JPH0580328A - Display device - Google Patents

Abstract

PURPOSE:To enable a non-light emitting type display device such a a liquid crystal display to perform display in both modes, transmission mode and a reflection mode. CONSTITUTION:This display device constituted of a rear light source consisting of a light source 14 and a light transmission plate 15 and a liquid crystal panel 11 is constructed so that a reflection film 12 wound around a winding shaft 13 may be pulled out and inserted into the display device. In the transmission mode (backlight is on), the reflection film 12 is wound around, and in the reflection mode (backlight is off), the reflection film 12 is pulled out. By such constitution, the display device which is bright both in the transmission mode and the reflection mode is obtained.

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 has a back light source and which can be switched between a transmissive type and a reflective type.

[0002]

2. Description of the Related Art Conventionally, among display devices, liquid crystal display devices have been widely used for portable equipment such as calculators and watches because of their thinness, light weight and low power consumption. In recent years, in order to reduce the thickness and weight of personal computers, the use thereof as a large-sized display device such as a laptop personal computer, a notebook personal computer, and a word processor, which is impossible with a CRT (cathode ray tube), is spreading.

Low power consumption is one of the conditions desired for such a display device related to portable OA equipment. This is because it is necessary to extend the operating life of the device driven by the battery as it becomes portable. Various efforts have been made to reduce power consumption in display devices of notebook computers and word processors. As one approach, in order to eliminate the power consumption of the back light source, the liquid crystal display element is configured not in the back light source type (transmission mode) but in the reflection mode using a reflection film.

However, the reflection mode has a problem that the visibility is lowered because the display brightness is lower than that in the transmission mode. Therefore, recently, a display device has been constructed using a film having a function of displaying both a reflective mode and a transmissive mode called a semi-transmissive mode. A mode has been adopted in which the mode is used and the reflection mode is used while moving in a train or a car.

[0005]

However, in the display system using the semi-transmissive film as described above, both the reflectance and the transmittance are reduced, and the visibility of the display device is greatly reduced especially in the reflection mode. There was a problem of doing it.

The present invention solves such a problem, and provides a thin display device having good display quality, excellent visibility, both reflective and transmissive displays, and low power consumption. The purpose is.

[0007]

In order to solve the above-mentioned problems, the present invention comprises a display element and a back light source, and a reflective element movable in the surface direction is provided between the back light source and the display element. It is what

[0008]

In the above structure, when the reflective film is used in the transmissive mode, it is brought into the transmissive state by moving it in the surface direction, and in the reflective mode, the reflective film is moved again to be in the reflective state, thereby displaying brighter reflective and transmissive modes. Becomes

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows the configuration of a display device according to Embodiment 1 of the present invention. As shown in the figure, the liquid crystal panel 11
Between the light source 14 and the back light source including the light guide plate 15,
A reflection film 12 (aluminum foil laminated with a resin film) is provided around a winding shaft 13. Polarizing elements 16 are provided on both surfaces of the liquid crystal panel 11.

In the display device having this structure, in the transmissive mode (backlight on), the reflection film 12 is entirely wound around the winding shaft 13, and the light from the back light source 14 can pass through as it is. The reflection film 1 wound around the winding shaft 13 in the reflection mode (backlight off)
By drawing 2 out, reflection from external light can be obtained. With this configuration, both the transmittance and the reflectance are high, and a good display with high visibility can be obtained.

(Embodiment 2) FIG. 2 shows the configuration of a display device according to Embodiment 2 of the present invention. As shown in FIG. 2, the liquid crystal panel 2
Rear light source 28 including light source 22 and light guide plate 23 behind 1
Was installed. Around the back light source 28, the reflective film 24
A ring-shaped film, which is a combination of the transparent film 25 and the transparent film 25, is provided so as to rotate around the two drive shafts 27. The back light source 28 is installed inside the ring-shaped film. Reference numeral 26 is a polarizing element for a liquid crystal panel. In this configuration, as in the first embodiment, in the transmissive mode (backlight on), the ring-shaped film is pivotally moved in the surface direction and the transmissive film 25 is moved to the liquid crystal panel side. Can pass through as is.

In the reflection mode (backlight off), the ring-shaped film is rotated to move the reflection film 23 to the liquid crystal panel side, whereby reflection from external light can be obtained. The same effect was obtained by using a diffusion film instead of the transmission film 25. With this configuration, it is possible to obtain a display device having high reflectance and transmittance.

FIG. 4 shows the configuration of an apparatus using the display device of the system of Examples 1 and 2. The system shown in FIG. 4 is a system for word processors and personal computers. A liquid crystal element 45 (TN method: twisted nematic method) was used as a display element. A drawer knob 42 is installed on the display device portion 41. The knob 42 can be moved along the notch slit 43 of the display device portion 41. By connecting the knob 42 and the reflection film 44 in advance, the reflection and transmission modes can be freely selected by moving the knob 42. Further, by providing a switch linked with the pull-out knob 42 so that the backlight is automatically turned off when the reflection mode is used, it is possible to more effectively reduce the power consumption of the display device.

(Embodiment 3) FIG. 3 shows the configuration of a display device according to Embodiment 3 of the present invention. As shown in FIG. 3, the liquid crystal panel 3
1, and a back light source 36 including the light source 32 and the light guide plate 33, a gap is provided between which the film-plate-shaped reflection element 34 can be taken in and out. The reflective element 34 is placed in this gap.
By putting in and out, it is possible to freely change both the reflective and transmissive modes, and it is possible to obtain high display quality in both modes.

Also in the configuration of the third embodiment shown in FIG. 3, the slit-shaped holes 5 are formed on the side surface of the display device 51 as shown in FIG.
2 is provided and the reflection element 53 in the form of a film plate is inserted, so that the reflection or transmission mode can be freely selected.
Also in this configuration, a switch (not shown) is provided so as to automatically turn off the backlight when the film-plate-shaped reflective element 53 is inserted.

(Embodiment 4) FIG. 6 shows the configuration of a display device according to Embodiment 4 of the present invention. As shown in the figure, in order to enhance the brightness and the visibility in the reflection mode, the polarizing element 63 on the rear light source 62 side of the liquid crystal panel 61 was installed on the rear light source 62 side without being attached to the liquid crystal panel 61. In this configuration, the polarization direction of the reflection film 65 with the polarizer 64 to be inserted is shifted by 90 degrees from the polarization direction of the polarization element 63 at the time of transmission. When using the transmission mode, the polarizing element 66 and the polarizing element 63 on the front surface are set in a direction parallel to each other to set the normally black mode. When using the reflection mode, they were placed in crossed Nicols and set to the normally white mode.

As described above, when the transmission mode and the reflection mode are used, by changing the polarization directions respectively, a display with high visibility can be obtained in both modes.

In the present embodiment, the structure in which the polarization direction of the reflection film is shifted by 90 degrees from the polarization direction of the polarizing element has been described, but the same effect can be obtained by shifting the polarization direction by 80 to 100 degrees.

(Embodiment 5) FIG. 7 shows the configuration of a display device according to Embodiment 5 of the present invention. As shown in FIG. 7, the liquid crystal panel 7
The polarizing element 73 on the back light source 72 side of No. 1 was installed on the back light source 72 side without being attached to the liquid crystal panel 71. The degree of polarization of the polarizing element 74 of the reflective film 75 with the polarizing element 74 inserted at this time was set low. The polarizing element used is the polarizing element 73 in the transmission mode, NPF-G1220DU manufactured by Nitto Denko.
(Polarization degree 99.95%, single transmittance 41.5%), the polarizing element 74 in the reflection mode is NPF-G322 manufactured by Nitto Denko.
8M (polarization degree 95%, single transmittance 46.5%) was used. As the polarizing element 76 on the front surface of the panel, the same one as the polarizing element 73 was used.

As described above, by using the polarizing elements having different degrees of polarization when the transmission mode is used and when the reflection mode is used,
We were able to obtain a highly visible display in both modes.

The configurations of Examples 4 and 5 (FIGS. 6 and 7) can be used in the configurations of Examples 1 and 2 (FIGS. 1 and 2), and the display system shown in FIGS. 4 and 5 can be used. Can also be used as

[0023]

As is clear from the description of the above embodiment,
Since the display device of the present invention is provided with the reflective element movable in the surface direction between the back light source and the display element, both reflective and transmissive display excellent in visibility can be performed, and a thin display device can be realized. ..

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a display device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a schematic configuration of a display device according to a second embodiment of the invention.

FIG. 3 is a sectional view showing a schematic configuration of a display device according to a third embodiment of the invention.

FIG. 4 is a front view of a display system including the display device according to the first and second embodiments of the present invention.

FIG. 5 is a perspective view of a display system including a display device according to a third embodiment of the invention.

FIG. 6 is a sectional view showing a schematic configuration of a display device according to a fourth embodiment of the present invention.

FIG. 7 is a sectional view showing a schematic configuration of a display device according to a fifth embodiment of the present invention.

[Explanation of symbols]

 11 liquid crystal panel 12 reflective film 13 winding axis 14 light source 15 light guide plate 16 polarizing element

Claims (12)

[Claims] 1. A display device comprising a display element and a back light source, wherein a reflection element is provided between the back light source and the display element so as to be movable in a surface direction, and the reflection element is moved by the movement of the reflection element. Or a display device adapted to display both of the transparent type. 2. The display device according to claim 1, further comprising a light source switch which is interlocked with the movement of the reflection element, and the rear light source is turned off when the reflection type display is performed. 3. The display device according to claim 1, wherein the reflective element is attached to and detached from the display element or the display device. 4. The display device according to claim 1, wherein the reflective element is moved by pulling out the wound reflective element. 5. The display device according to claim 1, wherein the reflective element is moved by rotating a ring-shaped element, a part of which is provided with the reflective element, in the plane direction of the display element. 6. The display device according to claim 4, wherein the reflective element is moved by rotating a ring-shaped element, in which the reflective element and the transmissive element are joined, in the surface direction of the display element. 7. The display device according to claim 4, wherein the reflective element is moved by rotating a ring-shaped element in which the reflective element and the diffusing element are joined together in the plane direction of the display element. 8. The display device according to claim 1, wherein the display element is a liquid crystal element. 9. The display device according to claim 8, wherein the reflective element is combined with a polarizing element. 10. The display device according to claim 9, wherein the polarization direction of the polarization element combined with the reflection element is different from the polarization direction of the polarization element used when the transmission method is used. 11. The display device according to claim 10, wherein the polarization direction of the polarization element combined with the reflection element is different from the polarization direction of the polarization element used in the transmissive mode by 80 to 100 degrees. 12. The display device according to claim 9, wherein the polarization degree of the polarization element combined with the reflection element has an upper limit of the polarization degree of the polarization element used when the transmission method is used.