US2909666A - Interval timing apparatus and method - Google Patents

Interval timing apparatus and method Download PDF

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Publication number
US2909666A
US2909666A US367937A US36793753A US2909666A US 2909666 A US2909666 A US 2909666A US 367937 A US367937 A US 367937A US 36793753 A US36793753 A US 36793753A US 2909666 A US2909666 A US 2909666A
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Prior art keywords
condenser
ray
grid
interval
voltage
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US367937A
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English (en)
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Jr Robert Godbarsen
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General Electric Co
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General Electric Co
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Priority to US367937A priority Critical patent/US2909666A/en
Priority to US367947A priority patent/US2809296A/en
Priority to FR1167459D priority patent/FR1167459A/fr
Priority to DEG14842A priority patent/DE1110769B/de
Priority to FR53987D priority patent/FR74415E/fr
Priority to DEG14876A priority patent/DE1010657B/de
Priority to GB20601/54A priority patent/GB780982A/en
Priority to NL189208A priority patent/NL105205C/nl
Priority to GB20602/54A priority patent/GB752971A/en
Priority to JP1471554A priority patent/JPS325672B1/ja
Application granted granted Critical
Publication of US2909666A publication Critical patent/US2909666A/en
Priority to JP1336059U priority patent/JPS3519055Y1/ja
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J47/00—Tubes for determining the presence, intensity, density or energy of radiation or particles
    • H01J47/12—Neutron detector tubes, e.g. BF3 tubes
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/30—Controlling
    • H05G1/38—Exposure time
    • H05G1/42—Exposure time using arrangements for switching when a predetermined dose of radiation has been applied, e.g. in which the switching instant is determined by measuring the electrical energy supplied to the tube
    • H05G1/44—Exposure time using arrangements for switching when a predetermined dose of radiation has been applied, e.g. in which the switching instant is determined by measuring the electrical energy supplied to the tube in which the switching instant is determined by measuring the amount of radiation directly

Definitions

  • Timing apparatus of the character mentioned may comprise means operable to measure any elapsed time interval, within the range of the equipnient'and controllingly associated with translation circuitry for the actuation of relay switch means at the beginning and end of the measured interval, such relay switch means being connected with apparatus such as ray generating equip ment to be operated during the measured time interval.
  • An inherent characteristic of relay switches is that the same do not operate instantly. Because of inertia forces, there is always a time delay or lag interval between the instant at which a thyratron fires and the moment of efiective response of the thyratron controlled relay switch means in disabling the associated ray generating apparatus, to thus terminate the exposure interval.
  • time delay or operational lag may be relatively short, that is to say, of the order of 0.005 to 0.01second, per switch, or 0.01 to 0.02 second where a pair of successively operating switch devices are involved, the delay, nevertheless, may represent a substantial and undesirable prolongation of an exposure interval, particularly where the exposure interval being measured is short.
  • the exposure interval is of the order of one-fifth second
  • a prolongation of the interval by as much as 0.02 second will represent a 10 percent increase in the duration of the exposure interval.
  • an exposure interval of one-fiftieth second in duration represents a 100 percent increase in the duration of the exposure interval.
  • An important object of the present invention is to provide an interval measuring or timing system of the char- .acter described having means for anticipating the end of .a timed interval and for starting operable equipment, such as thyratron actuated relay switch means, in operation, sufliciently in advance of the end of the interval being timed, to oitset the lag or delay in the eifective operation of such operable equipment, whereby to accomplish a desired control function precisely at the end of the interval being timed.
  • operable equipment such as thyratron actuated relay switch means
  • a thyratron valve under the control of an integrating condenser, by applying a varying negative bias in the system during the interval being timed, in order to cause the thyratron to fire sufficiently in advance of the end of the interval being timed to compensate for the operational lag of the switch means; a further object being to exponentially vary said compensating bias.
  • Another important object is to compensate for the operational lag time of mechanical elements in an interval measuring system embodying a thyratron valve for Patented Oct. 20,, 1959 actuating said elements at the end of the measured interval, which consists in determining empirically or otherwise the operational lag interval of said elements and applying a variable negative bias in the system to cause the valve to operate, in advance of the end of the interval being measured, by an interval equal to the operational lag interval of said elements, regardless of the duration of the interval being measured.
  • Another important object is to employ a control circuit embodying resistance and capacity factors for applying a variable negative bias in a system of the character mentioned.
  • Apparatus for measuring ray exposure intervals by means of a thyratron valve operable under the control of an integrating condenser to de-limit the end of an interval being measured may be operated by continuously charging the condenser, during the interval being measured,
  • Another important object is to provide means precisely responsive to the energy quanta of pulsating rays for measuring a ray exposure interval in terms of total ray quanta emitted pulsatingly during the interval and for actuating operating equipment, having inherent operational time lag characteristics, sufficiently in advance of the end of the interval being timed to permit the equipment to effectively complete its operational action precisely coincidentally with the end of the interval being measured.
  • Another important object is to include, in the integrating system, switch means operable to disable the integrating condenser during intervals between successive ray pulsations when no rays are delivered from the ray source; a still further object being to utilize electronic switching means for thus disabling the integrating condenser.
  • Another important object is to compensate for the operational time lag of mechanical equipment in an X-ray phototiming system embodying a thyratron valve, controlled by an integrating condenser, for actuating said equipment at the end of an exposure interval, which consists in determining said operational time lag, empirically or otherwise, and then providing for applying an exponentially variable bias on the integrating condenser to cause the same to actuate the thyratron to start the mechanical equipment in operation, in advance of the end of the interval being timed by a period equal to the lag interval of said equipment; a further object being to calibrate the equipment to bias the apparatus in accordance with the time constant of a resistance-capacity timing circuit approximating a selected exponential function, thereby providing the required bias conditions for causing precisely accurate operation of the equipment within a limited interval measuring range; a still further object being to provide equipment of the character mentioned embodying a plurality of resistance-capacity biasing systems, each adapted to bias the system in accordance with a'corresponding time
  • Fig. 1 is a diagrammatic view of conventional interval measuring apparatus of the sort embodying a thyratron valve controlled by a ray responsive integrating condenser, the same providing an operational environment for the present invention
  • Fig. 2 is a graphical representation of the performance of the integrating condenser in measuring ray quanta at various delivery rates in the conventional system shown in Fig. 1;
  • Figs. 3, 4, 5 and 6 are graphs illustrating the manner in which the integrating condenser is necessarily controlled, in accordance with the present invention, in order to correct for the operational lag times of operable meanscontrollably associated with the thyratron valve;
  • Fig. 7 is a diagrammatic view of interval measuring apparatus embodying the present invention.
  • Figs. 8, 9, 10, 11 and 12 are graphs illustrating the operation of the system shown in Fig. 7;
  • Fig. 13 is a diagrammatic showing of a preferred form of light sensitive detector which may be employed in systems embodying the invention.
  • FIG. 1 shows a controllable source of X-rays comprising a conventional X-ray generating tube 11 having an electron emitting cathode 12 and an anode 13 forming an electron target disposed in position to receive the impact of electrons emitted by and at the cathode.
  • the cathode and anode may be connected respectively with conductors 15 and '16 which extend outwardly of the envelope 14, through suitable seals, for the purpose of applying tube energizing power to excite the cathode for electron emission, and to drive cathode emitted electrons at high speed toward the anode under the influence of electron driving potential applied between the anodeand cathode.
  • the anode conductor 16 and one of the cathode conductors 15 may be connected with the secondary winding 18 of a step-up transformer 19, either directly, where the genera tor is to be operated as a self-rectified device, or through a suitable rectifier R if the device is to be operated by full wave rectified alternating current power.
  • the transformer 19 To energize the transformer 19, its primary winding 20 may be connected with the secondary winding 21 of a step-up transformer 23.
  • the primary winding 24 of this step-up transformer may be connected with a suitable power source 25, preferably through a disconnecting switch 26.
  • Means, such as an adjustable connection 2-7 with the secondary winding 21, may be and preferably is provided for varying the potential applied between the anode and cathode.
  • the conductors 15 may be connected with a secondary winding 28 of the transformer 23, preferably through an adjustable connection 29.
  • a control switch 30 may be interposed at any convenient location in the anode-cathode power supply system, the switch 30, as shown, being preferably connected in the power supply circuit to the primary winding of the transformer 19.
  • the switch 30 may comprise a normally open relay switch adapted to be closed, by an associated coil or solenoid 31, when and so long as said coil is energized, as from the source 25, i
  • the X-ray beam 17 may be applied toany useful purpose, including the therapeutic irradiation of the body 33 of a patient, which may be supported for treatment in the path of the beam 17, as on a treatment table 34.
  • the beam 17 may also be usefully employed for the production of X-ray shadow pictures of the body 33 or other object to be pictured, by mounting a sheet of X-ray sensitive film material 35, preferably enclosed in a suitable lighttight cassette 36 in the path of the beam 17 on the side of the body 33 remote from the X-ray source, so that the film material 35 may be exposed to the action of the ray beam after it shall have passed through the body '33, to thus impose, upon the film, an X-ray shadow picture of the body, in accordance with known X-ray photography procedures, which may include the arrangement of a Bucky diaphragm 37 between the body being pictured and the cassette enclosed film.
  • X-ray sensitive means may be disposed in any convenient location in the path of the X-ray beam 17. As shown, the sensitive means may be mounted upon the side of the body 33 remote from the X-ray source, so that rays, in reaching the sensitive means, will first pass through the body 33. Any suitable ray sensitive means may, of course, be employed for ray detecting purposes. To that end, the sensitive means may embody a detector element or cell 38 which may comprise crystalline, ray sensitive semi-conductor material, such as cadmium or mercury sulphide 'or cadmium selenide, of the sort disclosed in an application for United States Letters Patent Serial No. 250,141, filed October 6, 1951, on the invention of John E.
  • Such crystalline semi-conductor materials have impedance characteristics which vary precisely in proportion to the quanta of X-rays applied thereto, and, consequently, a unit 38 comprising such ray sensitive materials may be employed in a suitable electrical integrating system to precisely measure the X-ray quanta applied through the body 33 and upon the sensitive detector element 38.
  • the element 38 may comprise a photosensitive cell of the sort disclosed in United States Letters Patent No. 2,401,289 of May 28, 1946, covering a Photoelectric Timer System invented by Russel H. Morgan and Paul C. Hodges, such photoelectric unit serving to measure X-ray quanta applied upon a sheet of ray sensitive fluorescent material 38 in terms of the amount of light emitted by the fluorescent sheet under the influence of X--rays impinging thereon.
  • the cathode and anode 44 and 45 may be interconnected in an output circuit including a suitable power source 47 and the load device 42 which, in the illustrated embodiment, comprises the operating coil 48 of a normally closed relay switch 49.
  • the control grid 46 of the thyratron may be connected in a control circuit in which the sensitive element 38 is also operatively connected; and means is provided for electrically energizing the grid 46 for the control of the tube 43 in accordance with total current caused to flow in the element 38 during an X-ray exposure interval to be timed.
  • the sensitive element 38 accordingly, may be electrically connected with the grid 46 of the thyratron through a conductor 40.
  • the grid control circuit may also include a preferably uni-directional power source 50 and a variable resistor 51 interconnected in series with the power source and with the sensitive element 38 through a conductor 39.
  • the control circuit also includes an integrating condenser 52 connected between the grid of the thyratron 43 and a suitable source 53 of negative grid biasing power for the thyratron.
  • the control circuit may also include a normally closed disabling switch 54, interconnected in parallel across the integrating condenser 52, and a normally open anode circuit switch 58, connected between the anode 45 of the thyratron and ground in series with the power source 47 and the relay coil 48, the cathode of the thyratron being grounded, as shown, and hence connected with the grounded side of the power source 47. So long as the anode circuit switch 58 remains open, the valve 43 will continue to be inactive because its anode circuit will be open at the switch 58.
  • a negative bias of potential substantially in excess of that at which the thyratron fires, will be applied upon the thyratron grid '46 from the source of biasing potential 53.
  • the condenser 52 also will remain inactive so long as the same is short-circuited by the closed switch 54, both sides of the condenser 52 being at a potential with respect to the cathode 44 equal to the negative potential applied on the grid 46.
  • Means is provided for opening the switch 54 coincidentally with the closure of the switch 30 for the actuation of the X-ray generator at the start of an exposure interval. Accordingly, when the switch 54 opens and switch 58 simultaneously closes, the thyratron will continue to be inactive because biased beyond cut-off. In this connection, the condenser 52 will have no charge in so far as the grid of the thyratron is concerned, but its grid connected side will be at the negative potential with respect to said cathode 44 as supplied by the power source 53.
  • the grid connected side of the condenser 52 will progressively lose negative electrons, thereby becoming more and more positively charged.
  • the difference of potential between the control grid and cathode of the thyratron will increase to the bias voltage level at which the thyratron may fire.
  • the thyratron When the thyratron is thus fired or placed in operation, it will energize the relay coil 48 and cause the switch '49 to open. After being triggered, the thyratron 43 will continue in operation until the switch 55 is reclosed and the switch 58 reopened.
  • the normally open switch 57 may also be connected in series with the normally closed relay switch 49 and the operating coil 31 of the normally open switch 30, to form a series circuit connected with the power source 25.
  • the normally open switch 58 may be interconnected in the plate circuit of the thyratron, in series with the power source &7 and the operating coil 48 of the load device 42.
  • the switch 59 may be closed, as by the action of the roentgenologist in operative charge of the equipment, thereby energizing the relay coil 56 to open the switch 54 and to close the switches 57 and 53. Closure of the switch 57 will complete a relay energizing circuit through the switch 49, which at such time is in closed condition, and the operating coil 31 to thereby cause closure of the normally open switch 30, in order to start the X-ray generator 11 in operation.
  • the X-ray generator will remain in operation until a predetermined X-ray exposure, measured in terms of X-ray quanta, shall have been applied to the body 33.
  • the thyratron tube 43 may be caused to fire as the result of the integrating action of the condenser 52.
  • the thyratron thus is activated, it will complete an operating circuit through the switch 58, which at such time is in closed condition, in order to energize the coil 48 and thus open the energizing circuit of the coil 31 at the switch 49.
  • the switch 38 will open, thereby removing the electron driving potential from the anode and cathode of the X-ray tube, thus disabling the same as an X-ray source, whereby the application of the X-ray beam upon the body 33 will be discontinued.
  • the integrating condenser 52 may be operated substantially exactly for the measurement of X-ray quanta applied to the body 33 during an exposure in order to fire the thyratron precisely when the body has received a preselected amount of X-ray irradiation. It will be obvious, also, that opera tion of the X-ray generator 11 will be discontinued as the result of the operation of the thyratron after a short time interval required for the successive operation of the switches 49 and 3t). Ordinarily, the operation of such relay switch means requires an interval of the order of one-fiftieth second. Such delayed switch operation, accordingly, is a factor which, if disregarded, will introduce errors in the determination of X-ray exposure intervals, such errors becoming proportionally greater as the measured exposure interval becomes smaller.
  • the operation contemplated by the present invention is obtained by causing the bias voltage delivered from the source 53 to vary, during the course of the exposure interval being measured, whereby to .afiect the charging range of the condenser 52, so that, regardless of the rate of fiow of condenser charging current or the duration of the interval being measured, the thyratron will be caused to operate sufficiently in advance of the end of the 7 measured interval to compensate for the operational lag of relay switching means driven by the thyratron.
  • Line I represents the action of the condenser when rays are emitted at relatively high intensity such that the detector 38 releases condenser charging current at a rate such that the condenser is charged to thyratron firing condition during a single X-ray pulse interval.
  • the lines 1 -1 show condenser action where emitted ray intensities are such that the condenser is charged at rates respectively requiring the delivery of two-ten ray pulses to charge the condenser to thyratron firing condition.
  • the lines I 4 each include one or more portions representing inter-pulse intervals during which rays are suppressed and the condenser consequently is not charged.
  • the operational lag time of the relay switches and 49 may be empirically determined for any particular installation, the same ordinarily being of the order of 0.010.02 second, where a pair of sequentially operating devices are involved.
  • a graphical distance corresponding with, say, 0.01 second a series of points P P may be determined, such points representing the voltage transitorily applied on the thyratron grid 0.01 second before the condenser 52 becomes charged to the normal firing potential.
  • a series of points P P can be determined.
  • points representing any empirically determined lag time interval may be picked off on the lines 1 1
  • the lag interval would be compensated if the thyratron were caused to fire at the voltages represented by the points P P-P
  • the locus of the points P P is a function of time only.
  • the inter-pulse periods during which ray emission is suppressed, may be eliminated from the graph illustrated in Fig. 2, in order to produce the graph comprising Fig. 3 showing the lines il -1 with dead intervals removed and showing as curved lines a and b the loci of the points P P and the points P P
  • the locus of thyratron grid voltages theo retically required to anticipate and compensate for any operational lag interval can be determined.
  • the present invention contemplates the application of the bias voltage V upon the grid remote end of the condenser 52 in intermittent fashion so that the voltage V as applied to the condenser will alter only during ray pulse emission periods and will remain constant during inter-pulse intervals, such condition being illustrated, in Fig. 4, by the stepped line V the same comprising successive sections of the function V and intervening steps illustrating time intervals during which the voltage remains constant.
  • Fig. 4 also reproduces the stepped lines I and 1 which illustrate two of the several condenser charging rates shown in Fig. 2, said condenser charging rates being illustrated in terms of negative voltage at the grid connected side of the condenser.
  • the values of the lines I and 1 may be developed which illustrate the variant voltage, with respect to the grounded cathode of the thyratron which is made to appear at the grid connected end of the condenser, and hence upon the grid of the thyratron, as the combined result of the delivery of charging current to the condenser, under the control of the detector means 38, and the application of the variant voltage V at the grid remote side of the integrating condenser 52.
  • the stepped line AV illustrates the actual voltage applied upon the thyratron grid remote side of the condenser 52 from the power source 53 in accordance with the present invention, as shown in Fig. 7 of the drawings.
  • the power source 53 may comprise a full wave rectifying system 64 embodying an electron flow device 65 and a transformer 66 having a center tapped secondary winding and a primary winding interconnected in parallel with the winding 20 of the transformer 19 and hence powered from the same power source which energizes the X-ray generator.
  • Full wave rectified power thus may be delivered through a filtering network comprising interconnected condensers 67 and 68, resistors 69 and 70 and an adjustable potentiometer 71, between ground and a supply terminal 72, whence maximum bias potential may be delivered through the switch means 63 and the resistor 62 to the grid remote side of the condenser 52.
  • the present invention provides a control system 77 for actuating the switch 63 to switch the anticipator circuit comprising the exponential biasing means into and out of operation in concert with the ray pulsations emitted during the period being measured.
  • the cathode of the phototube may be connected with a suitable source 79 of relatively high voltage negative potentiaLpreferably through an adjustable resistance 80.
  • the anode of the detector tube by means of a conductor 81, may be connected with the translation system 77 to operate and control the same in accordance with the pulsations ofthe ray beam 17.
  • the 'end dynode D may be connected with the grid connected side of the integrating condenser 52 through the conductor 40, while the dynode D may be connected, as by means of a conductor 82, with a source 83 of relatively low voltage negative potential.
  • the control grid of "the valve V may be connected with the anode of the phototube 38 through a condenser 85 and with ground through a resistor 86 and a one-way current flow diode device 87 connected in parallel with respect to the resistor 86.
  • the grid of the valve V may be connected with the anode of the valve V through a resistor 88 and a condenser 89, the negative low voltage power source 83 being connected through resistors 90 and 91, in series, with the interconnected sides of the reslstance 88 and the condenser '89, a one-way current flow diode 92 being connected in parallel with the resistor 91 and the interconnected ends of the resistors 90 and 91 being connected to ground through a resistor 93.
  • the control grid of the valve V may be connected with the anode of the valve V through a condenser 94.
  • the control grid of the valve V may also be connected to ground through a resistor 95 and a one-way current flow dlode 96 connected in parallel with the resistor 95.
  • the control grid of the switch valve V may be connected with the anode of the valve V through a resistor 97 and a condenser 98. Power may be delivered, between the pulse intervals.
  • the secondary winding 101 of the transformer may supply power for energizing the cathode filaments of the valves V V V and V
  • One end of the secondary Winding 101 may be connected through a resistor 102 with the interconnected sides of the resistance 97 and the condenser 98, a one-way current flow diode 103 being connected in parallel with the resistor 102.
  • the other end of the winding 101 may be connected through a one-way cunrent flow diode 104 and a resistor 105 with the cathode of the switching valve V a condenser 106 being interconnected between the transformer connected ends of the resistors 102 and 105.
  • a resistor 107 also may be connected between the transformer connected end of the resistor 102 and the transformer remote end of the resistor 105.
  • the valve V is in conductive condition prior to the occunrence of an X-ray pulsation and is held conductive by the diode 87 and by virtue of the fact that there is no voltage drop across the resistor 86, the grid of the valve V being thus effectively tied to its cathode so that the tube remains in conductive condition.
  • valves V V and V respectively illustrate the operation of the valves V V and V It will be seen that while the valves V and V produce an amplification gain, they nevertheless do not become sharply conducting and nonconducting with the commencement and termination of a ray pulsation.
  • the plate voltage pattern developed in the valve V is fed through the condenser 89 upon the grid of the valve V Accordingly, when the X-ray pulse is a maximum, the valve V is in its maximum conducting condition, the voltage at the anode of the valve V being a minimum when the X-ray pulse is at its maximum value. Such minimum voltage is then applied through the condenser 94 to the grid of the valve V in order to decrease the conductivity thereof when the X- ray impulse is at maximum value. Accordingly the voltage developed at the anode of the valve V is a maximum when the ray impulse is at its maximum value. The anode voltage thus developed in the valve V is applied through the condenser 98 upon the grid of the switching valve V to render the same conductive during X-ray pulse intervals and non-conducting during interpulse intervals.
  • valve V should be relatively non-conductive during ray inter- Its grid voltage consequently must be negative with respect to its cathode during such intervals.
  • the necessary negative voltage may be derived from the source 83 through the voltage divider comprlsing the resistors 90, 91 and 93 and the diode 92.
  • the diode 92 as well as the other diodes 87, 96 and 103 serve as direct current restorers, that is to say, they permit the voltage change, which occurs when the pulse enters and leaves, to have a full etfect upon the grid of the valve with which connected, and they prevent the same from assuming opposite polarity due to the one-way conductivity of the diode.
  • the ray detecting means comprises a sensitive panel, screen or layer of fluorescent material 38 for the operation of a phototube
  • Ordinary fluorescent materials have image decay time constant characteristics such that the same may be employed for measuring intervals of duration of the order of 0.1 second or more, but have image persistence of such duration after the extinction or termination of exciting rays as to cause erroneous operation of an integrating system in which employed, where the interval being measured is short.
  • the integrating errors caused by image persistence can be compensated for by adjusting the bias supplied upon the thyratron from the power source 53, since the error, measured over several pulsations tends to become directly proportional to the length of the measured interval.
  • the exposure interval is of duration of the order of less than 0.1 second, equivalent to less than twelve ray pulsations, where the rays are produced in a tube energized by full wave rectified sixty cycle alternating current power
  • the error introduced as the result of slow image decay characteristics in the element 38 becomes appreciable.
  • the error furthermore, increases as the exposure time interval diminishes, the extent of error being somewhat erratic and dependent to some extent upon the relative position of the instant of exposure interval termination in or with respect to the ray source energizing power cycle.
  • the element 38' should comprise ray sensitive fluorescent material, such as calcium tungstate, having substantially instantaneous image decay characteristics, that is to say, material in which ray induced luminosity becomes extinguished as during an interval of the order of one-thousandth of a second, after the termination of ray impingement thereon.
  • ray sensitive fluorescent material such as calcium tungstate
  • the transformer 66 is energized by power derived from the adjustable secondary winding 21 of the transformer which supplies energy at desired adjustable voltage for application between the anode and cathode of the generator tube.
  • the output of the transformer 66 is subjected to full wave rectification and applied to the filter network comprising the condensers 67 and 68 and the resistor 69.
  • the voltage thus produced across the condenser 68 is applied across the resistor 70 and potentiometer 71, the positive end of the resistor 70 being grounded so that the voltage derived from the adjustable potentiometer 71 is negative with respect to ground.
  • This voltage is used as the full bias voltage, that is to say, the voltage labeled 100 percent in the graphical illustrations comprising Figs. 2-6.
  • Apparatus for actuating operable devices at the conclusion of a measured time interval comprising a gaseous conduction electron fiow valve having an anode, a cathode and a control grid, an integrating condenser connected on one side with said grid, a switch for initially biasing said grid and both sides of said condenser at selected negative voltage values with respect to the cathode of the flow valve to hold the same normally in non-conducting, inoperative condition, means for applying current pulses during successive intervals to charge the condenser and thus decrease the negativity of the voltage applied on the grid in accordance with the charging rate of said condenser, a circuit embodying a condenser operable to provide a progressively varying bias voltage, and a switch operable in synchronism with said current pulses for applying said bias voltage of progressively increasing negativity upon the grid remote side of the condenser during said pulse intervals only, to alter the condenser charging rate in accordance with said bias voltage for the operation of said operable devices
  • Control apparatus comprising a gaseous conduction valve having a control grid, an integrating condenser connected with said control grid, means to apply successive current pulsations upon the condenser to charge the same progressively and thus to alter the voltage applied upon said grid, a circuit including a condenser operable to provide a bias voltage of progressively changing value, and intermittently operable switch means for applying said progressively varying bias voltage upon the grid remote 14 side of said condenser to thereby alter the condenser charging rate in accordance with said bias voltage.
  • Control apparatus comprising the combination with a penertating ray source, means including a control switch for controlling the emission of ray energy pulsations from said source, and a ray responsive detector, of a gaseous conduction valve having a control grid, an integrating condenser connected with said control grid, means operable under the control of said detector for producing successive current pulsations, corresponding with ray quanta emitted by said source, and for applying such pulsations upon the condenser to charge the same progressively and thus to alter the voltage applied upon said grid progressively in accordance with emitted ray quanta, a circuit including a condenser operable to pro vide a bias voltage of progressively changing value, and an electron flow switch device operable in synchronism with said current pulsations for applying said progressively varying bias voltage upon the grid remote side of said condenser, at intervals corresponding with said current pulsations, to thereby alter the condenser charging rate in accordance with said bias voltage.
  • Control apparatus comprising the combination with a penetrating ray source, means including a control switch for controlling the emission of ray energy pulsations from said source, and a ray responsive detector, of a gaseous conduction valve having a control grid, an integrating condenser connected with said control grid, means operable under the control of said detector for producing successive current pulsations, corresponding with ray quanta emitted by said source, and for applying such pulsations upon the condenser to charge the same progressively and thus to alter the voltage applied upon said grid progressively in accordance with emitted ray quanta, an electron flow switch, amplifier means driven in synchronism with said pulsation producing means, under the control of said ray detector, for applying a progressively varying bias voltage upon the grid remote side of said condenser, at intervals corresponding with said current pulsations, to thereby alter the condenser charging rate in accordance with said bias voltage, and means, operable by said gaseous conduction valve, to actuate
  • apparatus for limiting an exposure to a predetermined quanta of X-ray energy, said apparatus comprising a ray sensitive device positioned to receive X-rays from said generating system, a biasing circuit for producing a varying bias voltage, an integrating condenser connected between the ray sensitive device and the biasing circuit, a relay switch connected across said integrating condenser for establishing an initial condition wherein said integrating condenser has no charge and wherein an initial bias voltage is applied thereto, said integrating condenser being operable to accumulate charge from the ray sensitive device in accordance with the X-ray intensity, a gaseous conduction device having a control grid coupled to the integrating condenser, said gaseous conduction device being responsive to the appearance of a grid voltage upon its control grid, said grid voltage being an addition 15 of the varying bias voltage and a voltage appearingtacross the integrating condenser corresponding to the charge
  • circuit for producing the bias voltage is coupled to a switching circuit for disabling the biasing circuit and holding the bias voltage constant during intervals between the pulsations of the X-rays, and thereby allowing the bias voltage to vary only during times of ray impingement upon the ray sensitive device.
  • the biasing circuit comprises a condenser resistively coupled across a source of unidirectional voltage by an electron tube, said electron tube being conductive during intervals of X-ray impingement upon said ray sensitive device and being nonconductive between the intervals of X-ray impingement, thereby allowing the condenser to charge only during the intervals of ray impingement.
US367937A 1953-07-14 1953-07-14 Interval timing apparatus and method Expired - Lifetime US2909666A (en)

Priority Applications (11)

Application Number Priority Date Filing Date Title
US367937A US2909666A (en) 1953-07-14 1953-07-14 Interval timing apparatus and method
US367947A US2809296A (en) 1953-07-14 1953-07-14 Switching system
FR1167459D FR1167459A (fr) 1953-07-14 1954-06-29 Système de réglage des intervalles de temps
DEG14842A DE1110769B (de) 1953-07-14 1954-07-09 Schaltungsanordnung zum Abschalten einer mit pulsierender Anodenspannung gespeisten Roentgenroehre
DEG14876A DE1010657B (de) 1953-07-14 1954-07-13 Schaltungsanordnung zum Betrieb einer Roentgenroehre
FR53987D FR74415E (fr) 1953-07-14 1954-07-13 Système de réglage des intervalles de temps
GB20601/54A GB780982A (en) 1953-07-14 1954-07-14 Improvements in and relating to electric switching apparatus
NL189208A NL105205C (nl) 1953-07-14 1954-07-14 Interval timing apparatus and method
GB20602/54A GB752971A (en) 1953-07-14 1954-07-14 Improvements in and relating to control systems responsive to x-ray emission
JP1471554A JPS325672B1 (de) 1953-07-14 1954-07-14
JP1336059U JPS3519055Y1 (de) 1953-07-14 1960-08-10

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US367937A US2909666A (en) 1953-07-14 1953-07-14 Interval timing apparatus and method

Publications (1)

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US2909666A true US2909666A (en) 1959-10-20

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US367947A Expired - Lifetime US2809296A (en) 1953-07-14 1953-07-14 Switching system
US367937A Expired - Lifetime US2909666A (en) 1953-07-14 1953-07-14 Interval timing apparatus and method

Family Applications Before (1)

Application Number Title Priority Date Filing Date
US367947A Expired - Lifetime US2809296A (en) 1953-07-14 1953-07-14 Switching system

Country Status (6)

Country Link
US (2) US2809296A (de)
JP (2) JPS325672B1 (de)
DE (2) DE1110769B (de)
FR (2) FR1167459A (de)
GB (2) GB780982A (de)
NL (1) NL105205C (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3152255A (en) * 1959-07-24 1964-10-06 Philips Corp Device for measuring the X-ray radiations absorbed by a specimen
US3557371A (en) * 1968-06-10 1971-01-19 Scope Corp X Method and apparatus for calibrating a cardiac x-ray synchronizer

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2958782A (en) * 1958-01-13 1960-11-01 Gen Electric Electronic timer
US2993145A (en) * 1958-04-30 1961-07-18 Bell Telephone Labor Inc Switching apparatus
US3046451A (en) * 1958-10-01 1962-07-24 Westinghouse Electric Corp Switching circuit
US3119932A (en) * 1960-02-12 1964-01-28 Philips Corp Polyphase current switching device for an x-ray tube supply circuit
US3094618A (en) * 1961-05-23 1963-06-18 Picker X Ray Corp X-ray tube protection mechanism
US3440422A (en) * 1965-06-24 1969-04-22 Picker Corp Biplane x-ray image system
US3573461A (en) * 1969-04-01 1971-04-06 Stig Arne Ohlsson Method and apparatus for timing exposures in x-ray photography

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2401289A (en) * 1943-07-22 1946-05-28 Nasa Photoelectric timer for roentgen photography
US2438303A (en) * 1947-02-28 1948-03-23 Simmon Brothers Inc Device for making color prints
US2453486A (en) * 1945-01-01 1948-11-09 Picker X Ray Corp Waite Mfg Electronic timer
US2494218A (en) * 1947-07-03 1950-01-10 Picker X Ray Corp Waite Mfg Stabilizer with condenser modulator
DE904916C (de) * 1939-04-27 1954-02-25 Aeg Steuerverfahren fuer elektrische Hoechstspannungsroehren
US2679598A (en) * 1950-12-04 1954-05-25 Westinghouse Electric Corp X-ray apparatus
US2747104A (en) * 1951-10-06 1956-05-22 Gen Electric Interval timing apparatus

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2473922A (en) * 1949-06-21 Breathing indicator
DE625011C (de) * 1932-12-17 1936-02-01 Bbc Brown Boveri & Cie Elektromagnetisches Wechselstromschuetz
BE410041A (de) * 1934-06-08
US2150440A (en) * 1936-06-10 1939-03-14 Western Union Telegraph Co Magnetic and resonator selector for carrier conveyers
DE691080C (de) * 1936-11-04 1940-05-16 Otto Muck Einrichtung zum Schalten eines Wechselstromkreises
US2165048A (en) * 1937-08-26 1939-07-04 Westinghouse Electric & Mfg Co Electric discharge apparatus
FR863046A (fr) * 1939-01-26 1941-03-21 Thomson Houston Comp Francaise Perfectionnements aux circuits de dispositifs à décharge
US2282182A (en) * 1939-09-07 1942-05-05 Westinghouse Electric & Mfg Co Amplifier circuit
US2361172A (en) * 1940-07-31 1944-10-24 Westinghouse Electric & Mfg Co Electronic power factor relay overload protection
US2413020A (en) * 1943-05-19 1946-12-24 Photoswitch Inc Electronic relay
US2422020A (en) * 1945-03-27 1947-06-10 Gen Electric Electric control circuit
US2561085A (en) * 1946-06-01 1951-07-17 Westinghouse Electric Corp Automatic exposure timer
US2573029A (en) * 1946-09-12 1951-10-30 Kelley Koett Mfg Company X-ray apparatus
DE951020C (de) * 1951-11-25 1956-10-18 Siemens Ag Drehstromschuetz fuer synchrones Ausschalten, dessen Kontakte zwecks Vermeidung von Schaltfeuer kurz vor dem Nulldurchgang des Stromes geoeffnet werden

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE904916C (de) * 1939-04-27 1954-02-25 Aeg Steuerverfahren fuer elektrische Hoechstspannungsroehren
US2401289A (en) * 1943-07-22 1946-05-28 Nasa Photoelectric timer for roentgen photography
US2453486A (en) * 1945-01-01 1948-11-09 Picker X Ray Corp Waite Mfg Electronic timer
US2438303A (en) * 1947-02-28 1948-03-23 Simmon Brothers Inc Device for making color prints
US2494218A (en) * 1947-07-03 1950-01-10 Picker X Ray Corp Waite Mfg Stabilizer with condenser modulator
US2679598A (en) * 1950-12-04 1954-05-25 Westinghouse Electric Corp X-ray apparatus
US2747104A (en) * 1951-10-06 1956-05-22 Gen Electric Interval timing apparatus

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3152255A (en) * 1959-07-24 1964-10-06 Philips Corp Device for measuring the X-ray radiations absorbed by a specimen
US3557371A (en) * 1968-06-10 1971-01-19 Scope Corp X Method and apparatus for calibrating a cardiac x-ray synchronizer

Also Published As

Publication number Publication date
GB752971A (en) 1956-07-18
JPS3519055Y1 (de) 1960-08-10
NL105205C (nl) 1963-02-15
FR1167459A (fr) 1958-11-25
US2809296A (en) 1957-10-08
JPS325672B1 (de) 1957-07-29
FR74415E (fr) 1960-12-19
DE1110769B (de) 1961-07-13
DE1010657B (de) 1957-06-19
GB780982A (en) 1957-08-14

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