JP2002318384A - Reflective liquid crystal panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal panel with a solar cell integrated thereinto. SOLUTION: The solar cell 6 is disposed on the rear side of a rear substrate 2R and, at the same time, a light absorption layer 8 is disposed on the rear side of the solar cell 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reflection type liquid crystal panel, and more particularly to a reflection type liquid crystal panel using a chiral nematic liquid crystal.

[0002]

2. Description of the Related Art As one type of display device for displaying information, a liquid crystal display device which is small, light and requires a small installation space has been known. A pair of substrates is used as a display portion of such a liquid crystal display device. A liquid crystal panel in which liquid crystal is sealed is used. Such a liquid crystal display device is used for many products such as a desk calculator and a digital clock. Such products such as a desk calculator and a digital clock often use a solar cell as a power supply. In a product using the solar cell as a power supply, the solar cell is generally arranged separately from the liquid crystal panel.

Further, various types of display methods of a liquid crystal panel used for a display unit of a liquid crystal display device have been proposed, but at present, a TN (twisted nematic) type and an STN (super twisted nematic) type are used. The liquid crystal panel is most widely used, and in such a liquid crystal panel, display is performed by using a polarizing plate to transmit and shield external light by changing the molecular arrangement of the liquid crystal.

[0004]

In the above-mentioned conventional liquid crystal panel, display is performed by using a polarizing plate to transmit and shield external light by changing the molecular arrangement of the liquid crystal. In the case of the reflective display, external light from the front is reflected by the reflective layer provided on the rear side of the liquid crystal layer.

Therefore, the conventional liquid crystal panel cannot incorporate a solar cell and cannot meet the demand for integrating the solar cell with the liquid crystal panel.

The present invention has been made in view of this point, and an object of the present invention is to provide a reflective liquid crystal panel in which a solar cell is integrated.

[0007]

In order to achieve the above-mentioned object, a reflection type liquid crystal panel according to the present invention according to claim 1 is characterized in that a solar cell is arranged on the rear surface of a rear substrate. The point is that a light absorbing layer is provided on the back surface of the solar cell. By adopting such a configuration, it is possible to easily and reliably arrange the solar cells on the rear surface of the rear substrate without affecting the display. As a result, since it is not necessary to arrange the solar cell at another position, the degree of freedom in designing a product using the solar cell as a power source is increased. Further, by providing the light absorbing layer in the solar cell, it is not necessary to separately provide the light absorbing layer on the rear substrate, and the overall configuration can be simplified.

[0008] A feature of the reflective liquid crystal panel of the present invention according to claim 2 is that, in claim 1, the solar cell is formed directly on the rear surface of the rear substrate. By employing such a configuration, the configuration can be further simplified, and the weight of the solar cell can be reduced, and the overall weight can be slightly increased.

According to a third aspect of the present invention, there is provided a reflective liquid crystal panel according to the second aspect, wherein the output electrode of the solar cell is provided on the same side of the rear substrate as the side on which the panel electrode terminals are formed. It is in that point. By adopting such a configuration, the electrical connection between the panel electrode terminals and the output electrodes and the printed circuit board provided with the external drive circuit can be simplified.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings.

FIG. 1 is a schematic sectional view showing an outline of the entire structure of a first embodiment of a reflection type liquid crystal panel according to the present invention.

The reflection type liquid crystal panel 1 of the present embodiment has a pair of substrates 2 formed of transparent glass having a thickness of 0.7 mm. One of the pair of substrates 2 shown on the lower side in FIG. 1 is a rear substrate 2R located on the downstream side in the viewing direction.
The other shown in the upper part of FIG. 1 is a front substrate 2F which is an opposing substrate located on the upstream side in the viewing direction. On the opposing surfaces of the substrates 2R and 2F, a transparent conductive film such as ITO (indium tin oxide) is formed by a thin film forming method and then patterned by a photolithographic method or the like. Display electrodes 3R and 3F having a predetermined shape are provided. Further, a cell gap, which is an interval between the rear substrate 2R and the front substrate 2F, is controlled to about 3 to 5 μm by a spacer formed of a resin ball or the like (not shown). Further, the rear substrate 2R and the front substrate 2F are bonded via a seal 4 disposed around the opposing surface, and a selective reflection wavelength is supplied from an injection port (not shown) provided in advance at the time of bonding. A chiral nematic liquid crystal 5 to which a chiral agent is added so as to have a thickness of 520 to 550 nm is injected by a vacuum injection method or the like, and then the injection port is sealed with an unillustrated ultraviolet curable resin to form the two substrates 2F and 2R. A chiral nematic liquid crystal 5 is enclosed between them.

A solar cell 6 having an output of 3 V is provided on the rear surface of the rear substrate 2R shown in the lower part of FIG. The solar cell 6 is formed on the lower surface of a rectangular transparent glass substrate 7 having a thickness of 0.7 mm, and the rear surface of the solar cell 6 shown in the lower part of FIG. A black light-absorbing layer 8 that also serves as a light-absorbing function is provided. The light absorbing layer 8 is formed by screen printing a black ink made of an alkyd resin or the like.

Since the structure of the solar cell 6 is conventionally known, its detailed description is omitted.

The rear substrate 2R and the solar cell 6 are
It is fixed by a double-sided tape (not shown) provided around the glass substrate 7 of the solar cell 6. Thus, the reflective liquid crystal panel 1 in which the solar cell 6 of the present embodiment is integrated on the rear surface of the rear substrate 2R is formed.

The other configuration is the same as that of the conventional reflection type liquid crystal panel, and the detailed description is omitted.

Next, the operation of the present embodiment having the above-described configuration will be described.

The reflection type liquid crystal panel 1 of the present embodiment uses a chiral nematic liquid crystal 5 obtained by mixing a nematic liquid crystal and an optically active substance (chiral material). The chiral nematic liquid crystal 5 can exhibit selective reflection in the planar state and can exhibit a fine scattering state in the focal conic state. In order to make a transition to the planar state or the focal conic state, a predetermined voltage may be applied. Each state when no voltage is applied is maintained until a new voltage is applied. Therefore, the reflective liquid crystal panel 1 is an element having a memory effect, can reduce power consumption, and can obtain a bright reflective display because it is not necessary to use a polarizing plate.

The principle of exhibiting the selective reflection color will be described. The chiral nematic liquid crystal 5 is sandwiched between a pair of parallel substrates 2 and the director, which is the arrangement direction of the chiral nematic liquid crystal 5, rotates at regular intervals. When the helical axis (spiral axis), which is the central axis, is arranged so as to be perpendicular to the substrate 2 on average, circularly polarized light corresponding to the direction of the twist is reflected. The central wavelength of the reflected light is the distance (pitch) on the helical axis during one rotation of the director of the chiral nematic liquid crystal 5 parallel to the substrate 2 due to the twist, and the distance parallel to the substrate surface of the nematic liquid crystal. It is the product of the average refractive index in the dimensional plane. Such a phenomenon that the chiral nematic liquid crystal 5 reflects circularly polarized light of a specific wavelength based on the pitch and the refractive index of the nematic liquid crystal is called selective reflection.

According to the reflection type liquid crystal panel 1 of the present embodiment, the solar cells 6 can be easily and reliably arranged on the rear surface of the rear substrate 2R without affecting the display. As a result, since it is not necessary to arrange the solar cell 6 at another position, the degree of freedom in designing a product using the solar cell 6 as a power source is increased.

According to the reflection type liquid crystal panel 1 of the present embodiment, the light absorbing layer 8 is provided on the solar cell 6, so that it is not necessary to separately provide the light absorbing layer 8 on the rear substrate 2R. It can be simplified.

Further, the reflection type liquid crystal panel 1 of the present embodiment
According to this, light energy can be converted into electric energy sufficient for driving the liquid crystal.

This means that the output of the solar cell 6 alone at a position 30 cm below the fluorescent lamp is 2.97 V, 32 μA.
The output of the solar cell 6 in the planar state of the reflective liquid crystal panel 1 of this embodiment is 2.96 V, 24 μA, and the output of the solar cell 6 in the focal conic state is 2.97.
V could be confirmed by the test result of 28 μA.

FIGS. 2 and 3 show a second embodiment of the reflection type liquid crystal panel according to the present invention. In the reflection type liquid crystal panel 1A of this embodiment, a solar cell 6A is directly formed on the rear surface of a rear substrate 2RA. Have been.

That is, as shown in FIG. 2, in the reflective liquid crystal panel 1A of the present embodiment, a solar cell 6A is directly formed on the rear surface of the rear substrate 2RA shown in the lower part of FIG. This solar cell 6A is formed by forming a glass substrate made of an alkali glass having a thickness of 0.7 mm serving as the rear substrate 2RA in a reaction chamber at a substrate temperature of 300 ° C. and a gas pressure of 20 Pa using a monosilane (SiH ₄ ) gas of 75 sccm (0 ° C.). , A flow rate converted to a standard state of 1 atm, cm ³ / min) + diborane (B ₂ H ₆ ) at 15 sccm, and an RF power of 5 KW
Plasma discharge at a thickness of 0.1
A p-type semiconductor layer 6Aa made of p-type amorphous silicon of about 5 μm is formed. Subsequently, only monosilane gas is introduced into the reaction chamber at 75 sccm, and plasma discharge is performed at an RF power of 5 KW to form an i-semiconductor layer 6Ab made of intrinsic (i) amorphous silicon having a thickness of about 0.20 μm on the surface of the p-type semiconductor layer 6Aa. I do. Then, 75 sccm of monosilane (SiH ₄ ) gas and 15 sccm of phosphine (PH ₃ ) gas are introduced into the reaction chamber, and the i semiconductor layer 6 is formed.
An n-type semiconductor layer 6Ac made of n-type amorphous silicon having a thickness of about 0.20 μm is formed on the surface of Ab. Thereby, the solar cell 6A is formed on the glass substrate. Materials for forming the solar cell 6A include Si, Ga
As, InP, Cd / CdTe, and the like.

Then, a transparent conductive film such as ITO is formed on both sides of the glass substrate on which the solar cell 6A is formed by a thin film forming method, and is then patterned by a photolithographic method or the like, so that the front surface of the glass substrate shown in FIG. The display electrode 3R is formed on the back surface of the glass substrate, and the output electrode 6Ad of the solar cell 6A is formed on the back surface shown in the lower part of FIG.

At this time, the formation position of the output electrode 6Ad of the solar cell 6A is set to the same side as the side where the panel electrode terminal 3Ra connected to the external drive circuit extended to the display electrode 3R of the rear substrate 2RA is formed. In the present embodiment, it is preferable to provide it on the right side of FIG. 2 in order to simplify the electrical connection with an external drive circuit and the like. That is, as shown in FIG. 3, panel electrode terminals 3Ra are formed on the upper surface on the right side of rear substrate 2RA, and output electrodes 6Ad are formed on the lower surface on the right side of rear substrate 2RA.

The output electrode 6Ad of the solar cell 6A is 2
One is connected to the p-type semiconductor layer 6Aa, and the other is connected to the n-type semiconductor layer 6Ac.

The rear surface, which is the lower surface of the solar cell 6A shown in FIG. 2, is provided with light that also serves to protect the solar cell 6A, similarly to the solar cell 6 of the reflective liquid crystal panel 1 of the first embodiment described above. A black light absorption layer 8 that exhibits an absorption function is provided.

The rear substrate 2RA on which the solar cell 6A is directly formed on the rear surface and the front substrate 2F on which the display electrodes 3F are formed are sealed in the same manner as in the reflection type liquid crystal panel 1 of the first embodiment. 4 and a chiral nematic liquid crystal 5 to which a chiral agent is added so that a selective reflection wavelength becomes 520 to 550 nm from an injection port (not shown) provided in advance at the time of bonding.
Is injected by a vacuum injection method or the like, and then the injection port is sealed with an ultraviolet curing resin (not shown), whereby the chiral nematic liquid crystal 5 is sealed between the two substrates 2F and 2RA, and the reflection type liquid crystal of the present embodiment is Panel 1A is formed.

According to the reflective liquid crystal panel 1A of the present embodiment having such a configuration, the same effects as those of the above-described reflective liquid crystal panel 1 of the first embodiment can be obtained, and the solar cell 6A can be mounted on the rear substrate 2RA. Because it is formed directly
The overall configuration can be made simpler. Further, the weight of the solar cell 6A can be reduced. This makes it possible to slightly increase the weight of the entire reflective liquid crystal panel 1A when the solar cell 6A is integrated. Further, the weight of the product can be reduced as compared with the conventional configuration in which the solar cells are arranged at different positions.

Further, the reflection type liquid crystal panel 1 of the present embodiment
According to A, light energy can be converted into electric energy sufficient for driving the liquid crystal.

This means that the output of the solar cell 6A in the planar state of the reflective liquid crystal panel 1A of the present embodiment is 2.9.
It could be confirmed from the test result that the output of the solar cell 6A in the focal conic state was 2.96 V and 29 μA at 6 V, 26 μA.

The reflection type liquid crystal panel 1A of the present embodiment
According to, the panel electrode terminal 3Ra is formed on the upper surface on the right side of the rear substrate 2RA, and the output electrode 6Ad of the solar cell 6A is formed on the lower surface on the right side of the rear substrate 2RA, so that the panel electrode terminal 3RA and the output electrode 6Ad are formed. And an electrical connection with a printed circuit board provided with an external drive circuit (not shown) can be simplified.

For example, as shown in FIG. 4, the right side of the rear substrate 2RA is sandwiched from above and below by a clip portion 11a of a PIN connector 11 made of phosphor bronze.
The PIN connector 11 can be electrically connected to each of the panel electrode terminal 3RA and the output electrode 6Ad. The mounting position of the PIN connector 11 can be easily fixed with an ultraviolet curing resin or the like.

Therefore, according to the reflection type liquid crystal panel 1A of the present embodiment, the output of the power supply voltage and the input of the drive signal are performed easily and reliably via the PIN connector 11 on the right side which is one side of the rear substrate 2RA. be able to.

The output electrode 6Ad is connected to a driving driver via a booster circuit, and the driving driver drives the reflective liquid crystal panel 1A.

The present invention is not limited to the above embodiments, but can be variously modified as needed.

[0039]

As described above, according to the reflective liquid crystal panel of the present invention according to the first aspect, it is possible to easily and reliably arrange a solar cell on the rear surface of the rear substrate without affecting the display. And so on.

Further, according to the reflection type liquid crystal panel of the present invention according to the second aspect, in addition to the effect of the reflection type liquid crystal panel of the first aspect of the invention, the structure can be further simplified, and This provides an extremely excellent effect such as a reduction in the weight of the solar cell and a slight increase in the overall weight.

According to the reflective liquid crystal panel of the present invention according to claim 3, in addition to the effects of the reflective liquid crystal panel of the present invention according to claim 2, a panel electrode terminal and an output electrode and an external drive circuit are provided. It is possible to obtain an extremely excellent effect such that the electrical connection with the printed circuit board on which is disposed can be simplified.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view schematically showing an overall configuration of a first embodiment of a reflective liquid crystal panel according to the present invention.

FIG. 2 is a view similar to FIG. 1, showing an outline of the overall configuration of a reflective liquid crystal panel according to a second embodiment of the present invention;

FIG. 3 is a plan view of FIG. 2;

4 is a perspective view showing a state in which a PIN connector is fixed to each of a panel electrode terminal and an output electrode of the reflective liquid crystal panel shown in FIG. 2;

[Explanation of symbols]

 1, 1A Reflective liquid crystal panel 2 Substrate 2F Front substrate 2R, 2RA Rear substrate 3F, 3R Display electrode 3Ra Panel electrode terminal 4 Seal 5 Chiral nematic liquid crystal 6, 6A Solar cell 6Aap p-type semiconductor layer 6Abi i-semiconductor layer 6Ac n-type semiconductor Layer 6Ad Output electrode 7 Glass substrate 8 Light absorbing layer 11 PIN connector 11a Clip section

Claims (3)

[Claims] 1. A reflection type liquid crystal panel using a chiral nematic liquid crystal, wherein a solar cell is disposed on a rear surface of a rear substrate, and
A reflection type liquid crystal panel, wherein a light absorbing layer is provided on the back surface of the solar cell. 2. The reflection type liquid crystal panel according to claim 1, wherein the solar cell is formed directly on a rear surface of the rear substrate. 3. The reflection type liquid crystal panel according to claim 2, wherein the output electrode of the solar cell is provided on the same side of the rear substrate as the side on which the panel electrode terminal is formed.