US3548855A - Electronic timer - Google Patents

Electronic timer Download PDF

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Publication number
US3548855A
US3548855A US3548855DA US3548855A US 3548855 A US3548855 A US 3548855A US 3548855D A US3548855D A US 3548855DA US 3548855 A US3548855 A US 3548855A
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US
United States
Prior art keywords
transistor
capacitor
switching
concentrate
coupled
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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English (en)
Inventor
George H Fathauer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eaton Corp
Original Assignee
Eaton Yale and Towne Inc
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Filing date
Publication date
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Publication of US3548855A publication Critical patent/US3548855A/en
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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/28—Modifications for introducing a time delay before switching
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03D—APPARATUS FOR PROCESSING EXPOSED PHOTOGRAPHIC MATERIALS; ACCESSORIES THEREFOR
    • G03D13/00—Processing apparatus or accessories therefor, not covered by groups G11B3/00 - G11B11/00
    • G03D13/007—Processing control, e.g. test strip, timing devices
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D21/00—Control of chemical or physico-chemical variables, e.g. pH value
    • G05D21/02—Control of chemical or physico-chemical variables, e.g. pH value characterised by the use of electric means
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/2496—Self-proportioning or correlating systems
    • Y10T137/2499—Mixture condition maintaining or sensing
    • Y10T137/2509—By optical or chemical property

Definitions

  • a photo copy toner density control device having means for sensing the concentrate density of a photo copier fluid and for developing an electrical signal indicative of the sensed concentrate thereof.
  • the output of the sensing means is coupled to a series of transistors so arranged as to have a substantially higher turn on" level than the turn off" level thereof.
  • a capacitive charging device is coupled to the input of the switching transistors, and a given voltage level which turns on the three transistors substantially simultaneously also causes the discharge of the capacitive means, the discharge of which determines the on time of an injection means for adding concentrate to the fluid being sensed.
  • the capacitive means also provides a delay to prevent the too rapid cycling of the timer and thereby avoid the adding of excessive concentrate to the fluid prior to the adequate mixing of the concentrate in the fluid and the associated sensing of the so mixed concentrate by the sensing means.
  • the drawing to the present invention is a schematic of a power supply, a photo sensing means and an electronic timing DESCRIPTION OF THE PREFERRED EMBODIMENT
  • the electronic timing circuit as shown on the drawing consists essentially of three transistors which are turned on" substantially simultaneously in response to the charging of an input capacitor.
  • the voltage level affecting the charging of the input capacitor is determined by the strength of a light beam passing through a sample of a photo copier fluid. Once a given voltage level is reached, the first transistor is turned on" and the subsequent transistors are also immediately turned on.” However, the turning on of the third transistor couples a feedback signal to the second transistor for reducing the biasing level of that transistor and, accordingly, reducing the input voltage level required to turn off the first transistor.
  • a differential is obtained between the turn on" and turn off voltages, which allows the discharge of the capacitor to occur through a period of time which corresponds to the time interval of conduction of the three transistors. Accordingly, a relay for adding toner concentrate to the photo copier fluid solution is held on for a period of time determined by the discharge of the capacitor between the turn on" voltage and the turn off voltage thereof. Also, the presence of the capacitor at the input of the switching devices or transistors prevents the too rapid recycling of the timer and thereby prevents the adding of excess toner concentrate to the photo copier fluid solution.
  • the electronic timer is supplied by means of a standard power supply utilizing a transformer 10 having a primary l1 and a secondary winding 12.
  • the primary 11 is supplied at a pair of terminals 13 and 14 by a standard ll5 volt 60 cycle signal.
  • the secondary winding 12 has a center tap 15 coupled to ground at 16 and has a pair of rectifiers l7 and 18 for providing full wave rectification.
  • a capacitor 19 is coupled to the output of the rectifiers l7 and 18 for smoothing the resulting signal and together with a resistor 20 and a zener diode 21 and a further resistor 22, provide a substantially uniform DC signal having a constant amplitude for supplying the electronic timer as indicated by the various plus connections shown in the drawing.
  • the voltage at the terminal 23 may be 9 volts DC and may be coupled to each of the terminals in the drawing indicated by a plus designation.
  • a sample of photo copier fluid such as a sample 24 may be contained in a translucent container 25 such that a light source 26 will pass a beam through the solution and such that the intensity of the beam after having passed through the solution may be monitored at a photo sensitive resistor 27.
  • the light source 26 is also energized from the standard power supply, and in this case, is directly energized through a line 28 which is coupled directly to the resistor 22.
  • the photo sensitive resistor 27 together with a set of resistors 29, 30 and 31 may be said to bean indicator means for developing an electrical signal which isrelated to the toner concentration of the fluid sample 24.
  • the resistor 30 is a variable resistor having a pointer 32 for adjusting the resistance thereof and is used to vary the sensitivity of the photo resistor 27.
  • a diode 33 is connected between a junction point 34 and a further junction point 35 and limits the input signal which may be applied to the electronic timing device.
  • the timing device consists generally of first, second and third devices or transistors 36, 37 and 38.
  • a capacitance means or capacitor 39 is coupled between the junction point 34 and ground at a point 40 and is also coupled to a base terminal 41 of the transistor 36.
  • the capacitor 39 attains a given voltage level due to the charging thereof through the resistor 31 by means of the positive source indicated at the junction point 42, the transistor 36 is placed in a conducting state.
  • the turning on of the transistor 36 causes the conduction of a current from the collector terminal 43 to the emitter terminal 44 thereof Such conduction then is coupled directly by means of a line 45 to an emitter 46 of the transistor 37, thereby turning on that transistor.
  • the turning on" of the transistor 37 then couples a positive signal from the collector 47 thereof through a resistor 48 and a bias resistor 49 to the base 50. of the transistor 38. In this way, the turning onof the transistor 36 controls the turning on of the transistors 37 and 38.
  • the energizing of the coil 52 operates a relay switch 57a which is illustrated schematically.
  • the closing of the switch 57a connects a voltage source at the junction point 58a to a solenoid operated valve 59a or the like and allowsttoner concentrate to flow from a reservoir 600 through a line 61 to the photo copier solution 24.
  • the relay 52 will, of course, remain on until means are provided for turning off the switching devices 36, 37 and 38? It” is desirable that the switching; devices 36, 37 and 38 remain on for a predetermined period of time, and after having been turned on,” it is desirable that they remain ofF until such time as the toner concentrate which has been added to the photo copier solution be allowed to mingle with the solution to assure thatthe reading provided by the photo sensitive resistor 27 is indicative of the measure of toner concentrate in the entire photo copier solution.
  • the combination of the transistors 36, 37 and 38 provides the necessary circuitry to assure that the relay 52 is turned on and held on for the predetermined period of time.
  • the transistors 36 and 37 work together in such a way that both transistors must be placed in a conducting state before either transistor can conduct.
  • the transistor 37 holds the transistor 36 in an condition until the turning on of the transistor 36 would result in sufficient current to turn on the transistor 37;
  • the transistor 38 after the turning on" of the transistor 37, the transistor 38 also turns on resulting in a sudden drop in voltage at the line 57 which is coupled directly to the base 58 of the transistor 37. Accordingly, thebias conditions for the transistor 37 are suddenly reduced by the turning on of the transistor 38. Hence, the turn off point for the transistor 36 will be substantially lower than the turn on point due to the change in bias conditions.
  • the time which the relay will remain on depends upon the discharge circuit of the capacitor 39.
  • a resistor 59 is connected in series with the capacitor 39 with respect to further diode 60 and the transistor 38.
  • the capacitor 39 is allowed to discharge through the resistor 59, the diode 60 and the transistor 38.
  • the on" time of the relay 52 is determined by the value of the resistor 59in combination with the capacitance of the capacitor 39.
  • the initial bias conditions for the transistor 37 are provided by a series of resistors 61, 62 and 63 together with a capacitor 64 which is coupled in parallel with the resistor 62.
  • the capacitor 39 provides a delay before the recycling of the electronic timer can be accomplished.
  • the capacitor 39 after the capacitor 39 has been reduced to two loads, for instance, the capacitor must recharge to the 7 volt level before the switching devices can be retriggered and before additional concentrate can be added to the photo copier solution 24. This allows sufficient time to lapse between injections of fluid into-the solution 24 to assure a proper mixing of the fluid and hence a proper sensing of the fluid concentrate level by means of the photo sensitive resistor 27.
  • An electronictiming and control device comprising:
  • sensor means for developing an electrical signal indicative of the concentrate density' of a fluid; injection means for adding concentrate to the fluid; and switching means for triggering the-operation of said injection means, said switching means being coupled to said sensor means, meansresponsive tosaid switching means for holding said injection means in an operating state for a predetermined period of time and for turning ofF' said injections means after the lapse of saidpredetermined. period of time, means for delaying a subsequent triggering on of said injections means, and said switching means for triggering the operation of said injection means including a first electronic switching device and capacitance means coupled to said sensor means and being chargeable therefrom and being coupled to the input of said switching device in such a manner as to provide the input triggering signal therefor.
  • said means for holding said injection means in an operating state comprises:
  • said second electronic switching device being coupled to said first electronic switching device in such a manner as to cause said first device to conduct only when said second device conducts, said third electronic switching device being coupled to said second device in a manner to be turned on by the conduction of said second device;
  • An electronic timing and control device in accordance with claim 2 wherein said means for altering the bias conditions of said second switching device includes feedback means from said third switching device to said second switching device for reducing the forward bias required at said first switching device to cause conduction of said first and second and hence said third switching devices.
  • said means for delaying a subsequent triggering on of said injection means comprises a capacitor having one terminal thereof coupled both to the output of said sensor means and to the input of said switching means, means for discharging said capacitor during the turn on" time of said injections means, and means biasing said switching means for turning on” the same at a given charge level of said capacitor.
  • the combination comprising: means for sensing the concentrate density of a fluid, indicator means for developing a signal indicative of the sensed concentration;
  • first, second, and third switching means said first switching means coupled to said. indicator means, said first and second switching means being coupled together such that the turn on conditions of both said first and second switching means must be satisfied prior to the conduction of either of said first and second switching means;
  • said second'switching means being coupled to saidthird?" switching means so as to turn on" the same, injection:
  • a capacitor is coupled to the output of said indicator means and to the input of said first switching means, wherein said indicator means charges said capacitor, agiven charge on said capacitor causing the conduction of said first switching means, and wherein the turning on" of said first, second and third switching means provides a discharge path for said capacitor, thereby ceasing the conduction of said switching means.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Wet Developing In Electrophotography (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
  • Sampling And Sample Adjustment (AREA)
  • Control Of Non-Electrical Variables (AREA)
US3548855D 1967-11-20 1967-11-20 Electronic timer Expired - Lifetime US3548855A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US68444567A 1967-11-20 1967-11-20

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US3548855A true US3548855A (en) 1970-12-22

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Application Number Title Priority Date Filing Date
US3548855D Expired - Lifetime US3548855A (en) 1967-11-20 1967-11-20 Electronic timer

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US (1) US3548855A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
DE (1) DE1808645A1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
ES (1) ES360047A1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3739800A (en) * 1971-05-04 1973-06-19 Copystatics Mfg Corp Toner supply system for copying machine
US4671309A (en) * 1984-06-29 1987-06-09 Mitsushita Graphic Communication Systems, Inc. Device for controlling concentration of a liquid developing machine

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2929013C2 (de) * 1979-07-18 1983-09-08 Krauss-Maffei AG, 8000 München Verfahren und Vorrichtung zum Messen der Gasbeladung von Flüssigkeiten

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3739800A (en) * 1971-05-04 1973-06-19 Copystatics Mfg Corp Toner supply system for copying machine
US4671309A (en) * 1984-06-29 1987-06-09 Mitsushita Graphic Communication Systems, Inc. Device for controlling concentration of a liquid developing machine

Also Published As

Publication number Publication date
DE1808645B2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1970-08-13
DE1808645A1 (de) 1970-01-15
ES360047A1 (es) 1970-06-16

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