Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3242497 A
Publication typeGrant
Publication dateMar 22, 1966
Filing dateApr 16, 1962
Priority dateApr 16, 1962
Publication numberUS 3242497 A, US 3242497A, US-A-3242497, US3242497 A, US3242497A
InventorsDonald A Caldwell, John J Heigl
Original AssigneeExxon Research Engineering Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Automatic recorder control device
US 3242497 A
Abstract  available in
Images(4)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

March 22, 1966 o. A.- CALDWELL ETAL AUTOMATIC RECORDER CONTROL DEVICE Filed April' 16, 1962 .CONTROL UNIT 4 Sheets-Sheet 1 WICK DRIVE MOTOR CONTROL X-Y RECORDER Donald A. Caldwell John J. Heiql Inventors By w W Patent Attorney March 2 1 D. A. CALDWELL ETAL 3,242,497

- AUTOMATIC RECORDER comnoz, DEVICE Filed April 16, 1962 4 Sheets-Sheet 2 Donald A. Caldwell John J H i Inventors Potent Aflorney March 22, 1966 o. A. CALDWELL ETAL 3,242,497

AUTOMATIC RECORDER CONTROL DEVICE Filed April 16, 1962 4 Sheets-Sheet 3 Donald A. Caldwell John J m Inventors Bypw M Patent Attorney United States Patent M 3 242,497 AUTOMATIC RECORDER CONTROL DEVICE Donald A. Caldwell, Mountainside, and John J. Heigl,

Short Hills, N.J., assignors t0 Esso Research and Englneering Company, a corporation of Delaware Filed Apr. 16, 1962, Ser. No. 187,776 16 Claims. (Cl. 34629) This invention relates to an automatic apparatus which controls the recording of signals. In particular, the invention relates to an automatic apparatus which controls both the recording of signals and electromechanical means of manipulating such signals. Even more particularly the invention relates to an apparatus and process for automatically controlling the propagation of and recording of electrical signals corresponding to both changes of light intensity and changes in temperature in order to ascertain luminometer numbers thereby.

Although the automatic apparatus of the invention can be used in any system wherein it is desired to automatically control the propagation and recording of various electrical signals, it finds particular utility in combination with a commercial luminometer. The preferred species of this invention is an automatic luminometer.

The preferred embodiment of the invention so used in combination with a commercial luminometer can be fully understood by referring to the following description and claims taken in conjunction with the accompanying drawings wherein:

FIGURE 1 shows a block diagram of the automatic apparatus in conjunction with a commercial luminometer;

FIGURE 2 is a view of the mounting of the wick drive motor apparatus and its operative connection with the lamp of the luminometer;

'FIGURE 3 is a view showing the mounting of switches on an X-Y recorder;

FIGURE 4 is a schematic wiring diagram showing the electrical circuit for the automatic apparatus in combination with a commercial luminometer.

-Luminometer Number is a dimensionless term which serves as a measure of flame temperature at a fixed flame radiation in the green-yellow band of the visible spectrum. This value is important since itcan be correlated with the combustion characteristics of fuels which are for use in combustion devices such as commercial aviation turbine engines. Conventionally, Luminometer Numbers are obtained by a technique described as ASTM Test D1740- 60T, 1961 Book of ASTM Standards, Part 7, pp. 905-912, published by American Society for Testing and Materials, 1916 Race Street, Philadelphia 3, Pa. The above-designated test description is incorporated herein in its entirety.

The conventional ASTM test employs an ASTM-CRC luminometer which currently is authorized for manufachim only by the Erdco Engineering Corp. at Madison, 111. This luminometer has three basic par-ts. These are a wick type lamp apparatus, comprising a lamp sample holder and a wick tube, in which a sample is burned, an optical filter and photocell circuit which indicates the intensity of flame radiation in the range of 4800 to 7000 A. and a dual thermocouple circuit and potentiometer which directly indicates the lamp temperature rise.

The conventional luminometer is manually operated by placing the test fuel and wick in the lamp, lighting the wick and warming up the photocell and thermocouple by the burning of the particular fuel being tested. The photocell readings on a meter and the thermocouple readings on a potentiometer are then made at a given wick height. The wick is then raised until the meter reads approximately ten units higher and after five minutes both meter and potentiometer readings are taken. This procedure is repeated until four data points have been obtained,

two of which are below and twoof which are above the normally occurs 1n the current luminometer.

ence fuels at a constant rating level.

3,242,497 Patented Mar. 22, 1966 rating level established with tetralin for the instrument as described herein. After each test run the lamp temperature rise in degrees Fahrenheit is manually plotted against the photoelectric cell reading expressed as the luminometer meter reading to obtain a curve representing flame radiation vs. temperature rise. Similarly, samples of ASTM reference fuel grade isooctane are run.

A rating level is obtained using tetralin This rating level corresponds to the luminosity at the flame height where a luminous tail (trace of smoke) just breaks out of the tip of the flame. The luminometer Number of the test fuel is then calculated as follows:

A T test fuel A T tetralin A T isoo ctane A T tetralin Luminometer Number= unit against the temperature rise across the burner measured by the diiference between a thermocouple placed just above the flame and a thermocouple which measures ambient temperatures. The temperature rise at the rating level is compared with that obtained on a pair of refer- To insure that the rating level is the same in all units it is defined as the smoke point of tetralin. Luminometer Number is calculated from the difference in temperature rise between the test fuel and the temperature rise for tetralin divided by the dilference in temperature rise for isooctane and tetralin.

From the above description it is apparent that the conventional determination of Luminometer Numbers requires the constant presence of a highly skilled operator, takes a great deal of time, and presents a decided opportunity for variants in results due to variations in the skill of the operator.

It is an object of the present invention to automatically and by electronic means determine and record necessary values for determining Luminometer Numbers.

It is a further object of the invention to reduce manhour requirements needed to accurately determine Lumisensing elements' In the preferred form of this invention, the basic operation of the ASTM-CRC luminometer in its original form -is in no way afiected. The new components which make up the preferred version of the invention are simply installed in and connected. to the original luminometer. Thus, it is possible by employing the apparatus and technique of the invention to provide an automation package for luminometers presently in use or luminometers to be obtained in the future with a minimum of modifica tion to the basic unit.

An additional feature of the invention is means to overcome zero or base line drift errors. In the current model commercial luminometer, the photocell meter must be repeatedly zeroed by an adjusting control located below the left-hand side of the meter because of the drift which These drift conditions are caused by the presence in the photocell circuit of'a D-.C. amplifier which is subject to drift. In the automated luminometer of the invention a floating zero is The drawings are now referred to. FIG. 1 is a schema Thus, the photocell output drives the Y axis and the thermocouple output drives the X axis of the X-Y recorder.

.Thewick drive motoris shown as block 5, and block 6 shows the zero check control unit. Both wick drive motor, block 5, and the zero check control unit, block 6,

are physically mounted inthe luminometer, block 1.

X-Y recorder, block 4, has been provided with three miniature, snap-action switches which are mounted on the X-Y recorder in such a manner as to initiate and stop the X-Y recording at preselected positions as well as to record automatically the floating zero and to reverse wick direction in order to return the wick to its original position. These miniature, snap-action switches after return of the wick to its original position also shut off the luminometer apparatus automatically.

Reference'is now made to FIG. 2 which shows the worm gear and clutch arrangement which enables the wick drive motor to power the upward and downward operation of the wick. Thus, in FIG. 2 motor 5 is rigidly attached with four bolts in a vertical wall 11 of the commercial luminometer 1. Drive shaft 12 extends horizontally from motor 5 through an aperture of wall 11, and through an aperture in lamp assembly 15. The portion of drive shaft 12 extending through lamp assembly is supported by ball bearings mounted in the aperture in said lamp apparatus 15. Drive shaft 12 has mounted thereon a helical, threaded worm 13 which meshes in sliding contact with a concave face gear ring 14 which is free to rotate in a slot in the base of lamp assembly 15. Gear ring 14 has internal threads engaged with mating external threads on sleeve 19 of lamp assembly 15. Rotation of gear ring 14 causes sleeve 19 to raise or lower depending on the directron of rotation. Gear ring 14 is identical to the knurled ring of the commercial luminometer except that the perimeter of the knurled ring is replaced by a cut gear. Sample .holder 19A containing fuel and a wick is detachably mounted in sleeve 19 so that raising or lowering sleeve 19 causes concomitant raising and lowering of sample holder 19A and its wick. At the end of drive shaft 12 is detach- .ably mounted annular knob 16. When clutch 17 is released by means of thumbscrew 18, drive shaft 12 can be rotated about its lateral axis by turning annular knob 16 thus causing sleeve 19 to be raised or lowered manually as desired.

FIG. 3 shows X-Y recorder, block 4. Upon carriage 20 of said X-Y recorder 4 is rigidly mounted rod 21. Rod 21 is attached to carriage 20 by metal posts 22 and 23 in such a manner that rod 21 is about A" above and uni- .21 are miniature snap action switches 24 and 25. Pen

assembly 26 of X-Y recorder 4 is provided with plastic camming lug 27 which adjusted so as to actuate miniature snap action switch 24 and miniature snap action switch in succession when pen assembly 26 passes beneath said miniature snap action switches. At the upper portion of carriage 20 located proximate to overhang 28 of X-Y recorder 14 is rigidly attached camming lug 29.

-Slidably mounted on overhang 28 is miniature snap action controlled by said switches.

.formly parallel to the lateral axis of carriage 20 throughout the entire length of rod 21. Slidably mounted on rod FIG. 4 is now referred to. It shows a schematic wiring diagram of the electrical components comprising a preferred version of the automatic luminometer. In FIG. 4 the parts shown in the wiring diagram which are physically located in blocks 1 to 6 of FIG. 1 are marked and labeled to correspond to the blocks of FIG. 1. It will be understood that such labeling of the schematic wiring circuit is only for the purposes of locating physically those components of the wiring system corresponding to the block diagrams of FIG. 1 and in no way affects the relationships of the circuit elements. The basic circuit elements used in FIG. 4, their symbols and where available commercially, if significant, are listed as follows. (All positions are shown unactivated unless otherwise indicated.)

AUTOMATIC LUMINOMETER COMPONENTS Bat6 volt, dry cell C1200 R, 3 WVDC Electrolytic (Sprague TE-l064) F1-5 amp. fuse L1-NE51 pilot lamp L2--6 v. pilot lamp MSl, 2, 3Cat. No. lSX1-T Basic Subminiature Microswitch with Cat. No. JX-25 Roller Lever Actuators (Microswitch Div., Minneapolis-Honeywell) PBl-Pushbutton, DP (double pole) momentary contact PB2-Pushbutton SP (single pole) momentary contact POT1Potentiometer, 10 turn precision 50 Kn POT2Potentiometer, 50 KS2 R1--Resistor, 7 megn R2--Resistor, 18009 R3Resistor IOKQ RYl, 2, 3, 4, 6Relay, DPDT (double pole double throw), 110 volt, A.C. (Potter & Brumfield KRPllAG) RYS, 7--Relays, 3 PDT (triple pole double throw) 110 volt, A.C.- (Potter & Brumfield KRP14AG) RY9-Relay, SPDT (single pole double throw), 2000 S2 coil, D.C. (Kurman 5D1 CA 40D) RY8-Relay, time delay, 12 sec. (Amperite) SWl-Switch, DPST (double pole single throw) SW2, 5Switch, SPDT (single pole double throw) SW3, 4Switch, DPDT (double pole double throw) SW6-Switch, SPST (single pole single throw) Wick-drive-Servo-Tek Velocity Servo, Model ST-536-I Motor and control-6 r.p.m.

X-Y recorder-Electro Instruments Model 400 X-Y recorder with model 421 general purpose modules Line-Connected to 110 AC. source WP1Wire pair 1, shielded cable leads from X-Y recorder 4 connected to the thermocouple circuit WP-2Wire pair 2, shielded cable leads from X-Y recorder 4 connected to the photocell circuit WP-S-Wire pair 3, shielded cable leads from the photocell circuit connected to the zero circuit.

Operation A new fuel sample and wick are put in sample holder I 19A which is mounted in sleeve 19 of lamp assembly 15.

The wick is then lighted and positioned so that a suitable flame is visible in lamp assembly 15. The positioning is accomplished by turning thumbscrew 18 to disengage clutch 17 of wick drive motor 5 and manually rotating drive shaft 12 by knob 16. After the flame characteristics have been adjusted, clutch 17 is re-engaged. The pen 26A on X-Y recorder 4 is positioned manually so that it is located in the lower left quadrant of the chart area. The location of the pen on the X (temperature) axis is adjusted to fall in the general range of the fuel to be tested. i

Switch SW-l is turned on which causes pilot light L1 to go on.

Switches SW-2, SW-S, and SW-4 are activated to the automatic mode. The actions of these switches are as follows:

With SW-3 in the manual mode, SW-2 controls direction of the wick drive motor. With SW-3 in the automatic mode, SW-2 must also be in the automatic mode. SW-3 and SW-4 control the power to wick drive motor -5 and the X-Y recorder 4, respectively, in both the manual and the automatic mode positions. When SW-3 and SW-4 are in the manual mode, then power is supplied directly from the line to wick drive motor control 2 and X-Y recorder 4. When SW-3 and SW-4 are in the automatic mode position, power is supplied only when relay RY-l is activated.

Switch SW-S, which is connected to the pen remote terminals of X-Y recorder 4, is turned to the automatic mode connecting terminal A with terminal B. This con trols the operation of the pen.liftand pen down on the X-Y recorder through the action of relay RY-6. By this means, the pen 26A is allowed to write only during that'period when the data of interest are to be plotted. When automatic pen control is not required, switch SW'5 is operated so that terminal B is connected to terminal C thus shorting the pen remote terminals'directly. Switch SW-6, mounted on the front panel of the CRC Luminometer 1-, is placed in the automatic mode position indicated by pilot light L-2; pilot light L-2 goes out as soon as the automatic run is started as described below. The automatic mode for switch SW-6 is closed.

On X-Y recorder 4, the function selector switch is placed in the pen down position. On the temperature indicating unit mounted as an integral part of the CRC Luminometer (referred to as Minimite), the function switch is turned to the OFF position. This prevents electrical interaction between the above unit and the balancing system of the X-Y recorder 4. On the luminosity measuring unit, mounted as an integral part of the CRC Luminometer 1, the function-switch is turned to the TEST position.

Forward speed is controlled by potentiometer, POT-1 and is set to duplicate the rate of luminosity increase specified in the ASTM Procedure. The reverse speed is controlled by POT-2 and is run at the maximum available'for the particular drive system employed, and is not critical.

1 Operation is startedby momentarily pressing switches PB-l and PB-2. On pressing switch-PB-1, relays RY-1 to RY-S inclusive are energized and maintained in the energized position by interaction of relays RY-l and. RY- 2 and switch MS-l.

The functions of the relays RY-l to RY-5 are as follows:

RY-1-Transmits line power to the-various components.

RY2-Causes relays RY-3, RY-4, RY-S to pull in (activated position).

RY-3 and RY-4-are polarity reversing switches for the wick drive motor 5.

RY5Selects speed for forward (slow) and (fast) operation of the wick drive motor 5.

On pressing switch PB-Z, relay RY-7 is activated and maintained in the energized position through switch MS-3. Relay RY-7' through normally closed time delay reverse relay RY-S causes deactivation of RY-9. This causes the electrical signal from'the photoelectric cell to be connected to Y axis input of X-Y recorder 4. After this sequence of operations the apparatus is now on automatic operation and no operator attention is required until completion of the run.

. The sequence of events during the automatic period of operation is as follows:

continuous function of the electrical luminosity signal from the photoelectric cell (Y axis) and the electrical temperature rise signal from the thermocouple circuit (X axis).

After the luminosity signal reaches a preset value close to the rating level, miniature snap action switch MS-2 (24), mounted on carriage 20 (Y axis) of the X-Y recorder is momentarily opened. This causes relay RY-7 to become deactivated, thus reactivating relay RY-9, which returns the output of the luminosity circuit to ground potential through resistor R-l. Time delay relay RY-8 has a heater circuit which is activated at this time causing contacts in relay RY-8 to open after about 10 seconds. The opening of relay RY-8 deactivates relay RY-9, which removes the luminosity circuit from ground potential through resistor R-1 and the luminosity circuit is reconnected to the Y axis of X-Y plotter 4.

The opening of miniature snap action switch MS2 (24), with subsequent deactivation of relay RY-7, reactivation of' relay RY-9 and activation of relay RY-8 provides a reference value for zero luminosity and thus corrects for any drift in the DO. amplifier in the photocell circuit of the commercial luminometer 1. The described relay circuit to provide a reference value for zero luminosity can be omitted if the DC. amplifier of the photocell circuit is one which has substantially no tendency to drift. Resistor R-l has the exact value as the input resistor of the voltage dividing circuit between the photocell and the first amplifier tube of the conventional luminometer.

After the luminosity reaches a preset value above the rating level, miniature snap action switch MS-3 (25), mounted on carriage 20 (Y axis) of the X-Y recorder 4 is momentarily opened. This action deactivates relay RY-2, which in turn causes deactivation of relays RY-3, RY-4, RY-S, and RY6. Relays RY-3 and RY-4 cause a reversal of polarity on wick drive motor 5 which causes a reversal in the direction of rotation of wick drive motor 5. Relay RY-5 by switching from POT-1 to POT-2, causes the speed of wick drive motor 5 to increase from SLOW to FAST. Relay RY-6 on deactivation causes pen assembly 26 on X-Y recorder 4 to go into lift position, thus preventing plotting of data during the wick retracting operation.

On return of carriage 20 toward its initial position miniature snap action switch MS-l (30) is operated to momentarily break contact between terminals B and C of miniature snap action switch MS-l- (30). This results in deactivating relay RY-l, shutting off line power from the various components. The automatic luminometer is now in a STANDBY condition and the sample holder 19A containing a wick and used fuel can be removed from lamp assembly 15.

The unused normally closed contacts on RY-l (not shown in FIG. 4) can be connected to abuzzer or other indicator to signal the end of the run if desired.

The apparatus can also be run manually by activating the appropriate switches in the manual mode as indicated in FIG. 4. Switch SW-6 is open for manual operation. At the point where a zero check is required, switch.SW-6 is closed, then returned to open.

While a variable speed type motor has been employed as shown on FIGURE 4, any reversible drive system capable of being operated at a low, fixed, forward speed and a high, fixed, reverse speed would be suitable. For manual operation (indicated in parenthesis in FIG. 4) switch SW-2 is put in the forward and reverse positions as desired. Also, while drive shaft 12 with annular knob 16 mounted thereon as shown in FIG. 2 is inside the housing of the commercial luminometer, drive shaft 12 can be extended horizontally through an aperture in the exterior wall of commercial luminometer 1. Annular knob 16 is then mounted on the portion of drive shaft 12. extending through the exterior wall. Thus, manual lowering and raising of the wick is facilitated.

In brief, with each automatic run of the automated luminometer a value can be obtained which is used to caleulate a Luminosity Number.

It will be understood that, although the above-described preferred embodiment of the invention employs an X-Y recorder, other recorder types can be suitably modified to perform satisfactorily. Moreover, in lieu of a single recorder which is preferred, provision can be made to use two or more single input strip recorders which are synchronized in time. Also many different kinds of switches can be used on the recorder.

It is also an advantage of the invention that a continuous curve or record is produced from which more complete interpretation of combustion characteristics can be obtained.

The term actuate, as used herein, refers to both activating and deactivating all switches and relays as well as opening and closing all switches'and relays.

Although the foregoing specification has described the invention with a certain degree of particularity, it will be understood that modifications and variations therein can be employed without departing from the spirit of the invention as hereinafter claimed.

What is claimed is:

1. Automatic recorder control apparatus for automatically controlling the limits of a legible record upon a chart of said recorder, comprising in combination:

(l) at least one recording instrument having indicating element responsive to variations in electrical signals produced by variation in the measurable magnitude of at least one physical property, and having at least one pen capable of lateral and transverse movement responsive to said indicating elements,

(2) adjustable switching means attached to said recording instrument and adapted to be actuated by movement of said moving pen,

(3) electronic circuit means responsive to said switching means whichcommand said signals produced by said variations in measurable magnitude, comprising:

(a) means for causing variations in the magnitude of said physical property to be measured,

(b) actuating means for causing said pen to be in a write position at a point prior to a range including the magnitude to be measured,

(c) means for causing said pen to be in a non write position at a point subsequent to said range to be measured,

(d) means for shutting E line power to said electronic circuit.

2. An automatic recorder control apparatus according to claim 1 wherein said electronic circuit means responsive to said switching means also commands electromechanical means for regulating the incidence of said physical property.

3. An automatic luminometer comprising in comblnation:

(1) a commercial CRC-luminometer having a sample holder adaptable to hold a liquid fuel, a wick in said sample holder, a photoelectric cell circuit, having a DC. amplifier with substantially nondrift characteristics, adapted to send electric signals proportional to the light intensity of a flame of said wick when ignited, and a thermocouple circuit adapted to send electrical signals proportional to the temperature above said flame,

(2) means to lower and raise said wick in said lamp,

(3) recorder means having a movable carriage upon which is mounted a movable pen responsive to both said signal from said photoelectric cell and said signa from said thermocouple, a

(4) electronic circuit means comprising:

(a) means for actuating said means for raising said wick,

(d) actuating means for said means for lowering 7 said wick, (e) means for shutting off line power to said electronic circuit.

4. An automatic luminometer according to claim 3 wherein the DC. amplifier of the photocell circuit of said CRC-luminometer has drift characteristics and wherein said electronic circuit also has means for obtaining a reference value for zero flame luminosity at a point close to the rating level.

5. An automatic luminometer according to claim 3 wherein said means of lowering and raising said wick in said lamp is a reversible drive system capable of being operated at both forward and reverse speeds and said means being positioned with respect to said lamp so as to cause upward and downward movement of said wick assembly.

6. An automatic luminometer according to claim 4 wherein said means of lowering and raising said wick in said lamp is a reversible drive system capable of being operated at both forward and reverse speeds and being positioned wtih respect to said lamp so as to cause upward and downward movement of said wick.

7. An automatic luminometer according to claim 3 wherein said recording means is an X-Y recorder having a'pen carriage parallel to the Y axis.

8. An automatic luminometer according to claim 4 wherein said recording means is an X-Y recorder having a pen carriage parallel to the Y axis.

9. An automatic luminometer according to claim 7 wherein said actuating means for causing said pen to be in a write position at a point prior to the rating level is a relay circuit actuated by an adjustable switch positioned so as to be actuated by movement of said pen carriage.

10. An automatic luminometer according to claim 8 wherein said actuating means for causing said pen to be in a write position at a point prior to the rating level is a relay circuit actuated .by an adjustable switch positioned so as to be actuated by movement of said pen carriage.

11. An automatic luminometer according to claim 9 wherein said actuating means for causingsaid pen to be in a nonwrite position is a relay circuit actuated by a switch adjustably mounted on said pen carriage so as to be actuated by movement of said pen.

12. An automatic luminometer according to claim 10 wherein said actuating means for causing said pen to be in a nonwrite position is a relay circuit actuated by a switch adjustably mounted on said pen carriage so as to be actuated by movement of said pen.

13. An automatic luminometer according to claim 11 wherein said actuating means for said means for lowering said wick is a relay circuit actuated by said switch adjustably mounted on said pen carriage.

14. An automatic luminometer according to claim 12 wherein said actuating means for said means for lowering said wick is a relay circuit actuated by said switch adjustably mounted on said pencarriage.

15. An automatic luminometer according to claim 14 wherein said means for obtaining a reference value for zero flame. intensity at a point close to the rating level is a relay circuit actuated by movement of said pen.

16. The automatic luminometer according to claim 15 in which the relay circuit comprises:

(a) switching means actuated bysaid pen,

(b) first relay means actuated by said switching means,

(c) second relay means actuated by said actuation of 9 10 said first relay means, said second relay means being References Cited by the Examiner adapted to cause grounding of said photoelectric cell UNITED STATES PATENTS circuit upon actuation through a resistor means, said resistor means having substantially the same resist- 2651400 9/1953 Young et 'ance as a similar resistor in the luminosity amplifier 5 2661260 12/1953 salzman 346 65 circuit, I OTHER REFERENCES time delay relay means adjusted so as to be actu- ASTM Test D 1740401", 1961 Book of ASTM Standated at a predetermined time after actuation of Said ards Part 7. Published by American Society for Testing first relay means and positioned in said relay circuit and Mat ria (PP- (Copy in Scientifi Li. so that upon actuation said second relay means is 10 brary.)

actuated and said photoelectric cell circuit is removed from said grounding connection. LEO SMILOW, Primary Emminer-

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2651400 *Aug 10, 1950Sep 8, 1953Trenholm Jr John BGraph plotting machine
US2661260 *May 23, 1950Dec 1, 1953American Cyanamid CoMultiple range recorder
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
USRE31896 *Jan 21, 1982May 21, 1985National Research Development Corp.Chart recorders
Classifications
U.S. Classification346/29, 346/111, 356/227, 200/56.00R, 346/139.00R
International ClassificationG01D9/40, G01R13/00
Cooperative ClassificationG01R13/00, G01D9/40
European ClassificationG01D9/40, G01R13/00