JPH11167111A - Reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device which makes it possible to sufficiently view its display screen even when used in a circumferentially dark place, saves the electric power, and improves the use efficiency of light. SOLUTION: A liquid crystal layer 4 is sandwiched between a top-side glass substrate 2 and a reverse-side glass substrate 5 and the circumference of the substrates is sealed with a liquid sealing seal 3; and a reflecting plate 7 is provided on the side of the reverse-side glass substrate 5 being in not contact with the liquid crystal layer 4 across a reverse-side polarizing plate 6 and a lighting unit 10 is provided on the side of the top-side glass substrate 2 being in not contact with the liquid crystal layer 4 across a top-side polarizing plate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type liquid crystal display device having an illumination means on a liquid crystal display surface.

[0002]

2. Description of the Related Art In recent years, downsizing technology has been advanced in liquid crystal display devices in response to demands for small size, light weight and thinness.

[0003] With the development of this technology, the convenience of use by anyone, anytime, anywhere, and its application as a selling point, the use of liquid crystal display devices has expanded to a wide range such as portable terminals and mobile communication devices, and has become extremely widespread. Used in a wide range of products.

[0004] With the rapid increase in the portable demand of such a liquid crystal display device, there is a reflection type liquid crystal display device in which the battery consumption is reduced so that it can be used for a long time. As shown in FIG. 4, the conventional reflection type liquid crystal display device comprises a front side deflection plate 1, a front side glass substrate 2, a liquid crystal sealing seal 3, a liquid crystal layer 4, a back side glass substrate 5, a back side deflection plate 6, a reflection plate 7, It is composed of

[0005] In this reflection type liquid crystal display device, liquid crystal display is performed by surrounding ambient light passing through the front glass substrate 2 and being reflected by the reflection plate 7 in the direction of the front glass substrate 2.

[0006]

However, the conventional reflection type liquid crystal display device has a problem that the reflected light is so small that the display screen cannot be viewed because the outside light which enters is not sufficiently obtained in a dark place. There is.

Further, as shown in FIG. 5, a half mirror 8 and a rear illumination unit 20 are attached to the back side of the display surface so that the external light can be reflected by the half mirror 8 so as to be seen even in a dark place. There is a semi-transmissive liquid crystal display device that performs display using reflected light and transmitted light formed by the back-side illumination unit 20.

In this transflective liquid crystal display device, the light formed by the rear-surface illuminating unit 20 is emitted toward the front of the display panel. 8, only half of the light is reflected by the rear-surface illumination unit 20, and only half of the light is transmitted. Therefore, there is a problem that the light use efficiency is low.

Further, there is a problem that the display contrast is low and the display quality is deteriorated as compared with the reflection type or the transmission type, and this is a serious obstacle in performing a monochrome display and a color display.

It is an object of the present invention to provide a reflection type liquid crystal display device which can display a display screen sufficiently even when used in a dark place, saves power, and improves light use efficiency. .

[0011]

In a reflection type liquid crystal display device according to the present invention, a liquid crystal layer is sandwiched between a pair of substrates, and a reflection plate is provided on a side of one substrate which is not in contact with the liquid crystal layer, and a reflection plate is provided on the other substrate. An illumination unit is provided on the side not in contact with the liquid crystal layer.

According to the present invention, it is possible to obtain a reflection type liquid crystal display device in which the display screen can be sufficiently viewed even when the device is used in a dark place, the power consumption is reduced, and the light use efficiency is improved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the invention described in claim 1 of the present invention, a liquid crystal layer is sandwiched between a pair of substrates, and a reflection plate is provided on a side of one substrate which is not in contact with the liquid crystal layer, and a reflection plate is provided on the other substrate. This is a reflection type liquid crystal display device provided with an illuminating means on the side not in contact with the liquid crystal layer, so that even when used in a dark place, the display screen can be sufficiently visually recognized, and light can be saved with low power consumption. Efficiency can be improved.

According to the second aspect of the present invention, the brightness of the external light is detected by the received light amount detecting means, and the illumination means includes:
A light source that is arranged in a peripheral portion not including the effective display area and generates display auxiliary light based on the output of the received light amount detection unit, and is arranged to cover the same or slightly larger than the effective display area, and Light guiding means for guiding the display auxiliary light so as to enter the inside of the present liquid crystal display device, and guiding the reflected light from the reflection plate so as to be emitted to the outside of the present liquid crystal display device. Item 1. A reflective liquid crystal display device according to item 1, wherein the display auxiliary light generated by detecting the brightness of the external light is supplied to the liquid crystal display device so that the display can be sufficiently viewed even in a dark place. In addition, the display can be viewed by external light without generating display auxiliary light in a bright place.

According to a third aspect of the present invention, there is provided the illumination device, wherein the illuminating means is disposed in a peripheral portion that does not include the effective display area to detect the brightness of external light, A light source that is arranged to generate display auxiliary light based on the output of the received light amount detection means, and is disposed so as to cover the same or slightly larger than the effective display area, and external light and the display auxiliary light are used in the main liquid crystal display. 2. A reflection type liquid crystal display device according to claim 1, further comprising light guide means for guiding light so as to enter the inside of the device and guiding light so as to emit reflected light from the reflection plate to the outside of the liquid crystal display device. By supplying the auxiliary display light generated by detecting the brightness of the external light to the liquid crystal display device, the display can be sufficiently viewed even in a dark place, and in a bright place. Outside without generating display auxiliary light You can see the display by.

According to a fourth aspect of the present invention, a light control means for controlling a light emission amount of an illumination means so as to be continuously or stepwise in inverse proportion to an incident light amount of external light is provided. The reflection type liquid crystal display device according to claim 2 or 3, wherein the reflection type liquid crystal display device is connected between the means and the light source. Usage efficiency can be improved.

According to a fifth aspect of the present invention, there is provided a switching means for turning off the illuminating means when the incident light amount of the external light is equal to or more than a threshold value, and for turning on the illuminating means when the incident light amount is equal to or less than the threshold value. Is connected between the received light amount detecting means and the light source, and controls the turning on and off of the illuminating means according to the amount of incident external light. can do.

According to a sixth aspect of the present invention, there is provided the switching means for turning off the illuminating means when the incident light amount of the external light is equal to or more than the threshold value, and for turning on the illuminating means when the incident light amount is equal to or less than the threshold value. And a dimming means for dimming the light emission amount of the illumination means so as to be continuously or stepwise inversely proportional to the incident light quantity of the light at the time of lighting, between the light reception light quantity detection means and the light source. According to a second aspect of the present invention, there is provided a reflective liquid crystal display device according to the second or third aspect, which controls lighting and extinguishing of the illuminating means in accordance with the amount of external light incident, and at the same time, controls the amount of light emitted. Light use efficiency can be improved.

According to a seventh aspect of the present invention, at least one of the dimming means and the switching means functions in conjunction with the received light amount detecting means. This is a liquid crystal display device, and can control the illumination means based on the output of the received light amount detection means.

Hereinafter, a reflection type liquid crystal display device of the present invention will be described based on specific embodiments. (Embodiment 1) In a reflection type liquid crystal display device according to Embodiment 1 of the present invention, as shown in FIG. 1, a liquid crystal layer 4 is sandwiched between a front glass substrate 2 and a back glass substrate 5 so that a liquid crystal is formed around the substrate. The liquid crystal layer 4 of the back glass substrate 5 is sealed with a sealing seal 3.
A reflector 7 is provided on the side not in contact with the backside polarizing plate 6, and an illumination unit 10 as lighting means is provided on the side of the front glass substrate 2 not in contact with the liquid crystal layer 4 via the front polarizer 1. It is a thing.

The lighting unit 10 is, as shown in FIG.
It is arranged on the upper surface of the front polarizing plate 1. The lighting unit 10 includes an outer peripheral portion 15 a of a lighting unit case 15.
A light source 13 and a received light amount detecting means 11 are provided, and a light guiding means 14 is provided at a central portion thereof except for an outer peripheral portion 15a.

Outer peripheral portion 15a of lighting unit case 15
Is a portion corresponding to a peripheral portion not including the effective display area of the reflective liquid crystal display device. Two point or linear fluorescent tubes serving as the light source 13 are provided in the outer peripheral portion 15a, and generate display auxiliary light (light supplemented inside the reflective liquid crystal display device so that the display can be sufficiently viewed). It is to let.

An optical sensor as the received light amount detecting means 11 detects an incident light 12 from the outside. The output from the received light amount detecting means 11 is electrically connected to the switching means of the lighting unit 10.

The light guide means 14 is formed using a resin material having translucency as a base material, has the same or larger area as the effective display area of the reflection type liquid crystal display device, and covers the effective display area. Is provided at a central portion excluding the outer peripheral portion 15a. The light guide means 14 guides the incident light 12 from the outside and the display auxiliary light 13a so as to enter the reflection plate 7 inside the reflection type liquid crystal display device, and reflects the reflection light from the reflection plate 7 into the reflection type. The light is guided so as to be emitted to the outside of the liquid crystal display device.

Further, in order to efficiently use the amount of incident light from the illumination unit 10, a reflecting means may be provided on the upper surface or side surface of the light guiding means 14. As shown in FIG. 3A, between the received light amount detecting means 11 and the light source 13, as shown in FIG.
And a switch 17 as switching means. The light control means 9 includes a lighting unit lighting circuit 16.
And a dimming circuit 18.

When the surrounding area is bright and the amount of incident external light is large, as shown in FIG. 3A, the switch 17 is opened in conjunction with the detection output of the received light amount detecting means 11, and the light control circuit 18 at the subsequent stage is opened. Since the light source 13 remains off without being connected to the lighting unit lighting circuit 16, the light source 13 is turned off.

When the surroundings are dark and the amount of incident external light is small, as shown in FIG. 3B, the switch 17 is closed in conjunction with the detection output of the received light amount detecting means 11, and the light control circuit 18 in the subsequent stage is used. The lighting unit 16 is turned on by being connected to the lighting unit lighting circuit 16 and the light source 13 is turned on. At this time, the display auxiliary light of the light source 13 is dimmed so as to be in inverse proportion to the incident light continuously or stepwise. That is, the dimming circuit 18 operates in accordance with the detection output of the received light amount detecting means 11 and generates an appropriate amount of light so as to always provide an appropriate display.

As described above, when the surroundings are bright, the illumination unit 10 arranged on the upper surface of the display polarizing plate 1 of the liquid crystal display device is turned off, and only the incident light 12 from the outside is used. Can be operated as
When the surroundings are dark, the illumination unit 10 is turned on to generate display auxiliary light 13a, and the display auxiliary light 13a is incident and supplemented with a small amount of incident light 12 from the outside to form a reflective liquid crystal display device. It can be operated, and a sufficient display can be performed without being affected by surrounding light and shade.

Also, by providing the switch 17, the dimming circuit 18, and the lighting unit lighting circuit 16 in the lighting unit 10, the lighting unit 10 can be used part-time according to the brightness of the external light. In addition, by dimming the light emission amount of the illumination unit 10 continuously or stepwise in inverse proportion to the incident light amount of the external light, it is possible to use an appropriate light amount and realize power saving. Can be.

In the first embodiment, both the light control means and the switching means are provided in the lighting unit. However, the same effect can be obtained even when only the light control means is used. (Embodiment 2) A reflection type liquid crystal display device according to Embodiment 2 of the present invention is obtained by removing the dimming circuit 18 of the illumination unit 10 shown in Embodiment 1 and otherwise excluding Embodiment 1. Is similar to

In this case, the lighting unit 10 is not provided with the dimming circuit 18 so that dimming cannot be performed, and the light source 13 is turned on when the incident light amount of the external light falls below the threshold value. In this case, the light source 13 is turned off, so that the lighting unit 10 is turned off or turned on.

As described above, when the surroundings are bright, the illumination unit 10 arranged on the upper surface of the display polarizing plate 1 of the liquid crystal display device is turned off, and only the incident light 12 from the outside is used. Can be operated as
When the surroundings are dark, the illumination unit 10 is turned on to generate display auxiliary light 13a, and the display auxiliary light 13a is incident and supplemented with a small amount of incident light 12 from the outside to form a reflective liquid crystal display device. It can be operated, and a sufficient display can be performed without being affected by surrounding light and shade.

Since the lighting unit 10 is not provided with the dimming circuit 18 and cannot perform dimming at the time of lighting, the effect of power saving is slightly reduced, but the circuit components constituting the dimming circuit 18 are not. Since it is necessary, the manufacturing cost can be reduced as compared with the case where the dimming circuit 18 is used.

In each of the embodiments, the received light amount detecting means is provided in the lighting unit. However, the same effect can be obtained even when the received light amount detecting means is used outside the lighting unit.

In each embodiment, the illumination unit has one received light amount detecting means. However, the same effect can be obtained even when a plurality of received light amount detecting means are provided. In each embodiment, the illumination unit has two light sources. However, the same effect can be obtained even when two or more light sources or only one light source is used.

[0036]

As described above, according to the reflection type liquid crystal display device of the present invention, the liquid crystal layer is sandwiched between a pair of substrates, and a reflection plate is provided on one side of the substrate which is not in contact with the liquid crystal layer, and the other is provided with a reflection plate. By providing the illuminating means on the side of the substrate which is not in contact with the liquid crystal layer, the display screen can be sufficiently visually recognized even when used in a dark place. Since all reflected light is reflected, the use efficiency can be maximized, and the illuminating means is operated when necessary according to the surrounding brightness. Obtainable.

Specifically, when the surroundings are bright, the illumination unit disposed on the upper surface of the display polarizing plate of the liquid crystal display is turned off, and the liquid crystal display is operated as a normal reflection type liquid crystal display using only the incident light of the external light. When the surroundings are dark, the lighting unit is turned on to generate display auxiliary light, supplement incident light, and operate as a reflective liquid crystal display device. It can display enough without receiving it.

Further, by operating the lighting unit lighting circuit in conjunction with the switching means based on the output of the received light amount detecting means, the lighting and turning off of the lighting means can be controlled, and the display auxiliary light can be supplemented at low cost. it can.

Further, by interlocking the light control means based on the output of the received light amount detection means, the light control means can control the light emission amount of the illumination means and adjust the supplementary light quantity.
Power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration sectional view of a reflective liquid crystal display device according to a first embodiment.

FIG. 2 is a schematic perspective view of a lighting unit according to the first embodiment.

FIG. 3 is a circuit block diagram of a lighting unit according to the first embodiment.

FIG. 4 is a cross-sectional view of a configuration of a conventional reflective liquid crystal display device.

FIG. 5 is a cross-sectional view of a configuration of a conventional transflective liquid crystal display device.

[Explanation of symbols]

 Reference Signs List 7 reflector 9 light control means 10 lighting unit 11 received light quantity detection means 12 externally incident light 13 light source 13a display auxiliary light 14 light guide means 15 lighting unit case 15a outer peripheral portion 16 lighting unit lighting circuit 17 switch 18 light control circuit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G02F 1/133 535 G02F 1/133 535 G09F 9/00 336 G09F 9/00 336B

Claims (7)

[Claims] 1. A liquid crystal layer is sandwiched between a pair of substrates, a reflector is provided on a side of one of the substrates which is not in contact with the liquid crystal layer, and an illuminating means is provided on a side of the other substrate which is not in contact with the liquid crystal layer. Reflective liquid crystal display. 2. The light receiving amount detecting means detects the brightness of the external light, and the illuminating means is arranged at a peripheral portion not including the effective display area, and the display auxiliary light is provided based on the output of the light receiving amount detecting means. A light source to be generated, disposed so as to cover the effective display area, and guides external light and the display auxiliary light so as to enter the inside of the present liquid crystal display device, and reflects reflected light from a reflecting plate to the main liquid crystal. 2. The reflection type liquid crystal display device according to claim 1, further comprising: light guide means for guiding light so as to be emitted to the outside of the display device. 3. The illuminating means includes a received light amount detecting means disposed at a peripheral portion not including an effective display area to detect the brightness of external light, and an output of the received light amount detecting means disposed at the peripheral portion. A light source that generates display auxiliary light based on the light source, and is disposed so as to cover the effective display area, and guides external light and the display auxiliary light so as to enter the inside of the present liquid crystal display device. 2. A reflection type liquid crystal display device according to claim 1, further comprising: a light guide means for guiding the reflected light from the liquid crystal display device to be emitted to the outside of the liquid crystal display device. 4. A light control means for controlling the light emission amount of the illumination means so as to be continuously or stepwise inversely proportional to the incident light amount of the external light is connected between the received light amount detection means and the light source. The reflective liquid crystal display device according to claim 2 or 3. 5. A switching means for turning off the illuminating means when the incident light quantity of the external light is equal to or more than the threshold value and turning on the illuminating means when the incident light quantity is equal to or less than the threshold value, between the light receiving light quantity detecting means and the light source. The reflective liquid crystal display device according to claim 2 or 3, wherein the reflective liquid crystal display device is connected to a liquid crystal display device. 6. A switching means for turning off the illuminating means when the incident light amount of the external light is equal to or more than a threshold value, and for turning on the illuminating means when the incident light amount is equal to or less than the threshold value. 4. The reflection device according to claim 2, wherein a light control means for controlling the light emission amount of the illumination means so as to be continuously or stepwise inversely linked in conjunction therewith is connected between the received light amount detection means and the light source. Liquid crystal display device. 7. The reflection type liquid crystal display device according to claim 4, wherein at least one of the light control means and the switching means functions in conjunction with the received light amount detection means.