Electronic print exposure analyzer

Claim 2

An electronic print exposure analyzer for providing a paper grade index and for automatically controlling the duration of an exposure time interval during the reproduction of a projected image, said analyzer comprising: means for providing a pair of contemporary control signals representative of the contrast range of said projected image, said means comprising first and second photosensitive elements, said first photosensitive element adapted to be arranged in the brightest portion of said projected image and said second photosensitive element adapted to be arranged in the darkest portion of said projected image, a measuring circuit coupled to said signal providing means for generating a signal representative of said paper grade index, said measuring circuit including a visible indicator and switch means for coupling said photosensitive devices in parallel to said visible indicator when in a balance adjust position and for coupling one of said photosensitive devices to said visible indicator when in a paper grade index position; input terminal means adapted to be coupled to a source of enabling voltage; a first pair of enabling voltage output terminals adapted to be coupled to an image exposure lamp and exposure time control circuit for controlling the coupling of said enabling voltage input terminal means to said first pair of enabling voltage output terminals an adjustable resistance device for enabling manual adjustment of said measuring circuit to a balance condition indicated by said visible indicator, the setting of said adjustable resistance device after said balance condition is attained providing a control parameter for establishing the duration of the exposure time interval; and coupling means for alternately coupling said adjustable resistance device to said measuring circuit and said exposure time control circuit.

Claim 3

The apparatus of claim 1 wherein said visible indicator includes a paper grade scale and a balance position, said balance position serving to indicate the proper adjustment of said adjustable resistance device when coupled to said measuring circuit.

Claim 4

The apparatus of claim 1 wherein said exposure time control circuit includes a switching device having an input coupled to said enabling voltage input terminal means, an output coupled to said first pair of enabling voltage output terminal means and a control member for coupling said switching decive input to said output in response to a control signal; means for generating said control signal; and means for disabling said generating means after said exposure time interval.

Claim 5

The apparatus of claim 3 wherein said disabling means includes a charge storage device and said coupling means includes means for coupling said adjustable resistance device to said charge storage device for the duration of said exposure time interval.

Claim 6

The apparatus of claim 1 further including a second pair of enabling voltage output terminals adapted to be coupled to additional associated equipment, and a multiple position switch having a pair of input terminals coupled to said enabling voltage input terminal means and having a plurality of contact members for alternately coupling said input terminals to said first and second pair of output terminals so that said exposure time control circuit can be by-passed.

Claim 7

An electronic print exposure anAlyzer for providing an index of optimum photosensitive paper grade matched to a projected image and for automatically controlling the exposure time interval during photographic printing of said projected image, said analyzer comprising: a measuring circuit for measuring the tonal contrast of said projected image, said measuring circuit including first and second photosensitive devices adapted to be arranged in the brightest and darkest portions, respectively, of said projected image for providing a pair of contemporary control signals representative of said tonal contrast, an adjustable resistance device for enabling adjustment of said circuit to a balanced condition, a visual indicator having a graduated paper grade scale and a balance position, means for coupling said indicator means to said photsensitive devices, said coupling means including a switch means for coupling both said first and second photosensitive devices to said visual indicator when in a balance position to permit adjustment of said measuring circuit to said balanced condition and for coupling one only of said photosensitive devices to said visual indicator when in a paper grade index position to permit said visual indicator to achieve a reading of said optium paper grade; an exposure time interval circuit for limiting the duration of said exposure time interval, said circuit including at least one input terminal coupled to a power source, at least one output terminal adapted to be coupled to an enlarger lamp, means having an actuated and a non-actuated state for coupling said input to said output, and control means for controlling the duration of said actuated state of said coupling means; and switching means for electrically disconnecting said adjustable resistance device from said measuring circuit and for electrically connecting said adjustable resistance device to said exposure time interval circuit, the state of adjustment of said adjustable resistance device required for said balanced condition providing a value to said control means for determining the length of said exposure time interval.

Claim 8

An electronic print exposure anAlyzer for providing an index of optimum photosensitive paper grade matched to a projected image and for automatically controlling the exposure time interval during photographic printing of said projected image, said analyzer comprising: a measuring circuit for measuring the tonal contrast of said projected image, said measuring circuit including first and second photosensitive devices adapted to be arranged in the brightest and darkest portions, respectively, of said projected image for providing a pair of contemporary control signals representative of said tonal contrast, an adjustable resistance device for enabling adjustment of said circuit to a balanced condition, a visual indicator having a graduated paper grade scale and a balance position, means for coupling said indicator means to said photsensitive devices, said coupling means including a switch means for coupling both said first and second photosensitive devices to said visual indicator when in a balance position to permit adjustment of said measuring circuit to said balanced condition and for coupling one only of said photosensitive devices to said visual indicator when in a paper grade index position to permit said visual indicator to achieve a reading of said optium paper grade; an exposure time interval circuit for limiting the duration of said exposure time interval, said circuit including at least one input terminal coupled to a power source, at least one output terminal adapted to be coupled to an enlarger lamp, means having an actuated and a non-actuated state for coupling said input to said output, and control means for controlling the duration of said actuated state of said coupling means; and switching means for electrically disconnecting said adjustable resistance device from said measuring circuit and for electrically connecting said adjustable resistance device to said exposure time interval circuit, the state of adjustment of said adjustable resistance device required for said balanced condition providing a value to said control means for determining the length of said exposure time interval.

Claim 9

The apparatus of claim 6 wherein said control means includes a charge storage device, means for charging said charge storage device to a predetermined reference potential when said coupling means is in the actuated state, a holding circuit for maintaining said coupling means in said actuated state wherein said input is coupled to said output, and means for coupling said charge storage device to said holding circuit.

Claim 10

The apparatus of claim 6 further including at least one additional output terminal adapted to be coupled to a safe lamp, and additional switching means having at least one input terminal coupled to said power source and selectively actuatable means for electrically coupling said power input terminal alternately to said safe lamp output terminal and said enlarger lamp output terminal, said additional switching means providing independent coupling of said power input terminal to said safe lamp and said enlarger lamp.