Device for measuring at least one dimension of an object and a method of operating said device
First Claim
1. In a device for measuring at least one dimension of an object, comprising a light source, means defining two independent light channels for conducting light from said source to respective photo-electric transducers, means for adjusting the relative quantities of light transmitted by said channels, and a comparison circuit connected to the outputs of said transducers in order to compare the relationship between the intensities of illumination thereof, whereby when the object to be measured is introduced into one of said channels the dimension thereof can be determined in terms of the deviation of said relationship from a preset condition;
- the improvement wherein said photo-electric transducers are connected to the input of an amplifier of said circuit in parallel and with their polarity mutually reversed with respect to one another, and the said amplifier is provided with a negative feedback resistance connected to its output and arranged to compensate the difference between the electric currents of the said two transducers.
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Accused Products
Abstract
A device for measuring at least one dimension of an object comprises two light channels of which one is intended to receive the object and the other serves as a reference channel. Light from the two channels is conducted to respective photo-electric transducers the outputs of which are connected to a comparison circuit. The relationship between the relative intensities of illumination of the transducers provides a measure of the dimension of the object. In order to improve the response characteristics of the transducers they are connected in parallel with mutually reversed polarity and the difference between the electric currents passed by the two transducers is compensated by negative feedback via a resistor connected to the output of an amplifier at the input of which the said transducers are connected.
71 Citations
25 Claims
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1. In a device for measuring at least one dimension of an object, comprising a light source, means defining two independent light channels for conducting light from said source to respective photo-electric transducers, means for adjusting the relative quantities of light transmitted by said channels, and a comparison circuit connected to the outputs of said transducers in order to compare the relationship between the intensities of illumination thereof, whereby when the object to be measured is introduced into one of said channels the dimension thereof can be determined in terms of the deviation of said relationship from a preset condition;
- the improvement wherein said photo-electric transducers are connected to the input of an amplifier of said circuit in parallel and with their polarity mutually reversed with respect to one another, and the said amplifier is provided with a negative feedback resistance connected to its output and arranged to compensate the difference between the electric currents of the said two transducers.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A device for measuring at least one dimension of an object, comprising a light source;
- an optical element for producing parallel light rays from said light source;
optical means for the lateral deflection of light beyond the ray path of said optical element;
a diaphragm having diaphragm apertures defining respectively the cross-sections of a first light channel into which the object to be measured is to be introduced and comprising rays derived directly from said optical element, and the cross-section of a second light channel comprising rays derived via said optical means and serving as a reference channel, the said diaphragm apertures being so dimensioned and arranged that the paths of light rays proceeding from said source to the respective channels are mutually exclusive;
means for adjusting the relative quantities of light transmitted by said channels;
a pair of photo-electric transducers arranged to be illuminated by the light transmitted by the said two channels, respectively; and
a comparison circuit connected to the outputs of said transducers in order to compare the relationship between the intensities of illumination thereof. - View Dependent Claims (18, 19)
- an optical element for producing parallel light rays from said light source;
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20. A device for measuring at least one dimension of an object, comprising a light source;
- means defining a first light channel for light rays from said source and having a cross-section in the shape of a slit;
means defining a second light channel of substantially smaller cross-section than the first;
a diaphragm leaf mounted for movement in the direction of the major dimension of said first light channel;
a micrometer coupled to said diaphragm leaf for effecting measured movement thereof;
means for finely adjusting the cross-section of said second light channel;
a pair of photo-electric transducers arranged to be illuminated by the light transmitted by the said two channels respectively; and
a comparison circuit connected to the outputs of said transducers in order to compare the relationship between the intensities of illumination thereof. - View Dependent Claims (21, 22, 23, 24, 25)
- means defining a first light channel for light rays from said source and having a cross-section in the shape of a slit;
Specification