JP3225959B2 - Liquid crystal display device and electronic equipment using liquid crystal 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 structure of a liquid crystal display and an electronic apparatus having the same.

[0002]

2. Description of the Related Art A conventional liquid crystal display device comprises a liquid crystal cell having a liquid crystal layer sandwiched between a pair of substrates having electrodes, and two polarizing layers disposed on both sides of the liquid crystal cell. In the case of using the liquid crystal cell, a structure in which a planar luminous body is provided outside the polarizing layer on the side opposite to the viewing side of the liquid crystal cell has been employed. Further, when the liquid crystal display device is used in a reflection type, a structure in which a reflection layer is disposed outside the polarizing layer on the side opposite to the viewing side of the liquid crystal cell has been employed. However, this liquid crystal display device has a problem that the display becomes dark because light incident on the liquid crystal display device passes through the polarizing layer four times before exiting the liquid crystal display device again. As a means for solving such a problem, a new reflective liquid crystal mode in which a polarizing layer 51 and a reflective layer 53 are arranged so as to sandwich a liquid crystal layer 52 as shown in FIG. Since the liquid crystal display device of this mode has only one polarizing layer unlike the conventional liquid crystal display device,
Light incident on the liquid crystal display device passes through the polarizing layer twice before exiting the liquid crystal display device again, resulting in a brighter display, and a display nearly twice as bright as the conventional liquid crystal display device is possible. It became.

[0003]

However, when the above-mentioned transmissive liquid crystal display device is incorporated in an electronic device, particularly a portable personal computer, and used, there is no problem when power can be supplied to the electronic device from the outside. When using a battery built into an electronic device without using an external power supply, the capacity of the built-in battery is small, so that there is a disadvantage that the usable time of the electronic device is shortened.

When a new reflection type liquid crystal display device having only one polarizing layer is used in an electronic apparatus, when used in a dark environment, the absolute amount of light incident on the liquid crystal display device is reduced. Therefore, the display is dark and the contents are difficult to recognize.

In order to solve the above-mentioned drawbacks, the present invention provides a liquid crystal display device which is of a transmissive type when the illuminant on the back of the liquid crystal cell is turned on, and has a single polarizing layer when it is not illuminated. The purpose is to use it as a reflective type in a bright environment to extend the usable time of electronic devices in a bright environment, and to use a transmissive type in a dark environment to provide a bright display. It is an object of the present invention to provide an obtained liquid crystal display device and an electronic device using the same.

[0006]

A liquid crystal display device according to the present invention comprises a pair of polarizing layers comprising a first polarizing layer and a second polarizing layer such that a liquid crystal layer is located therebetween.
In a liquid crystal display device capable of performing transmissive display and reflective display, a light reflecting layer capable of transmitting a part of incident light is provided between the second polarizing layer and the liquid crystal layer. Disposing, disposing a first retardation layer between the first polarizing layer and the liquid crystal layer, and disposing a second retardation layer between the second polarizing layer and the liquid crystal layer. And a light-emitting means provided on the side opposite to the light reflecting layer with respect to the second polarizing layer.

[0007]

An embodiment of the present invention will be described below.

FIG. 1 is a sectional view of a liquid crystal display device according to an embodiment of the present invention. 3 is a liquid crystal cell,
The cell gap is 8 μm, the Δn of the liquid crystal is 0.1, and the liquid crystal is twisted 260 ° to the left from the upper substrate (viewing side) to the lower substrate. Reference numeral 1 denotes an upper polarizing plate, and the angle between its polarization axis and the rubbing axis of the upper substrate is 32 °. 2 is a uniaxially stretched film, and the retardation value is 0.32 μm
And the angle between the stretching direction and the upper rubbing axis is 24 °. 4
Is a transflective plate whose transmittance is 40%. Reference numeral 5 denotes a lower polarizing plate, and the angle between its polarization axis and the rubbing axis of the upper substrate is 107 °.

When the liquid crystal display device of this embodiment is used in a bright environment, the light emitting body on the back of the panel is used in a non-lighting state. In this case, the liquid crystal display device is a reflection type liquid crystal display device. That is, the light incident from the upper polarizer passes through the uniaxially stretched film and the liquid crystal panel, is reflected by the reflector, and emerges again from the liquid crystal display device through the liquid crystal panel, the uniaxially stretched film and the upper polarizer. The contrast ratio of the display obtained at this time is about 1:10, and the brightness is about 1.10 of the conventional reflection type liquid crystal display device having two polarizing layers.
A display as bright as 5 times was obtained. Also, in this case, it is possible to save the power used to turn off the illuminant on the back of the panel, and to integrate the liquid crystal display device into an electronic device, particularly a portable personal computer, and drive the liquid crystal display device with a battery built into the electronic device. It is, of course, clear that the usable time can be extended.

On the other hand, when used in a dark environment, the luminous body is turned on. In this case, the liquid crystal display device is used as a transmission type. That is, the light exiting the light emitter passes through the lower polarizing plate, and then passes through the semi-transmissive reflecting plate, the liquid crystal panel, the uniaxially stretched film, and the upper polarizing plate in this order. The contrast ratio of the display obtained at this time was about 1: 5, and the brightness was slightly reduced to about 70% of that of the conventional transmissive liquid crystal display device, but was at a level without any problem.

[Embodiment 2] FIG. 3 is a sectional view of a liquid crystal display device according to an embodiment of the present invention. Reference numeral 23 denotes a liquid crystal cell having a cell gap of 8 μm, a Δn of the liquid crystal of 0.1, and a twist of 260 ° to the left from the upper substrate (viewing side) to the lower substrate. Reference numeral 21 denotes an upper polarizer, and the angle between the polarization axis of the upper polarizer and the rubbing axis of the upper substrate is 32 °. 22 is a uniaxially stretched film, and the retardation value is 0.2.
At 32 μm, the angle between the stretching direction and the upper rubbing axis is 24 °. Numeral 24 denotes a semi-transmissive reflection plate having a transmittance of 40%. Reference numeral 26 denotes a lower polarizing plate, and the angle between its polarization axis and the rubbing axis of the upper substrate is 107 °. Reference numeral 25 denotes a uniaxially stretched film provided between the transflector and the lower polarizing plate. The retardation of the film is 0.12 μm, and the angle between the stretching direction and the upper rubbing axis is 155 °.

When the liquid crystal display device of the present embodiment is used with the illuminant on the back of the panel turned off in the same manner as in the first embodiment, the contrast ratio of the obtained display is about 1:10, and the brightness is the same as that of the conventional device. A display as bright as about 1.5 times that of a reflection type liquid crystal display device having two polarizing layers was obtained. It is obvious that, even when the battery is used by being incorporated in an electronic device, the usable time of the battery built in the electronic device can be extended similarly to the first embodiment.

On the other hand, the contrast ratio of a display obtained when the light-emitting body is used in a lighting state is about 1:10,
Although the brightness was slightly reduced to about 70% of that of the conventional transmissive liquid crystal display device, it was at a level having no problem as in Example 1.

Embodiment 3 In Embodiment 1 described above, a uniaxially stretched film is inserted between the liquid crystal panel and the upper polarizing plate. In Embodiment 2, between the liquid crystal panel and the upper polarizing plate and between the transflective plate and the lower polarizing plate. Although a uniaxially stretched film is inserted into the film, the same effect can be obtained even when the uniaxially stretched film is not used, and in any position between the upper polarizing plate, the liquid crystal panel, the transflective plate, and the lower polarizing plate, The same effect can be obtained by inserting. In addition, the same effect can be obtained by combining them. Furthermore, the number of uniaxially stretched films to be inserted in one place does not need to be one, and it goes without saying that the same effect can be obtained with a plurality of films.

Example 4 It is apparent that the same effect as in Examples 1 to 3 can be obtained even when a uniaxially stretched film obtained by vapor-depositing a metal such as aluminum is used as the transflective plate. In this case, since the uniaxially stretched film and the transflective layer are integrated, there are also advantages such as reduction in thickness and improvement in reliability.

[0016]

As described above, the liquid crystal display device of the present invention is a liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates having electrodes, and a pair of polarizing layers is arranged so as to sandwich the liquid crystal layer. By providing a light reflection layer having the property of transmitting part of incident light between the polarizing layer and the liquid crystal layer on the side opposite to the viewing side, and by switching the light emitter on the back of the liquid crystal panel between lighting and non-lighting. It is possible to use the liquid crystal display device in both the transmission type and the reflection type, and when this liquid crystal display device is incorporated in electronic equipment, in a bright environment, the backside illuminant is turned off and the reflection type is used. In addition, it is possible to extend the usable time of the battery built into the electronic device, and also to provide a bright and easy-to-view display by turning on the light-emitting body on the back in a dark environment. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a view showing a relationship between a polarization axis of a polarizing plate, a rubbing direction, and a stretching axis direction of a retardation film in the liquid crystal panel of FIG.

FIG. 3 is a sectional view showing one embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a polarization axis of a polarizing plate, a rubbing direction, and a stretching axis direction of a retardation film in the liquid crystal panel of FIG.

FIG. 5 is a diagram showing a conventional liquid crystal display device.

[Explanation of symbols]

1. Polarizing plate 2. 2. Uniaxially stretched film Liquid crystal panel 4. Transflective plate 5. Polarizing plate 6. Light-emitting body 11. Rubbing direction of upper substrate 12. 12. Stretching direction of uniaxially stretched film 13. Polarization axis direction of upper polarizer 14. Rubbing direction of lower substrate 15. Polarization axis direction of lower polarizing plate 16. Angle between the rubbing axis of the upper substrate and the stretching direction of the uniaxially stretched film 17. Angle formed between rubbing axis of upper substrate and polarization axis of upper polarizing plate 18. Angle formed between rubbing axis of upper substrate and polarization axis of lower polarizing plate 21. Angle formed between rubbing axis of upper substrate and rubbing axis of lower substrate Polarizing plate 22. Uniaxially stretched film 23. Liquid crystal panel 24. Uniaxially stretched film 25. Transflective plate 26. Polarizing plate 27. Light emitter 31. Rubbing direction of upper substrate 32. 33. Stretching direction of upper uniaxially stretched film Direction of polarization axis of upper polarizer 34. Rubbing direction of lower substrate 35. 36. Direction of polarization axis of lower polarizing plate 37. Stretching direction of lower uniaxially stretched film 38. Angle between the rubbing axis of the upper substrate and the stretching direction of the upper uniaxially stretched film 39. Angle between rubbing axis of upper substrate and polarization axis of upper polarizing plate 40. Angle formed between rubbing axis of upper substrate and polarization axis of lower polarizing plate 41. Angle between the rubbing axis of the upper substrate and the stretching direction of the lower uniaxially stretched film 51. Angle formed between rubbing axis of upper substrate and rubbing axis of lower substrate Polarizing plate 52. Liquid crystal panel 53. reflector

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/1335 G02F 1/13363 G09F 9/00-9/46

Claims (3)

(57) [Claims] A first liquid crystal layer disposed between the first and second liquid crystal layers;
And a liquid crystal display device capable of performing transmissive display and reflective display, in which a pair of polarizing layers including a second polarizing layer and a second polarizing layer are arranged. A light-reflecting layer capable of transmitting a part of incident light therebetween, a first retardation layer between the first polarizing layer and the liquid crystal layer, A second retardation layer is disposed between a second polarizing layer and the liquid crystal layer, and a light emitting unit is provided on a side opposite to the light reflecting layer with respect to the second polarizing layer. Characteristic liquid crystal display device. 2. The light-emitting means is switchable between a lighting state and a non-lighting state. When the light-emitting means is in a lighting state, light from the light-emitting means emits light from the second polarizing layer to the light-reflecting state. Layer, the liquid crystal layer, and the first polarizing layer are sequentially transmitted to perform transmissive display. When the light emitting unit is in a non-lighting state, light transmitted through the first polarizing layer is transmitted to the liquid crystal layer. 2. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is configured to transmit light, reflect the light from the light reflection layer, transmit the liquid crystal layer and the first polarizing layer again, and perform a reflective display. 3. An electronic device powered by a battery, comprising the liquid crystal display device according to claim 1 or 2.