JP2005274832A - Reflection type liquid crystal display device with auxiliary light source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device with an auxiliary light source which has a photoelectric converting function as a solar battery and a function of automatically adjusting the quantity of light of the auxiliary light source and then has lower power consumption and further eliminates the need to add an extra optical detecting means to automatically control the quantity of light of the auxiliary light source. <P>SOLUTION: An auxiliary light source part 301 with a dimming function is added as an auxiliary light source to a reflection type liquid crystal display device which has both a display part 100 with a display function as reflection type liquid crystal and a photoelectric converting function as a solar battery, and a control part 302 determines luminance information based upon power generation quantity information obtained from the solar battery part 200 to adjust the quantity of light of the auxiliary light source part 301 with the dimming function. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a reflection type liquid crystal display device with an auxiliary light source to which a function of converting external light energy into electric energy is added.

  Power saving is important because mobile devices that are assumed to be used outdoors are powered by batteries and the like. The reflection type liquid crystal display device performs display by controlling the reflectance of incident light from the outside in units of liquid crystal cells, and does not require a backlight unlike the transmission type liquid crystal display device. Most of the power consumption of a transmissive liquid crystal display device is a backlight, and a reflective liquid crystal display device that does not require a backlight is widely used as a display device with low power consumption.

  However, in the reflective liquid crystal display device, when the ambient light is low, the visibility of the display content is lowered. For this reason, some apparatuses include an auxiliary light source such as a front light to directly illuminate the display surface. Even in this case, if the surroundings are sufficiently bright, an auxiliary light source is unnecessary, and it can be said that the display device is power saving compared to the transmissive liquid crystal display device.

  On the other hand, in order to efficiently use natural energy, development of electric energy generating means such as solar cells has been progressed, and it has been put to practical use in houses and building facilities. However, the photoelectric conversion efficiency is limited, and it is necessary to secure the installation area of the solar cell in order to obtain appropriate power. Therefore, when a solar cell is applied to a mobile device that is required to be small and thin, securing the mounting location has been a problem.

As an improvement measure, a display device combining a reflective liquid crystal and a solar cell has been proposed for power saving. Reflection and transmission by the wavelength selectivity of light are selected by the liquid crystal cell, and the light reflected by the liquid crystal cell is visually recognized as a bright display. The light transmitted through the liquid crystal cell is absorbed by a solar cell provided as an absorption layer and visually recognized as a dark state display. Thereby, a display and photoelectric conversion are realizable simultaneously (for example, refer patent document 1).
JP-A-60-147718

  However, this reflective liquid crystal display device has poor visibility when there is no auxiliary light source and the surroundings are dark. Therefore, in order to improve the visibility when the surroundings are dark, it is necessary to take measures such as adding an auxiliary light source.

  The problem to be solved is that in the reflective liquid crystal with an auxiliary light source, it is effective to realize the function of automatically adjusting the luminance of the auxiliary light source from the viewpoint of low power consumption. This means that a separate means for detecting ambient light is required.

  In a reflective liquid crystal display device with an auxiliary light source to which a photoelectric conversion function by a solar cell is added, the most important feature is that the amount of light of the auxiliary light source is automatically adjusted according to the amount of power generated from the solar cell.

  Since the reflective liquid crystal display device with an auxiliary light source of the present invention has a photoelectric conversion function as a solar cell and a function of automatically adjusting the light amount of the auxiliary light source, it means low power consumption and There is an advantage that it is not necessary to separately add a light detection means for automatically controlling the amount of light.

  In the reflective liquid crystal, the purpose of suppressing the addition of components used for automatic control of the auxiliary light source was realized by combining the light detection function using the result of power generation from the built-in solar cell for generating electric energy.

(Embodiment 1)
FIG. 1 shows a configuration of a reflective liquid crystal display device with an auxiliary light source according to the present invention.

  In FIG. 1, the display unit 100 and the solar cell unit 200 are stacked, the display unit 100 reflects and displays the incident light from the outside, and the solar cell unit 200 absorbs the light transmitted from the display unit 100. The auxiliary light source unit 300 irradiates the display unit 100 when the surroundings are dark.

  The display unit 100 and the solar cell unit 200 operate as a kind of reflective liquid crystal display device. An example of this configuration is shown in FIG. As shown in FIG. 2, the liquid crystal cell 102 is sandwiched between two outer transparent electrodes 105 and an inner transparent electrode 106, and the outer transparent electrode 105 and the inner transparent electrode 106 are supported by the outer glass substrate 101 and the inner glass substrate 103, respectively. It has become the composition.

  The outer glass substrate 101 corresponds to the display surface of the reflective liquid crystal display device with an auxiliary light source of the present embodiment. Usually, it is a glass substrate, but it may be a plastic and other transparent substrate or a flexible film substrate. External light enters through the outer glass substrate 101 and passes through the outer transparent electrode 105, and the liquid crystal cell 102 performs either light scattering, reflection by wavelength selectivity, or light transmission. As liquid crystal materials having such optical properties, cholesteric / nematic phase transition type cells, cells using polymer liquid crystal composite films as scattering types, cholesteric liquid crystal gel type cells, etc. are known. Even if it exists, it is feasible. The same can be realized with a fluid fine particle display. There is no particular limitation as long as the above-described light reflection and transmission can be selected.

  Reflection and transmission of light in the liquid crystal cell 102 are controlled by an electric field generated by the outer transparent electrode 105 and the inner transparent electrode 106. When incident light is reflected by scattering or wavelength selectivity in the liquid crystal cell 102, the reflected light is transmitted to the outside of the display device through the outer transparent electrode 105 and the outer glass substrate 101 and visually recognized as a display. On the other hand, when light is transmitted through the liquid crystal cell 102, the transmitted light reaches the solar cell unit 200 through the inner transparent electrode 106 and the inner glass substrate 103.

  The solar cell unit 200 absorbs light transmitted from the liquid crystal cell 102 and performs photoelectric conversion. In this case, since the light absorbed by the solar cell unit 200 cannot reach the display surface, a color corresponding to the light absorption characteristics of the solar cell unit 200 is perceived. The color expressed by light absorption is preferably black, but colors other than black may be expressed.

  Note that the type of the solar cell unit 200 is not particularly limited. A semiconductor or a semiconductor compound may be used, and a dye-sensitized solar cell, an organic solar cell, or a wet solar cell may be used.

  Since the auxiliary light source unit 300 is turned on when the surroundings are dark, the irradiation light irradiates the display unit 100 in the same manner as the external light, so that the visibility of the display content can be improved.

  In addition to the above, in the present embodiment, the power photoelectrically converted by the solar cell unit 200 may be used by the auxiliary light source unit 300, or may be used or charged inside and outside the apparatus.

  With such a configuration, both the display function as a reflective liquid crystal and the photoelectric conversion function as a solar cell are provided, which saves power and improves the visibility of display contents when the surroundings are dark by having an auxiliary light source. it can.

(Embodiment 2)
FIG. 3 is a diagram showing a configuration of a reflective liquid crystal display device with an auxiliary light source according to Embodiment 2 of the present invention.

  In FIG. 3, the same reference numerals are given to components that perform the same operations as those in the first embodiment, and description thereof is omitted. In FIG. 3, the control unit 302 generates luminance information based on the power generation amount information obtained from the solar cell unit 200, and the auxiliary light source unit with dimming function 301 changes the light amount based on the luminance information.

  That is, in this configuration, the auxiliary light source unit 300 of the configuration of the first embodiment is replaced with an auxiliary light source unit 301 with a dimming function, and a control unit 302 is added.

  The control unit 302 generates luminance information based on the power generation amount information obtained from the solar cell unit 200. The auxiliary light source unit with dimming function 301 changes the amount of light based on the luminance information. In the present embodiment, control is performed so that the amount of light emitted from the auxiliary light source unit with dimming function 301 is increased only when the surroundings are dark.

  An example of control by the control unit 302 is shown below. When the power generation amount notified by the power generation amount information from the solar cell unit 200 is less than a predetermined reference value, the “lighting” is notified to the auxiliary light source unit with dimming function 301 via the luminance information. . When the power generation amount notified by the power generation amount information from the solar cell unit 200 is equal to or greater than a predetermined reference value, the “light extinction” is notified to the auxiliary light source unit with dimming function 301 via the luminance information. .

  Furthermore, the luminance of the auxiliary light source unit 301 with a dimming function may be adjusted by control by the control unit 302. When the power generation amount of the solar cell unit 200 is less than the reference value, the light amount of the auxiliary light source unit with dimming function 301 may be increased according to the decrease in the power generation amount.

  The reference value of the power generation amount information obtained from the solar cell unit 200 is the power generation amount information when the reflective liquid crystal display device with the auxiliary light source deteriorates the visibility due to lack of ambient light and the auxiliary light source needs to be turned on. It is determined by actually measuring in advance.

  In addition to the above, in the present embodiment, the electric power photoelectrically converted by the solar cell unit 200 may be used in the auxiliary light source unit 301 with a dimming function, or may be used or charged inside and outside the apparatus.

  With such a configuration, both the display function as a reflective liquid crystal and the photoelectric conversion function as a solar cell are provided, which saves power and improves the visibility of display contents when the surroundings are dark by having an auxiliary light source. it can. In addition, the amount of light from the auxiliary light source can be automatically controlled, and there is no need to add additional light detection means necessary for the control.

  The present invention can also be applied to the case of a reflective color liquid crystal. Coloring methods in this case include side-by-side additive color mixing using a color filter that transmits each of the three colors of red, blue, and green, reflection of each of the three colors of cyan, magenta, and yellow by selecting the wavelength of the light and pigment. Any of subtractive color mixing realized by overlapping liquid crystal cell layers for selecting transmission may be used.

  It is a power-saving reflective liquid crystal display device that has a photoelectric conversion function as a solar cell and a function that automatically adjusts the amount of light from the auxiliary light source. It is necessary to maintain display for a long time with various mobile devices and low power. It can be applied to electronic books with

  Further, general display devices other than mobile devices can provide the advantage of power saving.

The figure which shows the structure of the reflection type liquid crystal display device with an auxiliary light source in Embodiment 1 of this invention. The figure which shows the detailed structure of the display part and a solar cell part The figure which shows the structure of the reflection type liquid crystal display device with an auxiliary light source in Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Display part 101 Outer surface glass substrate 102 Liquid crystal cell 103 Inner surface glass substrate 105 Outer surface transparent electrode 106 Inner surface transparent electrode 200 Solar cell part 300 Auxiliary light source part 301 Auxiliary light source part 302 with a light control function 302 Control part

Claims (3)

A display unit using a liquid crystal cell that selects reflection and transmission by light scattering or wavelength selectivity;
A solar cell part,
An auxiliary light source unit disposed at a position capable of irradiating the display unit,
Laminating the display unit and the solar cell unit,
The reflection type liquid crystal display device with an auxiliary light source, wherein the auxiliary light source unit irradiates the display unit when the surrounding is dark. Replace the auxiliary light source with an auxiliary light source with dimming function that adjusts the luminance based on the luminance information.
Based on the power generation amount information obtained from the solar cell unit, the dimming function by generating luminance information that increases the luminance when the power generation amount is smaller than a reference value and decreases the luminance when the power generation amount is larger than the reference value The reflective liquid crystal device with an auxiliary light source according to claim 1, further comprising a control unit for notifying the auxiliary light source unit with the auxiliary light source unit. The display unit sandwiches both sides of the liquid crystal cell with two transparent electrodes,
Each of the transparent electrodes is configured to support a glass substrate,
The reflective liquid crystal display with an auxiliary light source according to claim 1 or 2, wherein the liquid crystal cell selects reflection and transmission by light scattering or selectivity by an electric field generated between the two transparent electrodes. apparatus.

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