US2928328A - Exposure delay power circuit for a photographic printer - Google Patents

Description

March 15, 1960 w. c. KLEIN 2,928,328 EXPOSURE DELAY POWER CIRCUIT FOR A PHOTOGRAPHIC PRINTER Filed Jan. 30, 1959 'WvilliamaKlein XNVENTOR.

ATTORNEYS AC LINE VOLTAGE EXPOSURE DELAY rowan CIRCUIT FOR A PHOTOGRAPHIC PRINTER William C. Klein,.Rochester, N.Y., assignor'to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Application January 30, 1959, Serial No, 790,281

4 Claims. (or. 95-75 rial at a predetermined time and predetermined place on successive printed areas. As is well known, the mark is ultimately used to control actuation of a suitable chopping device for severing the web between successive printed areas. In these photographic printing machines, the web of light-sensitive print material is exposed simultaneously with the actuation of the marking device so that the print material is exposed while the marking device applies the mark thereto. One of the problems encountered in automatic photographic printing-machines of this type is "that the marking device in applying the mark causes the web to move slightly just as the exposure is being made. As a result, the print is ruined, or at best is blurred and hence rendered unacceptable. It is clear from this that a need exists in the photofinishing art for an improved photographic printing machine adapted to eliminate this objectionable problem. Applicants improved photographic printing machine is believed to more nearly achieve this objective than any other prior-known machines.

The primary object of this invention is to provide an improved photographic printing machine having means for operating the marking device and the exposure systern in sequential timed relation so that the marking device completes its function before the print material is exposed. i a

Another object of this invention is to provide improved power circuit for a printing machine for controlling the operation of the marking device and the exposure system in sequential timed relation.

'Still another object of the invention is to provide a power circuit having a relay-operated delay means in which the relay has an extremely fast drop-out time for electrically reconnecting the marking device to the power circuit during the short time interval existing between the termination of one printing cycle and the initiation of anotherwhich, during repeat prints, may be as short as a few tenths of a second. H I v Objects and advantages other than those set forth above will be apparent from the following description when read in connection with the accompanying drawing which is a diagrammatic representation of a photographic printer incorporating an automatic exposure delay power circuit constructedin accordance with a preferred embodiment of the present invention for controlling the operation of the marking device and exposure control system in sequential timed relation.

Referring now to the drawing, a preferred embodiment of the present invention is illustrated in combination with a photographic printer of the projection type consisting United States Patent 2,928,328 I Patented Mar. 15,

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of a negative carrier 2 defining a negative plane for supporting a transparent subject or negative 3 in a substantially fiat condition in optical alignment with a light source 4 by which it is illuminated. The subject 3 may be a black-and-white or a colored negative or positive transparency as is well known in the art. The image of the subject 3 is projected in enlarged form by a projection lens 5 onto a suitable printing material 6 adapted to be held in a substantially flat condition in the printing plane in superposed relation with the subject 3 by a suitable transparent or apertured support 7. As is custom ary in high production printers of this type, means, not shown, may be provided for intermittently feeding the printing material 6 in the form of a long web across the printing plane and means, not shown, may also be provided for intermittently feeding different subjects 3 into printing position in the negative plane. The exposure is controlled by an opaque shutter 8 pivoted at 9 to move betweena normally closed position shown in the draw.-

ing where it cuts the printing beam off from the printing material 6, and an open position wherein it is moved out of said printing beam and allows the projected light to fall on the printing material. The shutter 8 is normally moved to a closed position by a spring 11 and is moved to an open position. by the plunger 12 "of asolenoid 13 when the latter is energized.

A print marking device 14 is provided as an accessory unit for the printer for applying a black mark to the rear, or unsensitized side, of the print material 6 at a given'point on successive exposed areas in definite spaced relation to the point where it is desired to separate the prints by cutting transversely of the web of print material. As is well known, the black marks are adapted to trigger the actuation of a suitable chopping mechanism when the developed web of photographic paper is fed to a photog'raphic print chopper for'chopping the web into individual prints.' .The marking device 14 is provided with a sol enoid 15 which isadapted when energized to urge a marking wheel 16 into engagement with the web of print material 6 for applying a mark thereto, and deenergization of the solenoid 15 permits the marking wheel 16 to be returned to its inoperative position by spring 17. A marking device 14 of this general type is disclosed in detail in US. Patent No. 2,682,212 and accordingly nofurther reference thereto or detailed explanation is deemed necessary.

After a negative 3 has been placed in negative carrier 2, and the web of print material 6 properly positioned within apertured support 7, a hand or foot-operated printing cycle switch 18 is closed to connect a suitable source of power to the power circuit of the printer. For the purposes of this application, the printing cycle consists of i the marking operation, the exposure of the negative and the printing paper advance operation.

The photographic printer is normally provided with an exposure control system of any known type including a timer, which can be selectively adjusted by the operator' to vary the duration of the exposure. The exposure control system incorporated in this printer essentially comprises a normally closed switch 19 controlled by the timer and connected in series with a relay 21 across the line voltage. Relay 21 controls a switch 22 which is connected in series with a relay 23 across line voltage. Relay 23 controls a normally closed switch 20 and a hold-in switch 24 and is adapted when energized to open switch 20-and close switch 24, and when deenergized to close switch 20 and open switch 24. In the operation of this exposure control system, closing the printv 23 closes the hold-in switch 24 and opens switch 20 so that release of switch 18 by the operator will not afiect the printing cycle. Suitable circuitry is provided shown as a switch 34 and relay 35 to trigger a timer 36 at the same time solenoid 13 is energized to open shutter 8 and initiate the exposure. Since the timer 36 is a commercially available item and is important to the present invention only in the functions performed thereby, it has been designated in block diagram form. After a prede- 'terrnined duration of exposure determined by timer 36, means controlled by the timer opens the normally closed switch 19 deenergizing relay 23 and causing switch 24 to open terminating the printing cycle. The switches 19 and 211 are returned by their springs or any other suitable means to their normally closed positions in preparation for another printing cycle.

The power circuit of the printer assures operation of marking device 14 in sequential timed relation to the operation of the exposure cycle. As indicated heretofore, this power circuit delays the initiation of the exposure until marking device 14 has completed its marking operation thereby eliminating any movement of the print material 6 by the marking wheel 16 during the exposure cycle. The power circuit comprises'a relay 25 which is adapted to control the two position switches 26, 27. Switches 26, 27 are normally in a first position as shown in full lines, and are movable upon energization of relay 25 to a second position shown dotted. The power circuit has a resistor 30 connected to a half-wave voltage rectifier 28, which is in turn connected to one terminal of relay 25. A delay means incorporated in the power circuit comprises a pair of capacitors 29, 31 which, when switch 26 is in the first position are connected in parallel across relay 25. The capacitor 31 has a considerably larger capacitance than capacitor 29, and their total capacitance when charged is sufficient to maintain a relatively stable potential across relay 25. Another resistor 32 is provided which, when switch 26 is in the second position, is connected in series with capacitor 31 to discharge it. A bridge-type full-wave rectifier 33 has two terminals connected to marking device solenoid 15, and a third terminal connected to switch 27. The fourth terminal of rectifier 33, one side of capacitor 29, one side of capacitor 31 and one end of resistor 32 are all electrically connected to a terminal of relay 25 and are all maintained at a reference potential.

In the operation of this invention, let us assume initiallythat switches 18, 24 are open, and switches 26, 27 are in the normal first position. initiates the printing cycle by energizing marker solenoid 15 through switches 2t), 27. While marking device 14 is being operated, capacitors 29, 31 are being charged at a rate determined by their total capacitance and the ohmic value of resistor 30. When the voltage across capacitors 29, 31 reaches a predetermined value, relay 25 is actuated, moving contacts 26, 27 to the second or dotted position. Marking solenoid 15 is immediately deenergized, causing marking device 14 to be moved by spring 17 into its inoperative position. In the second position, switch 27 completes a circuit to solenoid 13 which is energized opening shutter 8 to initiate the exposure. Switch 26 connects the larger charged capacitor 31 in series with resistor 32 for discharging capacitor 31. Although capacitor 31 is discharged, the voltage across the smaller capacitor 29 is of a sufficient value to maintain relay 25 energized and the switches 26, 27 in the second position. Actually, the voltage across capacitor 29 varies cyclically, being charged up during one half cycle of the half-wave rectified input voltage and discharging through the resistance of the coil of relay 25 during the other half cycle. When switch 19 is opened by the exposure control system at the completion of an exposure, capacitor 29 due to its small capacity rapidly discharges through the coil of relay 25 causing the voltage across capacitor 29 to quickly drop to a value below the voltage required to hold relay 25 energized. Relay Closing switch 18 25 thereupon deenergizes and releases switches 26, 27 which are returned to the first position. This rapid release or drop-out of relay 25 is necessary in order to place the power circuit in condition for another printing cycle during the time interval existing between the termination of one printing cycle by hold-in switch 24 and the initiation of another printing cycle by the closing of switch 18, or if switch 18 is closed, the closing of switch 20; In some instances, such as when the operator is making repeat prints, switch 18 is held closed and the duration of time existing between the opening of switch 24 to terminate the exposure cycle and the closing of switch 20 to initiate a new printing cycle is only a few tenths of a second.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. In an exposure delay power. circuit for a photographic printer having a first switch adapted when closed to initiate a printing cycle, an electrically actuated device for marking a print material, and an electrically actuated shutter for initiating and terminating an exposure, the combination comprising: a relay; second switch means electrically connected to said first switch and movable upon operation of said relay from a normal first position electrically connected to said marking device, to a second position electrically connected to said shutter; and delay means connected to said relay and adapted to delay operation of said relay for a predetermined time interval after said first switch is closed whereby said shutter is operated in sequential timed relation to the operation of said marking device.

2. In an exposure delay power circuit for a photographic printer having a first switch adapted when closed to initiate a printing cycle, an electrically actuated marking device for marking a print material, and an electrically actuated shutter for initiating and terminating an exposure, the combination comprising: a relay; delay means electrically connected to said relay and said first switch and including first and second capacitors adapted to be connected in parallel with said relay to build up a voltage charge of suflicient value to operate said relay a predetermined time interval after said first switch is closed, said delay means further including a first resistor adapted to be connected in shunt relation with said first capacitor for discharging the same; a second switch connected to said first switch and movable upon actuation of said relay from a normal first position, wherein said first switch is connected to said marking device for actuating the same, to a second position, wherein said first switch is disconnected from said marking device and connected to said shutter for actuating the same; and a third switch movable upon actuation of said relay from a normal first position, wherein said first switch is connected in parallel relation with said second capacitor and relay, to a second position, wherein said first resistor is connected in shunt with said first capacitor for discharging thesarne to produce a rapid drop-out time for the relay upon opening of said first switch.

3. The combination according to claim 2 wherein said relay has a first terminal connected to a point of reference potential; said delay means comprises said first resistor having one end connected to said reference potential, said first capacitor having one side connected to said reference potential, said second capacitor having one side connected 'to said reference potential and its other side connected to a second terminal of said relay; and said third switch is movable between said first position connecting said other side of said first capacitor to said second terminal of said relay, and a second position connecting said other side of said first capacitor to the other end of said first resistor.

4. The combination according to claim 2 wherein said relay has a first terminal connected to a point of reference potential; said delay means comprises said first resistor having one end connected to said reference potential, a second resistor having one end connected to said first switch and the other end connected to a second terminal of said relay, said first capacitor having one side connected to said reference potential and said second capacitor having one side connected to said reference potential and its other side connected to said second ter- 10 2,682,212

minal of said relay; andsaid third switch is movable from said first position, wherein the other side of said first capacitor is connected to said second terminal of said relay, to said second position wherein the other side of said first capacitor is connectedto the other end of said first resistor.

References Cited in the file of this patent UNITED STATES PATENTS Knobel June 29, 1954

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