US 3900816 A
Description (OCR text may contain errors)
United States Patent [191 Kiyono ELECTROMAGNETIC DRIVEN VARIABLE RESISTANCE DEVICE [75} Inventor: Tetsuhiro Kiyono, WakuyaJapan Japan  Assignee: Alps Electric Co., Ltd., Tokyo,
Japan 221 Filed: on. 29, 1974  Appl.No.:5l8,950
[ Aug. 19, 1975 Attorney, Agent, or FirmGuy W. Shoup 5 7] ABSTRACT An electromagnetic driven variable electrical resistance device has a variable resistor mounted onto the front side of a case and provided with a rotatable shaft to which a drive-gear is attached. A pair of solenoids are mounted onto the bottom panel portion of the case. A pair of movable driving-pawl members are pivotally supported by the recess portions of an E-shaped spacer attached to the case and are biased by a pair of spring'means and held in an upper limit position by a T-shaped stopper plate. A wide blade portion of each driving-pawl member is positioned above each solenoid respectively The T-shaped stopper plate has a central projecting blade-portion borne by the rotatable shaft of variable resistor. Each of the movable driving-pawl members is twisted. The E-shaped spacer is made of non-metallic material and has a thin central flap-portion and a pair of thick side flap-portions.
6 Claims, 9 Drawing Figures PATENTEU AUGIQISYS 1900,5316
SIIIU 2 IF 2 ELECTROMAGNETIC DRIVEN VARIABLE RESISTANCE DEVICE This invention relates to a variable resistance device, and more particularly to a variable resistance device adapted for remote control and driven by an electromagnetic mechanism.
Recently, in television and radio receivers, it has been desirable to make one or more adjusting means operable by remote control, e.g., the sound volume control. Consequently, there has arisen a need for a variable resistance device which can be operated remotely as well as manually. A currently popular remote control system makes use of pulsative control signals typically transmitted by ultrasonic means. Therefore it is required that such a variable resistance device have a mechanism discretely driven by remote control means, and be able to complete the reciprocating action necessary for each discrete drive-step, accurately at a considerably high speed, and in accordance with each remote control pulse-signal. Furthermore, to facilitate efficient production and easy mounting, the variable resistance device must be of a simple and compact construction.
An objective of this invention is to provide an electromagnetic drive-variable resistance device able to fulfill the above-described requirements. In detail, a further objective of this invention is to provide an electromagnetic driven variable resistance device having an electromagnetic gear-drive mechanism in which the reciprocating action of driving-pawl members is completed smoothly at high speed in accordance with each of remote control pulse-signals.
According to this invention, an electromagnetic driven variable resistance device comprises a case, a variable resistor mounted onto the front face of the case, a drive-gear attached to the rotatable shaft of the variable resistor, a pair of solenoids mounted onto the bottom panel portion of the case, a pair of movable driving-pawl members of magnetic material which are pivotally mounted in the recess portions of E-shaped spaces and have a wide blade portion positioned above each solenoid respectively. A T-shaped stopper plate, for position-limitation of the movable driving-pawl members, is attached to the case. The drive-gear is rotated intermittently when either of the movable driving-pawl members is moved to strike a tooth of the drive-gear by the driving-pawl-portion thereof.
Furthermore, according to this invention, the T- shaped stopper plate has a central projecting bladeportion which is borne by the rotatable shaft of the variable resistor so as to secure a predetermined movement-distance of the movable driving-pawls.
Still further, according to this invention, the driving pawl-portion of each of the movable driving-pawl members, which engages with the drive-gear, is twisted so that the driving pawlportion contacts with a tooth of the drive-gear by a lessened contact-area on the way of returning-action thereof, that causes a decrease in friction and therefore results in the smooth retumingaction of the driving-pawl member.
Still further, the E-shaped spacer is made of nonmetallic material so as to decrease operational noise and is made to have a thin center flap-portion and a pair of thick side flap-portions so as to permit the movable driving-pawl members to return to a correct position for the next driving-action thereof.
FIGS. 1 to 8 illustrate a preferred embodiment of the electromagnetic driven variable resistance device according to this invention:
FIG. 1 is a side view thereof,
FIG. 2 is a partially sectional side view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a sectional view thereof taken along lines A, A in FIG. 4;
FIG. 6 is a sectional view of a part thereof for illustrating the relationship between the solenoid and the movable driving-pawl member;
FIG. 7 is a perspective view thereof, partially broken away, for illustrating the mounting-state of the movable driving-pawl member; and
FIG. 8 is a schematic diagram for illustrating the operation thereof.
FIG. 9 illustrates another embodiment of the electromagnetic driven variable resistance device according to this invention.
Referring now to FIGS. 1 to 8, in which there is shown an embodiment of the electromagnetic driven variable resistance device according to this invention, a case 1 having a rectangular shape which is constructed of sheet metal which is bent into the form shown. Variable resistor 2 is mounted onto the face panel-portion la of case I and comprises a cover 3, in which a resistance element and a sliding tap (not shown) are mounted, and a rotatable shaft 5 which has a projecting portion 4 projecting rearwardly through cover 3. The value of the resistance of variable resistor 2 is varied by rotating the shaft 5. Drive-gear 6 is fixedly mounted onto projecting portion 4 of rotatable shaft 5, so that the gear 6 rotates along with shafts. The drive gear 6 is made of, for example, synthetic plastic resin.
A pair of solenoids 7 and 7' are mounted onto the bottom panel-portion 1c of case 1 and are parallel to the rear panel-portion 1b of case 1.
As shown in FIGS. 6 and 7, each solenoid 7, 7' is comprised of an iron core 1 1, a cylindrical bobbin 8 of synthetic plastic resin and a wire coil 9 wound onto the bobbin. The pair of winding-ends of coil 9 are respectively connected to a pair of terminals 10 and 10 fixed into bobbin 8. The top flange-portion 1 la of iron core II is received in the expanded opening-portion at the upper end of bobbin 8, as shown in FIG. 6, and the top thereof is slightly lower than the upper edge 8b of bobbin 8.
As can be seen in FIG. 5, a T-shaped stopper plate 12 of synthetic resin, which comprises central projecting blade-portion 12b and a pair of wing-portions 12a and 12a, is attached into case 1 by fitting the ends of wingportions 12a and 12a into slots provided in both sides of panel-portions 1d and 1d of case 1 and by inserting projecting portion 4 of rotatable shaft 5 of variable resistor 2 into the hole of central projecting blade-portion 12b.
An E-shaped spacer 13 of rubber or other resilient material is attached to case 1 such that the spacer 13 covers the upper portion of rear face panel-portion 1b of case 1 as shown in FIG. 7. Central flap-portion 13a thereof is formed thin and a pair of side flap-portions 13b and 13b are formed thick, and therebetween a pair of recess-portions 13c and 13c are provided.
As shown in FIG. 7, movable driving-pawl members 14 and 14 are formed, for example by stamping, from a plate of magnetic material, such as a steel metal plate. Each driving pawl 14, 14' has a driving-pawl-portion 14a, a wide blade-portion 14b, neck-portion 14c and spring-retaining portion 14d. Each of the movable driving-pawl members 14 and 14 is positioned above each of solenoids 7 and 7 The neck-portion 14c thereof being put into recess-portion 130 of spacer l3 and driving-pawl-portion 140 being positioned in recess-portion 120, so that the pawl-end of driving-pawl-portion 14a is set at the position engageable with a tooth of drivegear 6 and wide blade-portion 14b thereof is set at the opposite position to iron core 11 of the corresponding solenoid. Coil springs 15 and 15 are connected between springretaining portion 14d of the corresponding driving-pawl member and projection 1f provided at the side edge of side panel-portion Id of case 1, respectively. Accordingly, each of the movable driving-pawl members 14 and 14' is pivotally biased around recessportion 13c as a pivot, that is; spring-retaining portion 14d is pulled obliquely down toward side panel-portion 1d of case 1 by coil spring 15 with neck-portion 14c acting as a fulcrum, and driving-pawl-portion 14a lifted obliquely upwards and held in an upper limit position by the corner of recess-portion 120 of stopper plate 12. Projections If and 1f of case 1 are formed to have a curved face-portion with a curvature nearly equal to that of ring-hooks 15a and 15a, to prevent deformation of ring-hooks 15a and 15a.
Furthermore, as shown in FIG. 8, driving-pawlportion 140 of movable driving-pawl member 14 is slightly twisted in the counter-clockwise direction and that of movable driving-pawl member 14' in clockwise direction. This decreases friction when driving-pawlportion 14a is removed from drive-gear 6 after driving engagement therewith, thereby securing a more stable rotation of drive-gear 6 and reducing the possibility of improper operation.
In the following description, the operation of the above-described electromagnetic driven variable resistance device embodying this invention will be made clear. It will be assumed that the invention is used for sound-volume control in a television or radio receiver. That is, sound-volume is adjusted manually by rotating rotatable shaft and remotely by supplying current pulses into solenoid 7 or 7'.
In the manual operation mode, or during nonoperating intervals in the remote operation mode, driving-pawl-portions 14a and 14a of movable drivingpawl-members l4 and 14' are at position X in FIG. 8 so that drive-gear 6 is freely rotatable. Rotatable shaft 5 can be rotated for manual sound control. In this state, assuming that a current pulse is supplied to solenoid 7 for remote control, solenoid 7 is thereby magnetized and will attract movable driving-pawl member 14 downwards and pivotally move it against coil-spring with neckportion 14c acting as a fulcrum, so that driving-pawl-portion 14a thereof falls vertically and then engages a tooth of drive-gear 6 as shown by position Y in FIG. 8. At this position, since driving-pawl-portion 14a is slightly twisted, the lower face thereof goes in face-contact with the inclined surface K of the tooth. Then, movable driving-pawl member 14 is further pulled down by solenoid 7 thereby moving drivingpawl-position 14a to position Z shown in FIG. 8, to rotate drive-gear 6 one step. Thus, rotatable shaft 5 is slightly rotated by the one-step-rotation of drive-gear 6 in the clockwise direction so that sound-volume is slightly increased.
ln the above-described operation, driving-pawlportion 14a falls non-vertically from position Y to position Z in H6. 8, that is, its movement defines a circle, with neck-portion 14c acting as a fulcrum, in accordance with the rotation of drive-gear 6. When drivingpawl-portion 14a moves to position Z, wide bladeportion 14b of movable driving-pawl member 14 strikes the upper edge 8b of bobbin 8 and driving-pawl-portion 14a is thereby stopped from further falling movement. At this position, driving-pawl-portion 14a is in linecontact with the tip of a tooth of drive-gear 6 on the side face thereof, as shown in FIG. 8.
As soon as the current pulse supplied to solenoid 7 comes to extinction, the magnetic force of solenoid 7 ceases and driving-pawl-portion 14a is lifted by the biasing force of coil-spring 15 in the direction shown by the arrow in FIG. 8 and returns to position X. Accordingly, if a series of current pulses are supplied to solenoid 7 so as to intermittently excite it, driving-pawlportion 14a of movable driving-pawl member 14 will rotate drive-gear 6 step by step, so that sound-volume is gradually increased.
On the other hand, if current pulses are supplied to solenoid 7', driving-pawI-portion 14a of movable driving-pawl-member 14' will rotate drive-gear 6, and thereby rotate shaft 5, in the counter-clockwise direction step by step, so that sound-volume is gradually decreased.
Turning now to FIG. 9, in which there is shown another embodiment of this invention, driving-pawlportion 14a of each of movable drivingpawl members 14 and 14' is twisted to an angle of such that smooth face T thereof, which is not corresponding to sections S and S made by stamping, comes in contact with the tip of a tooth of drive-gear 6 when returning from driving engagement thereof.
As described above, according to this invention, since stopper plate 12 has a central projecting bladeportion 12b which is borne by projecting portion 4 of rotatable shaft 5, the distance from rotatable shaft 5 to recess-portion 12c of stopper plate 12 will be a fixed length and consequently it will be possible to secure a uniform path of operation of movable driving-pawl members 14 and 14 in the manufacture of the invention to insure stable step by step rotation of drive-gear 6 therein.
Furthermore, since driving-pawl-portion 14a is so twisted as to make line or smooth contact with a tooth of drive-gear 6 when returning from driving engagement thereof, friction therebetween will be greatly decreased and the returning action of driving-pawlportion 14a will cause no rotation of drive-gear 6. This insures a reliable rotation of drive-gear 6. Additionally, since E-shaped spacer 13 for pivotally supporting movable driving-pawl members 14 and 14' has central flapportion 13a formed thin and both side flap-portions 13b and 131) formed thick, each of movable drivingpawl members 14 and 14 can be biased so that drivingpawl-portions 14a thereof will move toward the center when returning to its upper-limit position, as can be seen in H05. 1 and 8. This will also insure reliable ac tion in each succeeding rotation-step of drive-gear 6.
In addition, since stopper plate 12, bobbin 8 and spacer 13 are made of non-metallic material, it will be possible to decrease operational noises.
The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be efi'ected within the spirit and scope of the invention as described above and as defined in the appended claims.
What is claimed is:
1. An electromagnetic driven variable resistance device comprising a case having side walls,
a variable resistor provided with a rotating shaft and mounted onto one side-face of said case,
said shaft being rotatable to vary resistance value of said resistance device,
a drive-gear rotatably mounted on said rotating shaft,
a pair of electromagnetic solenoids mounted to said case and having electrical terminals,
a pair of movable driving-pawl members made of magnetic material each of which is pivotally mounted in relationship to said solenoid and positioned above said solenoids and able to engage a tooth of said drive-gear so as to rotate said drivegear,
a stopper plate attached to said case for positionlimitation of said pair of movable driving-pawl members, and
a spacer being attached to said case for pivotally sup- 6 porting said pair of movable driving-pawl members, said stopper plate and said spacer being made of nonmetallic material. 2. A variable resistance device as set forth in claim 1, wherein said stopper plate has a central projecting bladeportion which is born by said rotating shaft of said variable resistor.
3. A variable resistance device as set forth in claim 1, wherein said movable driving-pawl member is twisted at the driving-pawl-portion thereof which engages with a tooth of said drive gear.
4. A variable resistance device as set forth in claim 1, wherein said spacer being an E-shaped.
5. A variable resistance device as set forth in claim