Computer graphics processing and selective visual display system – Display driving control circuitry – Light detection means
Reexamination Certificate
2001-01-17
2004-06-08
Shankar, Vijay (Department: 2673)
Computer graphics processing and selective visual display system
Display driving control circuitry
Light detection means
C345S205000
Reexamination Certificate
active
06747638
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an adhesion type (contact type) area sensor having an image sensor function. In particular, the present invention relates to an adhesion type area sensor having an EL element as a light source and structured by a plurality of thin film transistors arranged in a matrix shape. The EL element called a light emitting element or a light emitting diode or an OLED (Organic Light Emission Diode) includes triplet-based light emission element and/or singlet-based light emission element, for example. Further, the present invention relates to a display device combined with an adhesion type area sensor.
2. Description of the Related Art
Solid state imaging devices having a photoelectric conversion element such as a diode or a CCD for outputting an electric signal having image information from an optical signal having information such as characters and drawings on a page, and picture information have come to be used in recent years. The solid state imaging devices are used in devices such as scanners and digital cameras.
There are line sensors and area sensors in solid state imaging devices having a photoelectric conversion element. A line sensor takes in an image as an electrical signal by scanning photoelectric conversion elements formed in a linear shape over a subject.
In contrast, an area sensor, also referred to as an adhesion type area sensor, has photoelectric conversion elements formed in a plane and arranged above a subject, and takes in an image as an electrical signal. It is not necessary to scan the photoelectric conversion elements with the area sensor, differing from the linear sensor, and therefore components such as a motor for scanning are unnecessary.
FIGS. 24A and 24B
show a structure of a conventional area sensor. Shown in
FIG. 24A
is a perspective view of the area sensor, while a cross sectional diagram of the area sensor is shown in
FIG. 24B. A
sensor substrate
2501
on which a photoelectric conversion element is formed, a backlight
2502
, and a light scattering plate
2503
are formed as shown in the figures.
Light from the backlight
2502
as a light source is refracted within the light scattering plate
2503
, and is irradiated to a subject
2504
. The irradiated light is reflected by the subject
2504
, and is irradiated on a photoelectric conversion element formed on the sensor substrate
2501
. An electric current of a size corresponding to the brightness of the light is generated within the photoelectric conversion element when the light is irradiated to the photoelectric conversion element, and image information from the subject
2504
is taken in as an electrical signal within the area sensor.
If the light from the backlight
2502
is not irradiated uniformly to the subject
2504
with the area sensor stated above, an irregularity develops in which the read in image becomes partially brighter and partially darker. It therefore becomes necessary to devise a structure of the light scattering plate
2503
is so that the light is irradiated uniformly to the subject
2504
, and to precisely regulate the position of the backlight
2502
, the light scattering plate
2503
, the sensor substrate
2501
, and the subject
2504
.
Furthermore, suppression of the size of the backlight
2502
and the size of the light scattering plate
2503
is difficult, and therefore making the area sensor itself smaller, thinner, and lighter is impeded.
SUMMARY OF THE INVENTION
In view of the above stated conditions, an object of the present invention is to provide an adhesion type area sensor which is small in size, thin, and lightweight, and in which irregularities in brightness of a read in image do not develop.
The area sensor of the present invention uses a photodiode as a photoelectric conversion element. Further, an EL (electroluminescence) element is used as a light source.
The photodiode herein has a cathode, an anode, and a photoelectric conversion layer formed between the cathode and the anode. An electric current develops due to the photovoltaic effect when light is irradiated to the photoelectric conversion layer.
Further, the EL element is a self-light emitting type element, and is mainly used in an EL display. The EL display is also referred to as an organic EL display (OELD) or an organic light emitting diode (OLED).
The EL element has a structure in which a layer containing an organic compound (hereafter referred to as an EL layer) is sandwiched between a pair of electrodes (an anode and a cathode), and the EL layer normally has a lamination structure. Typically, the lamination structure of a hole transporting layer/light emitting layer/electron transporting layer, proposed by Tang, et al., of Eastman Kodak Co. is used. This structure has extremely high light emitting efficiency, and nearly all research and development into EL displays at present employs this structure.
Electroluminescence generated by the application of an electric field is obtained in the EL element, which has an anode layer, an EL layer, and a cathode layer. There is emission of light in luminescence of the organic compound when returning to a base state from a singlet excitation state (fluorescence), and when returning to a base state from a triplet excitation state (phosphorescence), and the area sensor of the present invention may use both types of light emission.
Furthermore, a structure in which a hole injecting layer, a hole transporting layer, a light emitting layer, and an electron transporting layer are laminated in order on an electrode; and a structure in which a hole injecting layer, a hole transporting layer, a light emitting layer, an electron transporting layer, and an electron injecting layer are laminated in order on an electrode may also be used. Doping of a material such as a fluorescent pigment into the light emitting layer may also be performed.
All layers formed between one pair of electrodes are referred to generically as an EL layer within this specification. Therefore, the above stated hole injecting layer, hole transporting layer, light emitting layer, electron transporting layer, and electron injecting layer are all contained within the EL layer.
Photodiodes and EL elements are formed in a matrix shape on the same sensor substrate. The operation of the photodiodes and the EL elements is then controlled using thin film transistors (TFTs) formed on the substrate in the same matrix shape.
Light emitted from the EL elements is reflected by a subject and irradiated to the photodiodes. An electric current is generated in accordance with the light irradiated to the photodiodes, and an electrical signal having image information of the subject (image signal) is input to the area sensor.
No irregularities in the brightness of the read in image develop with the present invention because light is irradiated uniformly to the subject in accordance with the above structure. It is not necessary to form the backlight and the light scattering plate separately from the sensor substrate, and therefore it is also not necessary to precisely regulate the position of the backlight, the light scattering plate, the sensor substrate, and the subject, differing from the conventional example. A miniaturized, thin, light area sensor can therefore be realized. Furthermore, the mechanical strength of the area sensor itself is increased.
With the area sensor of the present invention it is possible to display an image by the area sensor using the EL elements. The EL elements in the present invention possess a combination of a function as a light source when reading in an image, and a function as a light source for displaying an image. Display of an image is therefore possible without forming a separate electronic display in the area sensor.
Structures of the present invention are shown below.
According to the present invention there is provided:
an adhesion type area sensor comprising a sensor portion, having a plurality of pixels, formed on a sensor substrate, characterized in that:
the plurality of pixels have a
Koyama Jun
Yamazaki Shunpei
LandOfFree
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