US2822781A - Electric pencil sharpener - Google Patents

Description

Feb. 11, 1958 E. F. BURTON 2,822,781

ELECTRIC PENCIL SHARPENER Filed Jan. 22, 1951 VIII/I JNVENToR. {an/Ae@ /7' 50e/'0N imgj United States Patent() F 2,822,781 ELECTRIC PENCIL. ASHARPENER Edward F.*Burton, Los Angeles, Calif. Application January 22, 1951, Serial No. 207,213 2 Claims. (Cl. 1Z0-96) This invention relates `to pencil Sharpeners and more particularly to power operated Sharpeners of the electric type having means to start and stop the motor automatically upon insertion and removal of a pencil.

Various automatic pencil Sharpeners have previously been proposed but they have not been commercially successful because they were too costly or complicated or failed after short periods of service. The present invention overcomes the various defects of prior art devices and provides an extremely simple machine which utilizes the most inexpensive electrical components available, at the same time giving maximum service and dependability.

One of the principal features of the device is the complete segregation of the cutting or sharpening mechanism from both the motor and the switch so that the wood Vshavings and more particularly the graphite particles produced in the sharpening operation cannot lbe deposited on either the motor or the switch. This makes it possible 'to use unencased, or skeleton type, motors and switches,

lthus greatly reducing the cost and making itfpossible to ymarket the machine at a price which the public will pay.

The machine includes a generally elongated casing lclosed at one endy and open at the bottom and at the other end, the second end being covered by a removable closure plate. A second plate closes the bottom of the casing. A vertical partition is provided at about the -midpoint of the casing, dividing it into two horizontally adjacent compartments, one containing the skeleton motor and the other containing the'sharpening'mechanism. Thus the wood shavings and graphite particles from sharpened pencils fall directly by gravity into a drawer located below the sharpening mechanism and the partition prevents them from being thrown or deposited on the motor.

#A snap action switch is carried by a second casing located externally of the closure plate and it is likewise completely protected from the deposit of wood shavings and graphite particles. The switch is operated by an actuator which traverses the opening provided in the closure .plate for access to thesharpening mechanism. When a pencil is inserted in the Sharpener it displaces the actuator before it reaches the cutting elements and closes the. switch, starting themotor so that the mechanism is running at full speed before the pencil contacts the cutting elements. This permits the use of a low starting torque motor, such as the shaded pole induction type, which is practically the most inexpensive type of motor obtainable.

The actuator cooperates with a portion of the closure plate to act as a pair of guide members to yieldably hold the pencil in substantial alignment with the axis of rotation of the mechanism during the sharpening operation and a single combination of guide members properly holds all of the usual sizes of pencils. Since the one .guide memberv is "stationary, the displacement of the actuator by the pencil is 'doubled and its movement is adequate even with the smallest size pencil to operate the snap action switch.

These and various other novel features will be more fully explained as the description proceeds. One of the forms which the invention may take is illustrated in the accompanying drawing in which:

Figure Lis a side elevational view in section showing .the relativearrangement of the major parts of the device;

2,822,781' Patented Feb. 11, 1958 Figure 2 is an-end elevational view of the device showing thek pencil opening traversed by the actuator;

Figure '3 is an elevational view of the closure plate taken substantially on line 3-3 of Figure 1 and including a section through the drawer;

Figure 4 is an elevational view of the casing for the switch and actuator taken substantially on line 4-4 of Figure l;

Figure 5 is a perspective view of the actuator; and

Figure 6 is a perspective view of the snap action switch.

The device, as best seen in Figure l, includes a casing or shell 10 having a closed end wall 12 at the left end, as viewed in Figure 1, and being open at the bottom and at the right end as seen in Figure l. A depending vertical partition 14 divides the main shell into two horizontally adjacent but completely segregated compartments 15 and 16. A closure plate 18 its against and completely seals off the open end of the casing.

A support k20, mounted to partition 14 by means of bolt 21, carries a bushing 22 for rotatively receiving one end cf a rotative pencil sharpening mechanism. The closure plate 18 is provided with a boss 23 having a central aperture 24 for passage of a pencil, the aperture being counterbored to carry a bushing 26 receiving the other end of a rotative pencil sharpening mechanism. The4 latter,.generally indicated at 27 is a standard two cutter rotative sharpening mechanism which may be identical with those used in manual pencil Sharpeners. It is provided with a cylindrical journal member 28 which seats in the bearing 22 and -with a shoulder 29 which engages the end of the bearing and positions the mechanism axially. Pinions 31 carried by cutters 32 engage with the internal ring gear 33 to produce rotation of the cutters about their own axes as the mechanism is rotated about its own horizontal axisA A second journal member 34 is provided at the right end of the mechanism to seat in bearing 26 and it is` provided with a shoulder`36 to engage the end of the bearing.

Driving power is transmitted to themechanism by shaft 37, jo-urnaled in bearing 38 and having a squared end 39 seating in a corresponding depression 40 in the end of journal member 23. The electric motor 41 is mounted on bosses 42 carried by end wall 12 so that the armature shaft 43 rotates about a horizontal axis. lts pinion 44 engages gear 46 carried on shaft 47 mounted in bearing 4S in the lower part of depending wall 49. Pinion 51, carried on the opposite end of shaft 46 engages gear 52 which is mounted on drive shaft 37. In addition to bearing 36, the drive shaft is also carried in bearing 53 in wall 49. The pinion and gears are keyed to their shafts in conventional fashion, as by taper pins. It will thus be seen that when the motor is energized it willv drive mechanism 27 through the gear train just described and the cutters 32 will in turn be rotated by virtue of their pinions 31 being engaged with ring gear 33.

To energize the motor, a pair of Wires 54, 56 may be connected to a source of power, not shown, to the motor 41, and to a snap action switch'?, closingof the switch completeing the circuit to drive the motor. r)She switch is a standard type available on the market includes a base 5S, a rst contact member 59, a second contact member 61, an over-center snap `spring contact arm 62 having a contact button 63, and an actuating arm 64. The arm passes through an opening 66 in contact member 61 and when it is depressed a predetermined amount its lower end raises the free end of the spring contact. arm far enough to cause button 63 to snap into circuit closing contact with contact member 59. Continued downward travel of arm 64 merely. keeps button 63 in contact. VOn release of pressure the arm 64 rises to the predetermined point and button 63 then snaps back out of engagement with member 59.

Vdeviation is negligible.

Closure plate 18 is held in engagement with the main casing or shell 1t) by screws 67 and by additional screws, not shown, engaging in laterally located bosses 68 carried 5, bythe shell.V VA semiconical guide section 69 leads to the pencil opening 24 and terminates in a liplike guide member 71 whichoverhangs a portion of the opening. As can be seen in Figure 2 it is generally arcuate and so dimensioned and located as to serve, in cooperation with another part of the device, to hold a pencil in proper alignment. The standard writing pencil, hexagonal or round, has a lateral dimension 4of nine thirty-seconds of an inch, a stenographic pencil one quarter inch, and a drafting ,pencil six-sixteenths of an inch. Consequently, if the distance 72 from the axis of rotation of the sharpening mechanism to the top of the arch 'of guide member 71 be made equal to the radius of the standard writing pencil it will then guide `it in exact alignment into the meche anism and will hold the other regular sizes only one sixty-fourth inch out of alignment,` so that the angular The radius of curvature of the guide member is atleast as large as that ofthe largest pencil to be sharpened.

Casing 73 is conformed to tit against the lower outer face of the closure plate and is Isecured thereto by screws 74. `Integral brackets 76 support the switch 57 and a recess 77, `cylindrical in its lower part and rectangular in its upper part is formed to receive an actuator 78 in the form of a plunger having a cylindrical shank 79 with an insulating tip 80 passing through an opening in the recess and a head 81. Spring 82 engages under the head to urge the plunger upwardly and a felt washer 83 under the spring holds lubricant for the shank and prevents dust and graphite from reaching the skeleton switch 57.

The upper side of head S1 has a conical guide section 84 and arcuate guide portion 86 complementary to members 69 and 71 and normally traverses Vand overlies a portion of the opening 24. When a pencil is inserted in the opening it displaces head 81 against the force of the spring and, since the shank 79 is in contact with arm 64 of the switch, its downward movement causes button 63 to snap into contact with member 59 as previously described, energizing the motor and rotating the cutters before the pencil reaches them. Since there is no cutting load when the motor starts it can be a low starting torque type such as a shaded pole induction motor.

Since the spring 82 continually urges the head upwardly it will cooperate with guide member 71 in holding the pencil in substantial alignment with the axis of the sharpening mechanism. The plunger thus serves the dual purpose of guide and switch actuator.

A drawer 88, provided with an inset handle 90, slides into compartment 16 from one side of the casing to receive the shavings and graphite produced in the sharpening operation. Since the drawer tits snugly with all four walls of the compartment all of the cuttings will fall into it by gravity. A plate 92, provided with resilient feet or pads 94, closes the bottom of compartments 15 and 16 and completely encloses and protects the motor.

It will now be seen that the invention provides a compact and convenient fully automatic sharpening device in which the electrical parts are completely isolated from the sharpening mechanism so that they cannot be fouled with pencil cuttings. It also provides a snap switch pre- -starting system which utilizes a low cost, low starting torque motor. It also provides firm and ac-curate guidance `for standard size writing pencils and also for the other usual sizes.

While a snap action switch has been illustrated in the drawing and is highly desirable for reasons of cost and dependability, it is possible to use any circuit making and breaking device, lsuch -as a mercury switch or a spring arm switch. The actuator need not be a slidable plunger but may instead be a pivoted arm, a toggle, or the like.

` It will be apparent that various changes in the details lasaafrsi lte 4 of construction and arrangement of parts may be made without departing from the spirit of the invention and it is intended that all such changes shall be embraced within the scope of the following claims.

Iclaim: 'u

1. Means for controlling the electric motor -of an electric pencil Sharpener of the type that includes a substantially hollow casing open at the one end thereof and including pencil sharpening means, comprising: a quickly detachable, double walled hollow closure plate attached to the casing at said open end so as to close same; means in said closure plate for guiding and supporting a pencil into the casing and into said sharpening means, said guiding means including a fixed pencil supporting jaw and a spring-loadedpencil supporting jaw together defining a pencil receiving aperture adjacent said sharpening means, the latter jaw Vhaving a depending portion; a horizontal bracket portion within said hollow closure plate provided with a vertical guide opening therein; a seal carried on said bracket portion; and the depending portion of said movable jaw slidably extending downwardly through said seal and said guide opening; and a snap action electrical switch mounted between the double walls of said hollow closure member sub-adjacent said depending portion to completely isolate said switch from the electrically conductive cuttings produced by said sharpening means, said switch including a pair of terminals electrically connected to said motor for energizing same and an overcenter snap action circuit-opening and closing member bridging said terminals and lying operatively subadjacent said depending portion so as to be urged over center to close said circuit and operate said motor by said depending portion upon insertion `of a pencil between said jaws, said bridging member being adapted to follow up said spring-loaded depending portion upc-n spring retraction thereof so as to open said circuit and de-energize said motor uponewithdrawal of said pencil.

2. In an electric pencil Sharpener that includes a horizontally elongated integral casing, an integral depending wall dividing said casing into a motor compartment and a sharpening means compartment, an open end on the sharpening means compartment, a vertical wall member detachably secured to said casing and closing said open end of said casing, anV inwardly extending boss on said wall member provided with means for engaging and supporting an end of said sharpening means, a hollow cover member detachably mounted on said wall member, a bracketcarried within said hollow cover member and having a vertically extending guide opening therein, support means carried within said hollow cover member below said bracket, an electrical switch mounted on said support means, actuator means having a depending stem slidably extending downward through said guide opening into contact with said switch means, a portion of said actuator means being exposed to contact by a pencil to be sharpened and movable downward thereby to actuate said switch means, said wall member and cover member cooperating to enclose said switch member and isolate it from electrically conductive cuttings produced by said sharpening means.

i References Cited in the file of this patent UNITED STATES PATENTS

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