JP2011248113A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device using a liquid crystal display element that has good visibility in a dark place.SOLUTION: A liquid crystal display device includes a liquid crystal display element, a housing, a printed board, and a luminous body. The liquid crystal display element and the luminous body are held by the housing and the printed board. The housing is provided with an opening in a size in which the effective display area of the liquid crystal display element is reduced by a prescribed offset amount. The luminous body is disposed at a position concealed by the housing.

Description

The present invention relates to a liquid crystal display device using a phosphorescent material as an illumination light source.

A liquid crystal display device, which is a display device in which a liquid crystal element performs an information display function, has been adopted as a display function component of various devices by taking advantage of light weight and power saving.

In applications where ambient light is sufficient, reflective liquid crystal display elements are often used, such as partially shielding the outside of the liquid crystal display element against external light, coloring based on birefringence, light absorption by dichroic dyes, etc. Information can be displayed by performing the operation. In this case, since the desired function is realized by driving only the liquid crystal display element, the advantage of power saving can be maximized.

However, since the liquid crystal display element is not a self-luminous element, it is necessary to use it together with a lighting device when used in an application where ambient light is not sufficient. A typical example is a backlight device disposed on the back surface of a liquid crystal display element.

As the backlight device, those using a surface light source such as an EL element as a light source, those using a point or line light source such as an incandescent light bulb, LED, CFL, etc., and those using a surface light source device in combination with a light guide are widely used. .

Here, use of a light emitter used for various light sources requires much higher power consumption than a liquid crystal display element. For this reason, the advantage of the power saving of the liquid crystal display element is impaired by the operation of the backlight device.
Especially in applications where various devices are in a stopped or standby state, or when the information display function is required and the time for which the liquid crystal display device operates is less than the total operation time of the device, the power consumption due to the light source lighting of the backlight device is This element cannot be ignored. In a device that uses a dry battery, a storage battery, or the like as a power source and has a limited supply power, it is necessary to ensure the operation time of the entire device by shortening the light source lighting time of the backlight device as much as possible. However, this usage mode cannot be used for purposes such as irregular status confirmation.

For example, when the time display of a device having a clock function is configured to be performed by a liquid crystal display element, the light source of the backlight device needs to be constantly lit during the operation period in order to respond to an arbitrary time confirmation request, In this mode of use, the operating time of the entire apparatus is shortened by the amount of power consumed by turning on the light source of the backlight device.
Also, when performing the time display, it is necessary to indicate the location of the display device itself in an environment where ambient light is scarce.

As one method for solving these problems, a display device using a phosphorescent material as a light source has been proposed in order to reduce or reduce the power consumption of the backlight device.

The device described in Patent Document 1 discloses a configuration in which a liquid crystal display panel is illuminated from the back by a light guide means and a light storage member formed in a U shape.

The device described in Patent Document 2 discloses an example in which a phosphorescent material is used for a sidelight type liquid crystal display device.
In both cited documents 1 and 2, a backlight type illumination structure is adopted as the illumination structure by the phosphorescent body.

By the way, since the illumination capacity of the phosphor is generally low with respect to a light source that emits light using electric power, there is a problem that it is difficult to obtain sufficient luminance when it is simply arranged as a light source of a direct type backlight. In addition, since the light emission by the phosphorescent material is performed with low luminance, the light emission is easily shielded even in a liquid crystal display element with a specification that does not necessarily have a low OFF transmittance particularly in a normally black liquid crystal display element, and the display device itself There is a problem in that it does not function sufficiently for use as an indicator for indicating the location.

JP-A-8-227073 JP 2002-270022 A

It is a point that power consumption is required for visual recognition of information in an environment where ambient light is scarce. In addition, it is difficult to efficiently perform illumination by the phosphorescent body and phosphorescence to the phosphorescent body.

The present invention comprises a liquid crystal display element, a light emitter including a phosphorescent body, and a light shielding body that prevents direct viewing of the light emitted from the phosphorescent body from the outside, and information on the liquid crystal display element is displayed in an environment rich in ambient light. It is possible to directly observe and simultaneously store the light in the phosphor, and in an environment where the ambient light is scarce, the information display of the liquid crystal display element and the confirmation of the location of the liquid crystal display element are facilitated by the light emission of the phosphor.

In another aspect, it includes a liquid crystal display element, a light emitter including a phosphorescent body, a light guide, and a light shielding body that prevents direct viewing of the light emitted from the phosphorescent body from the outside, and the ambient light is stored by the light guide. In the environment where ambient light is scarce, the light emitted from the phosphor is guided to the liquid crystal display element by a light guide so that the information display on the liquid crystal display element can be observed.

In another aspect, the surface area facing the light guide of the light emitter is increased by providing a large number of irregularities at the interface between the light guide and the light emitter, thereby improving the luminous efficiency of the phosphor and the light intake efficiency of the light guide. It is.

In another aspect, the light guide bending portion is configured to be thinner than the light guide light guide portion and the light storage agent facing portion, thereby guiding the external light to the light storage body and the liquid crystal display element for light emission of the light storage body. Guides light efficiently.

According to the present invention, it is possible to obtain a liquid crystal display device that can easily display information and confirm the location even in an environment with a low ambient light and does not increase power consumption.

FIG. 1 is a perspective view of a liquid crystal display element embodiment 1 of the present invention. FIG. 2 is a perspective view of Embodiment 2 of the liquid crystal display element of the present invention. FIG. 3 is a cross-sectional view of the liquid crystal display element example 1 of the present invention. FIG. 4 is a cross-sectional view of the liquid crystal display element embodiment 2 of the present invention. FIG. 5 is a cross-sectional view of one embodiment of the liquid crystal display element embodiment 2 of the present invention. FIG. 6 is a cross-sectional view of the liquid crystal display element embodiment 3 of the present invention. FIG. 7 is a cross-sectional view of a liquid crystal display element embodiment 4 of the present invention. FIG. 7 is a diagram showing the angle dependence of the light output intensity of the prism sheet. FIG. 9 is a diagram showing an embodiment in which the present invention is configured as a transmission type.

1 and 3 are views showing a first embodiment of the device of the present invention. FIG. 3 is shown as a cross-sectional view.
Reference numeral 1 denotes a liquid crystal display element, 2 a light emitter including a phosphorescent body, 3 a housing formed by bending a sheet metal, and 4 a printed circuit board on which a circuit for supplying power and signals to the liquid crystal display element is configured.

The liquid crystal display element 1 is fastened to the printed circuit board 4 together with the light emitter 2 by a housing 3.

The luminous body is made of a resin molded product containing a luminous pigment such as Luminova made by Nemoto Special Chemical. For example, it can be manufactured by injection molding the company's luminova pellets. In this case, for example, a molded product made of an acrylic resin containing 9.1% of G-300M manufactured by the same company as a luminous pigment is obtained.

The liquid crystal display element 1 is connected to the printed circuit board 4 by a flexible connector (not shown). For the connection, a clip terminal or a rubber connector may be used in addition to the flexible substrate.

In the liquid crystal display element, an effective display area 11 is set as an area viewed from the outside. The effective display area includes an area where pixels such as dots and characters are arranged, and has a boundary with an area not including liquid crystal such as a main seal. In the vicinity of the main seal, it is difficult to maintain the alignment uniformity of the liquid crystal. For example, in the case of a liquid crystal display element that performs normally black display, light leakage or coloring may occur. The effective display area is set as an area for maintaining display uniformity.

The housing 3 is provided with an opening 31 so that the effective display area 11 of the liquid crystal display element 1 can be observed from the outside. The opening 31 has a dimension that is offset inward by, for example, about 1 mm from the outer periphery of the effective display area 11 of the liquid crystal display element 1. This offset value is shielded so that the range other than the effective display area is not observed from the outside due to the assembly tolerance between the liquid crystal display element 1 and the housing 3 and the parallax due to the thickness of the transparent substrate of the liquid crystal display element when observed from an oblique direction. For this reason, a larger value is preferable, but a narrow frame product requires a smaller value. When the viewing angle range from the outside is about ± 45 ° and the thickness of the glass substrate is 0.7 mmt, for example, the preferred value is the combined value of the glass substrate thickness and the thickness of the front polarizing plate, etc. Is done.
The light emitter 2 is disposed between the liquid crystal display element 1 and the housing 3 at a position offset outward from the opening 31 so that the observation viewing angle range is not directly observed from a range of about ± 45 °, for example. In this case, the offset value is approximately equal to the thickness dimension of the light emitter 2.

By comprising in this way, in the environment with abundant external light, the light-emitting body 2 containing a phosphorescent body can expose the part 31 side end surface to the part of naturally scattered light, and can perform phosphorescence. Further, in an environment where the external light is scarce, the light emission of the phosphor stored in the light emitter 2 is irradiated directly onto the liquid crystal display element 1 without being visually recognized from the outside, and the information display is visualized. Further, a part of the irradiated light is scattered and illuminates the surface of the liquid crystal display element or the end of the opening 31 of the housing 3, and the location can be indicated even when the liquid crystal display element 1 is in a dark display state. It becomes.

2 and 4 are views showing a second embodiment of the apparatus of the present invention. It is described as a cross-sectional view.

In the second embodiment, the light guide 5 is employed while the arrangement positions of the light emitters 2 including the phosphorescent body are different.

The end surface on the opening 31 side of the light guide 5 is arranged with a predetermined offset from the opening 31 in the same manner as the light emitter 2 of the first embodiment.

The light guide 5 has a first portion 51 along the front side of the liquid crystal display element 1 so as to sandwich the liquid crystal display element 1, a second portion 52 along the end surface of the liquid crystal display element 1, and a third portion along the back surface of the liquid crystal display element 1. The portion 53 is provided.

The luminous body 2 including the phosphorescent body is formed in a thin plate shape, and is arranged so that the upper surface is in contact with the third portion 53 of the light guide 5. The arrangement of the light emitters 2 may be configured such that the lower surface of the light guide 5 is in contact with the light guide 5.

With this configuration, in an environment rich in outside light, part of the naturally scattered light is incident on the light guide 5 from the end surface on the opening 31 side of the first portion 51 of the light guide 5. The inside is guided and reaches the luminous body 2 including the luminous body, so that the luminous body included in the luminous body 2 can store the light.
In an environment where external light is scarce, the light emitted from the light emitter 2 including the phosphorescent material is guided through the light guide 5 and radiated to the outside from the end surface on the opening 31 side of the light guide 5.

At this time, by providing an appropriately shaped light distribution control structure, for example, a prism used for a prism sheet, on the end surface of the light guide 5 on the opening 31 side, the emitted light from the end of the light guide 5 is directed to the liquid crystal display element 1 side. It is possible to deflect and collect light. An example is shown in FIG. The general shape of the prism used in the prism sheet is an isosceles triangle having an apex angle of 90 degrees, and the guided light in the light guide is converged and radiated in the height direction of the isosceles triangle. For this reason, it is possible to converge the emitted light from the end face of the light guide 5 toward the liquid crystal display element 1 by inclining the reference plane 54 on which the prism is provided with respect to the normal line of the liquid crystal display element 1. In the case of a general prism sheet, the distribution of the output intensity shows a dispersion having a half width of about ± 50 ° as shown in FIG. Therefore, by setting the angle inclined from the normal line to about 50 ° at which the output intensity is halved, the illumination light component that does not contribute to illumination can be reduced and the liquid crystal display element can be illuminated efficiently.

FIG. 6 is a view showing a third embodiment of the apparatus of the present invention. It is described as a cross-sectional view.

The third embodiment is different from the second embodiment in that the end of the light guide 5 that is offset with respect to the opening 31 is not provided. Except for the configuration near the opening 31, the second embodiment is the same as the second embodiment.

In the third embodiment, the light guide 5 is configured to cover the entire front surface of the liquid crystal display element 1. With this configuration, the emitted light of the light emitter 2 can be more uniformly irradiated over the entire effective display area of the liquid crystal display element 1.

In a section exposed to the outside through the opening 31 of the light guide 5, it is preferable to include an optical control structure 55 that deflects light guided into the light guide 5 toward the liquid crystal display element 1. The optical control structure 55 is preferably configured so as not to hinder the observation of the liquid crystal display element 1. Specifically, the optical control structure 55 of the third embodiment is preferably a light extraction structure by refraction or reflection such as a prism or a light extraction structure by scattering such as halftone printing or embossing.

In the case of the optical control structure 55 that uses refraction, it is preferably provided on the liquid crystal display element 1 side of the light guide. In the case of the optical control structure 55 using reflection and scattering, it is preferable to provide the light guide on the outer surface side that is not the liquid crystal display element 1 side.

In any of the light extraction structure based on refraction or reflection and the light extraction structure based on scattering, it is preferable that each structure is arranged in a minute size and spaced apart so as not to disturb the observation of the liquid crystal display element 1. It is preferable that the size of one unit of each structure is generally less than 100 μm, preferably less than 50 μm, since the light emitting portion is not clearly visible.

When the optical control structure 55 is configured by a triangular prism, the height of the isosceles triangle of the prism portion is about 50 to 25 μm. Although there is no particular lower limit in terms of function, when the light guide 5 is formed of a resin molded product, the lower limit is approximately 10 μm because of technical difficulties in the molding process and mold processing. When the prism height is about 10 μm, the prism base is about 20 μm.

If the arrangement intervals of the structures are too close, observation of the liquid crystal display element 1 is hindered due to light emission and scattering by the optical control structure 55. For this reason, the arrangement interval is preferably about 1 mm. This value is approximately 10 times or more, preferably 20 times or more of the base dimension when the optical control structure 55 is formed of a prism molded product having a triangular cross section. The upper limit is about 50 times from the limit of molding processing accuracy. It becomes.

The optical control structure 55 can be configured in a dot shape or a line shape. In addition, in order to improve the uniformity of illumination, the interval between the optical control structures 55 is appropriately adjusted to increase the density of dark portions when arranged uniformly, and to reduce the density of portions that become brighter when arranged uniformly. Applicable.

When the optical control structure 55 is configured as a line, it is difficult to vary the density distribution in the direction parallel to the line. In this case, the arrangement density of the light extraction structure in the azimuth parallel to the line is adjusted by dividing the line and changing the line interval for each divided line, or by setting a section where no line is provided between the divided lines. can do.

In the case of a linear structure, it is preferable to arrange the line so that the direction of the line faces the second portion 52. This eliminates the arrangement in which the second portion 52 and the linear structure are orthogonal to each other when viewed from the front of the apparatus. The section exposed to the outside through the opening 31 of the light guide 5 can be regarded as a sidelight type illumination device including a linear light source in the vicinity of the second portion 52. At this time, it is possible to extract light with higher efficiency by arranging the linear structure so as to face the light source. The linear structure is not limited to an arrangement in a positional relationship parallel to the second portion 52. By arranging the linear structures so that the lines intersect each other, the anisotropy of the outgoing light distribution is compensated for each other, and more uniform light extraction is possible. It is also possible to apply the aforementioned line division and line intersection simultaneously.

FIG. 4 is a view showing a fourth embodiment of the apparatus of the present invention. It is described as a cross-sectional view.

The fourth embodiment is characterized in that the contact surface 21 of the light emitter 2 and the light guide 5 is provided with irregularities. Other configurations can be the same as those of the second and third embodiments.

Since the uneven processing on the contact surface 21 is accompanied by an increase in the surface area of the illuminant, there is an effect of increasing the incident light intensity for light emission and storage of the illuminant. The shape of the unevenness is not particularly limited.

The effect of the configuration of Example 4 can be further enhanced by integrally molding the light emitter 2 and the light guide 5. By integrally molding, a structure in which an air layer is not included between the light emitter 2 and the light guide 5 can be achieved, and this can suppress a decrease in efficiency due to reflection at the resin / air interface. The unevenness of the contact surface also has an effect of increasing the bonding strength between the light emitter 2 and the light guide 5 having different compositions.

When integrally molding, it is preferably formed by a multicolor molding method.

In any of the above embodiments, the liquid crystal display element is not specified as either a transmission type or a reflection type. For example, as shown in FIG. 1, a separate backlight unit 7 is provided directly below the liquid crystal display element. It can be. In the second to fourth embodiments, for example, the light emitter 2 is configured so as to surround the backlight unit 7 as shown in FIG. 9, or the light emitter 2 and the light guide so as to surround the backlight unit 7. 5 can be easily provided as a transmissive device having a backlight. Moreover, it can be set as a reflection-type apparatus in any aspect by making the back side polarizing plate of the liquid crystal display element 1 into a reflection type polarizing plate.

Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

It can be used for an apparatus using a liquid crystal display element used in a dark place.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display element 2 Light-emitting body 3 Housing 4 Printed circuit board 5 Light guide 7 Backlight unit 11 Effective display area 21 Contact surface 31 Opening part 51 1st part 52 2nd part 53 3rd part 54 Reference plane

Claims (5)

A display device comprising a liquid crystal display element, a housing, a printed circuit board and a light emitter,
The liquid crystal display element and the light emitter are sandwiched between the housing and the printed board,
The housing includes an opening having a size reduced by a predetermined offset amount from an effective display area of the liquid crystal display element,
The liquid crystal display device, wherein the light emitter is disposed at a position hidden in the housing. Furthermore, a display device comprising a light guide,
The light guide includes a first portion along the surface of the liquid crystal display element, a second portion along the end surface, and a third portion along the back surface,
The light guide is provided with an opening that is enlarged by a predetermined offset amount from the opening in the first part,
The liquid crystal display device according to claim 1, wherein the light emitter is in contact with the third portion. The opening end face of the light guide has a light distribution control structure,
The reference plane of the light distribution control structure is provided so as to be inclined with respect to a normal line of the liquid crystal display element in an orientation in which the reference plane faces the surface of the liquid crystal display element. Liquid crystal display device. Furthermore, a display device comprising a light guide,
The light guide includes a first portion along the surface of the liquid crystal display element, a second portion along the end surface, and a third portion along the back surface,
The light guide covers the opening,
The area covering the opening of the light guide includes an optical control structure for illuminating the liquid crystal display element,
The optical control structure is configured in a line shape or a dot shape,
The optical control structure is configured such that the interval is 10 to 50 times the bottom dimension of the optical control structure,
The liquid crystal display device according to claim 1, wherein the optical control structure has a structure width of 10 to 100 μm. The liquid crystal display device according to claim 2, wherein a contact surface between the light emitter and the light guide is configured to be uneven.

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