Apparatus for controlling the exposure of light sensitive material

Claim 2

Apparatus for controlling the exposure of a photosensitive material to light, comprising an electrical pulsing circuit capable of producing voltage pulses, a photocell responsive to the intensity of the light to control the pulsing circuit so that the frequency of the pulses is dependent on the intensity of the light, a capacitor which is manually adjustable to a predetermined value in accordance with the quantity of light needed for desired exposure of the material, first control resistor through which said pulses may be applied to charge said capacitor, said control resistor being manually adjustable in accordance with a given parameter, manually operable switching means to initiate exposure of said material to light and simultaneously to commence charging of said capacitor through said control resistor by said pulses, and trigger means operative to stop said exposure when the charge in said capacitor reaches said predetermined value.

Claim 3

Apparatus according to claim 1, for controlling primary exposure in a process camera, in which the parameter according to which said first control resistor is manually adjusted is the highlight density of graphic matter to be copied.

Claim 4

Apparatus according to claim 1, for controlling flash exposure in a process camera, in which the parameter according to which said first control resistor is manually adjusted is the excess density of graphic matter to be copied.

Claim 5

Apparatus according to claim 1, for controlling both primary and flash exposure in a process camera, comprising a first electrical pulsing circuit capable of producing voltage pulses, a first photocell responsive to the intensity of the light during primary exposure to control the first pulsing circuit so that the frequency of the pulses is dependent on the intensity of the light, a first control resistor for said first pulsing circuit, said first control resistor being manually adjustable in accordance with the highlight density of graphic matter to be copied to shape the pulses in a train of output pulses from said first pulsing circuit; a second pulsing circuit capable of producing voltage pulses of duration compatible with those produced by the first pulsing circuit, a second photocell responsive to the intensity of light during flash exposure to control the second pulsing circuit so that the frequency of the pulses is dependent on the intensity of the flash light, a second control resistor for said second pulsing circuit, said second control resistor being manually adjustable in accordance with the excess density of the graphic matter to shape the pulses in a train of outpuT pulses from said second pulsing circuit; a capacitor which is manually adjustable to a predetermined value in accordance with the quantity of light needed for desired exposure of the material, switch means for selecting the shaped train of output pulses from either said first or said second pulsing circuit to charge said capacitor manually operable switching means to initiate exposure of said material to light and simultaneously to commence charging of said capacitor by the selected train of output pulses, and trigger means operative to stop said exposure when the charge in said capacitor reaches said predetermined value.

Claim 6

Apparatus according to claim 2 in which said electrical pulsing circuit includes a circuit element which is manually adjustable in accordance with the required magnification or reduction of the graphic matter to control the shape of the voltage pulses produced by said pulsing circuit.

Claim 7

Apparatus according to claim 5 in which said electrical pulsing circuit is designed to produce substantially rectangular pulses and said circuit element controls the width of the pulses.

Claim 8

Apparatus according to claim 6 in which said electrical pulsing circuit includes a third control resistor which is manually adjustable to give fine control of the highlight density of the graphic matter and which is operative to control the height of the voltage pulses produced by said pulsing circuit.

Claim 9

Apparatus according to claim 7 in which said third control resistor is a set of resistors in series, and an output contact movable to a tapping between any two adjacent resistors.

Claim 10

Apparatus according to claim 5 in which said circuit element is a fourth control resistor comprising a set of resistors in series and a contact movable to a tapping between any two adjacent resistors.

Claim 11

Apparatus according to claim 4 in which said first electrical pulsing circuit includes a circuit element which is manually adjustable in accordance with the required magnification or reduction of the graphic matter to control the shape of the voltage pulses produced by said first pulsing circuit.

Claim 12

Apparatus according to claim 10 in which said first electrical pulsing circuit is designed to produce substantially rectangular pulses and said circuit element controls the width of the pulses.

Claim 13

Apparatus according to claim 11 in which said first electrical pulsing circuit includes a third control resistor which is manually adjustable to give fine control of the highlight density of the graphic matter and which is operative to control the height of the voltage pulses produced by said first pulsing circuit.

Claim 14

Apparatus according to claim 12 in which said third control resistor is a set of resistors in series, and an output contact movable to a tapping between any two adjacent resistors.

Claim 15

Apparatus according to claim 10 in which said circuit element is a fourth control resistor comprising a set of resistors in series and a contact movable to a tapping between any two adjacent resistors.

Claim 16

Apparatus according to claim 1 in which said control resistor is a bank of resistors connected in parallel, any one resistor of the bank being connectable between said pulsing circuit and said capacitor by a movable contact.

Claim 17

Apparatus according to claim 4 in which said first control resistor is a bank of resistors connected in parallel, any one resistor of the bank being connectable between said first pulsing circuit and said capacitor by a movable contact.

Claim 18

Apparatus according to claim 1 in which more than one primary exposure photocell is provided and the electrical pulsing circuit includes a switch for selecting any desired one of said primary exposure photocells to control the frequency of the pulses.

Claim 19

Apparatus according to claim 1 in which said photocell has adjustable filter means associated therewith.

Claim 20

Apparatus according to claim 3 in which the second control resistor is a set of resistors connected in series and an output contact movable to a tapPing between any two adjacent resistors.

Claim 21

Apparatus according to claim 4 in which the second control resistor comprises a first group of resistors in series connected in series to a second group of resistors in series, the first group having first and second tappings between adjacent resistors and the second group having only a first tapping between adjacent resistors, the control means for the first control resistor and settable in accordance with highlight density also controls an input contact movable over the second tappings, and independent control means settable in accordance with shadow density controls an output contact movable over the first tappings.

Claim 22

Apparatus according to claim 20 in which the independent control means is a knob on a spindle directly connected to the output contact, the knob being movable over a dial calibrated to show shadow density, and the knob can be released from the spindle and rotated independently thereof to compensate the setting of the output contact in accordance with the basic density of the photosensitive material.

Claim 23

Apparatus according to claim 20 in which the values of the resistors in the first group are higher than the values of the resistors in the second group.

Claim 24

Apparatus according to 20 in which each resistor in the first group has a diode connected in parallel therewith creating a short circuit between the input and output contacts if the input contact is on a tapping closer to the second group of resistors than the tapping that the output contact is on.

Claim 25

Apparatus according to 20 in which each resistor in the first group has a diode connected in parallel therewith creating a short circuit between the input and output contacts if the input contact is on a tapping closer to the second group of resistors than the tapping that the output contact is on.

Claim 26

Apparatus according to claim 1 in which the manually operable switching means is a push button for energizing a relay having a holding circuit, the relay having contacts closable to initiate said exposure, and the trigger means is operative to break the holding circuit to the relay when the charge in said capacitor reaches said predetermined value.

Claim 27

Apparatus according to claim 4 in which the manually operable switching means is a push button for energizing a relay having a holding circuit, the relay having contacts closable to initiate said exposure, and the trigger means is operative to break the holding circuit to the relay when the charge in said capacitor reaches said predetermined value.

Claim 28

Apparatus according to claim 25 in which the switch means for selecting the train of output pulses from either the first or second pulsing circuits is also effective, when the pulses from the first circuit are selected, to connect the closable contacts of the relay to a relay controlling the shutter of the process camera, and when the pulses from the second circuit are selected, to connect the closable contacts of the relay to a relay controlling a flash lamp.

Claim 29

Apparatus according to claim 26 in which the shutter control relay also controls the switching on and off of the lights for the primary exposure.

Claim 30

Apparatus according to claim 26 in which the flash lamp control relay also controls a safe light so that the safe light is on when the flash light is off and vice versa.

Claim 31

Apparatus according to claim 20 and including a switch for bypassing the relay to energize either the shutter control relay or the flash lamp control relay independently of the control circuits.