Method and apparatus for measuring material thickness

Claim 3

The method as recited in claim 1 wherein said steps of providing first and second electrical signals include providing electrical signals having first and second voltages varying with the light detected, respectively; and said converting step includes converting the first and second varying voltages to first and second varying frequency signals, respectively.

Claim 4

The method as recited in claim 2 wherein said steps of converting the first and second electrical signals to the first and second oscillating signals are performed during equal predetermined time periods.

Claim 5

Apparatus for measuring the thickness of a coating applied to a support film by a coating and drying machine comprising a first light source disposed upstream of the coating and drying machine to project light toward the support films; first light detecting means disposed to receive said projected light from the support film and providing first electrical signals corresponding to the amount of light received thereby; converter means connected with said first light detecting means to receive said first electrical signals and provide a first oscillating output signal having a frequency dependent upon said first electrical signals; memory means connected with said converter Means to store said first oscillating output signal; marking means disposed adjacent said first light detecting means to place an optical index mark at a specific portion of the support film; first control means connected with said memory means and said marking means to control the operation thereof, said memory means being responsive to said first control means to store said first oscillating signal corresponding to said first electrical signals determined by light from the specific portion of the support film and the coating thereon; a second light source disposed downstream of the coating and drying machine to project light toward the coating and support film; second light detecting means disposed to receive projected light from the coating and support film and providing second electrical signals corresponding to the amount of light received thereby; said converter means connected with said second light detecting means to receive said second electrical signals and provide a second oscillating output signal having a frequency dependent upon said second electrical signals; third light detecting means disposed to receive projected light from the coating and support film and providing an index signal upon sensing said optical index mark on the support film; reversible counting means connected with said memory means and said converter means to receive said first and second oscillating output signals and count the oscillations thereof; and second control means connected with said third light detecting means, said memory means and said counting means and responsive to said index signal to operate said memory means to supply said stored first oscillating output signal to said counting means and to operate said converter means to supply said second oscillating output signal corresponding to said second electrical signals determined by light from the specific portion of the support film and the coating thereon to said counting means, said counting means being operative to count in a first direction in response to said first oscillating output signal and in a second direction opposite to said first direction in response to said second oscillating output signal, whereby said counting means is operative to subtract the thickness of the specific portion of the support film from the thickness of the specific portion of the support film and the coating thereon to represent the thickness of the coating by the count stored therein.

Claim 6

Apparatus for measuring the thickness of a coating applied to a support film by a coating and drying machine comprising a first light source disposed upstream of the coating and drying machine to project light toward the support films; first light detecting means disposed to receive said projected light from the support film and providing first electrical signals corresponding to the amount of light received thereby; converter means connected with said first light detecting means to receive said first electrical signals and provide a first oscillating output signal having a frequency dependent upon said first electrical signals; memory means connected with said converter Means to store said first oscillating output signal; marking means disposed adjacent said first light detecting means to place an optical index mark at a specific portion of the support film; first control means connected with said memory means and said marking means to control the operation thereof, said memory means being responsive to said first control means to store said first oscillating signal corresponding to said first electrical signals determined by light from the specific portion of the support film and the coating thereon; a second light source disposed downstream of the coating and drying machine to project light toward the coating and support film; second light detecting means disposed to receive projected light from the coating and support film and providing second electrical signals corresponding to the amount of light received thereby; said converter means connected with said second light detecting means to receive said second electrical signals and provide a second oscillating output signal having a frequency dependent upon said second electrical signals; third light detecting means disposed to receive projected light from the coating and support film and providing an index signal upon sensing said optical index mark on the support film; reversible counting means connected with said memory means and said converter means to receive said first and second oscillating output signals and count the oscillations thereof; and second control means connected with said third light detecting means, said memory means and said counting means and responsive to said index signal to operate said memory means to supply said stored first oscillating output signal to said counting means and to operate said converter means to supply said second oscillating output signal corresponding to said second electrical signals determined by light from the specific portion of the support film and the coating thereon to said counting means, said counting means being operative to count in a first direction in response to said first oscillating output signal and in a second direction opposite to said first direction in response to said second oscillating output signal, whereby said counting means is operative to subtract the thickness of the specific portion of the support film from the thickness of the specific portion of the support film and the coating thereon to represent the thickness of the coating by the count stored therein.

Claim 7

The apparatus as recited in claim 4 wherein said first light source and said first light detecting means are disposed on opposite sides of the support film such that light received by said first light detecting means is transmitted through the support film, and said second light source and said second and third light detecting means are disposed on opposite sides of the coating and support film such that light received by said second and third light detecting means is transmitted through the coating and support film.

Claim 8

The apparatus as recited in claim 5 wherein said converter means includes a first converter connected with said first light detecting means to receive said first electrical signal and provide said first oscillating output signal to said memory means and a second converter connected with said second light detecting means to receive said second electrical signal and provide said second oscillating output signal to said reversible counting means, said second control means operating said second converter to supply said second oscillating output signal to said reversible counting means.

Claim 9

The apparatus as recited in claim 6 wherein said first control means controls said memory means to store said first oscillating output signals for a predetermined operating period.

Claim 10

The apparatus as recited in claim 7 wherein said first and second electrical signals provided by said first and second light detecting means are varying frequencies, and said first and second converters each include a voltage-To-frequency converter.