Electronic timing device

• US 3,989,374 A
• Filed: 06/23/1975
• Issued: 11/02/1976
• Est. Priority Date: 06/23/1975
• Status: Expired due to Term

• Current Assignee: David J. Leveille, Henry C. Latka
• Original Assignee: David J. Leveille, Henry C. Latka
• Inventors: Latka, Henry C., Leveille, David J.
• Primary Examiner(s): Adams, Jr., Russell E.
• Application Number:
  US05/589,424
• Time in Patent Office: 498 Days
• Field of Search: 355/35, 355/36, 355/37, 355/67, 355/69, 355/70, 355/71, 355/115, 315/360, 328/131, 328/129, 317/141 S, 317/142, 307/293 R, 307/293 E, 307/293 F, 307/293 G, 307/293 H, 307/293 I, 307/293 J, 307/293 T, 307/294
• US Class Current: 355/69
• CPC Class Codes: G03B 27/72 Controlling or varying light intensity, spectral composition, or exposure time in photographic printing apparatus
• CPC Class Codes: G04F 1/005 using electronic timing, e.g. counting means pulse time delay arrangements H03K5/13; modifications of electronic switches for introducing a time delay before switching H03K17/28

Abstract

A novel electronic timing apparatus is described which contains means for selecting a preset time interval and means for selecting an actual interval to be timed which is equal to or less than, and also a function of, the preset interval. When the apparatus begins timing an actual interval, a first energy source is activated and a second energy source is deactivated. When timing of the actual interval is completed, the first energy source is deactivated and the second energy source is activated. The appartus is powered by a power supply means which furnishes a regulated direct current to integrated circuits requiring such and furnishes line frequency current to other circuits. It also contains means for generating and shaping periodic pulses from line frequency current to form an electronic time base signal for its operation. A time base prescaler means reduces the number of periodic pulses contained in the electronic time base signal, the reduction being proprotionately responsive to a signal generated by the actual interval selection means. The time base prescaler means is continually reprogrammed with the signal generated by the actual interval selection means by a time base prescaler control logic means. An electronic counting means counts the number of periodic pulses contained in the electronic time base signal after the signal has been modified by the time base prescaler means. When the electronic counting means reaches a timed out state representative of the elapse of the actual interval being timed, a system logic control provides a signal which is used to deactivate the first energy source and activate the second energy source. Other features of the invention, such as its use in photographic applications and its ability to be reset under various timing conditions, are described herein.

Claims

1. Electronic timing apparatus for use in combination with a photographic enlarger light power source comprising:

a. power supply means for converting line frequency alternating current to a regulated direct current;

b. means for generating and shaping periodic pulses from a line frequency current, said periodic pulses forming an electronic time base signal for the operation of said apparatus;

c. preset exposure time means for presetting the time period the enlarger light source is to provide exposure for a photographic print;

d. actual exposure time selection means for selecting the actual exposure time period and for generating a signal representative of the actual time period for which the enlarger light source is to provide exposure for a photographic print, said actual exposure time period being of equal or lesser duration than said preset time period and an arithmetic function thereof;

e. time base prescaler means for reducing the number of periodic pulses per second in said electronic time base signal, said periodic pulses being proportionately reduced responsive to the signal generated by the actual exposure time selection means;

f. time base prescaler control logic means for reprogramming the time base prescaler means with the signal generated by the actual exposure time selection means;

g. electronic counting means for counting the number of periodic pulses contained in the electronic time base signal after said signal has been modified by the time base prescaler means;

h. system logic control means for providing a controlled output signal when the electronic counting means reaches a timed out state representative of the actual exposure time period; and

i. an enlarger light power source which is deactivated by the controlled output signal from said system control logic.

2. The apparatus of claim 1 wherein the means for generating and shaping periodic pulses utilizes 60 Hz line frequency current to generate 120 pulses per second.

3. The apparatus of claim 1 wherein the preset exposure time means is utilized to provide a preset time period in tenths of a second.

4. The apparatus of claim 1 wherein the actual exposure time selection means is utilized to provide an actual exposure time period which is 25, 50, 75 or 100% of the preset time period.

5. The apparatus of claim 2 wherein the time base prescaler means reduces the number of pulses per second in the electronic time base signal by dividing said pulses per second by 12, 9, 6 or 3.

6. The apparatus of claim 1 wherein the electronic counting means comprises at least one synchronous four-bit binary counter.

7. The apparatus of claim 1 wherein the electronic counting means comprises a series of three synchronous binary coded decimal decade counters, the first of which counts pulses, the second of which counts pulses in sets of ten with respect to the first counter and the third of which counts pulses in sets of one hundred with respect to the first counter.

8. The apparatus of claim 1 including a safelight power source which is activated by the controlled output signal from said system control logic.

9. The apparatus of claim 8 including an output logic and driver means for generating a signal to deactivate the enlarger light power source and activate the safelight power source responsive to the controlled output signal from the system control logic.

10. The apparatus of claim 1 including a switch means for manually activating the enlarger light power source and overriding the controlled output signal from the system control logic.

11. The apparatus of claim 1 including a stop input switch means for manually deactivating the enlarger light power source and activating the safelight power source at any time while the apparatus is timing a function.

12. The apparatus of claim 1 wherein the periodic pulses of the electronic time base signal are generated near the end of each half wave cycle of the line frequency current.

13. The apparatus of claim 12 wherein the means for generating and shaping periodic pulses near the end of a half wave cycle comprises:

a. a full wave rectifier circuit comprising a first diode, a second diode and a transformer;

b. a circuit having a programmable unijunction transistor (PUT), a first time constant means for controlling the (PUT) anode potential, a second time constant means for controlling the (PUT) gate potential and a diode for controlling the charging of one of said time constant means; and

c. a squaring and buffer stage comprising a transistor, a direct current source and a pull-up resistor connected to the collector of said transistor and to the direct current source.

14. Electronic timing apparatus for activating and deactivating an energy source comprising:

a. power supply means for supplying a regulated direct current to integrated circuits in the apparatus and for supplying line frequency current to the remaining circuits in the apparatus;

b. means for generating and shaping periodic pulses from the line frequency current, said periodic pulses forming an electronic time base signal for the operation of said apparatus;

c. preset activation time means for presetting the time period the energy source is to remain in an active state;

d. actual energy time selection means for selecting the actual energy time period and for generating a signal representative of the actual time period for which the energy source is to remain in an active state, said actual energy time period being of equal or lesser duration than said preset time period and an arithmetic function thereof;

e. time base prescaler means for reducing the number of periodic pulses per second in said electronic time base signal, said periodic pulses being proportionately reduced responsive to the signal generated by the actual energy time selection means;

f. time base prescaler control logic means for reprogramming the time base prescaler means with the signal generated by the actual energy time selection means;

g. electronic counting means for counting the number of periodic pulses contained in the electronic time base signal after said signal has been modified by the time prescaler means;

h. system logic control means for providing a controlled output signal when the electronic counting means reaches a timed out state representative of the actual energy time period; and

i. an energy source which is deactivated by the controlled output signal from said system control logic.

15. Novel electronic timing apparatus for activating and deactivating a device comprising:

a. power supply means for supplying a regulated direct current to integrated circuits in the apparatus and for supplying line frequency current to the remaining circuits in the apparatus;

b. means for generating and shaping periodic pulses from the line frequency current, said periodic pulses forming an electronic time base signal for the operation of said apparatus;

c. preset activation time means for presetting the time period the device is to remain in an active state;

d. actual energy time selection means for selecting the actual energy time period and for generating a signal representative of the actual time period for which the device is to remain in an active state, said actual energy time period being of equal or lesser duration than said preset time period and an arithmetic function thereof;

e. time base prescaler means for reducing the number of periodic pulses per second in said electronic time base signal, said periodic pulses being proportionately reduced responsive to the signal generated by the actual energy time selection means;

f. time base prescaler control logic means for reprogramming the time base prescaler means with the signal generated by the actual energy time selection means;

g. electronic counting means for counting the number of periodic pulses contained in the electronic time ase signal after said signal has been modified by the time base prescaler means;

h. system logic control means for providing a controlled output signal when the electronic counting means reaches a timed out state representative of the actual energy time period; and

i. a device which is deactivated by the controlled output signal from said system control logic.