Apparatus for detecting irregularities in the light transmission properties of materials

Claim 2

Apparatus for detecting the presence of areas of a material having light transmission properties which differ from those of the remainder of the material, including: means for generating a light-intensity signal dependent on the intensity of light received from different portions of the material, including means for scanning an area of interest of the material in a series of lines, a number of delay means connected in series the first delay means being connected to receive the light intensity signal and each delay line imparting a delay equal to the time taken to scan one line, integrator means for forming a continuous threshold signal dependent on the sum of the integral for a predetermined preceding interval of the light-intensity signal as applied at the input to the first delay means and the integrals for the predetermined preceding interval of the output signals of the delay means, and comparator means for comparing the light-intensity signal with the threshold signal to provide signals indicating when the value of the light-intensity signal exceeds that of the threshold signal.

Claim 3

Apparatus for detecting the presence of areas of a material having light transmission properties which differ from those of the remainder of the material, including: means for generating a light-intensity signal dependent on the intensity of light received from different portions of the material, including means for scanning an area of interest of the material in a series of lines, a number of delay means connected in series the first delay means being connected to receive the light intensity signal and each delay line imparting a delay equal to the time taken to scan one line, integrator means for forming a continuous threshold signal dependent on the sum of the integral for a predetermined preceding interval of the light-intensity signal as applied at the input to the first delay means and the integrals for the predetermined preceding interval of the output signals of the delay means, and comparator means for comparing the light-intensity signal with the threshold signal to provide signals indicating when the value of the light-intensity signal exceeds that of the threshold signal.

Claim 4

Apparatus for detecting the presence of areas of a material having light transmission properties which differ from those of the remainder of the material, including: means for generating a light-intensity signal dependent on the intensity of light received from different portions of the material, including means for scanning an area of interest of the material in a series of lines, a number of delay means connected in series the first delay means being connected to receive the light intensity signal and each delay line imparting a delay equal to the time taken to scan one line, integrator means for forming a continuous threshold signal dependent on the sum of the integral for a predetermined preceding interval of the light-intensity signal as applied at the input to the first delay means and the integrals for the predetermined preceding interval of the output signals of the delay means, and comparator means for comparing the light-intensity signal with the threshold signal to provide signals indicating when the value of the light-intensity signal exceeds that of the threshold signal.

Claim 5

Apparatus for detecting the presence of areas of a material having light transmission properties which differ from those of the remainder of the material, including: means for generating a light-intensity signal dependent on the intensity of light received from different portions of the material, the scanning means, in operation, including means for scanning the material in a series of lines, threshold-determining means for forming a threshold signal dependent on the light transmission properties of the material physically adjacent the portion from which light is received by the generating means at any time during operation, and comparator means for comparing the light intensity signal with the threshold signal and producing signals indicating the detection of said areas, the threshold-determining means comprising a plurality of delay means connected in series, with the first delay means connected to receive the light intensity signal, a number of integration means each providing, in operation, a continuous output signal dependent on the integral for a predetermined preceding interval of the input signal thereto, each integrator means except one having its input circuit coupled at the output of one delay means particular thereto, and the said one integrator means having its input circuit coupled to receive the light intensity signal, and means for summing the output signals from the integrator means in providing the threshold signal.

Claim 6

Apparatus for detecting the presence of areas of a material having light transmission properties which differ from those of the remainder of the material, including: means for generating a light-intensity signal dependent on the intensity of light received from different portions of the material, the scanning means, in operation, including means for scanning the material in a series of lines, threshold-determining means for forming a threshold signal dependent on the light transmission properties of the material physically adjacent the portion from which light is received by the generating means at any time during operation, and comparator means for comparing the light intensity signal with the threshold signal and producing signals indicating the detection of said areas, the threshold-determining means comprising a plurality of delay means connected in series, with the first delay means connected to receive the light intensity signal, a number of integration means each providing, in operation, a continuous output signal dependent on the integral for a predetermined preceding interval of the input signal thereto, each integrator means except one having its input circuit coupled at the output of one delay means particular thereto, and the said one integrator means having its input circuit coupled to receive the light intensity signal, and means for summing the output signals from the integrator means in providing the threshold signal.

Claim 7

Apparatus according to claim 2 wherein the comparator means provides a binary output signal having one value when the threshold signal is exceeded by the light intensity signal and another value at other times, and logic means are provided for coupling the input circuit of the threshold-determining means to the output circuit thereof instead of the scanning means when the binary signal indicates that the threshold signal is exceeded.

Claim 8

Apparatus according to claim 2 wherein each integrator includes a shunt capacitor and series resistor.

Claim 9

Apparatus according to claim 2 wherein the scanning means is a flying spot scanner.

Claim 10

Apparatus according to claim 2 wherein the scanning means is such that the magnitude of its output signal depends on the opacity of the material.

Claim 11

Apparatus as in claim 2 wherein the scanning means is a television camera.