KR0176749B1 - Flast image detecting circuit - Google Patents

Abstract

The present invention relates to the construction of an image sensing circuit in a two-dimensional matrix, and in the case of a series type, unit cell thin film transistors (Q1.1-Q1.n) arranged in the x-axis direction --- (Qn.1-Qn unit cell thin film transistors Q1.1-Qn.1 arranged in the Y-axis direction and connected to the respective gate lines GL1 --- GLn. The drain of Qn.n) is connected to each data line DL1 --- (DLn), and in the case of an alternating type, the gate line GL1 --- GLn and data line DL1 --- The two-dimensional image sensing circuit can be realized by configuring the DLn interchangeably.

Description

2D image sensing circuit

1 is a general series image sensing circuit diagram.

2 is a general alternate image sensing circuit diagram.

3A to 3D are timing charts of waveforms supplied to respective parts of FIG.

4A to 4D are timing charts of waveforms supplied to respective parts of FIG.

5 is a series two-dimensional image sensing circuit diagram of the present invention.

6 is an actual layout diagram of the unit cells of FIG.

7 is an alternate two-dimensional image sensing circuit diagram of the present invention.

8 is an actual layout diagram of unit cells of FIG.

9A to 9D are timing charts of waveforms supplied to respective parts of FIG.

(A) to (d) of FIG. 10 are timing charts of waveforms supplied to respective parts of FIG.

* Explanation of symbols for main parts of the drawings

PD1.1-PDn.n: Photodiode Q1.1-Qn.n: Thin Film Transistor

The present invention relates to an image sensing circuit used for a facsimile PC image input device, a PC image input device, and the like. In particular, an image sensor having a one-dimensional structure does not require such scanning unlike a two-dimensional image obtained through scanning. The present invention relates to a two-dimensional image sensing circuit capable of detecting a two-dimensional image.

FIG. 1 is a general series image sensing circuit diagram, and FIG. 2 is an alternate image sensing circuit diagram. As shown therein, an x-axis includes a unit cell array including one photodiode and a thin film transistor for switching the same. It is arranged in a direction and has a linear structure.

These unit cells are grouped in units of blocks based on the addressing and output signal processing methods. In the case of the serial system of FIG. 1, one block 10A is composed of m unit cells. It will be in the form listed.

In the case of the shift formula of FIG. 2, one block 20A is composed of n unit cells, and the blocks are arranged in M, and the operation thereof is described below.

First, as shown in FIG. 2, an alternate circuit as shown in FIG. 2 is a block composed of n units of cells, and M blocks are arranged in the form of M cells. In the circuit of, all of the thin film transistors, which are m switching elements, are connected to the gate line GL in one block, so that signals are output in units of each of the blocks 10A-10N. In the alternate circuit, since the thin film transistors Q1.1, Q2.1 --- Qm.n of the first cell of each block 20A-20N are connected to one gate line G1, the output signal is Such as the first photodiode (PD1.1, PD2.1 --- PDm.1) or second photodiode (PD1.2, PD2.2, --- PDm.2) of each block 20A-20N. The output data line DL1-DLn becomes the number of blocks 20A-20M. In both methods, the number of blocks and the number of photodiodes of one block are reversed.

However, the principle of operation of the unit cell is the same in series and alternating formula, and when this is explained, the photodiode of the unit cell receives light reflected from a document or picture to be input to generate a photocurrent, which is a photocurrent. Since it is proportional to the intensity of light incident on the diode, the photocurrent is minimized in the black portion of the document and vice versa in the white portion of the document. The photocurrent is output by a thin film transistor, which is a switching element, and the shape of a document or picture is detected by processing at a specific gray level according to the magnitude of the current value.

(A) to (d) of FIG. 3 and (a) to (d) of FIG. 4 show photodiodes, gate lines, and data lines of the series circuit shown in FIG. 1 and the alternate circuit shown in FIG. It also timings the waveform.

In the case of the series linear image sensing circuit, when a high potential is supplied to the gate line GL1, the thin film transistors Q1.1 to Q1.m of m cells are turned on in the image sensing unit 10A, and the image sensing unit is turned on. M data signals are output through the photodiodes PDL1-PDLm present at 10A.

On the other hand, in the case of the alternating linear image sensing circuit, when the high potential is supplied to the gate line GL1, the thin film transistors Q1.1, Q2.1 --- Qm, 1 of the first cell in each image sensing unit 20A-20M. ) Is turned on, and m data signals are output through the first photodiodes PD1.1 and PD2.1 --- PDn.1 of each image sensing unit 20A-20M.

In this manner, the gate voltage is sequentially scanned to read a line of data signals.

However, in such serial and alternating image sensing circuits, since the image sensors are arranged in the x-axis direction, for example, when reading a document, only one image can be read in the x-axis direction.

Therefore, in order to read the front of the document, a continuous scanning mechanism in the Y-axis direction is required, and for this, a scanning system and a circuit using a precise stepping motor are required. This circuit mainly consists of a photosensor.

When recognizing a document in this way, it is very difficult to perform accurate stepping in the Y-axis direction. Therefore, there is a disadvantage that the resolution in the Y-axis direction becomes worse than that in the x-axis direction. After reading one line of image in the direction, the corresponding action must be taken to read the next line of image, which increases the processing speed of the document, which slows down the transmission speed. There was a fault.

The present invention has been made to read a two-dimensional image in a fixed state without a stepping process in order to solve such a defect will be described in detail by the accompanying drawings as follows.

5 is a series sensing circuit diagram of the two-dimensional image sensing circuit of the present invention, one of the photodiodes PD1.1-PDn.n and one of the thin film transistors Q1.1-Q1.n. A matrix circuit is constructed with one cell as a basic sensing unit cell, but each thin film transistor (Q1.1-Q1.n) and (Q2.1-Q2.n) --- (Qn.1-) arranged in the x-axis direction. The gates of Qn.n are connected to the respective gate lines GL1 and GL2 to GLn, and each of the thin film transistors Q1.1 to Qn.1 and Q1 arranged in the Y-axis direction. A drain of the .2-Qn.2) --- (Q1.n-Qn.n) is connected to each of the data lines DL1 and (DL2) --- (DLn), and the photodiode PD1.1 -PD1.n), (PD2.1-PD2.n) --- (PDn.1-PDn.n) photodiode bias line (PDL1), (PDL2) --- (PDLn ), And the connection point was connected to the pad terminal (VPD) in common.

7 shows an actual layout of unit cells in a series two-dimensional image sensing circuit of the present invention, where '1' is a thin film transistor, '2' is a transparent electrode line of a photodiode, '3' is a gate line, ' 4 'is the data line,' 5 'is the contact, and' 6 'is the upper electrode of the photodiode.

7 is an alternate sensing circuit diagram of the two-dimensional image sensing circuit of the present invention, one of the photodiodes PD1.1-PDn.n and one of the thin film transistors Q1.1-Qn.n. A matrix circuit is constructed using the basic sensing unit cells, and the thin film transistors Q1.1-Q1.n and Q2.1-Q2.n are arranged in the x-axis direction. The thin film transistors Q1.1-Qn.1, (Q1.2) connected to the respective data lines DL1 and (DL2) --- (DLn) and arranged in the Y-axis direction A gate of -Qn.2) --- (Q1.n-Qn.n) is connected to the gate lines GL1 and (GL2) --- (GLn), respectively, and the photodiodes PD1.1-PD1. n), the anodes of (PD2.1-PD2.n) --- (PDn.1-PDn.n) to photodiode buslines (PDL1), (PDL2) --- (PDLn) arranged on the x-axis. After each connection, the connection point was configured by common connection to the pad terminal VPD again.

8 shows the actual arrangement of unit cells in an alternating two-dimensional image sensing circuit of the present invention, wherein '11' is a thin film transistor, '12' is a transparent electrode line of a photodiode, '13' is a gate line, and '14' Is the data line, '15' is the contact, and '16' is the upper electrode of the photodiode.

The present invention configured as described above will be described in detail with reference to FIGS. 8 to 10.

In the area image sensing circuit of the present invention, the operation principle of a unit cell including one photodiode and a thin film transistor is the same.

It should be noted, however, that the signal processing on the tandem, alternating area image sensing circuit of the present invention shown in Figs. 5 and 7 shows a single line of unit cells arranged in the x-axis direction or the Y-axis direction at a time unlike the prior art. After processing, the next line of data is read immediately without going through the reset process.

First, referring to the operation of the series region image sensing circuit as shown in FIG. 5, when a high potential as shown in FIG. 8B is supplied to the gate line GL1, the thin film transistors present in the unit cells connected to the gate line GL1 are provided. Since (Q1.1-Qn.n) is on, the photoelectrically converted signals such as (c) and (d) of FIG. 8 through the photodiode PD1.1-PD1.n are placed in the Y-axis direction. Each of the photoelectric conversion signals, that is, the image signals thus output, is applied to the image signal processing unit connected to the next stage and output.

Thereafter, the high potential supplied to the gate line GL1 is cut off, and at the same time, the reset process and the saturation process of the photodiode PD2.1-PD2.n are performed as shown in (c) and (d) of FIG. 8. The unit cells connected to the gate line GL2 are turned on immediately without passing through the second recording line image signal as described above, and through this process, the image on the front side of the document is quickly processed without stepping.

On the other hand, referring to the operation of the alternating area image sensing circuit as shown in FIG. 7, when the high potential is supplied to the gate line GL1 as shown in FIG. 9B, the unit in the Y-axis direction connected to the gate line GL1 is shown. Since the thin film transistors Q1.1-Qn.n existing in the cells are turned on, n data lines DL1- 1 in which photoelectric signals such as (c) and (d) of FIG. 9 output from each cell are placed in the x-axis direction. Are output via DLn).

In this case, the first unit cell (PD1.1-Q1.1) --- (PDn.1, Qn.1) of the unit cell line connected to each data line DL1-DLn in the x-axis direction is used. Since only an image signal is output, such signal processing must be performed n times in an alternating manner so that an image signal of one line in the x-axis direction on the document is completed at the same time.

As described in detail above, the present invention enables the two-dimensional image signal to be read in a fixed state without being steered, so that the resolution in the Y-axis direction can be kept the same as the x-axis direction, and the images are accurately reproduced. There is an advantage in that the photodiode is not required to be recharged in order to read the image signal of the next line, and thus the image signal can be processed more quickly.

Claims (1)

A multi-dimensional matrix structure is constructed of a plurality of unit cells consisting of a photodiode (PD) for sensing input data and a thin film transistor (Q) for switching the photodiode to output data. The thin film transistors Q1.1-Qn.1 to Q1.n-Qn.n are commonly connected to the gate lines GL1 to GLn in the x-axis direction or m-bit lines in the y-axis direction. And a drain electrode of the thin film transistor having a common connection to the data lines (DL1-DLn) along the y-axis to sense an alternating two-dimensional image.