Photoelectrical conversion system for pattern-recognizing apparatus and the like

Claim 2

A photoelectric conversion system for pattern-recognition apparatus and the like, having photosensitive means for producing pattern signals including a direct current component and alternating current component and means for stabilizing the respective components of the signals, said respective signal stabilizing means comprising: a variable gain amplifier comprising an amplifier stage and a load impedance and connected to each of said photosensitive means for amplifying said pattern signals; said load impedance comprising a field-effect transistor operated as a linear variable resistor; a direct current selecting circuit connected to said variable gain amplifier for extracting said direct current component of said pattern signal: A time constant circuit connected to said direct current selecting circuit for producing amplitude envelopes of said direct current component; A comparator circuit for providing a difference signal representative of the difference between said amplitude envelopes and a standard level provided thereto; and said difference signal being fed to said field-effect transistor of said variable gain amplifier to control the gain in a negative feedback mode.

Claim 3

A photoelectric conversion system according to claim 1, wherein each of said photosensitive means is provided with a current source composed of a direct current component and a pulsing current component.

Claim 4

A photoelectric conversion system for pattern-recognition apparatus and the like, comprising: a plurality of blank pattern sensing means for producing blank pattern signals, at least one of which is arranged to detect only the blank portions of said pattern; a signal level detecting circuit through which is detected the highest level of each of said blank pattern signals and which comprises a plurality of diodes, each receiving respective signals from said plurality of blank pattern sensing means at one end, each one of said plurality of diodes being connected together at the opposite end thereof; a direct current amplifying stage amplifying said detected highest level of signals; photosensitive means for producing pattern signals; and at least one variable gain amplifier comprising a field-effect transistor operating as a remote cutoff amplifying device, amplifying said pattern signals and controlled by said highest level of said blank pattern signals, In such a manner as to suppress background variations.

Claim 5

A photoelectric conversion system for pattern-recognition apparatus and the like, comprising: a plurality of blank pattern sensing means for producing blank pattern signals, at least one of which is arranged to detect only the blank portions of said pattern; a signal level detecting circuit through which is detected the highest level of each of said blank pattern signals and which comprises a plurality of diodes, each receiving respective signals from said plurality of blank pattern sensing means at one end, each one of said plurality of diodes being connected together at the opposite end thereof; a direct current amplifying stage amplifying said detected highest level of signals; photosensitive means for producing pattern signals; and at least one variable gain amplifier comprising a field-effect transistor operating as a remote cutoff amplifying device, amplifying said pattern signals and controlled by said highest level of said blank pattern signals, In such a manner as to suppress background variations.

Claim 6

A photoelectric conversion system for pattern recognition apparatus and the like, comprising: a plurality of blank pattern sensing means for producing blank pattern signals, one of which is arranged to detect only the blank portions of said pattern; a signal level detecting circuit for detecting the highest level of said blank pattern signals; said signal level detecting circuit comprising a plurality of diodes for receiving signals from said plurality of blank pattern sensing means at one end of each of said diodes, said plurality of diodes being connected together at the opposite end of each of said diodes; and photosensitive means for producing pattern signals having a direct current component and an alternating current component, and means for stabilizing the respective components of the signals having; a variable gain amplifier for amplifying one of said blank pattern signals and said pattern signals, a direct current selecting circuit connected to said variable gain amplifier for extracting said blank pattern signal, a time constant circuit connected to said direct current selecting circuit for producing amplitude envelopes of said blank pattern signals, and a comparator circuit providing a difference signal representative of the difference between said amplitude envelopes and a standard level signal provided thereto, said difference signal being fed to said variable gain amplifier to control the gain in the negative feedback manner.

Claim 7

A photoelectric conversion system for pattern recognition apparatus and the like, comprising: a plurality of blank pattern sensing means for producing blank pattern signals, one of which is arranged to detect only the blank portions of said pattern; a signal level detecting circuit for detecting the highest level of said blank pattern signals; said signal level detecting circuit comprising a plurality of diodes for receiving signals from said plurality of blank pattern sensing means at one end of each of said diodes, said plurality of diodes being connected together at the opposite end of each of said diodes; and photosensitive means for producing pattern signals having a direct current component and an alternating current component, and means for stabilizing the respective components of the signals having; a variable gain amplifier for amplifying one of said blank pattern signals and said pattern signals, a direct current selecting circuit connected to said variable gain amplifier for extracting said blank pattern signal, a time constant circuit connected to said direct current selecting circuit for producing amplitude envelopes of said blank pattern signals, and a comparator circuit providing a difference signal representative of the difference between said amplitude envelopes and a standard level signal provided thereto, said difference signal being fed to said variable gain amplifier to control the gain in the negative feedback manner.

Claim 8

A photoelectric conversion system according to claim 4, wherein said variable gain amplifier comprises an amplifier stage and a load impedance, said load impedance comprising a field-effect transistor operating as a linear variable resistor, said field-effect transistor being controlled by said difference signal.

Claim 9

A photoelectric conversion system for pattern recognition apparatus and the like, comprising: a plurality of blank pattern sensing means for producing blank pattern signals, one of which is arranged to detect only the blank portions of said pattern; a signal level detecting circuit for detecting the highest level of said blank pattern signals; and photosensitive means for producing pattern signals having direct current component and an alternating current component, and means for stabilizing the respective components of the signals having, a variable gain amplifier for amplifying one of said blank pattern signals and said pattern signals, said variable gain amplifier comprising an amplifier stage and a load impedance, said load impedance comprising a field-effect transistor operating as a linear variable resistor, a direct current selecting circuit connected to said variable gain amplifier for extracting said blank pattern signal, a time constant circuit connected to said direct current selecting circuit for producing amplitude envelopes of said blank pattern signals, and a comparator circuit providing a difference signal representative of the difference between said amplitude envelopes and a standard level signal provided thereto, said difference signal being fed to said field-effect transistor of said variable gain amplifier to control the gain in the negative feedback manner.

Claim 10

A photoelectric conversion system for pattern recognition apparatus and the like, comprising: a plurality of blank pattern sensing means for producing blank pattern signals, one of which is arranged to detect only the blank portions of said pattern; a signal level detecting circuit for detecting the highest level of said blank pattern signals; and photosensitive means for producing pattern signals having direct current component and an alternating current component, and means for stabilizing the respective components of the signals having, a variable gain amplifier for amplifying one of said blank pattern signals and said pattern signals, said variable gain amplifier comprising an amplifier stage and a load impedance, said load impedance comprising a field-effect transistor operating as a linear variable resistor, a direct current selecting circuit connected to said variable gain amplifier for extracting said blank pattern signal, a time constant circuit connected to said direct current selecting circuit for producing amplitude envelopes of said blank pattern signals, and a comparator circuit providing a difference signal representative of the difference between said amplitude envelopes and a standard level signal provided thereto, said difference signal being fed to said field-effect transistor of said variable gain amplifier to control the gain in the negative feedback manner.