Tristimulus colorimeter
First Claim
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1. A comparison type optical measuring apparatus, comprising:
- photosensitive means for producing an electrical output representative of light received thereby,optical means for sequentially directing unknown and reference light beams to said photosensitive means thereby to cause said photosensitive means to produce, respectively, unknown and reference electrical signals,integrator means for integrating in one polarity direction one of said unknown and reference electrical signals for a predetermined duration to produce an integrated signal level and then in the opposite polarity direction the other of said unknown and reference electrical signals, and common circuit means for directing said unknown and reference electrical signals to said integrator meansoutput means for producing an electrical output signal indicative of the time required for said integrator means to integrate said other of said unknown and reference electrical signals from such integrated signal level to a predetermined signal level, whereby said electrical output signal is representative of a comparison of said unknown and reference light beams.
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Abstract
A tristimulus colorimeter employs a multiplexed dual slope integrator digital voltmeter wherein unknown and reference light beams are compared by sequentially applying unknown and reference electrical signals representative of the two respective light beams to the non-inverting and inverting inputs, respectively, of the integrator amplifier. Moreover, a compensating circuit provides for compensation of the colorimeter output signals with respect to reflectance error encountered in the optics portion of the colorimeter.
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Citations
38 Claims
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1. A comparison type optical measuring apparatus, comprising:
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photosensitive means for producing an electrical output representative of light received thereby, optical means for sequentially directing unknown and reference light beams to said photosensitive means thereby to cause said photosensitive means to produce, respectively, unknown and reference electrical signals, integrator means for integrating in one polarity direction one of said unknown and reference electrical signals for a predetermined duration to produce an integrated signal level and then in the opposite polarity direction the other of said unknown and reference electrical signals, and common circuit means for directing said unknown and reference electrical signals to said integrator means output means for producing an electrical output signal indicative of the time required for said integrator means to integrate said other of said unknown and reference electrical signals from such integrated signal level to a predetermined signal level, whereby said electrical output signal is representative of a comparison of said unknown and reference light beams. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A comparison type optical measuring apparatus, comprising:
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photosensitive means for producing an electrical output representative of light received thereby, optical means for sequentially directing unknown light beams of different respective colors to said photosensitive means thereby to cause said photosensitive means to produce for each color respective unknown electrical signals, integrator means for sequentially integrating in one polarity direction each of said unknown electrical signals for a predetermined duration to produce respective integrated signal levels and then a reference electrical signal in the opposite polarity direction, output means for producing electrical output signals indicative of the times required for said integrator means to integrate said reference electrical signal from each of such integrated signal levels to a predetemined signal level, whereby said electrical output signals are representative of respective comparisons of said unknown and reference electrical signals, calibrating means for adjusting the magnitude of said electrical output signals, said calibrating means including amplifier means operatively coupled between said photosensitive means and said integrator means for amplifying the electrical output of the former prior to delivery to the latter, and means for changing the gain of said amplifier means for each color of said unknown light beam detected by said photosensitive means, said means for changing including a plurality of circuit channels, each including at least one selectively adjustable impedance means for establishing respective basic gains for said amplifier means, said calibrating means further including circuit channel means for establishing a predetermined gain for said amplifier means, multiplexing means for operatively coupling respective circuit channels to said amplifier means when respective colors of said unknown light beam are detected by said photosensitive means, said multiplexing means further including further means for operatively coupling said circuit channel means to said amplifier means whenever said unknown light beam is not being detected by said photosensitive means; and means for applying said reference electrical signal to said amplifier means - View Dependent Claims (25)
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26. A comparison type optical measuring apparatus, comprising:
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photosensitive means for producing an electrical output representative of light received thereby, optical means for sequentially directing unknown light beams of different respective colors to said photosensitive means thereby to cause said photosensitive means to produce for each color respective unknown electrical signals, integrator means for sequentially integrating in one polarity direction each of said unknown electrical signals for a predetermined duration to produce respective integrated signal levels and then a reference electrical signal in the opposite polarity direction, output means for producing electrical output signals, indicative of the times required for said integrator means to integrate said reference electrical signal from each of such integrated signal levels to a predetermined signal level, whereby said electrical output signals are representative of respective comparisons of said unknown and reference electrical signals, calibrating means for adjusting the magnitude of said electrical output signals, said calibrating means including amplifier means operatively coupled between said photosensitive means and said integrator means for amplifying the electrical output of the former prior to delivery to the latter, and means for changing the gain of said amplifier means for each color of said unknown light beam detected by said photosensitive means, said means for changing including a plurality of circuit channels, each including at least one impedance means for establishing respective basic gains for said amplifier means, multiplexing means for operatively coupling respective circuit channels to said amplifier means when respective colors of said unknown light beam are detected by said photosensitive means, said multiplexing means including counter-like controller means for controlling respective operative couplings of said circuit channels and said amplifier means, means for applying said reference electrical signal to said amplifier means during at least part of the time that an unknown electrical signal is not being applied thereto, means for indicating to said multiplexing means the color light being detected by said photosensitive means thereby to synchronize said multiplexing means and said optical means, display means for visually displaying in digital form the values of said electrical output signals as indications of the relative intensities of each detected color light of said unknown light beam, electrical oscillator means for producing a clock signal, and wherein said output means comprises counter means for producing a digital output signal in response to said clock signal, said counter means producing and delivering to said controller means a control signal upon achiving a predetermined digital output signal for sequentially operating the latter, logic means for controllably coupling said digital output signals to said display means, and comparator means for detecting the occurrence of said predetermined signal level to control said logic means to deliver said digital output signals to said display means. - View Dependent Claims (27, 28, 29)
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30. A comparison type measuring apparatus, comprising:
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transducer means for producing an electrical output representative of an input thereto, means for cyclically directing an unknown input to said transducer means thereby to cause the latter to produce unknown electrical signals, integrator means for integrating in one polarity direction one of said unknown electrical signals for a predetermined duration to produce an integrated signal level and then a reference electrical signal in the opposite polarity direction, said integrator means having first and second inputs, one of said inputs being inverting with respect to the other, and further comprising switch means for sequentially delivering one of said unknown and reference electrical signals to said non-inverting input and the other said unknown and reference electrical signals to said inverting input, and output means for producing an electrical output signal indicative of the time required for said integrator means to integrate said reference electrical signal from such integrated signal level to a predetermined signal level, whereby said electrical output signal is representative of a comparison of said unknown and reference electrical signals. - View Dependent Claims (31, 32, 33, 34, 35)
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36. A comparison type optical measuring apparatus, comprising:
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transducer means for producing an electrical output representative of an input thereto, means for directing an unknown input to said transducer means thereby to cause the latter to produce unknown electrical signals, integrator means for integrating in one polarity direction one of said integrated signal level and then the other of said unknown and reference electrical signals in the opposite polarity direction, output means for producing an electrical output signal indicative of the time required for said integrator means to integrate said reference electrical signal from such integrated signal level to a predetermined signal level, whereby said electrical output signal is representative of a comparison of said unknown and reference electrical signals, and compensating means for modifying said electrical output signal to compensate for error in said means for directing, said compensating means including storage means for storing a compensating electrical signal as a percentage of said reference electrical signal representative of such error, and delivery means for delivering said compensating electrical signal to an inverting input of said integrator means when said unknown electrical signal is delivered to a non-inverting input thereof. - View Dependent Claims (37, 38)
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Specification