JP3086927B2 - Compact optical pattern recognition device and its driving method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of optical information processing and optical measurement, in which two-dimensional images directly obtained from an imaging device such as a CCD camera or an object are subjected to optical correlation processing using coherent light. Thus, the present invention relates to an apparatus for automatically performing pattern recognition and measurement.

[0002]

2. Description of the Related Art Conventional optical pattern recognition devices and correlation processing devices include a joint transform correlator (Joint Tran correlator).
sform Correlator) is well known. For example, a patent in this system is disclosed in Japanese Patent Application Laid-Open No. 57-138616.
JP, JP-A-57-210316, JP-A-57-210316
No. 21716 has been proposed. FIG. 3 shows an example of a conventional correlator based on this method. In this method, an input image 24 is an image in which a reference image serving as a reference for recognition and a correlated image to be recognized are simultaneously arranged adjacently. The light beam emitted from the laser 21 is expanded by the beam expander 22 and then split by the beam splitter 23 into two light beams. The light flux transmitted through the beam splitter 23 irradiates an input image 24, and converts the input image 24 into a coherent image. This coherent image is subjected to Fourier transform using a first Fourier transform lens 25, and the light intensity distribution of a joint Fourier transform image of the reference image and the correlated image is written to a light-writing type liquid crystal light valve 26 disposed on the conversion plane. Display. Here, the joint Fourier transform image is an interference fringe pattern obtained by two-beam (or multi-beam) interference between the Fourier transforms of the correlated image and the reference image, and each of the correlated image and the reference image. The complex conjugate component of

Next, the light beam reflected by the beam splitter 23 is reflected by mirrors 29 and 30 and the polarizing beam splitter 5 to irradiate a light-writing type liquid crystal light valve 26, thereby displaying the joint Fourier transform image displayed. Convert the light intensity distribution into a coherent image. This coherent image is read as a negative image or a positive image by transmitting through the polarization beam splitter 5 acting as an analyzer, and the CCD camera 28 disposed on the conversion surface thereof.
Is received at. In this way, a correlation peak representing a two-dimensional correlation coefficient between the reference image and the correlated image can be obtained.

In the above example, a reflective light-writing type liquid crystal light valve 26 is used as a light-writing type spatial light modulator.
An optical writing type spatial light modulator using (i ₁₂ SiO ₂₀ crystal) can be used. In addition, instead of the optical writing type spatial light modulator, there is a method of taking a joint Fourier transform image with a CCD camera and displaying the image on an electric writing type spatial light modulator such as a liquid crystal television.

[0005]

However, as shown in FIG. 3, in the conventional joint transform optical correlator, it is necessary to obtain a joint Fourier transform image of the reference image and the correlated image, In order to obtain a correlation peak corresponding to a two-dimensional correlation coefficient between
The system was very large because four Fourier transform lenses had to be used. Therefore, instead of the optical writing type liquid crystal light valve, an optical writing type spatial light modulator using the BSO crystal, which is a transmission type spatial light modulator, is used, and the two Fourier transform lenses are connected to the same one Fourier transform lens. By adopting a system using a conversion lens, a method of miniaturizing the system can be considered. However, an optical writing type spatial light modulator using a BSO crystal has a high speed using direct modulation of a laser diode because of a low writing sensitivity to the oscillation wavelength of the laser diode and a high driving voltage of several kV. However, there was a problem that it was not possible to operate with. The resolution of the optical writing type spatial light modulator using the BSO crystal is 15 to 30 lp /
mm, when a small image is used as an input image, the reference image and the correlated image must be arranged very close to each other or a Fourier transform lens having an extremely long focal length must be used. There is a problem that it is difficult to reduce the size of the system.

Furthermore, the above-mentioned conventional optical writing type spatial light modulator requires about 100 times for recording, reading and erasing an image.
Since it takes about msec, it has been difficult to operate an optical pattern recognition device using these optical writing type spatial light modulators at high speed.

[0007]

The compact pattern recognition apparatus of the present invention performs an optical correlation process using coherent light on a two-dimensional image obtained directly from an object or obtained from a CCD camera or the like. , In an optical pattern recognition device that automatically recognizes and measures the required pattern,
Means for converting at least one reference image including a desired target displayed on the image display means and at least one newly input correlated image into a coherent image, and optically Fourier transforming the coherent image, Means for obtaining a joint Fourier transform image of the image and the correlated image, means for converting the joint Fourier transform image into an intensity distribution image, and displaying the intensity distribution image on a light-writing type spatial light modulator; Means for reading out the intensity distribution image displayed on the spatial light modulator using coherent light, and performing a Fourier transform on the read out intensity distribution image to obtain a two-dimensional correlation image distribution between the reference image and the correlated image. Means for obtaining a correlation peak intensity corresponding to a correlation coefficient between the reference image and the correlated image included in the correlation image distribution. In a joint conversion correlator comprising an electric conversion element, means for converting at least one reference image including a required target displayed on the image display means and at least one newly input correlated image into a coherent image is an oscillation wavelength. The means for reading out the intensity distribution image displayed on the optical writing type spatial light modulator using coherent light includes a laser diode having an oscillation wavelength of 660 nm or more. A spatial light modulator is a light-writing type ferroelectric liquid crystal light valve not having a light reflection layer using hydrogenated amorphous silicon as a photoconductive layer, optically Fourier transforming the coherent image,
Means for obtaining a joint Fourier transform image of the reference image and the correlated image, and a Fourier transform of the intensity distribution image read from the optical writing type spatial light modulator, and a two-dimensional correlation image between the reference image and the correlated image By configuring the means for obtaining the distribution to be the same Fourier transform lens,
The problem relating to the miniaturization of the joint conversion optical correlator has been solved.

Further, the driving method of the optical pattern recognition apparatus of the present invention may be arranged such that image display means for displaying at least one reference image including the required target and at least one correlated image newly inputted; An optical writing type ferroelectric liquid crystal light valve having no layer;
A laser diode having a wavelength of
The laser diode having a wavelength of 0 nm or more operates in synchronization with each other, and a time during which a required image is displayed on the image display means, a light emitting time of the laser diode having an oscillation wavelength of 900 nm or less, and the light reflecting layer is not provided. The writing voltage application time of the optical writing type ferroelectric liquid crystal light valve coincides at least for a predetermined time, and the erasing voltage application time of the optical writing type ferroelectric liquid crystal light valve not having the light reflection layer and the oscillation wavelength The light emission time of the laser diode having a wavelength of 660 nm or more matches at least a predetermined time,
The problem relating to the high-speed operation was solved by adopting a driving method in which the laser diode having the oscillation wavelength of 900 nm or less and the laser diode having the oscillation wavelength of 660 nm or more do not emit light at the same time.

[0009]

First, the structure of the optical writing type ferroelectric liquid crystal light valve used in the present invention will be described. FIG. 6 (a)
FIG. 1 is a configuration diagram showing an example of a photo-writing type ferroelectric liquid crystal light valve having no light reflection layer used in the present invention. Transparent substrates 33a and 33b, such as glass or plastic, for holding liquid crystal molecules have transparent electrode layers 3 on their surfaces.
4a, 34b, 85 degrees from 75 degrees from the normal direction of the transparent substrate
An alignment film layer 35a obtained by obliquely depositing silicon monoxide in a range of degrees;
35b is provided. The transparent substrates 33a and 33b are arranged so that the alignment film layers 35a and 35b are opposed to each other by controlling the gap via a spacer 39, and sandwich the ferroelectric liquid crystal layer 36. Further, on the transparent electrode layer 34a on the writing side by light, a photoconductive layer 37 is laminated and formed between the alignment film layer 35a, and on the cell outer surface of the transparent substrate 33a on the writing side and the transparent substrate 33b on the reading side. , Anti-reflection coatings 38a and 38b are formed. FIG. 6 (b)
FIG. 6 is a structural view showing an example of a photo-writing type ferroelectric liquid crystal light valve having a light reflecting layer used in the present invention.
The difference from the optical writing type ferroelectric liquid crystal light valve having no light reflection layer shown in FIG. 11A is that a light shielding layer 43 and a dielectric mirror 42 are formed between the photoconductive layer 37 and the alignment film layer 35a. That is the point.

Next, a method of initializing the optical writing type ferroelectric liquid crystal light valve having the above structure will be described. The first method is to once irradiate the entire surface of the writing surface of the optical writing type ferroelectric liquid crystal light valve (or the reading surface in the case of a ferroelectric liquid crystal light valve having no light reflection layer), A transparent electrode layer 34 applies a pulse voltage or a DC bias voltage sufficiently higher than the operation threshold voltage or a DC bias voltage on which an AC voltage of 100 Hz to 50 kHz is superimposed.
This is a method in which a ferroelectric liquid crystal molecule is aligned in a stable state in one direction by applying a voltage between a and 34b, and the state is stored. The second method is to apply a pulse voltage, a DC bias voltage, or a DC bias voltage in which an AC voltage of 100 Hz to 50 kHz is superimposed on the transparent electrode layer 34a, irrespective of whether or not there is light irradiation. In this method, the ferroelectric liquid crystal is aligned in a stable state in one direction by applying a voltage between the ferroelectric liquid crystals and the state, and the state is stored.

Next, the operation after the optical writing type ferroelectric liquid crystal light valve is initialized as described above will be described. A pulse voltage or a DC bias voltage having a polarity opposite to that of the initialization, which is lower than the operation threshold voltage at the time of darkness and higher than the operation threshold voltage at the time of light irradiation, or 100 Hz to 50
Optical writing of an image is performed by a laser or the like while applying a DC bias voltage on which a kHz AC voltage is superimposed between the transparent electrode layers 34a and 34b. When hydrogenated amorphous silicon is used as the photoconductive layer 37, if the wavelength of the laser light to be irradiated is about 900 nm or less, carriers are generated in the photoconductive layer in the region irradiated with the laser light, and the generated light is generated. The applied carriers drift in the direction of the electric field due to the applied voltage, and as a result, the driving threshold voltage is lowered, and a bias voltage having a voltage higher than the operation threshold voltage and having the opposite polarity to that at the time of initialization is applied to the region irradiated with the laser beam. The dielectric liquid crystal undergoes inversion of molecules due to inversion of spontaneous polarization, and transitions to the other stable state, so that the image is binarized and stored. This stored image remains stored even when the drive voltage becomes zero.

The binarized and stored image is irradiated with readout light of linearly polarized light whose polarization axis is aligned in the direction of alignment of liquid crystal molecules (or a direction perpendicular thereto) aligned by initialization, and By passing the light through an analyzer arranged so that the polarization axis is perpendicular (or parallel) to the polarization direction of the light reflected by the mirror 42, it is possible to read out in a positive state or a negative state.

When hydrogenated amorphous silicon is used as the photoconductive layer 37, light having a wavelength longer than about 660 nm is transmitted through the photoconductive layer 37. Accordingly, in this case, the readout light of the optical writing type ferroelectric liquid crystal light valve having no light reflection layer has a wavelength of 660 nm.
When a laser beam of m or more is used, the light-writing type ferroelectric liquid crystal light valve can be used as a transmission-type light-writing type spatial light modulator. In particular, if the stored image is read while being held at the driving voltage of zero, the stored image can be read without erasing.

The laser diodes used as the writing light source and the reading light source can directly modulate at high speed. Therefore, by synchronizing their driving currents with the driving voltage of the optical writing type ferroelectric liquid crystal light valve,
The compact optical pattern recognition device of the present invention can be operated at high speed.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment relating to a small pattern recognition device of the present invention will be described with reference to the drawings. FIG.
1 is a configuration diagram showing one embodiment of a small pattern recognition device according to the present invention, and 1 is a writing laser diode (Laser).
Diode: hereinafter abbreviated as LD), 2 is a first collimator lens, 3 is a first beam shaping prism, 4 is an electric writing type spatial light modulator, 5 is a polarization beam splitter, 6 is a Fourier transform lens, and 7 is 8 is a reading LD, 9 is a second collimator lens, 10 is a second beam shaping prism, 11 is a photodiode, 12 is a drive control circuit, 13 is a power supply,
4 is an amplifier, 15 is an image input terminal, and 16 is an output terminal. The means for converting the at least one reference image including the required target displayed on the image display means and the at least one correlated image newly inputted into a coherent image includes a writing LD 1, a first collimator lens 2, A beam shaping prism 3, an electric writing type spatial light modulator 4, a polarization beam splitter 5, an image input terminal 15, a drive control circuit 12, and a power supply 13. The coherent image is optically Fourier transformed, and the reference image is The means for obtaining the joint Fourier transform image of the correlated image is the Fourier transform lens 6, which converts the joint Fourier transform image into an intensity distribution image, and displays the intensity distribution image on the optical writing spatial light modulator. A light-writing type ferroelectric liquid crystal light valve 7, a drive control circuit 12, and a power supply 13; Means for reading the displayed intensity distribution image in the optical modulator using coherent light, read LD8 and the second collimator lens 9 and the second beam shaping prism and the drive control circuit 12 and the power supply 13,
Means for Fourier-transforming the read-out intensity distribution image to obtain a two-dimensional correlation image distribution between the reference image and the correlated image includes a Fourier transform lens 6 and a polarizing beam splitter 5, which are included in the correlation image distribution. The photoelectric conversion element for detecting the intensity of the correlation peak corresponding to the correlation coefficient between the reference image and the correlated image is a photodiode 11 and a power supply 13.
, An amplifier 14 and an output terminal 16.

The coherent writing light emitted from the writing LD 1 is expanded by a first collimator lens 2 and then converted into a parallel light beam having a predetermined beam diameter. It is shaped into a shape and irradiates the electric writing type spatial light modulator 4. In this embodiment, the beam diameter is 10 mmφ. A video signal or a digital image signal from a computer, an image processing device, a CCD camera, or the like is input to the electric writing type spatial light modulator 4 through an image input terminal 15, and an input image as shown in FIG. Have been. In the input image shown in FIG. 4, the letter A of the alphabet is arranged adjacent to each other as the correlated image and the reference image, but in general, the number of correlated images and the number of the reference images may be plural. . The electric writing type spatial light modulator 4 used in the present invention will be described later in detail.

The coherent writing light applied to the electric writing type spatial light modulator 4 converts the input image displayed on the spatial light modulator into a coherent image, and then enters the polarization beam splitter 5. At this time,
The polarization direction of light emitted from the writing LD 1 is determined in advance so that the coherent image is incident on the polarization beam splitter 5 in a p-polarized state. Therefore, most of the coherent image passes through the polarizing beam splitter 5, is subjected to Fourier transform by the Fourier transform lens 6, and is written on the writing surface of the optical writing type ferroelectric liquid crystal light valve 7 arranged on the Fourier transform surface. Is irradiated. In this manner, the joint Fourier transform image of the correlated image and the reference image is stored in the optical writing type ferroelectric liquid crystal light valve 7 in the same manner as described in the related art and operation. Recorded as intensity distribution image
Is displayed. This optical writing type ferroelectric liquid crystal light valve 7 is a transmission type optical writing type ferroelectric liquid crystal light valve having no light reflection layer shown in FIG.
As the photoconductive layer 37, an intrinsic hydrogenated amorphous silicon layer having a thickness of 2 to 3 μm is used. It goes without saying that a hydrogenated amorphous silicon layer having a pin junction structure may be used as the photoconductive layer 37. Therefore, as described in the operation, since the photosensitivity of the hydrogenated amorphous silicon layer becomes lower with respect to light having a wavelength of around 900 nm or more, the joint Fourier transform image is converted to the optically-written ferroelectric liquid crystal light valve. In order to record the data on No. 7, as the writing LD1,
An oscillation wavelength of about 900 nm or less must be used. Preferably, the oscillation wavelength is 70 as the writing LD1.
It is better to use one having a thickness of 0 nm or less. In this embodiment,
Oscillation wavelength 780 nm, output 3 as writing laser 1
The one with 0 mW was used.

Next, the coherent readout light emitted from the readout laser 8 is expanded by a second collimator lens 9 and then converted into a parallel light beam having a predetermined beam diameter. Is formed into a circular beam shape by the optical writing type ferroelectric liquid crystal light valve 7.
Is irradiated on the readout surface. In this embodiment, the beam diameter of the readout light is set to 8 mmφ.
It is determined by the width of the spatial frequency domain of the light intensity distribution of the joint Fourier transform to be handled. As described above, since the intrinsic hydrogenated amorphous silicon layer is used as the photoconductive layer of the optical writing type ferroelectric liquid crystal light valve 7 of the present invention, the oscillation wavelength of the reading LD 8 is 660 nm or more. If it is,
The reading light passes through the optical writing type ferroelectric liquid crystal light valve 7. Oscillation wavelength 800nm if possible
Although it is desirable to use the above-described reading LD8, in this embodiment, the oscillation wavelength is 780 nm as the reading LD8.
Was used. This is the same as the oscillation wavelength of the writing LD1, but the oscillation wavelength of these LDs does not necessarily have to be the same. The polarization direction of the readout light is previously adjusted to the direction of the alignment of the liquid crystal molecules (or a direction perpendicular thereto) aligned by initialization, and the polarization direction of the readout light transmitted through the optical writing type ferroelectric liquid crystal light valve. By passing through an analyzer arranged so that the polarization axis is perpendicular (or parallel), the joint Fourier transform image can be read out as a positive image or a negative image. In this embodiment,
The polarization beam splitter 5 is used as the analyzer. As the polarization beam splitter 5, it is preferable to use a polarization beam splitter having a small dependence on the incident angle and the wavelength. The joint Fourier transform image read out in this manner is subjected to Fourier transform by the Fourier transform lens 6, and only the s-polarized component is reflected by the polarization beam splitter 5. Generate a correlation function between an image and a reference image. In the joint transform correlator, the correlation peak included in the correlation function appears at a position determined by the relative distance between the correlated image and the reference image. Therefore, if the photoelectric conversion surface of the photodiode 11 is set in advance at a position where the correlation peak appears, the correlation peak intensity corresponding to the correlation coefficient between the target image to be correlated and the reference image becomes the voltage of the photodiode 11. Obtained as output. When there are a plurality of reference images or correlated images, it is necessary to use a plurality of photodiodes or a multi-division photodiode or a photodiode array having a plurality of photoelectric conversion surfaces as the photodiodes 11 in order to cause a plurality of correlation peaks to appear. is there.

The electric signal indicating the correlation peak intensity corresponding to the correlation coefficient between the detected image to be correlated and the reference image is amplified by the amplifier 14 and then output to the output terminal 16.
Is output to another processing system. The amplifier 14 is connected to the power supply 13
Needless to say, power is supplied by The electric writing type spatial light modulator 4 is on the front focal plane of the Fourier transform lens 6, the optical writing type ferroelectric liquid crystal light valve 7 is on the back focal plane of the Fourier transform lens 6, and the photodiode 11 is the Fourier transform lens 6. Are located on the back focal plane.

As shown in FIG. 4, for example, the correlated image and the reference image are displayed adjacently on the electric writing type spatial light modulator 4 at the same time. At this time, a light intensity distribution corresponding to the correlation function as shown in FIG. 5 is obtained on the correlation surface including the photoelectric surface of the photodiode 11. In FIG. 5, if the positions of the correlated image and the reference image in FIG. 4 are (x + a, y + b) and (x−a, y−b), respectively, the correlation peak 31 is (± a, ± b). A pair appears at the position. Moreover, there are multiple reference images, the position of the correlation images (x, y), the position of the reference image _{(x + a i, y +} b i), if (i is a natural number) is the correlation peaks (± 2a _i , ± 2b _i ). Therefore, if the photodiode 11 is arranged so that the photoelectric conversion surface is located at a position where such a correlation peak appears, only a desired correlation peak intensity can be detected. At this time, DC component 3 unnecessary for pattern recognition
2 affects the detection of the correlation peak intensity as noise, and thus it is desirable to remove it with an optical mask or the like.

FIG. 12 shows the relationship between the spatial frequency and the correlation peak intensity of the joint Fourier transform image written in the optical writing type ferroelectric liquid crystal light valve in the small optical pattern recognition device shown in FIG. As can be seen from FIG. 12, even if the joint Fourier transform image is written to the optical writing type ferroelectric liquid crystal light valve 7 at a high spatial frequency of 60 lp / mm, the obtained correlation peak intensity is reduced only by about 50%. Depending on the arrangement of the image and the reference image, a Fourier transform lens having a short focal length of 40 to 80 mm can be used. Further, since the Fourier transform lens for performing the joint Fourier transform and the Fourier transform lens for performing the correlation operation are used together with one of the Fourier transform lenses 6, the total length of the apparatus is reduced by half compared to the conventional joint transform optical correlator. be able to. As a result, the size of the compact optical pattern recognition device of the present invention can be reduced to 1/10 to 1/2 the size of the conventional optical pattern recognition device.

In this embodiment, in order to operate the system in real time, the drive LD 1 and the read LD 1 are used by using the drive control circuit 12 supplied with power from the power supply 13.
8, the electric writing type spatial light modulator 4 and the optical writing type ferroelectric liquid crystal light valve 7 are operated in synchronization.
Therefore, a driving method of the small optical pattern recognition device according to the present embodiment will be described below. FIG. 7 is a diagram showing the relationship between the driving method of the optical writing type ferroelectric liquid crystal light valve, the writing LD, and the reading LD used in the present invention and the optical response of the optical writing type ferroelectric liquid crystal light valve. FIG. 7A shows a driving waveform of the optical writing type ferroelectric liquid crystal light valve, FIG. 7B shows a driving waveform of the writing LD, FIG. 7C shows a driving waveform of the reading LD, and FIG.
(D) shows a change in light response of the optical writing type ferroelectric liquid crystal light valve. The driving waveform of the optical writing type ferroelectric liquid crystal light valve shown in FIG. 7 (a) is read out in the optical writing type ferroelectric liquid crystal light valve having no light reflection layer shown in FIG. 6 (a). Side transparent electrode layer 34b
3 shows a voltage change of the photoconductive layer 37 when the ground is grounded. As can be seen from this figure, a pulse voltage in which the voltage polarity of the photoconductive layer 37 of the photo-writing type ferroelectric liquid crystal light valve 7 in FIG. 1 is repeated in the order of positive, negative and zero voltage is applied to the transparent electrode layer 34a, The optical writing type ferroelectric liquid crystal light valve 7 is operated by continuously applying the voltage during 34b. At this time, in the same manner as described in the operation,
The polarization direction of the reading light is determined so that the joint Fourier transform image to be read becomes a positive image. Then, the optical writing type ferroelectric liquid crystal light valve 7
Means that the image is erased when the readout light is applied at the same time as the positive voltage 44 is applied, the image is written when the write light is applied at the same time as the negative voltage 45 is applied, and the zero voltage is applied. At 46, an image is read when the reading light is irradiated.

As shown in FIG. 7B, the writing light is irradiated in synchronization with the negative voltage 45 applied to the optical writing type ferroelectric liquid crystal light valve 7.
An operating current 47 flows through the writing LD1. Then, at times other than the time of writing, the operating current of the writing LD is set to the zero current 48 state. The time during which a current flows through the writing LD 1 is a time sufficient to write a desired joint Fourier transform image into the optical writing type ferroelectric liquid crystal light valve 7, and is a time about the time during which the negative voltage 45 is applied. deep. This depends on the writing light intensity, but in the present embodiment, the time was about 0.2 to 5 msec. The frequency of the driving voltage waveform is 1 to 2 k.
When the frequency is less than or equal to Hz, writing, reading and erasing can be sufficiently performed.

As shown in FIG. 7C, when a zero voltage 46 and a positive voltage 44 are applied to the optical writing type ferroelectric liquid crystal light valve 7, an operating current 49 is supplied to the reading LD8. It is. At least when the negative voltage 45 is applied to the optical writing type ferroelectric liquid crystal light valve 7, the state is set to the zero current 50. In the present invention,
Since the light writing type ferroelectric liquid crystal light valve 7 having no light reflection layer is used for the display of the joint Fourier transform, the light writing type ferroelectric liquid crystal light valve 7 is irradiated with the reading light. When the positive voltage 44 is applied, the photoconductive layer is excited by the reading light, and the recorded image corresponding to the light intensity distribution of the joint Fourier transform is erased. For the same reason, when applying a negative voltage 45 to the optical writing type ferroelectric liquid crystal light valve 7 and writing the joint Fourier transform image with the reading light, the writing of the optical writing type ferroelectric liquid crystal light valve 7 is performed. The characteristics are affected and change. Of course, when a negative voltage 45 is intentionally applied to the optical writing type ferroelectric liquid crystal light valve 7 and a joint Fourier transform image is written, readout light having an appropriate intensity is applied to the optical writing type ferroelectric liquid crystal light valve. Although it is possible to control the writing characteristics of the bulb 7, such a method is usually not very suitable for the purpose of operating the compact optical pattern recognition device of the present invention at high speed. Of course, as described in the operation, when the optical writing type ferroelectric liquid crystal light valve 7 is initialized, a positive voltage 44 is applied to the optical writing type ferroelectric liquid crystal light valve 7, Initialization is performed by applying an operating current 49 to the LD 8 and irradiating the LD 8 with read light.

FIG. 7 (d) shows the optical response of the thus obtained optical writing type ferroelectric liquid crystal light valve. FIG. 7D shows a temporal change of the transmitted light intensity of the reading light in the optical writing type ferroelectric liquid crystal light valve 7 in the embodiment shown in FIG. As can be seen from this figure, when the zero voltage 46 is applied to the optical writing type ferroelectric liquid crystal light valve 7, the transmission intensity of the reading light reaches the maximum level 51, and when the positive voltage 44 is applied, the reading light is read. The light transmission intensity becomes the low level 52. Of course, when the driving current of the reading LD 8 is zero current 50, the transmission intensity of the reading light is zero level 5
It becomes 3. The light-writing type ferroelectric liquid crystal light valve 7 has a memory property and is not excited at all by the reading light when the zero voltage 46 is applied. However, the image information recorded in the optical writing type ferroelectric liquid crystal light valve 7 does not disappear. Therefore, if the driving method of the small optical pattern recognition device is used, a correlation peak of a desired intensity can be obtained only by adjusting the reading light intensity, that is, the value of the driving current of the reading LD 8.
Further, the read light intensity when the positive voltage 44 is applied is not the zero level 53 but the low level 52 because the read light of the optical writing type ferroelectric liquid crystal light valve 7 is completely impermeable. Is extremely difficult.

Next, the electric writing type spatial light modulator 4 used in the embodiment of FIG. 1 will be described. As mentioned above,
The optical writing type ferroelectric liquid crystal light valve 7 used in the small optical pattern recognition device of the present invention operates at an extremely high speed, but generally the operating speed of the electric writing type spatial light modulator is:
30 or 6 for scanning one frame at video rate
Since 0 Hz is required, the operation speed of the small optical pattern recognition device of the present invention is rate-limiting. Therefore, it is preferable to use an electro-optic ceramic such as PLZT, a magneto-optical material such as yttrium iron garnet, or a ferroelectric liquid crystal or the like which operates at a high speed as the light modulating material as the electric writing type spatial light modulator 4. In this embodiment, an electric writing type ferroelectric liquid crystal spatial light modulator is used as the electric writing type spatial light modulator 4. FIG. 9 is a schematic perspective view showing the structure of an electric writing type ferroelectric liquid crystal spatial light modulator used in the present invention. 59a and 59b are arranged such that their polarization axes are perpendicular (or parallel). It is a polarizing plate arranged, and 60
a and 60b are glass carriers; 61 is a common electrode; 62 is a silicon semiconductor layer made of polycrystalline silicon or single crystal silicon; 63 is a ferroelectric liquid crystal layer; 64 is a Y driver;
Is an X driver, 66 is a transistor, 67 is a pixel electrode,
68 is a signal line, and 69 is a scanning line.

The driving circuit of the electric writing type ferroelectric liquid crystal spatial light modulator shown in FIG. 9 is composed of an integrated circuit formed on the silicon semiconductor layer 62. This integrated circuit comprises a plurality of field effect gate transistors 6 arranged in a matrix.
6 is included. The source electrode of the transistor 66 is connected to the corresponding pixel electrode 67, the gate electrode is connected to the scanning line 69, and the drain electrode is also connected to the signal line 68. The integrated circuit further includes an X driver 65, and is connected to a column-shaped signal line 68. Further, it includes a Y driver 64 and is connected to a row-shaped scanning line 69.

Next, a method of inputting image information to the above-described electric writing type spatial light modulator will be described. The image information input from the image input terminal 15 shown in FIG.
Are input to the X driver 65 and the Y driver 64 shown in FIG. The x component of the image information is input to the X driver 65, and the y component of the image information is input to the Y driver 64. The x component and the y component of the image information are synchronized by a clock signal. FIG. 10 shows a scanning line voltage waveform diagram output from the Y driver 64 for driving the scanning line 69.
The voltage applied to the scanning line 69 is synchronized by the clock signal 78, and is applied to the first scanning line, the second scanning line, the third scanning line, and the Nth scanning line. ON voltages 70, 72, 74, and 76 are applied to each scan line with a predetermined time delay, and the first scan line, the second scan line, the third scan line, the Nth The OFF voltages 71, 73, 75, and 77 applied to the scan lines are simultaneously applied to all the scan lines after the ON voltage 76 is applied to the Nth scan line, which is the last scan line for displaying an image frame. Is done. While the first scanning line ON voltage 76 is being applied, the ON voltage is applied to a predetermined signal line among the first signal line, the second signal line, and the Nth signal line. For example, the transistor 66 attached to the pixel electrode 67 corresponding to the signal line to which the ON voltage is applied on the first scanning line is excited, and as a result, between the common electrode 61 and the pixel electrode 67 to which the voltage is applied. Since an electric field sufficient to invert the liquid crystal molecules of the ferroelectric liquid crystal layer 63 is generated, and the polarization characteristics of light transmitted through the portion of the ferroelectric liquid crystal layer 63 are changed, a pixel is displayed. Become. In this way, image information is displayed on the electric writing type ferroelectric liquid crystal spatial light modulator by sequentially displaying pixels on predetermined pixels on each scanning line. The image information displayed on the electric writing type ferroelectric liquid crystal spatial light modulator is read after the ON voltage 76 is finally applied to the N-th scanning line for displaying the image and all the image information is displayed. , The OFF voltages 71, 73, 75, and 77 are applied to all the scanning lines.
Is applied until all image information is erased.
It is needless to say that the clock signal 78 at this time is the same as or synchronized with the clock signal of the write LD1, read LD8, and optical write type ferroelectric liquid crystal light valve 7.

By using the electric writing type ferroelectric liquid crystal spatial light modulator configured as described above, an extremely high-speed image input could be electrically executed. For example, an embodiment will be described in which an electric writing type ferroelectric liquid crystal spatial light modulator having 300 × 480 pixels is used. In this case, as shown in FIG. 6, a region for displaying a correlated image and a region for displaying a reference image are each divided into two regions each including 300 × 240 pixels. Then, the image in one of the area for displaying the correlated image and the area for displaying the reference image may be sequentially rewritten. That is,
The OFF voltages 71 and 7 are applied only to the pixel electrodes in this rewrite area.
3, 75 and 77 may be applied. For example, when the letter "A" of the alphabet is given as the correlated image and the identification is made to be A, the reference image is rewritten one after another without changing the display of the correlated image and the most correlated peak is displayed. What is necessary is just to select a strong reference image. As a result of such an operation, it was found that the time required to rewrite the reference image once can be reduced to 7 msec or less. In addition, since the ferroelectric liquid crystal has a bistable memory property, displayed image information is not erased unless an erase voltage is applied to the pixel electrode. The time required for writing the joint Fourier transform image in the optical writing type ferroelectric liquid crystal light valve 7 depends on the writing light intensity, but about 0.2 to 5 msec is sufficient. Therefore,
The time required for performing pattern recognition using the electric writing type ferroelectric liquid crystal spatial light modulator is 7.2 to 12 ms.
ec. This is about three to five times the operating speed when a conventional liquid crystal television is used as the electric writing type spatial light modulator of the small optical pattern recognition device of the present invention.

Next, a second embodiment of the small optical pattern recognition device of the present invention will be described. FIG. 2 is a diagram showing a configuration of an embodiment in which an optical writing type ferroelectric liquid crystal light valve is used instead of an electric writing type spatial light modulator as image information input means. A type ferroelectric liquid crystal light valve, 18 is an image forming lens, 19 is an object to be input, and 20 is a mirror. The means for converting the at least one reference image including the required target displayed on the image display means and the at least one correlated image newly inputted into a coherent image includes a writing LD 1, a first collimator lens 2, Beam shaping prism 3
, A second optical writable ferroelectric liquid crystal light valve 17, a polarization beam splitter 5, a drive control circuit 12, and a power supply 13.
Means for optically Fourier transforming the coherent image to obtain a joint Fourier transform image of the reference image and the correlated image includes a Fourier transform lens 6 and a mirror 2
Means for converting the joint Fourier transform image into an intensity distribution image and displaying the intensity distribution image on the light-writing type spatial light modulator comprises a light-writing type ferroelectric liquid crystal light valve 7 and a drive control circuit 12 Means for reading out the intensity distribution image displayed on the optical writing type spatial light modulator by using coherent light. The reading means includes a reading LD 8, a second collimator lens 9, a second beam shaping prism 10, and the like. The drive control circuit 12 and the power supply 13 are means for performing a Fourier transform on the readout intensity distribution image to obtain a two-dimensional correlation image distribution between the reference image and the correlated image. The photoelectric conversion element for detecting the intensity of the correlation peak corresponding to the correlation coefficient between the reference image and the correlated image included in the correlation image distribution is a photodiode. Over de 11 and a power source 13 and the amplifier 14 and the output terminal 16.

The embodiment shown in FIG. 2 is different from the embodiment shown in FIG. 1 in that a means for inputting an input image composed of a reference image and a correlated image uses a light-writing type ferroelectric liquid crystal light valve and a And the arrangement of constituent optical systems is different in order to make the optical system more compact. First, the input image input means will be described.
The object 19 to be input is, for example, an object such as an electronic component or a mechanical component, or an object obtained by forming an image on a photographic film or the like, and is an object to be compared with a reference object which is a reference object for comparison. And at least one correlated object. This is similar to the arrangement of the input image described in the first embodiment. Light including an object image generated from the input object 19 is passed through the imaging lens 18 to the second optical writing type ferroelectric liquid crystal light valve 1.
The image is formed and displayed on the writing surface 7. The input image displayed on the second optical writing type ferroelectric liquid crystal light valve 17 in this manner is irradiated from the writing LD 1 and then enlarged by the first collimator lens 2 to be converted into a parallel light beam. The beam is illuminated and read by the reading light converted into a circular beam shape by the first beam shaping prism 3. This is the basic operation of the input unit of the input image in the embodiment shown in FIG. Note that the same components as those used in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

The input image read in this manner is subjected to Fourier transform, and is displayed as a joint Fourier transform on a light-writing type ferroelectric liquid crystal light valve 7, which is read out by reading light from a reading LD 8. The method of obtaining the correlation peak representing the correlation coefficient between the correlated object and the reference object included in the input image by performing the Fourier transform again is the same as in the first embodiment shown in FIG.

FIG. 13 shows an example of the input method of the input image in the embodiment shown in FIG. 2, and shows an example in which the small optical pattern recognition device of the present invention is applied to an automatic assembling device or the like. It is a thing. In FIG. 13, reference numeral 83 denotes an illumination optical system including a light source and a reflection / condensing optical system, 84 denotes a moving carrier such as a belt conveyor, 85 denotes a fixed carrier, 86 denotes a correlated object, 87 denotes a reference object, and 88 denotes the present invention. Is a small optical pattern recognition device. In automatic assembly equipment, etc.
A correlated object 86 such as an electronic component or a mechanical component used for assembling is placed on a moving carrier 84 such as a belt conveyor and transported. On the other hand, the reference object 87 may move together with the correlated object 86, but generally, the reference object 86 is often used by being fixed on the fixed carrier 85.

The illumination light emitted from the illumination optical system 83 is
The light is reflected by the correlated object 86 and the reference object 87 and reaches the small pattern recognition device 88 of the present invention. Since the illumination light reaching the small light pattern recognition device 88 of the present invention includes the object images of the correlated object 86 and the reference object 87, the illumination light of the present invention follows the basic operation of the input means of the input image. It is input to the small optical pattern recognition device 88. That is,
The correlated object 86 and the reference object 87 are the object 1 shown in FIG.
It acts as 9. At this time, the illumination light is also reflected from the surfaces of the movable carrier 84 and the fixed carrier 85, so that the colors and brightness of the movable carrier 84 and the fixed carrier 87 are adjusted so that the correlated object 86 and the reference object 87 are input with good contrast. Is preferably adjusted. For example, if the correlated object 86 and the reference object 87 have a white color tone, the moving carrier 84
The fixing carrier 85 is preferably black. Further, it is preferable that the color and brightness of the movable carrier 84 and the fixed carrier 87 are the same.

Although the input image input method shown in FIG. 13 uses a reflective illumination system, it goes without saying that the movable carrier 84 and the fixed carrier 85 may be made transparent and a transmission projection illumination system may be used. No. The second light-writing type ferroelectric liquid crystal light valve 17 shown in FIG. 2 includes the light-writing type ferroelectric liquid crystal light valve (a) without the light reflection layer shown in FIG. 6 and the light reflection layer. Either of the optical writing type ferroelectric liquid crystal light valve (b) may be used, but the light reflection is required because the illumination light does not affect the correlation optical system and the reflectance of the reading light is increased. It is preferable to use a reflection type optical writing type ferroelectric liquid crystal light valve (b) having a layer. When a binarized input image is input to the small optical pattern recognition device of the present invention shown in FIG. 2, the second type of optical writing type ferroelectric liquid crystal light valve shown in FIG. The driving method of the optical writing type ferroelectric liquid crystal light valve 17 may be the same as the driving method of the optical writing type ferroelectric liquid crystal light valve described in the first embodiment.

FIG. 8 shows a second embodiment of the light-writing type ferroelectric liquid crystal light valve 17 having a dielectric mirror as a light reflection layer shown in FIG. In the case where a light-writing type ferroelectric liquid crystal light valve having no dielectric mirror is used as the light reflection layer shown in FIG. It is an example of an operation waveform of the pattern recognition device. The second optical writing type ferroelectric liquid crystal light valve 17, the optical writing type ferroelectric liquid crystal light valve 7, the writing LD 1 and the reading LD 8 are synchronized and controlled by the drive control circuit 12. FIG. 8A shows a driving waveform of an optical writing type ferroelectric liquid crystal light valve having a dielectric mirror.
FIG. 8B shows a voltage change of the photoconductive layer 37 when the transparent electrode layer 34b on the reading side in the optical writing type ferroelectric liquid crystal light valve having the light reflecting layer shown in FIG. FIG. 6 (a) is a driving waveform of an optical writing type ferroelectric liquid crystal light valve having no dielectric mirror.
FIG. 8 (c) shows a voltage change of the photoconductive layer 37 when the transparent electrode layer 34b on the reading side in the optical writing type ferroelectric liquid crystal light valve having no light reflecting layer is grounded. 8) shows the change of the current flowing through the writing LD1 with the driving waveform of the writing LD1, and FIG. 8D shows the change of the current flowing through the reading LD8 with the driving waveform of the reading LD8. Things,
FIG. 8 (e) shows the optical response of the optical writing type ferroelectric liquid crystal light valve having the dielectric mirror shown in FIG. 8 (a), and the read light from the writing LD1 is transmitted from the optical writing type ferroelectric liquid crystal light valve. FIG. 8 (f) shows a change in the intensity of the reflected light, and FIG. 8 (f) shows the readout by the optical response of the optical writing type ferroelectric liquid crystal light valve having no dielectric mirror shown in FIG. 8 (b). FIG. 9 shows a change in the intensity of transmitted light that passes through the optical writing type ferroelectric liquid crystal light valve when the reading light from the LD 8 is used.

8 (a) and 8 (b), the voltage of the photoconductive layer 37 of the ferroelectric liquid crystal light valve having a dielectric mirror and the optical writing type ferroelectric liquid crystal light valve having no dielectric mirror is shown. A pulse voltage whose polarity is repeated in the order of positive, negative, and zero voltage is applied to the transparent electrode layer 34a,
34b to operate these light-writing type liquid crystal light valves. However, a positive voltage 4 applied to an optical writing type ferroelectric liquid crystal light valve having a dielectric mirror
4 is set to be sufficiently higher than the inversion threshold voltage in the dark state described in the operation, and the negative voltage 45 is set to be higher than the inversion threshold voltage in the light state and lower than the inversion threshold voltage in the dark state. It is. At this time, in the same manner as described in the operation, the writing LD1 is set so that the read input image and the joint Fourier transform image become positive images.
The direction of polarization of read light from a ferroelectric liquid crystal light valve having a dielectric mirror from the light source and read light from a read LD 8 to a light-writing type ferroelectric liquid crystal light valve not having a dielectric mirror are determined. And These light-writing type ferroelectric liquid crystal light valves are designed such that when the positive voltages 44 and 54 are applied and the reading light is irradiated at the same time, the image is erased and the negative voltages 45 and 55 are applied. At the same time, image writing is performed when writing light is irradiated, and reading is performed when reading light is irradiated at zero voltages 46 and 56.

However, the positive voltage 44 was applied to the optical writing type ferroelectric liquid crystal light valve having the dielectric mirror regardless of whether writing light for writing an input image or reading light from the writing LD 1 was present. Sometimes initialization or image deletion is performed. Next, when a negative voltage 45 is applied to write an input image, the written input image is stored and held even when the input image reaches a state of zero voltage 46. The input image stored and read is read out by the readout light from the writing LD 1 oscillated by passing the current 47 and converted into a coherent input image. The light is applied to the writing surface of the dielectric liquid crystal light valve 7. FIG. 8E shows the change in the intensity of the joint Fourier transform image at this time. That is, when the operating current 47 of the writing LD 1 is flowing, the read light intensity from the optical writing type ferroelectric liquid crystal light valve having the dielectric mirror is at the high level 57, and at other times is at the zero level 58. Become.

In addition, the optical writing type ferroelectric liquid crystal light valve having no dielectric mirror transmits the reading light from the reading LD 8 oscillated by flowing the current 49a or 49 while applying the positive voltage 54. The irradiation initializes or erases the image. The current 49a is a drive current for generating read light for initialization. As can be seen by comparing FIGS. 8 (b), 8 (c) and 8 (d), when the joint Fourier transform image is applied to the optical writable ferroelectric liquid crystal light valve having no dielectric mirror, the reading is performed. The reading light is not irradiated from the LD 8 for use. When writing a joint Fourier transform image to an optical writing type ferroelectric liquid crystal light valve having no dielectric mirror, a writing LD
1 is performed by applying a drive current 47 to the writing light of the joint Fourier transform image and simultaneously applying a negative voltage 55 to an optical writing type ferroelectric liquid crystal light valve having no dielectric mirror. The written joint Fourier transform image is recorded and held in a light-writing type ferroelectric liquid crystal light valve having no dielectric mirror even at the state of zero voltage 56, which is read from the reading LD 8 generated by the driving current 49. Read by light. In the optical writing type ferroelectric liquid crystal light valve having a dielectric mirror and the optical writing type ferroelectric liquid crystal light valve having no dielectric mirror, the image recorded and held at zero voltage has the intensity of the read light. No matter how strong it is, it will not be erased. In this way, the joint Fourier transform image read from the optical writing type ferroelectric liquid crystal light valve having no dielectric mirror is again subjected to Fourier transform by the Fourier transform lens 6 and the correlated image included in the input image. It is converted into a correlation peak corresponding to the correlation coefficient with the reference image. FIG. 8F shows the change in the correlation peak intensity. However, FIG.
The state of the low level 52 of the transmitted light intensity in (f) corresponds to the noise level when the joint Fourier transform image is not written in the optical writing type ferroelectric liquid crystal light valve having no dielectric mirror. I have. When operated in this manner, the small optical pattern recognition device of the present invention shown in FIG. 2 was capable of inputting an input image with a resolution of 100 lp / mm or more and moving at an operation speed of 1 kHz or less.

However, when comparing and discriminating feature amounts included in a person's face, scenery, radiographs, and the like, there are cases in which the density, shading, and the like of an input image have an important meaning. Therefore, a method of inputting an input image having continuous gradation to the small optical pattern recognition device of the present invention shown in FIG. 2 will be described. FIG. 11 shows operation waveforms of respective components in the small optical pattern recognition device of the present invention shown in FIG. 2, and FIG. 11 (a) shows a second optical writing type ferroelectric liquid crystal light valve 17. Driving waveform of an optical writing type ferroelectric liquid crystal light valve having a used dielectric mirror, (b) is an optical writing type ferroelectric having no dielectric mirror used as an optical writing type ferroelectric liquid crystal light valve 7 (C) is a driving waveform of a writing LD, (d) is a driving waveform of a reading LD, and (e) is a driving waveform of an optical writing type ferroelectric liquid crystal light valve having the dielectric mirror. Change in light response, (f)
Indicates a change in light response of the optical writing type ferroelectric liquid crystal light valve having no dielectric mirror.

The driving waveform of the optical writing type ferroelectric liquid crystal light valve having the dielectric mirror shown in FIG.
The reading-side transparent electrode layer 3 in the optical writable ferroelectric liquid crystal light valve having the light reflecting layer shown in FIG.
4b corresponds to a voltage change of the photoconductive layer 37 when grounded. As can be seen from this figure, a pulse voltage in which the voltage polarity of the photoconductive layer 37 of the second photo-writing type ferroelectric liquid crystal light valve 17 in FIG. The voltage is continuously applied during the period 34b to operate the second optical writing type ferroelectric liquid crystal light valve 17. At this time, the DC bias voltage 79 is superposed between the transparent electrode layers 34a and 34b so that the positive voltage 44a is higher than the negative voltage 45a. However, the negative voltage 45a is set so that the negative voltage 45a does not become higher than the inversion threshold voltage in the bright state described in the operation.
It is assumed that the C bias voltage 79 is superimposed. At this time,
In the same manner as described in the operation, the polarization direction of the reading light from the writing LD 1 is determined so that the input image to be read becomes a positive image. And the second
The optical writing type ferroelectric liquid crystal light valve 17 performs erasing of an input image when a positive voltage 44a is applied, and writing and reading of an input image when a negative voltage 45a is applied. When such an asymmetric pulse voltage is applied between the transparent electrode layers 34a and 34b, at the time of writing, a writing voltage (negative voltage) proportional to the light intensity applied to the photoconductive layer 37 is applied. The inversion force proportional to the writing voltage acts on the ferroelectric liquid crystal molecules applied to the ferroelectric liquid crystal 36, but at the same time, the relaxation force for returning to the original stable state due to the asymmetry of the applied voltage acts on the ferroelectric liquid crystal molecules. For this reason, the read light intensity at the time of writing of the second optical writing type ferroelectric liquid crystal light valve 17 using the driving method increases in proportion to the writing light intensity and disappears with time. Since the disappearance time is determined by the relaxation time of the ferroelectric liquid crystal molecules, the frequency of the asymmetric pulse voltage is preferably about 100 Hz or more. By using the driving method described above, it is possible to write an input image having a continuous gradation to the second optical writing type ferroelectric liquid crystal light valve 17 in real time.

The driving waveform of the optical writing type ferroelectric liquid crystal light valve having no dielectric mirror shown in FIG. 11B has a transmission type optical writing type ferroelectric liquid crystal light shown in FIG. 6A. Transparent electrode layer 34 on reading side in bulb
This corresponds to a voltage change of the photoconductive layer 37 when b is grounded. As can be seen from this figure, a pulse voltage in which the voltage polarity of the photoconductive layer 37 of the photo-writing type ferroelectric liquid crystal light valve 7 in FIG.
The second optical writing type ferroelectric liquid crystal light valve 17 is operated by continuously applying the voltage between the transparent electrode layers 34a and 34b. However, in this case, the pulse voltage to be applied is a symmetrical pulse voltage unlike the case of the above-mentioned reflection type optical writing type ferroelectric liquid crystal light valve. Further, the pulse voltage is applied with the completely same phase and cycle as the asymmetric pulse voltage. At this time, in the same manner as described in the operation, the polarization direction of the reading light from the reading LD 8 is determined so that the input image to be read becomes a positive image. The optical writable ferroelectric liquid crystal light valve 7 erases the input image when the positive voltage 44b is applied, and writes and reads the input image when the negative voltage 45b is applied. When such an operation is performed, a binarized image is displayed on the optically writable ferroelectric liquid crystal as described in the operation and the first embodiment.

As shown in FIG. 11C, the pulse voltage is applied to the optical writing type ferroelectric liquid crystal light valve 7 and the second optical writing type ferroelectric liquid crystal light valve 17 in synchronization with the pulse voltage. A pulse-like operating current is supplied to the write LD 1 so that the write light (read light) is irradiated. The phase of the operating current is advanced by π / 4 with respect to the phase of the pulse voltage applied to the optical writing type ferroelectric liquid crystal light valve 7 and the second optical writing type ferroelectric liquid crystal light valve 17. (Running late.

As shown in FIG. 11D, the read L
A pulse-like operating current is supplied to D8 so that the reading light is irradiated in synchronization with the pulse voltage applied to the optical writing type ferroelectric liquid crystal light valve 7. The phase of the operating current is advanced (lagged) by π / 2 with respect to the phase of the operating current flowing through the writing LD 1. 11A to 11D are synchronized by the drive control circuit 12 to which power is supplied from the power supply 13.

The initialization of the second light-writing type ferroelectric liquid crystal light valve 17 and the erasing of the input image are performed by the second light-writing type liquid crystal light valve 1 because of the asymmetric pulse voltage.
Irrespective of the intensity of the write light and the read light applied to the light 7, the operation is performed when the positive voltage 44 a is applied. Also, an optical writing type ferroelectric liquid crystal light valve 7 is used.
Is initialized and the joint Fourier transform image is erased by applying a positive voltage 44b to the optical writing type ferroelectric liquid crystal light valve 7.
Is applied and readout light is irradiated.

The optical response of the optical writing type ferroelectric liquid crystal light valve having the dielectric mirror shown in FIG. 11E is determined by the second optical writing type ferroelectric liquid crystal light valve 17 reading from the writing LD 1. It shows the time change of the reflection intensity of light, and 80a, 80b, and 80c each show the reflection light intensity when the writing light intensity of the input image sequentially decreases. As can be seen from the figure, when the writing LD 1 is oscillating, the positive voltage 4 is applied to the second optical writing type ferroelectric liquid crystal light valve 17.
4a, the intensity of the reflected light becomes a very weak level 81, but the second optical writing type ferroelectric liquid crystal light valve 17
It can be seen that when a negative voltage 45a is applied to the light-emitting device, a reflected light intensity corresponding to the writing light intensity of the input image is obtained. Of course, when the writing LD 1 is not oscillating, the second light-writing type ferroelectric liquid crystal light valve 17 is not irradiated with the reading light, so that the reflected light intensity becomes zero level.
become. This indicates that an input image having a continuous tone could be written to and read from the second optical writing type ferroelectric liquid crystal light valve 17.

The optical response of the optical writing type ferroelectric liquid crystal light valve having no dielectric mirror shown in FIG. 11F is obtained from the reading LD 8 of the optical writing type ferroelectric liquid crystal light valve 7 of FIG. 5 shows the change over time of the transmission intensity with respect to the read light. The input image from the second light-writing type ferroelectric liquid crystal light valve 17 in FIG. 2 having the dielectric mirror is read by the reading light from the writing LD 1, and is read by the light writing type ferroelectric liquid crystal light valve 7. When the negative voltage 45b is applied, binary recording is performed as a joint Fourier transform image on the optical writing type ferroelectric liquid crystal light valve 7 in the same manner as described in the first embodiment. While the negative voltage 45b is applied to the optical writing type ferroelectric liquid crystal light valve 7, even if the writing LD 1 does not oscillate, the binary recorded joint Fourier transform image is in a memory state. Therefore, if the reading LD 8 is oscillated at this time, the binary recorded Fourier transform image is read out from the optical writing type ferroelectric liquid crystal light valve 7, and FIG.
It is read out as the maximum transmitted light intensity represented by 51 in (f). The optical writing type ferroelectric liquid crystal light valve 7
A positive voltage 44 b
Are initialized and erased. Therefore, even if the reading LD 8 is oscillated, the optical writing type ferroelectric liquid crystal light valve 7 having no dielectric mirror can be used.
When the positive voltage 44b is applied, the read light from the read LD 8 does not pass through the optical writing type ferroelectric liquid crystal light valve 7 and the transmitted light intensity is weak as shown by 52 in FIG. It becomes something. Of course, when the reading LD 8 is not oscillating, the state shown in FIG.
As indicated by 53, the readout light passing through the optical writing type ferroelectric liquid crystal light valve 7 having no dielectric mirror becomes zero.

By using the configuration and the driving method shown in the second embodiment, 100H can be achieved without using the special electric writing type spatial light modulator used in the first embodiment.
It has been found that the small pattern recognition device of the present invention can be operated at a high speed operation of z or more. Further, by arranging the components of the embodiment shown in FIG. 2, the overall length can be further reduced to about １ ／ compared to the small optical pattern recognition device of the present invention shown in FIG. A compact pattern recognition device with a more compact configuration was realized. It can be easily inferred that the arrangement of the components can be applied to a case where an electric writing type spatial light modulator is used as the image input means.

Further, the compact optical pattern recognition device of the present invention is configured with a joint transform optical correlator that binarizes a joint Fourier transform image as a basic algorithm. Can achieve extremely good S / N recognition, but as the number of reference images to be recognized at a time increases, the noise rapidly increases, resulting in lower S / N and incorrect recognition. Problems arise. In order to avoid such a problem, a plurality of correlation peak intensities corresponding to correlation coefficients between a correlated image and a plurality of reference images obtained once by joint transform correlation are used to calculate the correlation between the reference image and the correlated image. By means of obtaining a two-dimensional correlation coefficient, and the spatial light modulator for mask disposed before or after the reference image, the transmittance or reflectance of the portion corresponding to each reference image, the correlation coefficient On the other hand, by providing a means for changing in a linear or non-linear relationship, by forming a feedback loop in the small optical pattern recognition device of the present invention, accurate pattern recognition can be performed even when a large number of reference images are used at the same time. Needless to say, it can be done.

[0050]

As described above, the compact optical pattern recognition device of the present invention performs optical correlation processing using coherent light on a two-dimensional image obtained directly from an object or a CCD camera. In the optical pattern recognition apparatus for automatically recognizing and measuring a required pattern, at least one reference image including a required target displayed on the image display means and at least one newly input reference image are displayed.
Means for converting the two correlated images into coherent images;
Means for optically Fourier transforming the coherent image to obtain a joint Fourier transform image of the reference image and the correlated image, and converting the joint Fourier transform image into an intensity distribution image; Means for displaying on the light modulator, means for reading out the intensity distribution image displayed on the optical writing type spatial light modulator using coherent light, and Fourier transforming the intensity distribution image read out, the reference image A joint for obtaining a two-dimensional correlation image distribution with the correlated image, and a photoelectric conversion element for detecting the intensity of a correlation peak corresponding to the correlation coefficient between the reference image and the correlated image included in the correlation image distribution In the conversion correlator, at least one reference image including a required target displayed on the image display means and at least a new input image are input. The means for converting the two correlated images into a coherent image includes a laser diode having an oscillation wavelength of 900 nm or less, and the means for reading out the intensity distribution image displayed on the optical writing type spatial light modulator using coherent light includes an oscillation wavelength. A light-writing type spatial light modulator comprising a laser diode having a wavelength of 660 nm or more, wherein the light-writing type spatial light modulator does not have a light reflection layer made of hydrogenated amorphous silicon as a photoconductive layer; Optically Fourier transform the coherent image, means for obtaining a joint Fourier transform image of the reference image and the correlated image, and Fourier transform the intensity distribution image read from the optical writing type spatial light modulator, the reference image and The means for obtaining a two-dimensional correlation image distribution with the correlated image is the same Fourier transform lens By a formed, compared with the conventional joint transform correlator 1/10 to 1
/ 2 or a length of 1/20 to 1/4, and a video rate of 30 Hz
Alternatively, a high-speed operation of typically 100 Hz or more is possible, which has the effect of increasing the speed of a pattern recognition sensor or an image discriminating apparatus for an X-ray photograph used in an automatic assembling apparatus with practical device dimensions.

Since the compact optical pattern recognition device of the present invention is essentially a device for performing correlation operations between images in parallel, optical computing for high-speed parallel processing of two-dimensional information such as images is performed. Can be used as a device,
The effect of making these small and practical devices is significant.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a small optical pattern recognition device of the present invention.

FIG. 2 is a configuration diagram showing another embodiment of the small optical pattern recognition device of the present invention.

FIG. 3 is a configuration diagram showing an example of a conventional joint conversion optical correlator.

FIG. 4 is an explanatory diagram showing an example of an input image in a joint transform correlator.

FIG. 5 shows one of correlation peaks in a joint transform correlator.
It is explanatory drawing which shows an example.

FIG. 6 is a structural view showing an example of a photo-writing type ferroelectric liquid crystal light valve used in the present invention. FIG. 6 (a) shows a photo-writing type ferroelectric liquid crystal light valve having no light reflection layer. One example, (b), is an example of an optical writing type ferroelectric liquid crystal light valve having a light reflection layer.

FIG. 7 is a diagram showing a driving method of an optical writing type ferroelectric liquid crystal light valve, a writing LD, and a reading LD used in the present invention and the optical response of the optical writing type ferroelectric liquid crystal light valve. ) Is the driving waveform of the optical writing type ferroelectric liquid crystal light valve, (b) is the driving waveform of the writing LD, (c) is the driving waveform of the reading LD, and (d) is the optical writing type ferroelectric liquid crystal light valve. FIG. 4 is a diagram showing an optical response of the present invention.

8A and 8B are diagrams showing an example of an operation waveform of the small optical pattern recognition device of the present invention, wherein FIG. 8A shows a drive waveform of an optical writing type ferroelectric liquid crystal light valve having a dielectric mirror,
(B) is a driving waveform of an optical writing type ferroelectric liquid crystal light valve having no dielectric mirror, (c) is a driving waveform of a writing LD, (d) is a driving waveform of a reading LD,
(E) is a diagram showing the optical response of an optical writing ferroelectric liquid crystal light valve having a dielectric mirror, and (f) is a diagram showing the optical response of an optical writing ferroelectric liquid crystal light valve having no dielectric mirror. is there.

FIG. 9 is a schematic perspective view showing a structure of an electric writing type ferroelectric liquid crystal spatial light modulator used in the present invention.

FIG. 10 is a waveform diagram showing a scanning voltage waveform of the electric writing type ferroelectric liquid crystal spatial light modulator used in the present invention.

11A and 11B are diagrams showing an example of an operation waveform of the small optical pattern recognition device of the present invention, wherein FIG. 11A shows a drive waveform of an optical writing type ferroelectric liquid crystal light valve having a dielectric mirror,
(B) is a driving waveform of an optical writing type ferroelectric liquid crystal light valve having no dielectric mirror, (c) is a driving waveform of a writing LD, (d) is a driving waveform of a reading LD,
(E) is a diagram showing the optical response of an optical writing ferroelectric liquid crystal light valve having a dielectric mirror, and (f) is a diagram showing the optical response of an optical writing ferroelectric liquid crystal light valve having no dielectric mirror. is there. .

FIG. 12 is a graph showing the relationship between the spatial frequency and the correlation peak intensity of the joint Fourier transform image written in the optical writable ferroelectric liquid crystal light valve in the compact optical pattern recognition device of the present invention.

FIG. 13 is a schematic diagram showing an example of an input method of an input image in the embodiment shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 writing LD 2 first collimator lens 3 first beam shaping prism 4 electric writing type spatial light modulator 5 polarization beam splitter 6 Fourier transform lens 7 light writing type ferroelectric liquid crystal light valve 8 reading LD 9 second 10 collimator lens 10 second beam shaping prism 11 photodiode 12 drive control circuit 13 power supply 14 amplifier 15 image input terminal 16 output terminal 17 second optical writing type ferroelectric liquid crystal light valve 18 imaging lens 19 object 20 mirror 21 Laser 22 Beam expander 23 Beam splitter 24 Input image 25 First Fourier transform lens 26 Optical writing liquid crystal light valve 27 Second Fourier transform lens 28 CCD camera 29 First mirror 30 Second mirror 31 Correlation peak 32 DC Success 33a, 33b Transparent substrate 34a, 34b Transparent electrode layer 35a, 35b Alignment film layer 36 Ferroelectric liquid crystal layer 37 Photoconductive layer 38a, 38b... Positive voltage 45 Negative voltage 46 Zero voltage 47 Operating current 48 Zero current 49 Operating current 50 Zero current 51 Maximum level 52 Low level 53 Zero level 54 Positive voltage 55 Negative voltage 56 Zero voltage 57 High level 58 Zero level 59a, 59b ... Polarizing plate 60a, 60b ... glass carrier 61 common electrode 62 silicon semiconductor 63 ferroelectric liquid crystal layer 64 Y driver 65 X driver 66 transistor 67 pixel electrode 68 signal line 69 scanning line 70 ON voltage applied to the first scanning line 71 first O added to the scan line of F voltage 72 ON voltage applied to the second scanning line 73 OFF voltage applied to the second scanning line 74 ON voltage applied to the third scanning line 75 OFF voltage applied to the third scanning line 76 nth ON voltage 77 applied to the scanning line of the present invention 77 OFF voltage applied to the nth scanning line 78 Clock signal 80a Reflected light intensity when the readout light intensity is maximum 80b Reflected light intensity when the readout light intensity is intermediate 80c Readout light intensity Reflected light intensity at minimum 81 Weak level 82 Zero level 83 Illumination optical system 84 Moving carrier 85 Fixed carrier 86 Correlated object 87 Reference object 88 Small optical pattern recognition device of the present invention

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-20720 (JP, A) JP-A-1-315723 (JP, A) JP-A-3-39774 (JP, A) JP-A-3-39774 21914 (JP, A) JP-A-63-307441 (JP, A) JP-A-59-10928 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/135 G02F 1 / 13 505 G06K 9/74 G02F 3/00-7/00

Claims (5)

(57) [Claims] 1. A light for automatically recognizing and measuring a required pattern by performing an optical correlation process using coherent light on a two-dimensional image obtained directly from an object or obtained from a CCD camera or the like. A pattern recognition device for converting at least one reference image including a required target displayed on the image display means and at least one newly input correlated image into a coherent image, and optically Fourier-converting the coherent image. Means for obtaining a joint Fourier transform image of the reference image and the correlated image, converting the joint Fourier transform image into an intensity distribution image, and displaying the intensity distribution image on a light-writing type spatial light modulator. Means for reading out the intensity distribution image displayed on the optical writing type spatial light modulator using coherent light, and Means for performing a Fourier transform on the readout intensity distribution image to obtain a two-dimensional correlation image distribution between the reference image and the correlated image, and a correlation coefficient between the reference image and the correlated image included in the correlation image distribution A joint conversion correlator comprising a photoelectric conversion element for detecting the intensity of a correlation peak corresponding to at least one reference image including a required target displayed on the image display means and at least one correlated image newly input Means for converting the light into a coherent image includes a laser diode having an oscillation wavelength of 900 nm or less, and means for reading out the intensity distribution image displayed on the optical writing type spatial light modulator using coherent light means a laser having an oscillation wavelength of 660 nm or more. includes a diode, the optical writing type spatial light modulator hydrogenated amorphous silicon as a photoconductive layer There, and a photo-writing type ferroelectric liquid crystal light valve having no light reflecting layer, the coherent image optically Fourier transform, means for obtaining a joint Fourier transform image of the reference image and the correlation image And a means for Fourier-transforming the intensity distribution image read from the optical writing type spatial light modulator to obtain a two-dimensional correlation image distribution between the reference image and the correlated image is the same Fourier transform lens. Small optical pattern recognition device. 2. An image display means for displaying at least one reference image including the required target and at least one correlated image newly input is a photo-writing type ferroelectric liquid crystal light valve having a light reflection layer. 2. The small pattern recognition device according to claim 1, wherein: 3. An image display means for displaying at least one reference image including the required target and at least one correlated image newly inputted is an electric writing type ferroelectric liquid crystal spatial light modulator. 2. The small pattern recognition device according to claim 1, wherein: 4. An image display means for displaying at least one reference image including the required target and at least one correlated image newly inputted, and a light-writing type ferroelectric which does not have the light reflection layer. A liquid crystal light valve; a laser diode having an oscillation wavelength of 900 nm or less;
A laser diode having a wavelength of 60 nm or more operates in synchronization with each other, and a time during which a required image is displayed on the image display means, a light emitting time of the laser diode having an oscillation wavelength of 900 nm or less, and the light reflecting layer is not provided. The writing voltage application time of the optical writing type ferroelectric liquid crystal light valve coincides at least for a predetermined time, and the erasing voltage application time of the optical writing type ferroelectric liquid crystal light valve that does not have the light reflection layer and the aforementioned The emission time of a laser diode having an oscillation wavelength of 660 nm or more coincides at least for a predetermined time, and the laser diode having an oscillation wavelength of 900 nm or less and the laser diode having an oscillation wavelength of 660 nm or more do not emit light at the same time. Or a driving method of the small pattern recognition device according to 3. 5. A display system of the electric writing type ferroelectric liquid crystal light valve, wherein a voltage applied to each display segment is sequentially applied in an xy direction, and a display segment which is turned ON once displays one image frame. Display without turning off until the end of
5. The driving method for a small pattern recognition device according to claim 4, wherein a display method is used in which time is synchronized with the end of inputting one frame of said electric writing type spatial light modulator.