JPS5819188B2 - image sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image sensor, and more particularly to an image sensor having both an imaging function and a video signal storage function.

CTD (charge transfer device), MO8 for optical information processing
Several structural image sensors have been proposed,
The signals obtained by these image sensors are discriminated by a binary circuit into two signal levels corresponding to the white and black levels of the object, and then stored in a separately provided memory.

The above-mentioned signals stored in the memory are inputted to, for example, a computer and subjected to information processing.

However, when information processing is performed using a conventional image sensor as described above, it is necessary to separately provide a memory for storing signals obtained from an object, which has the disadvantage of complicating the configuration of the information processing device.

The present invention was made in view of the above-mentioned points, and has both an imaging function and a storage function, and also has a random access (Random access) function.
The present invention provides a novel image sensor capable of achieving a

Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

Figure 1 shows embodiments of the present invention, 11, 12° 13.
. . , 21, 22, 23, . . . are electrodes of photoelectric cells arranged in a matrix.

This photoelectric cell has an MO8 structure and consists of a semiconductor substrate, a transparent electrode, and an insulating film between the two. A voltage is applied to the electrode to create a depletion layer in the semiconductor substrate, and when a light image is projected from above the transparent electrode, a depletion layer is formed in the semiconductor substrate. An amount of charge corresponding to the brightness of the optical image is generated in the semiconductor substrate and accumulates in the depletion layer as the irradiation time progresses.

Sl, S2... are those in the same row of these electrodes 1
There are conductors connecting 1, 12, 21, 22, and so on.

A charge transfer gate electrode T corresponding to each electrode of the photoelectric cell,
11. T12. T13...T21, T22.
T23...... is provided, and M
It has an O8 structure.

However, it does not have a photosensitive function.

B1. B2. B3... is a signal line and is formed of a floating diffusion layer.

Wl, W2゜W3... are those of the same row of gate electrodes T11゜T21. T31..., T12.
T22. T32..., T13. T23. T33
It is a conductor that connects...

A reproducing circuit is connected to each of the signal lines B1, B2, B3, . . ., and FIG. 2 shows a reproducing circuit F2 including one of the signal lines B2.
is the electric charge of the photoelectric cells obtained corresponding to the optical image projected onto the photoelectric cells 21, 22, 23, . . .
. . . A signal line B2 reset FETQ2r for selecting and detecting with Wn and supplying an amount of charge corresponding to the detection signal level to the photoelectric cell,
Output FET Q2o.

It consists of a capacitor C2, a resistor R1 connected to the source of an output FET Q2o, a binary conversion circuit N, and a switch SW2.

The input terminal of the binarization circuit N is connected to the source of the output FET Q2o, and the output terminal of the binarization circuit is connected to the switch SW2.
and is connected to the signal line B2 via the capacitor C2.

A constant voltage VD is applied to the drain of the 2FET Q2o.

Next, the operation of this device will be explained with reference to FIGS. 1 and 2.

For convenience of explanation, the conductivity type of the substrate is assumed to be P type.

Also, each switch SWi is closed. Conductor 81 of photoelectric cell group. Applying H (bi) level voltage to S2......, each electrode 11, 12, 13...21.22,
23... Form a depletion layer in the underlying semiconductor substrate,
When a light image is projected onto the entire surface of the photocell group in such a state, a signal charge is generated in the depletion layer under each electrode in an amount corresponding to the intensity of the light irradiated to the electrode and, therefore, the brightness of the picture element. do.

After projecting a light image for a predetermined period of time, a signal charge corresponding to the light image is detected.

That is, the gate electrode Tij (j=1
, 2, 3..., i = 1.2.3... songs) by applying an H level voltage to the conductor Wj connected to When a depletion layer deeper than the gate electrode Tij is formed, the charges stored in the photovoltaic cell corresponding to the selected gate electrode Tij, that is, the depletion layer under the electrode ij, pass through the depletion layer under the gate electrode Tij and are transferred to the floating diffusion layer. It flows into the formed signal line Bi.

The potential fluctuation of the signal line Bi due to the inflow of charges causes the output FET Qi to change.

This is output from the source of the FET and input to the binarization circuit N.

After this, the voltage Vr is applied to the gate electrode of the reset FET Qir.
is applied to turn on the FET, and the signal line Bi is brought to a positive potential to complete the reset.

The binarization circuit binarizes the signal detected by the signal line Bi in accordance with the intensity of the light irradiated onto the photoelectric cell ij, and therefore the brightness and darkness of the optical image.

That is, when the light irradiated to the photocell is strong, in other words, when a bright part of the optical image is projected onto the photocell, the signal line Bi is connected to the signal line Bi via the capacitor Ci.
A negative voltage is applied from the value circuit.

At the same time, a positive H-level voltage is applied to the gate electrode Tij, so a predetermined amount of charge flows into the depletion layer below the gate electrode Tij.

This charge is transferred to an adjacent photocell.

That is, when an H level voltage is applied to the electrode ij of the photocell and at the same time the voltage of the gate electrode Tij is switched from the H level to the L level, the charge under the gate electrode Tij is transferred to the photocell.

If the light irradiated to the photocell in this way is strong,
This means that a predetermined amount of charge has been stored in the photocell.

Furthermore, when the light irradiated to the photoelectric cell is weak, in other words, when a dark part of the optical image is projected onto the photoelectric cell, the output of the binarization circuit N is zero, so that the output from the signal line Bi to the gate electrode is No charge is supplied to the depletion layer of .

Therefore, when the light irradiated onto a photocell is weak, no charge is stored in the photocell.

In this way, the presence or absence of charge stored in these photocells is determined depending on the brightness or darkness of the light image irradiated onto the photocell group.

Therefore, when information is processed using the signals stored in the photoelectric cells, erroneous processing due to unevenness of these signal levels is eliminated.

In order to read out the signal under a specific photocell electrode ij among the signals stored in each photocell in this way, the switch SWi attached to the output terminal of the binarization circuit N is opened. After that, an H level voltage is applied to the conductor Wj connecting the gate electrode to introduce the charge of the photoelectric cell into the signal line Bi, and the potential fluctuation of the signal line Bi is detected by the output FET Qio to convert the binarization circuit N. Output terminal Pi at normal binary level
Take it out.

In the above embodiment, the photocells are arranged in a matrix, but the present invention is not limited to this, and the photocells may be arranged in any desired manner, for example, they may be arranged linearly in one dimension.

Furthermore, in the above-described embodiment, each column of photocells and charge transfer gate electrodes arranged in a matrix, that is, each signal line B1, B2 . Although it is assumed that the reproducing circuit is provided in B3..., the present invention is not limited to this, and only one reproducing circuit is provided, and each of the signal lines and the reproducing circuit are connected via a changeover switch. Alternatively, the connection may be made selectively.

As is clear from the above description, the image sensor according to the present invention has the advantage of serving both as an imaging section and a storage section, and can be randomly accessed, and is extremely useful for use in information processing such as pattern identification.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing a main part of the output section of FIG. 1. 11.12,13...21,22,23...
...: Photocell electrode, T11. T12. T13...
...T21. T22. T23...: Gate electrode, B1. B2
゜B3...: Signal line, Qir, Qio: F
ET, N: Binarization circuit.

Claims (1)

[Scope of Claims] 1. A plurality of photocells having transparent electrodes formed on a semiconductor substrate via an insulating layer, and charges of the photocells obtained in response to an optical image projected onto the group of photocells. regeneration circuit means for detecting the amount of charge and resupplying the photoelectric cell with a specific amount of charge corresponding to the detected signal level; and a charge transfer gate electrode provided between the means and the photoelectric cell. An image sensor that is characterized by: 2. The image sensor according to claim 1, wherein the photoelectric cells and the charge transfer gate electrodes corresponding to the photoelectric cells are arranged in a matrix shape. 3. The image sensor according to claim 2, wherein the reproducing circuit means is provided for each row or column of the charge transfer gate electrodes arranged in a matrix. 4. The regeneration circuit means has a signal line indicating a potential corresponding to the amount of charge stored under the charge transfer gate electrode, a circuit for extracting the potential of the signal line, and an output terminal using the output of the extracting circuit as an input signal. 2. The image sensor according to claim 1, wherein the image sensor comprises a binarization circuit connected to the signal line via a capacitor.