Produce grader

Claim 2

In combination in an inspection signal path in which detector means produces a low level d.c. inspection signal and chopper means controlled by at least a first gating signal having a first duty cycle converts the low level d.c. signal to an a.c. signal which then is amplified in a.c. amplifier means, and wherein means including synchronous detector means reconvert the amplified a.c. signal to a d.c. signal, the improvement of gain control means for changing the gain of the inspection signal path, comprising means for producing a second gating signal having a second duty cycle which is adjustable from a maximum time period to a minimum time period, said maximum time period being no greater than said first duty cycle of said first gating signal, and means for coupling said second gating signal to said synchronous detector means for controlling its operation, whereby a change in said second duty cycle changes the magnitude of a reconverted d.c. signal thus changing the gain of said inspection signal path.

Claim 3

The combination claimed in claim 1 and further including at least a second inspection signal path that includes detector means, chopper means, a.c. amplifier means, and synchronous detector means all constructed and arranged similarly to the corresponding means in said first inspection signal path, gating signal generating means for generating said first and second gating signals and for generating a third gating signal substantially synchronous with said second gating signal, means for coupling said first gating signal from said gating signal generating means to said chopper means in each of said signal paths, means for coupling said second gating signal from the gating signal generating means to the synchronous detector means in one of said signal paths, and means for coupling said third gating signal from said gating signal generating means to the synchronous detector means in the other one of said signal paths.

Claim 4

The combination claimed in claim 2 wherein said gating signal generating means includes a duty cycle adjustment means for adjusting the duty cycle of said second gating signal, whereby adjustment of said duty cycle adjustment means changes the gains in all inspection signal channels associated with said second gating signal.

Claim 5

The combination claimed in claim 2 and further including, means responsive to the reconverted d.c. signals in said two signal paths for comparing or evaluating the two reconverted d.c. signals, whereby an adjustment in the duty cycle of the second gating signal changes the calibration of said means for comparing or evaluating said two reconverted d.c. signals.

Claim 6

In a produce grader or the like having detector means for producing at least first and second d.c. signals corresponding to respective detected characteristics of an article of produce being graded, wherein the produce grader includes first and second respective signal paths for said two d.c. signals, wherein each signal path includes chopper means for chopping the d.c. signal into an a.c. signal, a.c. amplifier means for amplifying the a.c. signal, and means including synchronous detector means for reconverting the amplified a.c. signal to a d.c. signal, and wherein the reconverted d.c. signals in the signal paths are compared and/or evaluated according to a desired calibration to form a basis for grading an article, the improvement of adjustable calibration means for simply and reliably adjusting the calibration of the grader, said improvement comprising gating signal generating means for generating at least a first gating signal for controlling said chopper means in said signal paths and for generating second and third gating signals for controlling said synchronous detector means in the respective signal paths, said gating signal generating means including means for adjusting the time duration of at least one of said second and third gating signals, whereby the magnitude of at least one of said reconverted d.c. signals may be changed as a function of the duty cycle of its respective synchronous detector gating signal, thereby to change the calibration of said produce grader.

Claim 7

In a produce grader or the like having detector means for producing at least first and second d.c. signals corresponding to respective detected characteristics of an article of produce being graded, wherein the produce grader includes first and second respective signal paths for said two d.c. signals, wherein each signal path includes chopper means for chopping the d.c. signal into an a.c. signal, a.c. amplifier means for amplifying the a.c. signal, and means including synchronous detector means for reconverting the amplified a.c. signal to a d.c. signal, and wherein the reconverted d.c. signals in the signal paths are compared and/or evaluated according to a desired calibration to form a basis for grading an article, the improvement of adjustable calibration means for simply and reliably adjusting the calibration of the grader, said improvement comprising gating signal generating means for generating at least a first gating signal for controlling said chopper means in said signal paths and for generating second and third gating signals for controlling said synchronous detector means in the respective signal paths, said gating signal generating means including means for adjusting the time duration of at least one of said second and third gating signals, whereby the magnitude of at least one of said reconverted d.c. signals may be changed as a function of the duty cycle of its respective synchronous detector gating signal, thereby to change the calibration of said produce grader.

Claim 8

The combination claimed in claim 5 wherein said produce grader includes a plurality of said detector means and a plurality of pairs of said signal paths, each pair of signal paths being associated with respective detector means and the signal paths of each pair being substantially identical to said first and second signal paths, means for coupling said first gating signal from said gating signal generating means to the chopper means in each of said plurality of paths, means for coupling said second gating signal from said gating signal generating means to the synchronous detector means in the first signal path of each pair, and means for coupling said third gating signal from said gating signal generating means to the synchronous detector means in the second signal path of each pair, whereby an adjustment in the means for adjusting the time duration of at least one of said second and third gating signals produces substantially identical adjustments of the calibrations in all pairs of signal paths.