JPS62151068A - Photo-image sensor - Google Patents

Abstract

PURPOSE:To realize a static photo-image sensor that requires no light source with a simple constitution by designating in order a light emitting/receiving cell that is arranged on a plane in a grid shape as a photo-array and is constituted with a light emitting diode as a light receiving and a light emitting cells. CONSTITUTION:A document on which a graphic to be read is posted is fixed bringing into contact with the photo-array of a photo-image sensor. At a time t=Ti on the way of a reading with the address designation of an address selection circuit, one light emitting/receiving cell shown as work A in figure performs a light receiving operation, and light emitted from six light emitting/receiving cells in the neighborhood of the above cell shown as work B in figure reflecting corresponding to the graphic on the document is received, then being converted to a photoelectric current. Also, at a time t=Ti+1, a light receiving cell is shifted by one to the right, and according to that, six light emitting cells which consist a light source are shifted by one to the right as a whole. The designation of the light receiving cell is moved to the next line after the completion of the shift of one line, and corresponding to the shift, the shift of the light emitting cell enclosing the light receiving cell is repeated, and the reading on all of the planes of the document can be performed without shifting the document mechanically.

Description

[Detailed Description of the Invention] (Technical Field) This invention relates to a photo image sensor.
For example, the present invention relates to a technology that uses a light emitting diode as a light emitting/receiving element and is effectively used in a photo image sensor that reads graphic patterns and the like.

[Background technology]

A light-emitting diode emits light by passing an appropriate direct current in the forward direction, but by applying an appropriate reverse bias voltage and irradiating it with light, the reverse current is changed and a light-receiving device is used to obtain a so-called photocurrent. It is known that it can also be used as a diode.

On the other hand, a photo image sensor for optically reading a document with a graphic and converting it into an electrical signal has conventionally used a light emitting source for reading and a light receiving element for converting the optical signal into an electrical signal separately. Since the device is provided in a large area, the device configuration is complicated and large.

[Purpose of the invention]

An object of the present invention is to provide a photo image sensor with a simple configuration.

The above and other objects and novel features of this invention include:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, a photo array is constructed using a light receiving/emitting circuit including a light receiving/emitting element as a unit cell, and when a particular light receiving/emitting cell is operated for receiving light, a plurality of neighboring light receiving/emitting cells are operated as a light source to emit light. By repeating this process while changing the position, a static photo image sensor is realized.

〔Example〕

FIG. 1 shows the operating status of a photo array of an embodiment of a photo image sensor to which the present invention is applied. This photoarray is manufactured by using known semiconductor integrated circuit manufacturing techniques, but is not limited to this, in which one or more light emitting/receiving cells formed on a semiconductor substrate such as single crystal silicon are arranged in a lattice pattern on a plane. It is part of the In the figure, the document with the figure to be read is fixed in contact with the photo array of the photo image sensor, and its surroundings are darkened in some way to prevent unnecessary light from irradiating it. .

In this embodiment, time t-T during reading
In i, the light emitting/receiving cell shown by the circle is performing a light receiving operation, and the light emitted by the six surrounding cells shown in the figure is reflected according to the shape of the document surface. , which is converted into photocurrent.

Further, at time t=Ti÷1, the light-receiving cell is shifted by one to the right, and accordingly, the six light-emitting cells that serve as the light source are also shifted by one to the right. To specify the light receiving cell,
When you finish shifting one row, move to the next row,
Along with this, the light-emitting cells are repeatedly moved to surround the light-receiving cells, and the entire document can be read without mechanically moving the document.

FIG. 2 shows a circuit block diagram of an embodiment of the photo image sensor according to the present invention. In the figure, the address counter AD-CONT is incremented by a clock signal sent from the timing control circuit TC, and sequentially specifies the addresses of cells designated for light reception among the light receiving/emitting cells of the photo array P-ARY. Row address decoder RDCR and column address decoder CDCR
receives the complementary address signal formed by the address counter AD-CONT, and forms row and column selection signals for determining which cell to operate as a light-receiving cell among the light-receiving and emitting cells on the photo array P-ARY. At the same time, 6 (I & I
Row and column selection signals for specifying light emitting cells are also formed. In the photo array P-ARY, light emitting and receiving cells are arranged in a grid pattern on a plane, and the photo array P-ARY is fixed in close proximity to a document to be read. In this state, the address counter AD-
Row address decoder RDCR and column address decoder C according to the address specified by t from CONT.
In response to a selection signal sent from the DCR, a specific light receiving/emitting cell is used as a light receiving cell, and the six nearby surrounding cells are used as a light source, so that they are sequentially activated as light emitting cells. This allows us to read the shapes written on the document,
Send it as an electrical signal to the output amplifier circuit OAMP. The output amplification circuit OAMP further amplifies the read signal sent from the photo array P-ARY, converts it to an appropriate signal level, and outputs it to the outside.

The timing control circuit TC receives a control signal C supplied externally.
TL generates timing signals for controlling the operation of each circuit, such as a clock for incrementing the address counter AD-CONT.

FIG. 3 shows a circuit diagram of an embodiment of a photo array of a photo image sensor to which the present invention is applied.
In the figure, the number of light receiving/emitting cells pc constituting the photo array is mXn, and in the row direction (X axis) there are pcoo to PCmO.
In the 5th column direction (Y axis), the light receiving/emitting cells PC00 to PCOn are located at the top positions.

Each light emitting/receiving cell pc includes a light emitting diode PD, as represented by the light receiving/emitting cell PCij shown in the lower part of FIG.
N-channel type MO5FETQI for light emission control switch
, N-channel type MO3FETQ for light reception control switch
2. NPN transistor TR for amplification, N-channel MO3FET Q3 for output control switch, and resistor R
1. The row and column selections are made using the row selection lines Xai and 2 of each of the column selection lines Yaj and Ybj specified by being decoded by the address decoder CDCR.
It is done by the selection line of the book. That is, when the light receiving cell (X-i, Y=J) is specified by the address counter AD-CONT, the potential of the row selection line Xai changes from high impedance to the power supply voltage Va, and the potential of the row selection line Xbi changes to ground. The potential changes from the low level to the high level of the power supply voltage Va, the potential of the column selection line Yaj changes from the low level of the ground potential to the high level of the power supply voltage Vp, and the light receiving/emitting cell PCij is selected as a light receiving cell. Furthermore, six light receiving/emitting cells PC (i-1
) (j-1), PC(i-1)(j+1), p
ci (j-1), PCi (j+1), PC(
i+1 ) (j-1) , and PC(i↑1
)(j+1) as a light-emitting cell to operate °ζ, the magnetic potential of the row selection lines X a i-1 and X ai+1 is changed from high impedance to the power supply voltage Va, and the column selection line Ybj-1 is changed from high impedance to the power supply voltage Va.
The potential of Ybj+1 is changed from the low level of the ground potential to the high level of the power supply voltage Vp. In this way, the row selection line
ai changes from high impedance when not selected to power supply voltage Va when selected, thereby supplying operating power supply voltage to the light emitting diode of the light receiving/emitting cell that receives or emits light. Column selection line Yaj! By changing from the low level of the ground potential when not selected to the high level of the power supply voltage Va when selected, the light reception control MO3FET Q2 of the light receiving/emitting cell to be operated to receive light is turned on. The column selection line Ybj changes from the low level of the ground potential when not selected to the high level of the selected special power supply fE voltage Vp, so that the MO3FE for light emission control of the light receiving/emitting cell to be operated to emit light is changed.
Turn on TQI. In addition, the row selection line Xbi changes from the low level of the ground potential when not selected to the high level of the power supply voltage Va when selected, so that the row selection line Xat-L
Among the light receiving/emitting cells PC(i-1)j, PCij, and PC(i+1)j which are in the light receiving operation state by Xai+1 and the column selection line Yaj, only the output of the light receiving cell PCij is enabled, so the three light receiving/emitting cells are Among the cells, the output control MO3FETQ3 of the light receiving cell PC1j is turned on. At this time, the output control MOS FETQ3 of the n light receiving/emitting cells connected to the row selection line Xbi are turned on all at once, but the light receiving control MO3FETQ2 of the cells other than the light receiving cell PCij is off, so the amplification is not performed. transistor TR is in the cutoff state, and the light receiving cell PCij
Only the output signal is output. Although not shown, the drains of the output control MO3FETQ3 of all the light receiving and emitting cells are commonly connected and connected to the load resistor RL as an input of the output amplifying circuit OAMP.

At the timing shown as an example in FIG. 3, the light receiving/emitting cell PC22 is designated as the light receiving cell, and the surrounding six light receiving/emitting cells PCII, PCl3, pc21, PC23
, PC31 and PC33 are designated as light-emitting cells. In the light receiving cell PC22, the light emitting diode PD
The power supply voltage Va is applied to the cathode of MO3 for light reception control.
Power supply voltage Va is applied to the base of FETQ2. Here, the power supply voltage given to the light receiving and emitting cells is y p >
V a > V sε (V is the amplification transistor 1
For example,
These are voltages such as vp-ioV and Va-5v. As a result, MO3FETQ2 for light reception control is turned on,
The light emitting diode PD becomes reverse biased at a voltage of (Va-VBE). Furthermore, the output control MO5FET Q3 is also supplied with the power supply voltage Va to its base and is turned on.

In this state, the light emitting diode P emits light from the surrounding light emitting cells and reflects light that changes depending on the character pattern on the document.
D receives the light, and a reverse current of the light emitting diode PD, that is, a photocurrent, flows depending on the strength of the current. This photocurrent is given as the base current of the amplification transistor TR, and due to its amplification action, a collector current multiplied by hFE flows through the load resistance of the output amplification circuit OAMP (hFE is the current amplification factor of the amplification transistor TR). , six light receiving/emitting cells PCIL PCl3 designated as light emitting cells,
In P C2L P G23, PC31 and pc33,
Since the power supply voltage Va is applied to the cathode of the light emitting diode PD and the light emission control MO3FET Ql is turned on, a forward current of, for example, several tens of mA flows through the light emitting diode PD, and the light emitting diodes of the six light receiving/emitting cells are turned on. emits light all at once.

After the above operation, set the address of the light receiving cell to pco.

By repeating the process while changing sequentially up to PCmn, reading of the document is completed. By supplying m and n from the outside, it is possible to specify the reading end position of the photo array, and it is possible to read documents of any size.

The read signal output from the light-receiving cell is amplified by the output amplification circuit OAMP to an appropriate signal level, and then output to the outside via the output terminal D OUT.

〔effect〕

<1) A static photo image sensor that does not require a light source is realized with a simple configuration by sequentially specifying the light receiving and emitting cells arranged in a grid pattern on a surface as a photo array for light receiving and emitting. You can get the effect that you can.

(2) By configuring the light receiving and emitting elements with light emitting diodes, it is possible to achieve the effect that the photo image sensor described in the above item (1) can be realized using conventional semiconductor integrated circuit manufacturing technology.

(3) As shown in Figure 3, by configuring the switch for the light emitting diode's reception/emission operation using a MOSFET and providing a separate photocurrent amplification section, a large-scale photo array with low power consumption and high sensitivity can be created. The effect is that it is possible to realize a photo image sensor with

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that this invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor. For example, the selection pattern of the light-receiving and light-emitting cells shown in the embodiment of FIG. A line scanning method for each column may be used. Furthermore, the configuration of the photoarray shown in the example of FIG. Various embodiments may also be adopted accordingly. moreover,
The block configuration of the photo image sensor shown in the embodiment of FIG. 2 is as follows:
The address counter may not be provided, and the output amplification circuit may not be provided either.

[Application field]

The present invention can be widely used as a static photo image sensor for reading written, printed, or printed documents, including facsimile machines and computer-based character recognition devices.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the operation of a photo array of a photo image sensor showing an embodiment of the present invention, FIG. 2 is a block diagram of the photo image sensor, and FIG. 3 is a diagram of the photo array in FIG. FIG. 2 is a circuit diagram showing an example of a relay C; P-ARY...Photo array A D-CON "1"...Address counter RDC
R...Row address decoder CDCl'? ...
... Column address decoder OAMr' ... Output amplifier circuit TC ... Timing control circuit PD ...
・・Light emitting diode Ql-Q3・・・・N channel MO3FETTR・・
...NPN transistor RIRL...Resistance pcoo~PCmn...Receiving/emitting circuit cell agent patent attorney
Katsuma Ogawa, ``'' Figure 1 Rorororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororororoloro

Claims (1)

[Scope of Claims] 1. A photo array in which a light receiving/emitting circuit including a light receiving/emitting element is used as a unit light receiving/emitting cell, which is arranged in a grid pattern on a surface, and a specific light receiving/emitting cell can be selectively selected by addressing. What is claimed is: 1. A photo image sensor comprising: an address selection circuit that puts the sensor into an operating state for receiving light and selects surrounding light receiving/emitting cells close to the light receiving/emitting cell selected for light receiving as a light emitting source. 2. The photo image sensor according to claim 1, wherein the light receiving and emitting circuit is constructed using a light emitting diode as a light receiving and emitting element. 3. The above-mentioned light receiving/emitting circuit includes a light emitting diode as a receiving/emitting element, and a first conductivity type MIS for switching the receiving/emitting operation.
3. The photodiode according to claim 1 or 2, characterized in that it includes an FET switch, a second conductivity type MISFET switch, an amplifying section for amplifying a photocurrent, and a MISFET for an output switch. image sensor.