JPH03126983A - Display device - Google Patents

Abstract

PURPOSE:To obtain a multifunction, inexpensive, compact display device by permitting a light projecting means to irradiate the rear side of the surface on which external light such as solar light from a thin film solar battery formed on a substrate possessing transmittance is made incident are displaying characters. CONSTITUTION:A device is provided with the thin film solar battery 102 formed on the substrate 101 possessing light transmittance and the light projecting device 103. Since the solar battery absorbs the external light 105, the substrate 102 looks dark, viewed from the rear side of the projecting surface of the external light 105, and display is feasible by irradiating the surface of forming the solar battery 102 with the light from the light projecting device 103. The film thickness of the component material of the thin film solar battery 102 and a light absorption coefficient are changed to adjust the transmittance of the external light 105. In addition, the solar battery 102 can be directly employed as the power source of the light projecting device 103. Consequently, the inexpensive, compact display device which serves as the power source of the solar battery 102 and serves to adjust transmittance can be obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a display device using solar cells.

The present invention relates to a window or lens that transmits outside light such as sunlight, such as a display device that uses a car window, a display device that uses a building window, or a display device that uses an eyeglass lens. Applicable to display devices using

[Prior art and problems to be solved by the invention] Conventionally,
Solar cells have been used as a power source for various electrical devices.

In addition to power sources, solar cells are also used to adjust the transmittance of external light such as sunlight. In other words, solar cells are formed on a transparent substrate such as glass using a thin film material that allows visible light to pass through, or solar cells are formed on a transparent substrate by patterning so that light can partially pass through. These include things that form batteries.

These devices function to block ultraviolet rays, regulate excessive external light, and act as a power source, and are being applied to window glass, automobile sunroofs, and other applications.

In addition to the function of adjusting the amount of external light, there are also examples in which solar cells are used as part of the display element.

For example, in Japanese Patent Laid-Open No. 59-i95267, the back surface of a liquid crystal display device is made to function as a part of the display material by taking advantage of the dark color of the surface of the solar cell.

However, there are few examples in which a solar cell also serves as a part of a display device, and the above-mentioned liquid crystal display device also has a relatively limited use. Therefore, the development of display devices using solar cells remains a challenge for the future.

[Object of the Invention] An object of the present invention is to provide a new display device using solar cells in view of the above-mentioned problems.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention includes a thin film solar cell formed on a light-transmitting substrate and a light irradiation device, The display device is characterized in that it performs display by irradiating light emitted by the light irradiation device onto the back side of an incident surface of external light that generates electric power.

Further, a display device characterized in that the solar cell allows transmission of external light; and a display device characterized in that the electromotive force of the solar cell is used as a power source for the light irradiation device. , which attempts to solve the above problems.

Further, a display device characterized in that it has a secondary battery that stores electrical energy generated by the solar cell, and a display device characterized in that an LED is used as the light irradiation device. Further, the display device is characterized in that a laser that emits visible light is used as the light irradiation device, and the light emitted by the light irradiation device is directed to a position away from a surface on which a solar cell is formed. The present invention attempts to solve the above-mentioned problems with a display device characterized by adjusting an optical path so as to form a virtual image.

Examples of embodiments of the present invention will be described below.

The device of the present invention utilizes the reflection of light from the material forming the solar cell as a display. In the present invention, the solar cell serves both as a power source and as a display material.

Furthermore, by changing the thickness and light absorption coefficient of the constituent materials of the thin-film solar cell, the transmittance of external light can be adjusted. For example, by increasing the thickness of the constituent materials of the thin-film solar cell, or By using a constituent material with a small optical bandgap, the transmittance of external light is reduced, and the solar cell formation surface appears dark when viewed from the back side of the external light irradiated surface.

In addition, by reducing the film thickness of the solar cell constituent materials or using constituent materials with a large optical band gap, the transmittance of external light increases, making it brighter when viewed from the back side of the surface irradiated with external light. .

In this way, the amount of transmitted external light could be adjusted.

In this case, the solar cell has three functions: as a power source, as a display material, and as an adjuster for the amount of transmitted external light.

Furthermore, a solar cell can be used directly as a power source for the light irradiation device. In this case, since no structural members are required other than the solar cell and the light irradiation device, it is possible to provide a low-cost and compact display device.

Moreover, the electric power generated by the solar cell can be stored in a negative secondary battery, and the secondary battery can be used as a power source for the light irradiation device. In this case, a secondary battery is required, but even if the output of the solar cells decreases or almost disappears due to decreased external light, display can be performed using the power stored in the secondary battery.

Additionally, the power stored in the secondary battery can be used for other electrical equipment.

In the present invention, the transparent substrate is a plate-like or sheet-like material that transmits part or all of the wavelengths of visible light, and can be made of, for example, glass, polyimide, polyethylene, or the like.

Alternatively, a solar cell can be formed on a transparent substrate in the form of a film sheet and attached to a transparent substrate such as glass or plastic.

The solar cell used in the display device of the present invention is a thin film solar cell, and the constituent material thereof is amorphous silicon, a compound of amorphous silicon and other elements, CdS, CdTe, CuxS, or C
uIn5ea, CuIn5*, etc. are preferred.

Furthermore, the structure of the solar cell used was a pn junction type, a pin type, or a Schottky type. Furthermore, as electrodes, transparent electrodes such as Snow, ITO, AI, Ag, etc.
Metal electrodes such as Cr and Au were used.

The light irradiation means in the present invention measures the area of the solar cell or the area of the display part, the amount of external light transmitted by the solar cell, the intensity of the scattered external light from around the display part, the usage time of the display, etc. It is selected as appropriate.

When using solar cells as a direct power source, it becomes a low-cost, compact display device, and since the display is performed only when the solar cells are generating power, it consumes relatively little power.
It is preferable to use an ED or a lamp.

In the case of using a secondary battery and displaying even when the solar cell is not generating power, or displaying a large area, it is preferable to use a visible light laser or the like in addition to an LED or a filament.

Regarding the secondary battery used in the display device of the present invention, performance such as type and capacity should be determined by taking into account the area and output of the solar cell, the power consumption of the light irradiation means, and the power consumption of other electrical equipment. Used selectively. For example, a nickel-cadmium battery, a lead-acid battery, or the like is suitable in view of charging and discharging characteristics, life span, and reliability.

In the display device of the present invention, the contrast of displayed characters and patterns is adjusted depending on the purpose of use. That is,
If you want to suppress the amount of external light transmitted and make the display clear, you can reduce the amount of transmitted light from the solar cells so that the back side of the external light irradiated surface looks dark, or in addition, increase the light intensity of the light irradiation device. By increasing the contrast of displayed characters and designs, increase the contrast of displayed characters and patterns. Also, if you need a certain amount of outside light to pass through, that is, if you want to be able to see the outside through the solar cells, increase the amount of light that passes through the solar cells and lower the contrast of the letters and designs so that both the outside and the display can be seen. Make it.

Also, when using secondary batteries to display information when the solar cells are not generating power, the outside light is reduced and the surface of the solar cells is inevitably darker, compared to when the outside light is strong. Similar contrast can be achieved with lower power consumption.

In the display device of the present invention, when it is desired to visually recognize both the outside and the display while reducing the amount of transmitted external light, the difference between the viewpoint from which the outside is viewed and the viewpoint from which the display surface is viewed is large, or the display surface is If the display is difficult to see because it is too close to the eyes, use optical path adjustment means such as lenses to direct the light emitted from the light irradiation device to a place close to the viewpoint from which the outside is viewed, rather than onto the solar cell forming surface. By adjusting the optical path so as to form a virtual image, it is possible to reduce the difference between the viewpoint of viewing the outside through the solar cell and the viewpoint of viewing the display, making it easier to see both the outside and the display.

[Example] FIG. 1 is a schematic diagram showing the concept of the structure in an example of the display device of the present invention. In the figure, 101 is a transparent base, 102 is a thin film solar cell formed on the base 101,
103 is a light irradiation device; 104 is a light irradiation device; 104 is a light irradiation device; 105 is external light such as sunlight; and 106 is electricity generated by the solar cells. This is the wiring that supplies the device 103.

As the solar cell 102 absorbs the external light 105, the base 101 on which the solar cell is formed appears dark when viewed from the back side of the surface irradiated with the external light 105. By irradiating the solar cell forming surface with light from the light irradiation device 103, display could be performed.

Here, the thin film solar cell 102 may be formed on either side of the base 101. Therefore, the reflective surface of the displayed light is the surface of the thin film solar cell 102 or the surface of the solar cell 102.
This is the interface between the substrate 101 and the substrate 101 .

The light irradiation device of the display device of the present invention includes a light emitting section and an optical path adjustment section. For example, a filament or LED is used in the light emitting part.
When using this, the configuration is as shown in FIG.

In FIG. 4, 201 is a transparent substrate, 202 is a solar cell, 204 is a light irradiation device, 404 is a light emitting section, and 405 is an optical path adjustment section. The light emitted by the light emitting unit 404 is transmitted to the lens 4.
05, an image is focused on the surface of the solar cell 202.

An enlarged view of the light emitting section 404 is shown in FIG. 5 or 6.

Figure 5 shows a tungsten filament 50 as a light emitter.
1 is used to form a display segment 502.

503 is a reflection plate.

Further, FIG. 6 shows an example in which a dot matrix is formed using LEDs, where 601 indicates a dot that is emitting light, and 602 indicates a dot that is not emitting light. FIG. 7 is a sectional view showing the structure of each dot in FIG. 6, where 701 is an LED chip, 702 is a reflector, and 703 is a substrate.

Of course, it is also possible to form segments using LEDs. For example, if the display section is small, the LED chip itself can be used as the fifth segment.
It can also be formed into a segment 502 as shown.

Further, the lens 404 uses one or more flat lenses such as a convex lens or a Fresnel lens made of a material such as glass or plastic.

Further, when a laser is used for the light emitting section, the configuration is as shown in FIG. 8.

In FIG. 8, 5801 is a transparent substrate, 802 is a solar cell,
803 is a displayed character or pattern, 804 is a laser oscillator, and 805 is a scanning device.

The scanning device 805 is composed of a plurality of movable mirrors, movable lenses, and a rotating scanning mirror, and according to an external signal,
By scanning the optical path of the laser beam, characters and patterns are displayed on the surface of the solar cell 802.

The laser oscillator 804 is preferably one with relatively low power consumption, such as a He-Ne laser, and if the area of the display portion is small, a visible light semiconductor laser can also be used.

In the present invention, an example of the circuit when a secondary battery is not used is the configuration shown in FIG.

In FIG. 9, 901 is a solar cell, 902 is a light irradiation device,
903 is a Zener diode, and 904 is a switch. The Zener diode 903 protects the circuit of the light irradiation device 902 when the irradiation intensity of external light is strong and the output of the solar cell 901 becomes excessive. Light irradiation device 9
Depending on the type of 02, it may not be necessary.

Moreover, FIG. 3 is an example of a circuit configuration when a secondary battery is used in the present invention. In FIG. 3, 202 is a solar cell, 302 is a secondary battery, 204 is a light irradiation device, 30
4 is a switch, 305 is a voltage control circuit, and 306 is a backflow prevention diode. The voltage control circuit 305 prevents overcharging of the secondary battery 302 and controls the voltage of the secondary battery 302, and the backflow prevention diode 306 prevents overcharging of the secondary battery 302.
This is to prevent backflow from the secondary battery 302 when the output of the secondary battery 302 decreases.

An example of the structure of the thin film solar cell according to the present invention is shown in FIG. 10 or FIG. 11.

FIG. 10 is a cross-sectional view of an amorphous silicon (hereinafter abbreviated as a-5i) single cell.

1001 is a glass substrate, 1002 is a patterned lower metal electrode, 1003.1007 is a transparent conductive film, 10
04 is a p-type a-3L film, 1005 is an intrinsic a-SL film, 1
006 is an n-type a-Si film, 1008 is a patterned upper metal electrode, and 1009 is a surface protection film made of resin or the like.

Furthermore, a tandem cell in which pin N is stacked in two stages or a triple cell in which three stages are stacked can also be used.

FIG. 11 shows an example of a ■-■ group solar cell, where 1101 is a glass substrate, 1102 is a transparent conductive film, and 1103 is CdS.
, 1104 is GdTe, 1105 is Au electrode, 1
106 is a surface protective layer.

The above examples are two examples of thin film solar cells used in the present invention, and solar cells with various other structures can be used as necessary.

In addition, when using a solar cell with the above structure in the circuit shown in FIG. 3 or 9, in order to match the output voltage of the solar cell to the voltage of the light irradiation device or the secondary battery,
Use by wiring several stages in series. Furthermore, the output current of the solar cells per stage is determined by changing the area or by connecting them in parallel, depending on the light irradiation means or the charging of the secondary battery.

As described above, according to the present invention, by suppressing the amount of transmitted external light such as sunlight and displaying by irradiating light on the back side of the surface irradiated with external light, it is possible to see both the outside and the display. It is possible to provide a multifunctional, low-cost, and compact display device in which the display material itself has power generation capacity.

(Example 1) FIG. 2 shows an automobile display device to which the display device of the present invention is applied. In FIG. 2, 201 is a front window of a car, 202 is a solar cell, 203 is a displayed character or pattern, 204 is a light irradiation device, and 205 is sunlight.

The circuit configuration of the automobile display device of this embodiment is shown in FIG. 3. As the secondary battery 302, a lead acid battery for automobiles was used.

Electric power generated by the solar cell 202 was stored in a lead-acid battery 302, and when necessary, a switch 304 was turned on to display characters and designs on the surface of the solar cell 202 using the light irradiation device 204.

In this example, the solar cell 202 was formed on a polyimide film, and the polyimide film on which the solar cell 202 was formed was attached to the upper part of the front window 201. The solar cell 202 has a structure in which two pin layers having the structure shown in FIG. 10 are stacked. A-5i/a-3i tandem cells were used.

The photoelectric conversion efficiency of the solar cell is AMl, 0 irradiation, average 6.
0%, and with a solar cell of approximately 1000 cm,
The maximum output during light irradiation was 6W. Moreover, the light transmittance of the solar cell was 20% for light with a wavelength of 633 rv.

Furthermore, the solar cells 202 used were those connected in 22 stages.

As the light irradiation device, one having the structure shown in FIG. 4 was used.

A tungsten filament with the configuration shown in Figure 5 is used for the light emitting part, and each segment is turned on and off by an integrated circuit.
The numbers were displayed by controlling OFF.

Further, the automobile display device of this example was able to function as a charger for an automobile battery when no display was performed.

(Example 2) In an automobile display device having a structure similar to that of Example 1, a Ni-Cd battery was used as a secondary battery independently of the automobile's lead-acid battery. The solar cells were formed directly on part of the side glass of the car.

Electric power generated by the solar cells was stored in a plurality of Ni-Cd batteries, which were turned on as needed to display letters and designs on the surface of the solar cells using a light irradiation device.

The solar cell is made of CdS/CdTe with the configuration shown in FIG.
Using solar cells. The photoelectric conversion efficiency of a solar cell is AMl,
0 irradiation with an average of 4.5% and an area of approximately 500 cm.
During MI light irradiation, a maximum output of 2.25 W was obtained.

Further, 8 Ni-Cd batteries were connected in series and had a terminal voltage of IOV, and 24 stages of solar cells were connected in series.

As the light irradiation device, one with the structure shown in Fig. 4 was used.
The light emitting part includes a dot matrix type LE shown in Figure 6.
D was used. The structure of each dot was as shown in FIG.

An integrated circuit controlled the ON and OFF of each dot to display a single character or pattern.

The Ni--Cd battery of the display device of this example could also be used by connecting other electrical equipment.

(Example 3) Using a glass substrate on which a solar cell was formed, a window glass for a residence was formed, and a display device for displaying characters and designs on the window glass using the laser irradiation device shown in Fig. 8 was created. Configured.

The circuit configuration shown in FIG. 3 was used, and a lead-acid battery was used as the secondary battery. The laser uses a He-Ne laser, and the power source for the laser is DC12V.
A power source that boosts the voltage to 1.5 kV was used.

In FIG. 8, power generated by a solar cell 802 is stored in a lead-acid battery, and the lead-acid battery is used as a power source to generate He-N
The e-laser 804 is oscillated and the laser beam is sent to the scanning device 8.
05, a rotating scanning mirror or the like was used to scan and display on the solar cell forming surface.

Here, the solar cell was formed on the entire surface of the window glass, and the structure of the solar cell was as shown in FIG. 10.

However, in order to maintain the optical transparency of the window glass, a-3iC, which has a wider optical bandgap than a-3i, is used as the intrinsic layer, and p-type microcrystal SiC is used instead of pTMa-Si as the p layer. was used.

The light transmittance of the solar cell having the above configuration was 45% for light having a wavelength of 633 nm, and it was possible to sufficiently see the outside scenery as a window.

The photoelectric conversion efficiency of the solar cell is AMl, average 4.0 at 0 irradiation.
%, and the maximum output was 4°W for an area of 1 m'', although it depended on the area of the window glass on which the solar cells were formed.

Furthermore, 30 solar cells connected in series were used.

The power generated by solar cells and stored in lead-acid batteries could also be used to power other electrical devices.

As mentioned above, you can also use it as a window to see the outside scenery.
It was possible to generate electricity using solar cells and display information.

(Embodiment 4) FIGS. 12 and 13 are explanatory diagrams of an example in which the display device of the present invention is applied to eyeglasses. FIG. 12 is an overall view, and FIG. 13 is a cross section on two sides of FIG. 12. FIG. In FIG. i2, 1201 is an eyeglass lens, 1202 is a solar cell formed on the eyeglass lens, 1203 is a light irradiation device, and 1204 is a displayed character or pattern.

Using the power generated by the solar cell 1202, a light irradiation device emits light to display characters and patterns on the solar cell surface 1202.

The circuit configuration shown in FIG. 9 was used. A Zener diode 903 was used to protect the circuit of the light irradiation device when the power generated by the solar cell became excessive.

FIG. 13 is a detailed explanation of the light irradiation device shown in FIG. 12 using two sectional views, in which 1201 is an eyeglass lens, 1202 is a solar cell, 1203 is a light irradiation device, 13
04 is a light emitting unit, 1305 is an optical path adjustment lens, 1206
is the handle of the glasses, 1307 is the eyeball, 1308 is the retina, 130
9 is an image of the light emitting part formed on the retina.

In FIG. 13, when the light emitted from the light emitting unit 1304 is directly irradiated onto the solar cell surface 1202, or when the image is formed on the solar cell surface 1202, the light emitted from the display portion is too close to the eyeball. unable to focus. Therefore, by adjusting the optical path of the light emitted by the light emitting unit 1304 with the lens 1305, the image was formed on the retina as shown in FIG. 13.

At this time, the displayed characters and designs are on the solar cell surface 120.
A virtual image is formed not on the solar cell surface 1202 but at a location away from the solar cell surface 1202.

Here, the distance between the light emitting unit 1304 and the lens 1305 or the distance between the lens 1305 and the eyeball 1307,
Alternatively, by adjusting the focal length of the lens 1305, it was possible to almost eliminate the difference between the focal point of the eye when viewing a distant external scene and the focal point of the eye when viewing the display section. This makes it possible to reduce the change in focus of the eyes when looking at the outside scenery and when looking at the display section, thereby reducing eye fatigue.

In the display device of this example, an LED in which a segment pattern or a dot matrix pattern is formed on a substrate is used as a light emitting portion.

In addition, a plastic lens or a selfoc lens was used as a lens for adjusting the optical path.

As the solar cell, an a-Si single cell having the structure shown in FIG. 10 was used. The conversion efficiency of the solar cells was 5.0% on average when irradiated with AMl and 0, and 6 stages were connected in series. The light transmittance of the solar cell was 20% for light with a wavelength of 633 nm.

As described above, we have provided compact, low-cost glasses with a display device that adjust the transmittance of external light such as sunlight using solar cells and allow you to see characters and designs while looking at the outside scene.

In this embodiment, the solar cell serves as a transmittance adjuster for external light, a power source, and a display unit.

[Effects of the Invention] As described above, the solar cell is composed of a thin film solar cell formed on a translucent substrate and a light irradiation means, and a light amount of q. A display device that performs display by irradiating light emitted by one means has achieved the following combined effects.

1. You can adjust the amount of outside light.

2. You can see the outside view and the display at the same time.

3. Since the display member itself has a power generation function, it is compact and has a wide range of applications.

Furthermore, by using a secondary battery in combination, it could be used even in cases where there is little external light such as sunlight.

In addition, by adjusting the optical path of the light irradiation device so that the virtual image is focused at a distant location rather than on the solar cell formation surface, the difference in viewpoint between viewing the outside scenery and viewing the display is reduced, reducing eye strain. We were able to create an easy-to-read display with less clutter.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the basic concept of an embodiment of the display device of the present invention. FIG. 2 is an explanatory diagram of Example 1 of the display device of the present invention. FIG. 3 is an example of a circuit diagram of a display device of the present invention. FIG. 4 is an explanatory diagram of the light irradiation device of the display device of FIG. 2. FIG. 5 is an explanatory diagram of an example of a light emitting section of the light irradiation device. FIG. 6 is an explanatory diagram of another example of the light emitting section of the light irradiation device. FIG. 7 is an explanatory diagram of an example of details of the light emitting section of the light irradiation device. FIG. 8 is an explanatory diagram of another example of the light irradiation device. FIG. 9 is another example of the circuit diagram of the display device of the present invention. FIG. 10 is a sectional view of an example of a solar cell used in the display device of the present invention. FIG. 11 is a sectional view of another example of a solar cell used in the display device of the present invention. FIG. 12 is an explanatory diagram of Example 4 of the display device of the present invention. FIG. 13 is a cross-sectional view of the display device of FIG. 12 on two sides. 101... Substrate having light transmittance, 102... Solar cell, 103... Light irradiation device, 104... Displayed characters and designs, 105, 205... External light such as sunlight,
106...Power cable for light irradiation device, 201...
Car front window, 202... solar cell,
203... Displayed characters and patterns, 204... Light irradiation device, 302... Secondary battery, 304... Switch, 305... Voltage control circuit, 306... Backflow prevention diode, 404 ... Light emitting part, 405 ... Lens,
501...Tungsten filament, 502...
Segment, 503...Reflector, 601...Dot in light emitting state, 602...Dot in dark state, 701...
- LED chip, 702...Reflector, 703...Substrate, 801...Light transmitting base, 802...
Solar cells, 803...Displayed characters and designs, 804
... Laser emitting unit, 805 ... Scanning device, 8
06... Optical path of laser light, 901... Solar cell,
902... Light irradiation device, 903... Zener diode, 904... Switch, 1001... Substrate having light transmittance, 1002... Buttered metal electrode, 1003... Transparent electrode, 1004...p
Type a-3L layer, 1005--Intrinsic a-3i layer, 100
6-.-n type a-3L layer, 1007... transparent electrode, 1
008... Buttered metal electrode, 1009
...Surface protective layer, 1101...Substrate having light transmittance, l 102-...Transparent electrode, 1103-CdS layer,
1104- CdTe layer, 1105...Au electrode, 1
106... Surface protective layer, 1201... Eyeglass lens,
1202...Solar cell, 1203...Light irradiation device,
1204...Displayed characters and designs, 1206...
Handle of glasses, 1304... Light emitting part, 1305... Lens, 1307... Eyeball, 1308... Retina,] 30
9...Image point.

Claims (7)

[Claims] (1) It has a thin film solar cell formed on a light-transmitting substrate and a light irradiation device, and the light irradiation device emits light on the back side of the incident surface of external light that generates an electromotive force in the solar cell. 1. A display device that performs display by irradiating light. (2) The display device according to claim 1, wherein the solar cell allows transmission of external light. (3) The display device according to claim 1, wherein the solar cell is used as a power source for the light irradiation device. (4) Claim 1, further comprising a secondary battery that stores electrical energy generated by the solar cell.
The display device described in . (5) The display device according to claim 1, wherein an LED is used as the light irradiation device. (6) The display device according to claim 1, wherein a laser that emits visible light is used as the light irradiation device. (7) The display device according to claim 1, wherein the optical path is adjusted so that the light emitted by the light irradiation device forms a virtual image at a position away from a surface on which the solar cells are formed.