with reference to the drawings.

FIG. 5 is a block diagram of the display device 100 of the present invention. The basic arrangement is in accordance with the second embodiment described above, in which a three-dimensional object 2 is arranged as a transmission image forming means, a color liquid crystal display element 1 is arranged as a reflection image forming means, and a hologram 9 is arranged as a combining means of two images. The light source 6 was a three-wavelength emission type fluorescent lamp, and the illumination light 7 was a continuous wavelength emission tungsten lamp.

The hologram 9 has substantially the same spectral characteristics as the dichroic mirror 8 and reflects light having three peak wavelengths of R, G, and B and transmits other wavelength regions. That is, about 100% of the reflected image and about 80% of the transmitted image can reach the viewer 4 through the observation window 5.

The method of forming the hologram 9 is technically established as a foil stamping method for embossed holograms. If only the original mold is made, the cost becomes very small in mass production, and it is possible to provide the display device 100 that is significantly lower in price than the dichroic mirror 8 described above.

As in the second embodiment, the liquid crystal display element 1 and the three-dimensional object 2 may be replaced with each other. In addition to the liquid crystal display element 1 using a three-wavelength emission type fluorescent lamp as a light source 6 as an image forming means, an electronic display which emits light in a narrow band wavelength is used, and its spectral characteristics are shifted between a reflection image and a transmission image and adjusted to that. It is obvious that the production of the hologram 9 can improve the efficiency and form the bright display device 100.

[0037]

As described above, according to the present invention, the polarization beam splitter is arranged in the synthesizing means of the transmitted image and the reflected image, at least one of which is emitted as the polarized light. Since the brightness of the means is not attenuated, it is possible to provide a bright display device.

Further, the wavelength characteristics of the outgoing light of the transmitted image and the reflected image are shifted from each other, and a dichroic mirror or a hologram is arranged in the synthesizing means so as to have spectral characteristics matched to the respective outgoing light of the reflected image and the transmitted image. By doing so, it is possible to increase the brightness of the display device.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a display device of the present invention.

FIG. 2 is a perspective view of a polarization beam splitter of the display device of the present invention.

FIG. 3 is a configuration diagram showing another embodiment of the display device of the present invention.

FIG. 4 is a spectral characteristic diagram of a dichroic mirror, a light source, and illumination light.

FIG. 5 is a configuration diagram showing another embodiment of the display device of the present invention.

[Explanation of symbols]

1 Liquid crystal display element 2 three-dimensional objects 3 Polarizing beam splitter 4 Viewer 5 Observation window 6 light source 7 Illumination light 8 dichroic mirror 9 hologram 10 Prism plate 11 Polarizing film 12 incident light 13 p polarized light 14 s polarized light 100 display device

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-84573 (JP, A) JP-A-2-181138 (JP, A) JP-A-5-19386 (JP, A) JP-A-3- 107190 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02B 27/02 G02B 27/22 G03H 1/00-5/00

Claims (2)

(57) [Claims] 1. A display device comprising a means for forming a transmission image, a means for forming a reflection image, and a combining means for combining the transmission image and the reflection image, wherein the means for forming the transmission image comprises: The light emitted from one of the means for forming the reflected image has a narrow band wavelength range in red light, green light, and blue light, and the light emitted from the other side has a wavelength other than the narrow band wavelength range. At least a region, the synthesizing means, when the light emitted from the means for forming the transmission image has the narrow band wavelength region, transmits the narrow band wavelength region, The light emitted from the means for reflecting a wavelength band other than the narrow band wavelength band, or for forming the reflected image,
When it has the narrow band wavelength range, it is configured by a single dichroic mirror that reflects the narrow band wavelength range and transmits the wavelength range other than the narrow band wavelength range. Display device. 2. A display device comprising means for forming a transmission image, means for forming a reflection image, and combining means for combining the transmission image and the reflection image, wherein the means for forming the transmission image comprises: The light emitted from one of the means for forming the reflected image has a narrow band wavelength range in red light, green light, and blue light, and the light emitted from the other side has a wavelength other than the narrow band wavelength range. At least a region, the synthesizing means, when the light emitted from the means for forming the transmission image has the narrow band wavelength region, transmits the narrow band wavelength region, The light emitted from the means for reflecting a wavelength band other than the narrow band wavelength band, or for forming the reflected image,
A display device comprising a hologram which, when having the narrow band wavelength band, reflects the narrow band wavelength band and transmits the wavelength band other than the narrow band wavelength band.