JP2823436B2 - Flat panel display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat display device used for a display unit of an OA related device such as a personal computer.

[0002]

2. Description of the Related Art A liquid crystal display panel has been conventionally used as a flat display device used for a display section of an OA-related device such as a personal computer, and the size and weight of the device have been reduced. For example, in a so-called notebook type personal computer or word processor, as shown in FIG. 11, an openable and closable display unit 10 is provided for a device main body 11, and usually used with the display unit 10 opened. By closing, the keyboard on the upper surface of the device main body and the display panel of the display unit 10 are protected and the portability is enhanced. Such a small personal computer or word processor also has a built-in floppy disk drive and modem,
Although small in size, it has advanced information processing functions.

[0003]

However, in a simple matrix type liquid crystal display panel, which is the mainstream of the current flat type display device, since the viewing angle is narrow, the liquid crystal display panel must be in front of or in a direction slightly inclined from the front. It was difficult to use outdoors because it was hard to see and the operating temperature range was narrow. Furthermore, an image scanner can be connected to a personal computer or the like as shown in FIG. 11 in order to input image data, but the image scanner is not so small compared to the size of the main body. There has been a problem that the portability of the personal computer itself is impaired.

Further, a secondary battery built in a personal computer main body can normally be driven for only about one hour from a fully charged state, and thereafter needs to be charged from a commercial power supply. Generally, there is a trade-off between the capacity of the secondary battery, which determines the operable time, and the size and weight of the main body, and there is a limit in maintaining portability and extending the driving time of the secondary battery.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image scanner which can be used as a display panel having a wide viewing angle and a wide operating temperature range, and which can read image information such as characters and figures of a document. It is an object of the present invention to provide a flat display device which can be used.

Another object of the present invention is to provide a flat display device that can be used as a display panel having a wide viewing angle and a wide operating temperature range, and can also be used as a photovoltaic device, that is, a solar cell. To provide.

Another object of the present invention is to provide a flat display device which can be used as a display panel having a wide viewing angle and a wide operating temperature range, as an image scanner, and as a solar cell.

[0008]

According to a first aspect of the present invention, there is provided a flat display device comprising a plurality of thin film type LEs on an insulating substrate.
An LED panel in which D elements are arranged, display control means for driving each of the thin-film LED elements in a forward bias state according to display data, and a part or all of the thin-film LED elements in a reverse bias state; Image reading control means for detecting a photocurrent of each thin-film LED element, which is changed by reflected light from an image of a document placed close to each thin-film LED element, and reading the image of the document. And

According to a second aspect of the present invention, there is provided a flat panel display device comprising: an LED panel in which a plurality of thin film type LED elements are arranged on an insulating substrate; and each of the thin film type LED elements is sequentially arranged according to display data. Display control means driven in a bias state, and each of the thin-film LED elements is in an unbiased state,
Photoelectromotive force generation control means for taking out, as a power supply, an electromotive force generated by receiving external light from each thin-film LED element.

According to a third aspect of the present invention, there is provided a flat panel display device comprising: an LED panel in which a plurality of thin-film LED elements are arranged on an insulating substrate; and the thin-film LED elements are sequentially arranged according to display data. Display control means driven in a bias state, and each of the thin-film LED elements is in an unbiased state,
Photovoltaic power generation control means for extracting an electromotive force generated by receiving external light from each thin-film LED element as a power source;
A part or the whole of the ED element is set in a reverse bias state, and a photocurrent of each thin-film LED element that changes due to reflected light from an image of the original placed in close proximity to each thin-film LED is detected, and an image of the original is detected. Image reading control means for reading the image.

[0011]

In the flat display device according to the first aspect, the panel itself has a plurality of thin-film LED elements formed on an insulating substrate, and the display control means controls each thin-film LED according to display data.
The D element is driven in a forward bias state. Further, the image reading control means sets a part or all of the thin-film LED elements in a reverse bias state, and sets each thin-film LED element which is changed by reflected light from an image of a document arranged in proximity to each thin-film LED element.
The image of the document is read by detecting the photocurrent of the D element. For example, when a document is placed in close contact with the flat display device and each thin-film LED element receives light transmitted through the document, all the thin-film LED elements are in a reverse bias state.
Since the thin-film LED element has a pn junction structure,
If a closed circuit is formed by applying a reverse bias to the n-junction, a depletion layer is formed at the junction, and electrons and holes generated by light irradiation are accelerated to the n-layer and the p-layer, respectively, and the photocurrent is transmitted to an external circuit. Can be taken out. Thus, each thin-film LED
An image projected on the flat panel display device can be read as image data by detecting the amount of current supplied to the element. Further, by driving a plurality of thin-film LED elements arranged in such a manner that adjacent thin-film LED elements are in a forward-biased state and a reverse-biased state, the thin-film LED elements in the forward-biased state emit light, and The surface is irradiated, and the reflected light is received by the thin-film LED element in a reverse bias state. Therefore, in this case, the thin film type LE in the reverse bias state is used.
The reflected image of the document can be read from the photocurrent of the D element.

In the flat display device according to the second aspect, the panel itself has a plurality of thin-film LED elements formed on an insulating substrate, and the display control means sequentially switches the thin-film LED elements according to display data. Drive in bias state. Further, the photovoltaic power generation control means puts each of the thin-film LED elements in an unbiased state and takes out an electromotive force generated by receiving external light from each of the thin-film LED elements as a power supply. Since the LED element has a pn junction structure, if light is received in an unbiased state, electron-hole pairs are generated by light energy, and power can be extracted by connecting a load. If this photovoltaic power is used to charge a secondary battery built into the main body of the device, the built-in secondary battery is usually used as a power source. By receiving light, the secondary battery can be charged even in a place where there is no commercial power supply.

[0013] In the flat display device according to the third aspect, the panel itself has a plurality of thin-film LED elements formed on an insulating substrate, and the display control means controls each thin-film LE of the LED panel.
The display is performed by driving the D element in a forward bias state, and the photovoltaic power generation control means sets each of the thin-film LED elements to an unbiased state and uses the electromotive force generated by receiving external light from each thin-film LED element as a power supply Take out. The image reading control means reads an image of an original placed close to each of the thin-film LED elements by setting a part or all of the thin-film LED elements in a reverse bias state. In this way, the original can be read only by the main unit without connecting an external image scanner, and the main unit is not equipped with a large-capacity secondary battery. You will be able to use it for hours.

[0014]

1 and 2 show the structure of a notebook personal computer provided with a flat display device according to an embodiment of the present invention.

FIG. 1 is an external perspective view, 10 is a display unit,
11 is a main body. In this state, the display unit 10
, Which is a use state when the keyboard is used or when the display unit 10 is irradiated with external light.

FIG. 2 is a right side view in a state where the display unit is closed. In this example, the document 4 is held between the main body 11 and the display unit 10. The image of the document 4 is read using a flat display device provided on the display unit 10 as described later.

Next, the configuration of the flat display device provided in the display unit 10 is shown in FIGS. FIG. 3 is a schematic external perspective view of the flat display device, and FIG. 4 is a schematic side view. In FIG. 3, reference numeral 1 denotes an insulating substrate on which a plurality of thin-film LED elements indicated by 2 are arranged. These thin film types L
As shown in FIG. 4, the ED element is configured by alternately arranging a red LED element 2R, a green LED element 2G, and a blue LED element 2B in a matrix. Here, GaAsP or GaAlAs is used as a red LED element, GaP is used as a green LED element, and GaN or SiC is used as a blue LED element.
System materials can be used. However, the material of the thin-film LED for RGB is not limited to these, and any material that can emit RGB light can be used. These thin-film type LED elements are formed by a liquid phase or gas phase epitaxial growth method,
It is manufactured by OCVD, MBE or the like.

Thus, the red, green,
FIG. 1 shows an LED panel in which blue LED elements are arranged.
, The viewing angle and operating temperature range are extremely wide, and the panel itself emits light, eliminating the need for a backlight or sidelight, thereby reducing the thickness. Become like

Next, FIG. 5 shows an example of a circuit in the case where the flat display device shown in FIGS. 3 and 4 is used as an original display device.
Shown in In FIG. 5, 2R, 2G and 2B correspond to FIG.
As shown in (1), there are a red LED, a green LED, and a blue LED, and a switching transistor Q is connected in series to the cathode side of each LED. VRf is red LED2R
Power supply circuit for applying a forward bias voltage to
f is a power supply circuit for applying a forward bias voltage to the green LED 2G, and VBf is a power supply circuit for applying a forward bias voltage to the blue LED 2B. When a flat display device is used as a display device, each red LED 2R
_1, 2R ₂ ··· 2R _n anode connected to the positive side of VRf of, connecting the negative side of each VRf through the cathode to the transistor Q of each red _{LED2R 1, 2R 2 ··· 2R n} . Therefore, the control signals SR ₁ , SR ₂ ,... SR _n for the gate of each transistor Q
Of the corresponding red LED 2R ₁ , 2R _2.
.. 2R _n can be selectively driven. Similarly VGf the anodes of the green LED2R _1, 2R ₂ ··· 2R _n
Of the green LEDs 2G ₁ , 2G _2.
Respectively, to the cathode of the 2G _n via the transistor Q is connected to the negative side of the VGF. Therefore, the control signals SG ₁ , SG ₂ ,.
By signal of ·· SG _n, the corresponding green LED2
G ₁ , 2G ₂ ... 2G _n can be selectively driven. The same applies to the blue LED, and each blue LED 2
B _1, 2B ₂ ··· Connect the positive side anode of VBf of 2B _n, each blue LED2B _1, 2B ₂ ··· 2B _n
Are connected to the negative side of VBf via a transistor Q. Therefore, each transistor Q
Control signal SB ₁ of to the gate, SB _2, ··· SB
_The corresponding blue LED 2B ₁ , 2B ₂
... the 2B _n can be selectively driven.

FIG. 6 shows the relationship between the flat display device and the original when the flat display device is used as an image scanner. FIG. 6 is a partial schematic cross-sectional view, wherein 1 is an insulating substrate of an LED panel, 2R, 2G, and 2B are each a red LED, a green LED, and a blue LED as described above, and 3 is a surface of the LED panel. It is a protection plate that protects. Reference numeral 4 denotes a document to be read. This manuscript 4
The body 11 is further provided at the lower part of the main body 11 as shown in FIG. In this example, each red LED 2R, 2R, 2R,.
Respectively emit light, and green LEDs 2G,
, And blue LEDs 2B, 2B,... Receive reflected light from the original. In this state, the red component of the image described on the document 4 is detected by the green LED and the blue LED.

FIG. 7 shows a circuit example in this case. In FIG. 7, VRf is the same as the case shown in FIG.
This is a power supply circuit for applying a forward bias voltage to each of R ₁ , 2R ₂ ... 2R _n . VGb is green LE
A power supply circuit for applying a reverse bias voltage to D2G ₁ , 2G ₂ ... 2G _n , and VBb is a blue LED 2B ₁ ,
Power supply circuits for applying reverse bias voltages to 2B ₂ ,... 2B _n respectively. In addition, the power supply circuit VGb
A current detection circuit indicated by reference numeral 23 is provided in the current path, and a current detection circuit 24 is provided in the current path of the power supply circuit VBb. In this circuit, control signals SR1, SR2,.
- in a state of being lit all of the red LED by SRn, for example by applying a reverse bias voltage to the green LED2G ₁ by the control signal SG _1, the green LED2G
Current corresponding to _one received light amount flows through the current path of the power supply circuit VGb. The current amount is detected by the current detection circuit 23.
Next, the green LED2G ₂ for example by the control signal SR ₂
A reverse bias voltage is applied only to this green LED 2G.
_The current corresponding to the amount of received light is detected by the current detection circuit 23. Similarly, a photocurrent corresponding to the amount of light received by each green LED is detected by the current detection circuit 23. Also, the control signal S
The B ₁ by applying a reverse bias voltage only to the blue LED 2B _1, detects the current amount of the photocurrent corresponding to the received light amount of the blue LED 2B ₂ by the current detecting circuit 24. Similarly, by sequentially selecting the control signals SB2,..., SBn, a photocurrent corresponding to the amount of light received by the blue LED is detected by the current detection circuit 24.

The examples shown in FIGS. 6 and 7 are examples in which the red component of the document is read. For example, when reading the green component, the green LEDs 2G ₁ , 2G ₂ ,.
_A forward bias voltage is applied to _n and red LEDs 2R ₁ ,
2R ₂ ,... 2R _n and blue LED 2B ₁ , 2
A reverse bias voltage is sequentially and selectively applied to B ₂ ,... 2B _n to detect a photocurrent. Similarly, reading of the blue component is performed. A switching circuit for switching RGB reading is provided in a power supply circuit portion for each LED.

Next, FIG. 8 shows a circuit configuration when the flat display device is used as a solar cell.

In FIG. 8, each LED is in a non-biased state, and a red LED, a green LED and a blue LED connected in parallel are connected in series to form a red LE.
D2R ₁ , 2R ₂ ,... 2R _n and green LED 2G ₁ ,
2G ₂ ,... 2G _n and blue LED 2B ₁ , 2
The respective electromotive voltages of B ₂ ,... 2B _n are added. At that time, all the transistors Q connected to each LED are turned on. In FIG. 1, BB is a secondary battery used as a power source of the load 21 and is charged by the photovoltaic power. The charge control circuit 20 is a circuit for preventing the rechargeable battery BB from being overcharged. When the rechargeable battery BB is fully charged, the thyristor SCR is turned on to prevent the rechargeable battery BB from being charged further. Diode D is a diode for preventing backflow, and is used for rechargeable battery B at night or in low illuminance.
The current is prevented from being discharged from B to each LED element.
Note that a circuit for boosting the finally obtained electromotive voltage may be provided as necessary, so that the circuit can be used under lower illuminance.

Next, by switching to the circuit configurations shown in FIGS. 5, 7 and 8, the overall configuration of the control unit in the flat display device for use as a display device, an image scanner and a solar cell is shown in a block diagram. FIG. In FIG. 9, reference numeral 30 denotes an LED panel of the flat-panel display device shown in FIGS. The selection / drive circuits 31 and 32 are circuits that select or drive the row direction and the column direction of the LED panel 30 together with the selection. Registers 33 and 34 supply selection signals to selection / drive circuits 31 and 32 in accordance with the input data. 3
Reference numerals 5 and 36 denote switching circuits, respectively, which input one of the two inputs to the registers 33 and 34 according to the signal So. The display memory 37 stores display data of a dot pattern to be displayed on the LED panel 30, and the display control circuit 38 sequentially reads out the display memory 37 and outputs data to the registers 33 and 34, respectively. At this time, for example, data is output to the register 33 so that a fixed row selection signal is generated regardless of the display contents.
Outputs data corresponding to the display contents. This allows
The contents of the display memory 37 are displayed on the LED panel 30.

The image reading timing signal generating circuit 39 supplies data for scanning the reading position to the registers 33 and 34, so that the selecting / driving circuits 31 and 32 emit LEDs and light receiving LEDs.
An ED selection instruction is performed. Further, the image reading timing signal generating circuit 39 supplies a reading timing signal to the reading control circuit 40. The reading control circuit 40 reads the photocurrent output from the selection / drive circuits 31 and 32 according to the timing signal given from the image reading timing signal generating circuit 39, converts the photocurrent into image data, and stores the content in the image memory 41. Write sequentially. Thus, the read image data is written in the image memory 41.

The connection switching circuit 42 includes the selection / drive circuit 31,
32, a control signal is given to each LED, so that each LED is in a non-biased state. Further, the connection state of the LED panel 30 is switched via the selection / drive circuits 31, 32, and the voltage +
Generate V.

Although the embodiment shown in FIG. 4 shows an example in which each of the RGB thin-film LED elements is arranged on the insulating substrate 1, for example, as shown in FIG.
The ED, the green LED, and the blue LED may be stacked in three layers. In this case, a transparent insulating substrate is used for laminating in the order of BGR and emitting light on the insulating substrate 1 side. Thin film LE
If the stacking order of the D elements is reversed, light can be emitted on the element formation surface side, and thus the insulating substrate may be opaque. By stacking the three primary color LED elements in this manner, the arrangement density of the elements is increased, and high-resolution display can be performed.

[0029]

According to the flat display device of the present invention,
As a display device having a wide viewing angle and a wide operating temperature range, it can withstand outdoor use, and the flat display device according to claim 1 has a function as an image scanner. It is not necessary to connect to the device, and the portability of the device main body can be improved.

In the flat display device according to the second aspect, since the flat display device also has a function as a solar cell, a relatively low-capacity secondary battery that can be easily charged even in a place without a commercial power supply is used. , While increasing the portability of the device,
The usage time of the secondary battery can be substantially extended. Further, in the flat display device according to the third aspect, since it also has a function as an image scanner and a function as a solar cell, it is not necessary to connect the image scanner to the outside, and a relatively low-capacity secondary battery can be used. Since it can be used, portability is extremely improved, and new use in a field of use requiring a portable and image input is possible.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a notebook personal computer using a flat display device according to an embodiment of the present invention.

FIG. 2 is a side view of another use mode of the device shown in FIG.

FIG. 3 is a schematic perspective view illustrating a configuration of a flat display device according to an example.

FIG. 4 is a schematic side view of the flat display device shown in FIG.

FIG. 5 is a circuit configuration diagram when used as a display device.

FIG. 6 is a side view illustrating a relationship between a flat display device and a document when used as an image scanner.

FIG. 7 is a circuit configuration diagram when used as an image scanner.

FIG. 8 is a circuit configuration diagram when used as a solar cell.

FIG. 9 is a block diagram illustrating a configuration of a control unit of the flat panel display according to the embodiment of the present invention.

FIG. 10 is a schematic side view of a flat panel display according to another embodiment.

FIG. 11 is an external perspective view showing a usage form of a notebook personal computer including a conventional display device.

[Explanation of symbols]

 1-Insulating substrate 2-LED element 2R-Red LED element 2G-Green LED element 2B-Blue LED element 3-Protective plate 4-Document 10-Display unit 11-Main unit 23,24-Current detection circuit 35,36-Switch circuit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 33/00 H01L 33/00 J

Claims (3)

(57) [Claims] 1. An LED panel having a plurality of thin-film LED elements arranged on an insulating substrate; a display control means for driving each of the thin-film LED elements in a forward bias state according to display data; A part or all of the LED devices are set in a reverse bias state, and the photocurrent of each thin-film LED device that changes due to the reflected light from the image of the document placed close to each thin-film LED device is detected, and the A flat-panel display device, comprising: image reading control means for reading an image. 2. An LED panel in which a plurality of thin-film LED elements are arranged on an insulating substrate; display control means for driving each of the thin-film LED elements in a forward bias state according to display data; A flat-panel display device comprising: a photovoltaic power generation control unit that puts the thin-film LED elements in a non-bias state and takes out an electromotive force generated by receiving external light from each thin-film LED element as a power supply. 3. An LED panel in which a plurality of thin-film LED elements are arranged on an insulating substrate; display control means for driving each of the thin-film LED elements in a forward bias state according to display data; A photovoltaic power generation control means for taking the electromotive force generated by receiving external light from each thin film type LED element as a power source, and setting a part or all of the thin film type LED element to a reverse bias state. And image reading control means for detecting a photocurrent of each thin-film LED element, which is changed by reflected light from an image of a document placed close to each thin-film LED element, and reading the image of the document. Characteristic flat display device.