JP2004309973A - Mobile electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile electronic device capable of obtaining excellent visibility irrelevant to ambient lightness. <P>SOLUTION: The mobile electronic device 100 having a reflection type liquid crystal display part 130 provided with a reflecting plate 133 on the reverse surface side of a liquid crystal display plate 132 is characterised by being equipped with a light transmission plate 131 which is provided on the top surface side of the liquid crystal display plate 132 and variable in light transmissivity, a light quantity detection part 140 which detects lightness outside the device, and a control part 160 which controls the light transmissivity of the light transmission plate 131 according to the lightness outside the device detected by the light quantity detection part 140 to control the quantity of light incident on the liquid crystal display plate 132. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a portable electronic device such as a mobile phone and a personal digital assistant, which is portable and miniaturized, and particularly to a portable electronic device having a reflective liquid crystal display.
[0002]
[Prior art]
In a portable electronic device having a reflective liquid crystal display unit, a reflection means such as a white acrylic plate is arranged on the back side of a liquid crystal display panel constituting the liquid crystal display unit, and light incident from the outside on the reflection surface of the reflection means. Upon receiving the light, the light is reflected on the liquid crystal display panel side to illuminate, thereby enhancing the visibility (see Patent Document 1). Normally, the reflectivity of the reflecting surface of the above-mentioned reflecting means is set to 20 to 30% in accordance with outdoor use during the day, thereby ensuring good visibility during use during the day. I have.
[0003]
According to the above-described prior art, when the reflectance of the reflecting surface is higher than 30% in daytime use, the surface becomes like a mirror surface. Therefore, the setting is set as low as 20 to 30%. For this reason, visibility in the morning and evening or indoors becomes poor. As a technique for improving this, there is a technique in which a light guide plate is provided between a liquid crystal display panel and a reflection surface, and a light emitting element for a backlight is arranged near the light guide plate. When the light guide plate is provided, light of the light emitting element is guided into the light guide plate from a side surface or the like of the light guide plate. The light receiving element detects the surrounding brightness, and when the surrounding brightness is higher than a predetermined light amount, the light emitting element is illuminated only by the reflector without turning on the light emitting element. The visibility is enhanced by illuminating the liquid crystal display panel with light that propagates (see Patent Documents 2 and 3).
[0004]
[Patent Document 1]
JP 2001-274880 A [Patent Document 2]
JP 2001-217740 A [Patent Document 3]
JP 2001-305976 A
[Problems to be solved by the invention]
However, according to the conventional technique using only the above-described reflecting means, the reflectance of the reflecting surface is as low as 20 to 30%, and the visibility is significantly reduced in a dark place. Further, according to the related art in which the light guide plate is provided between the liquid crystal display panel and the reflection surface, it is necessary to further provide a dedicated light emitting element and a light receiving element.
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a portable electronic device that can obtain good visibility regardless of ambient brightness.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a portable electronic device according to the invention described in claim 1 is a portable electronic device having a reflection type liquid crystal display unit in which a reflection plate is provided on the back side of a liquid crystal display panel. A light-transmitting plate provided on the display surface side of the liquid crystal display panel and having a variable light transmittance, a light amount detecting unit for detecting brightness outside the device, and the outside of the device detected by the light amount detecting unit. Control means for controlling the light transmittance of the light transmitting plate according to the brightness of the liquid crystal panel, and adjusting the amount of light incident on the liquid crystal display panel.
[0007]
According to a second aspect of the present invention, in the portable electronic device, a liquid crystal light adjusting plate is used as the light transmitting plate.
According to a third aspect of the present invention, in the portable electronic device, a black and white liquid crystal plate is used as the light-transmitting plate.
The invention described in claim 4 is the portable electronic device, wherein the control means controls the light transmittance of the light transmitting plate so that the light amount incident on the liquid crystal display panel is suppressed as the outside of the device is brighter. Is controlled.
According to a fifth aspect of the present invention, in the portable electronic device, the control unit controls the light transmittance of the light transmitting plate so that the amount of light incident on the liquid crystal display panel is constant. And
[0008]
According to a sixth aspect of the present invention, in the portable electronic device, the reflectance of the reflector is higher than 30%.
According to a seventh aspect of the present invention, in the portable electronic device, a light guide plate is disposed between the liquid crystal display panel and the reflection plate, and a light emitting unit is provided near the light guide plate. .
The invention according to claim 8 is the portable electronic device, wherein the light-transmitting plate is disposed in a liquid crystal display window provided in a housing, and the light-transmitting plate is also used as a protective cover for the liquid crystal display plate. It is characterized by having done.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 to 3 show a first embodiment of a portable electronic device according to the present invention. FIG. 1 is a perspective view of a mobile phone 100 as a preferred example of the present portable electronic device, and FIG. 2 is a sectional view of the mobile phone 100 in a folded state. As shown in FIG. 1, the mobile phone 100 has a structure in which a first housing 110 on which operation keys are arranged and a second housing on which a liquid crystal display unit 120 is arranged are foldably connected to each other. In addition, a light receiving window 140 is formed near the liquid crystal display unit 130 of the second housing 120.
[0010]
As shown in FIG. 2, a light transmitting plate 131, a liquid crystal display plate 132, and a reflecting plate 133 are arranged inside the second housing 120 as the above-described liquid crystal display unit 130. Reference numeral 131 denotes the surface of the liquid crystal display unit 130. The light-transmitting plate 131 has a function of changing the light transmittance according to an applied voltage, and for example, a light control plate is used. Although there are various types of light control plates, a liquid crystal light control plate (light control glass) with low power consumption is suitable for a portable electronic device. Further, a black and white liquid crystal plate can be used as the light transmitting plate 131.
[0011]
A reflection plate 133 is attached to the back surface of the liquid crystal display panel 132, and the liquid crystal display plate 132 is arranged so that its display surface faces the light transmission plate 131, and is transparent on the display surface side of the liquid crystal display plate 132. The light plate 131 is arranged. As the reflection plate 133, for example, a white acrylic plate having a reflectance of 50 to 60% is used. The reflectance of 50 to 60% is a value suitable for improving the visibility of the liquid crystal display surface when the light transmittance of the light transmitting plate 131 is controlled to almost 100% in indoor use during the day. It is. The reflectivity of the reflecting surface of the reflector 133 may be any value as long as it is higher than the conventional reflectivity (30%) within a range where visibility under room light can be improved.
[0012]
In addition, inside the second housing 120, a light amount detection unit 150 is arranged in alignment with the light receiving window 140. The light amount detection unit 150 includes a light receiving element 151 that receives light external to the device and performs photoelectric conversion, and an A / D converter that converts a photoelectrically converted current signal into a digital signal. The control unit 160 controls the dimming of the liquid crystal display unit 130, and controls the light transmittance of the light transmitting plate 131 in accordance with the output signal of the light amount detection unit 150, thereby controlling the ambient light outside the device. The amount of light incident on the liquid crystal panel 132 is adjusted accordingly. In the daytime indoor brightness, the light transmittance is set to almost 100%, and the light transmittance decreases as the brightness becomes higher. The control of the light transmittance of the light transmitting plate 131 is performed so that the amount of light reflected by the reflecting plate 133 is substantially uniform according to the surrounding brightness during the day.
[0013]
In the first embodiment, the above-described light-transmitting plate 131 used to change the light transmittance also functions as a protective cover for protecting the display surface of the liquid crystal display panel 132. When the light control glass is used as the light transmitting plate 131, it has a sufficient strength as a protective cover as it is, and is particularly suitable. When a black-and-white liquid crystal plate is used as the light-transmitting plate 131, it may be used as a protective cover by increasing the strength by integrating it with a glass substrate. In this example, the light-transmitting plate 131 is also used as a protective cover. However, a conventional protective cover is provided, and the light-transmitting plate 131 is disposed between the protective cover and the liquid crystal display panel 132. Is also good. In this case, the light transmitting plate 131 may be either a light control glass or a black and white liquid crystal plate.
[0014]
Next, the principle of dimming control of the liquid crystal display unit in the portable electronic device of the present embodiment will be described with reference to FIG. FIG. 3A shows the amount of transmitted light by dimming control under room light. As shown in the figure, under room light, the light transmittance of the light transmitting plate 131 is controlled to almost 100% by the control unit 160, so that room light, which is light outside the device, is hardly attenuated. The light enters the display surface of the display plate 132. Then, a part of the light is reflected by the reflection plate 133 provided on the back surface of the liquid crystal display panel 132 and transmits through the light transmission plate 131 again. The transmitted light enters the user's eyes E to form an image. Here, since the light transmittance of the light transmitting plate 131 is set to 100%, the light transmitted through the light transmitting plate 131 is hardly attenuated. Further, since the reflectance of the reflecting plate 133 is set to 50 to 60%, a sufficient reflected light can be obtained by the reflecting plate 133. Therefore, an appropriate amount of light is emitted from the display surface 130 under room light, and good visibility can be obtained.
[0015]
FIG. 3B shows the amount of transmitted light by dimming control under outdoor light. As shown in the figure, under outdoor light that is brighter than indoor light, the light transmittance of the light transmitting plate 131 is suppressed by the control unit 160, so that outdoor light, which is light outside the device, is attenuated and the liquid crystal display The light enters the display surface of the plate 132. Then, a part of the light is reflected by the reflection plate 133 provided on the back surface of the liquid crystal display panel 132, and is transmitted through the light transmission plate 131 again. The transmitted light enters the user's eyes E to form an image. Here, as described above, the light transmittance of the light transmitting plate 131 is controlled such that the amount of light reflected by the reflecting plate 133 becomes substantially constant according to the surrounding brightness. That is, the outdoor light is attenuated by the light transmitting plate 131 and the reflected light from the reflecting plate 133 is attenuated so that the amount of light reaching the user's eyes is substantially equal to the amount of indoor light. Therefore, even under outdoor light, an appropriate amount of light is emitted from the display surface 130, and good visibility can be obtained.
[0016]
As described above, in the first embodiment, under the control of the control unit 160, the light transmittance of the light transmitting plate 131 is controlled according to the brightness of the outside of the device detected by the light amount detection unit 150, and the liquid crystal display is controlled. The amount of light incident on the display surface of the plate 132 is adjusted. In addition, the light transmittance of the light transmitting plate 131 is controlled by the control unit 160 such that the light amount incident on the liquid crystal display panel 132 is suppressed as the outside of the device becomes brighter. As a result, the amount of light emitted from the liquid crystal display unit 130 is kept optimal, and the visibility is improved.
[0017]
Next, FIG. 4 shows a second embodiment of the portable electronic device according to the present invention. In the figure, the same reference numerals are given to the elements common to the elements shown in FIG. As shown in FIG. 4, in the second embodiment, a light guide plate 134 is arranged between the liquid crystal display panel 132 and the reflector 133, and a light emitting element 135 for backlight is arranged near the light guide plate 134. ing. The light emitting element 135 is turned on under the control of the control unit 160 when the amount of received light detected by the light amount detection unit 150 is equal to or less than a predetermined light amount, and illuminates the liquid crystal display panel 132. As a result, even in a situation where the surroundings are dark and the visibility is reduced only by the reflection plate 133 in a room or the like, good visibility can be secured as well as the above-described first embodiment. Also in the second embodiment, the reflectance of the reflector 133 is set to 50% to 60%, which is higher than 30% of the conventional reflector, so that the light emission amount of the light emitting element 135 is reduced. Even if it is smaller than the backlight, it is possible to obtain the same amount of illumination light as that of the above-described first embodiment, and it is possible to obtain good visibility while suppressing power consumption.
[0018]
【The invention's effect】
According to the present invention, good visibility can be obtained regardless of the surrounding brightness. Also, in the case of a backlight system using a light guide plate, since the reflectance of the reflection plate is higher than that of the conventional one, the amount of light emitted from the light emitting element for illumination can be reduced, and power consumption can be reduced. Further, by using a light-transmitting plate having a function of changing light transmittance for the protective cover (window for liquid crystal display), miniaturization and thinning can be achieved without increasing the number of components.
[Brief description of the drawings]
FIG. 1 is a perspective view of a mobile phone according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of the mobile phone according to the first embodiment of the present invention.
FIG. 3 is an explanatory diagram for explaining the principle of dimming control according to the first embodiment of the present invention.
FIG. 4 is an explanatory diagram for explaining the principle of dimming control according to a second embodiment of the present invention.
[Explanation of symbols]
110; first housing, 120; second housing, 130; liquid crystal display unit, 131; translucent plate, 132; liquid crystal display plate, 133; reflecting plate, 134; light guide plate, 135; Window, 150; light amount detection unit, 151; light receiving element, 152; A / D converter, 160; control unit.

Claims (8)

In a portable electronic device having a reflection type liquid crystal display unit in which a reflection plate is provided on the back side of the liquid crystal display panel,
A light-transmitting plate that is provided on the display surface side of the liquid crystal display panel and has a variable light transmittance;
Light amount detection means for detecting brightness outside the device,
Control means for controlling the light transmittance of the light transmitting plate according to the brightness of the outside of the device detected by the light amount detecting means, and adjusting the light amount incident on the liquid crystal display panel. Portable electronic devices. The portable electronic device according to claim 1, wherein a liquid crystal light control plate is used as the light-transmitting plate. The portable electronic device according to claim 1, wherein a black and white liquid crystal plate is used as the light-transmitting plate. The control means,
The light transmittance of the light transmitting plate is controlled such that the light amount incident on the liquid crystal display panel is suppressed as the outside of the device becomes brighter, wherein the light transmittance is controlled. Portable electronic devices. The control means,
The portable electronic device according to any one of claims 1 to 4, wherein the light transmittance of the light transmitting plate is controlled so that the amount of light incident on the liquid crystal display panel is constant. The portable electronic device according to any one of claims 1 to 5, wherein the reflectance of the reflector is higher than 30%. 7. The portable electronic device according to claim 6, wherein a light guide plate is disposed between the liquid crystal display panel and the reflection plate, and a light emitting unit is provided near the light guide plate. 8. The liquid crystal display according to claim 1, wherein the light transmitting plate is disposed in a liquid crystal display window provided in a housing, and the light transmitting plate is also used as a protective cover for the liquid crystal display panel. Portable electronic device as described.

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