JPH04312080A - Image information detecting method for photoelectric conversion element - Google Patents

Abstract

PURPOSE:To enable the continuous recording of optical information, and the extraction of the outline by periodically modulating the light intensity of an entire optical input signal, and inputting it. CONSTITUTION:A photosensitive element is that of a type sensitively responding to the change of the quality of light, that is, a differential sensitive type optical sensor. As for the photosensitive material suited to this purpose, a photosensitive color protein is recommended. However, the further desirably used photosensitive material is a bacteriorhodopsin. This photoelectric conversion element is constituted of the two kinds of electrodes, and the thin film of the bacteriorhodopsin and a hypoliminion including an electrolyte, interposed between the electrodes. The light having incident information to this sensor is finally made incident to the light receiving face of the sensor in a state accompanied with the change of the intensity, after the intensity is timewise modulated when the light passes through an optical system. Thus, the emphasis of moving components, or the extraction of the outline components can be executed from the image information.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a novel method for detecting optical image information, and in particular, when image information is processed using a photoelectric conversion element, specific information processing is performed in a photosensitive element that is a window for light. The present invention relates to a detection method that can be applied. The present invention relates to a detection method that can effectively bring out the characteristic optical information processing function of a photosensitive pigment protein such as bacteriorhodopsin when the photosensitive element is used in the photosensitive element.

0002

BACKGROUND OF THE INVENTION In recent years, with advances in microfabrication technology and optical lithography, the recording density of image information is increasingly reaching new records. However, the current development of high-sensitivity optical sensors and high-density recording devices relies mostly on microfabrication technology using silicon as a substrate, and the current state is that the characteristics of silicon and its bonding elements control the functions of photosensitive devices. It is. Therefore, although the recording density is improved, the processing of input image information is burdened by circuits and software.

[0003] A CCD element mainly made of silicon is typical of an image sensor that inputs image information at high density. Here, the optical signal is converted into an amount of charge and then electrically stored. This memory is read by one-dimensional sequential processing on the circuit side and then displayed as two-dimensional information. This method employs an operation that sequentially resets the memory at regular time intervals in order to track changes in information over time.

0004

[Problems to be Solved by the Invention] However, solid-state devices mainly made of silicon have various functions required for next-generation image information processing systems, such as information identification such as pattern recognition and movement extraction of animal vision. It does not have the necessary processing functions, which leads to limitations in its use as a so-called inteigent element. In order to make solid-state devices work as a visual information processing system,
This inevitably increases the burden on the computer that processes the output information. For example, in order to recognize a shape and compare it with a pattern in memory, the outline structure of an object must be extracted. Extraction of contour components is an important factor in pattern recognition. Furthermore, in order to detect the movement of an object, it is necessary to be able to immediately extract only the dynamic component in the input optical information in real time. In addition, auxiliary functions such as adaptability to brightness and enhancement of contour contrast are also important in extracting this information. The above functions are important functions originally performed by visual receptors, and are the functions that the next generation of optical sensors are aiming for, but they are difficult to achieve with current solid-state devices themselves.

[0005]

[Means for Solving the Problems] In order to solve the above problems, the inventors of the present invention do not rely on solid-state devices, but instead seek biological materials for their functions, and also create devices equipped with information processing means learned from vision. We proceeded with the idea of building one. As a result, as disclosed in the present invention, in a photoelectric conversion element in which a plurality of photosensitive pixels that directly convert an optical input signal into an electrical signal are arranged on a light receiving plane, the photosensitive pixels output a change in the amount of light of the input signal. The image information detection method is characterized in that the image information is input to the optical sensor after periodically modulating the overall light intensity of the optical input signal. So, I was able to solve the problem.

The photosensitive element effectively used in the present invention is a type of photosensitive element that responds sensitively to changes in light amount, that is, changes in light intensity over time; in other words, it is a differentially sensitive type photosensor. . In such a sensor, a change in the amount of light (time differential value) is output as an amount of electricity, an increase in the amount of light is output as a positive amount of electricity, and a decrease in the amount of light is output as a negative amount of electricity.

Photosensitive materials suitable for this purpose include photosensitive dye proteins. This is because in photosensitive pigment proteins, directional charge separation occurs with high efficiency under the absorption of visible light. Among them, bacteriorhodopsin is particularly preferably used. Bacteriorhodopsin is a typical photosensitive pigment protein along with the photosynthetic reaction center chlorophyll protein, and is also known as a typical retinal protein that uses retinal as a chromophore, along with the visual substance rhodopsin. Bacteriorhodopsin is produced from the highly halophilic bacterium Halobacterium.
For example, from the plasma membrane of D. ium halobium). Oesterhalt, W. Stoecken
ius, Methods in Enzymolo
zy, 31, pp667-678 (1974), disc-shaped membrane fragments called purple membranes (
0.5 μm in size). Bacteriorhodopsin is therefore generally used in the form of this purple membrane. Bacteriorhodopsin consists of the protein part opsin and retinal embedded within it that forms a Schiff bond with the opsin. A long wavelength shift called an opsin shift caused by this Schiff bond imparts broad visible absorption (maximum at 550 to 570 nm).

Bacteriorhodopsin is a type of membrane protein with a transport function, and its function is to vectorially transport hydrogen ions from the inside of the membrane to the outside under light absorption, and in this sense it is a proton pump. It is also called. Regarding this proton pump function, see "Proteins, Nucleic Acids, and Enzymes" by Akira Ikegami, Vol. 34, pp. 440-461 (198
9) Or A. Ikegami, et al. ,S
pringerProc. Phys. ,20,pp17
There is an explanation in 3-182 (1987). The movement of protons, or positive charges, by light is an important phenomenon that allows bacteriorhodopsin to exhibit various photoelectric effects.

[0009] Examples of utilizing the photofunction of bacteriorhodopsin for photoelectric conversion in vitro include, for example, K. Singh, e.
tal. , Biophy. J. , 31, pp393
~402 (1980), K. Ihara and
Y. Mukohata, FEBS Letters, 24
0, pp 148-152 (1988), or S. Y
．． Liu, Biophys. J. , 57, pp943~
950 (1990) and its cited references. The most common method is to create a sandwich-type dry voltaic cell by sandwiching an oriented thin film of bacteriorhodopsin or purple membrane between two types of electrodes, and to measure the photovoltaic force generated between the electrodes. The basics are, for example, G. Var
o, Acta Biol. Acad. Sci. Hun
Gary, 32, pp. 301-310 (1981).

As a photoelectric change element capable of responding to changes in the amount of light used in the present invention, the element most suitable for the purpose is an element having the following configuration. That is,
A photoelectric conversion element consists of two types of electrodes (a working electrode and a counter electrode) sandwiched between them and a hydrophilic layer containing a thin film of bacteriorhodopsin and an electrolyte.One side of the thin film of bacteriorhodopsin serves as the working electrode, and the other side is bonded to a hydrophilic electrolyte layer, resulting in a bonded structure of working electrode/bacteriorhodopsin layer/hydrophilic electrolyte layer/counter electrode. With such a wet type junction element, differential response to light can be extracted efficiently. By configuring the working electrode as a large number of small electrode groups, a plurality of photosensitive pixels can be arranged on the light receiving plane.

Next, the optical information detection method of the present invention will be explained. The optical sensor used in the present invention is a type of sensor that responds sensitively to the amount of change in light, and the light that is incident on this sensor and has information changes its intensity over time as it passes through the optical system. By being modulated, the light is finally incident on the sensor with intensity changes at the light receiving surface of the sensor. Oscillation of the intensity of incident light over time
(on) pattern is not limited to any type, but it is necessary that it be performed at a constant time period for a certain short period of time (for example, 1 second). The oscillation of the intensity of the incident light over time may be an ON/OFF oscillation such as light chopping, or may be an oscillation with an amplitude within a certain intensity change range.

[0012] Vibration of the light intensity can be achieved by inserting a rotating sector or an opening/closing shutter into the optical system, or by inserting an optical spatial modulation element made of liquid crystal material or the like and driving these electrically. . Among these means, a method using an optical spatial modulation element (liquid crystal shutter, etc.) is more desirable in that it does not generate mechanical vibrations.

The period of oscillation of light intensity is 25H as a frequency, since moving image information can be tracked with a certain degree of time resolution and image information can be displayed with a certain degree of continuity.
z or more and a period of 50 ms or less, and more preferably a frequency of 50 Hz or more and a period of 30 ms or less.

[0014] When optical information is subjected to periodic ON/OFF chopping by a rotating sector or a modulation element,
In devices using bacteriorhodopsin as a photosensitive material, the light brightness (ON/O
It is desirable that the time ratio of FF) falls within the range of 1/1 to 1/4, and particularly desirably falls within the range of 1/2 to 1/4.

A feature of the optical image detection method according to the method of the present invention is that a certain degree of contrast is added to the contour portion or boundary portion (the portion where the color or intensity of the light forming the image changes) in the input image information. The point is that image information can be input in an added form. In particular, if this method is followed, the sensor can capture the entire still image, while at the same time
The contour image of this object can be emphasized and detected with a higher sensitivity for moving images than for stationary images. These distinctive sensing characteristics (extraction of moving images, extraction of image outlines) are achieved by periodically positioning the sensor itself or the optical system that guides light to the sensor in a direction parallel to the light-receiving surface of the sensor. It can be further emphasized by applying vibration.

In the present invention, the following operations can be performed in conjunction with the purpose of information processing. (1) An operation in which only sensors or pixels with a specific photosensitive wavelength range are selected and the light intensity is oscillated in order to separate a color image and process information. (2) An operation in which the vibration operation of the light intensity shown in the present invention is performed by discontinuously changing the vibration conditions. (3) An operation in which two or more types of photoelectric conversion elements are used together for a single input image to perform multifaceted processing of image information.

Examples of the present invention are shown below, but the present invention is not limited thereto.

[0018]

[Example] Oesterhalt, et al. ,M
methods in Enzymology, 31
, 667 (1974) using density gradient centrifugation.
The purple membrane containing bacteriorhodopsin was separated and purified from the bacterial cells of M. um and dispersed in pure water to prepare a suspension with an absorbance of 6.0 (560 nm).

[0019] 1 part hexane to 100 μl of the aqueous dispersion solution of purple membrane.
00 μl and 20 μl of DMF were added and placed in a shaking mixer to prepare a suspension for developing a purple membrane monolayer.

This suspension was spread on the pure water phase of a monomolecular film production water tank to produce a monomolecular film of bacteriorhodopsin with one layer of purple membrane arranged on the water surface. After compressing this monomolecular film to a surface pressure of 30 mN/m, ITO (indium
The layer was transferred onto the surface of a transparent electrode substrate (3 x 3 cm) on which a square pixel pattern (pixel size: 1 x 1 mm, number of pixels: 256) of a tin oxide layer was provided, and the adhesion operation was repeated to finally form a 20-layer purple film. was accumulated on the substrate. Next, the purple membrane layer was dipped in a 1% aqueous glutaraldehyde solution and washed with water to crosslink and fix the purple membrane.

[0021] On a patterned ITO substrate (thickness 1.1 mm) supporting bacteriorhodopsin,
A gold electrode (thickness: 1 mm) as a common counter electrode was placed through a hollow spacer made of Teflon of
) was injected. In this way, a photoelectric conversion element consisting of a junction of ITO/bacteriorhodopsin/electrolyte/gold electrode was produced. A bias of -0.6 V was applied to the ITO pixel side of the device through an external circuit. The current output from the element is converted into a voltage by an operational amplifier, and after amplification, the voltage signal is sent to a light emitting element (L), which also has 256 pixels.
ED) for two-dimensional display of the signal.

In this way, an image information processing system consisting of a differentially sensitive photoelectric conversion element (image sensor) having 256 pixels and an LED display panel was completed. Various character images were applied as optical information to this sensor from the ITO substrate side using a slide projector.

When a character image is incident, a light modulation element (3.5 x 3.5 cm, using ITO electrodes) consisting of a ferroelectric liquid crystal and an orthogonal polarization plate is installed as an optical shutter 3 cm in front of the light source side of the sensor, and this liquid crystal 6 through the drive circuit to the element
A V ON/OFF intermittent signal was input at a cycle of 40 ms, and the shutter opening/closing time ratio was set to 1/3. By this operation, the light incident on the shutter was modulated into oscillating light with an intensity ratio of 10/1. Incidentally, this intensity ratio can be arbitrarily changed by changing the accuracy of the deflection plate, and was adjusted in the range of 20/1 to 2/1 depending on the purpose.

First, the letter T was incident on the image sensor as continuous light with the optical shutter open, and as a result, the entire image of the letter T was momentarily displayed on the LED display panel. disappeared immediately. This is because the intensity change of the light occurred only for a moment of irradiation. Therefore, next, the optical shutter was driven in a vibrating state at a period of 40 ms. Then, the entire image of the letter T was clearly and continuously displayed on the LED display panel. Next, with the light intensity vibrating in this way, the slide projector was moved so that the letter T moved horizontally and vertically parallel to the light-receiving surface of the sensor, and as a result, it was detected as a static image on the display panel. The movement of the letter T was displayed with a higher contrast than that of the letter T, and with the outline highlighted. As a result of examining the contour components to be emphasized, it was found that the emphasized portions are components perpendicular to the direction of movement. Detection of image information with similar characteristics could be reproduced for all 26 letters of the alphabet.

When similar text information was detected by changing the period of vibration modulation from 40 ms to 20 ms, 20 m
Under the conditions of s, a clear image with better temporal continuity was displayed on the LED display panel.

[0026]

[Effects of the Invention] As described above, by using the image information detection method of the present invention, characteristic information processing such as emphasizing moving components and extracting contour components from image information, which cannot be expressed with conventional silicon-based solid-state devices, can be performed. It is clear that this can be done at the input of the sensor.

Claims (4)

[Claims] 1. A photoelectric conversion element in which a plurality of photosensitive pixels that directly convert an optical input signal into an electrical signal are arranged on a light receiving plane, in which the photosensitive pixels output a change in the amount of light of the input signal. 1. A method for detecting image information, comprising a sensor, and comprising inputting an optical input signal after periodically modulating the entire light intensity of the optical input signal to the optical sensor. 2. The method for detecting image information according to claim 1, wherein the photosensitive pixel is an element containing bacteriorhodopsin or a similar compound thereof. 3. The method for detecting image information according to claim 1, wherein the period of modulation of the light intensity is 50 ms or less. 4. The method for detecting image information according to claim 1, wherein the period of modulation of light intensity is 30 ms or less.