US 3678975 A
An electric pencil sharpener including a pencil holding unit provided with a start switch, a motor circuit to which there are connected an electric motor and rotating sharpening mechanism operated by said motor, detecting means for detecting the sharpened condition of a pencil, switching means actuated by said detecting means whereby, upon completion of the sharpening of the pencil to a desired first degree, a lamp is illuminated, and upon completion of sharpening to a second sharper degree, the switching means is operated to open the circuit of the motor to stop it with the lamp remaining illuminated, thereby indicating the end of the sharpening so as to prevent the pencil from being excessively sharpened. A flywheel is coupled to the rotating sharpening mechanism to prevent immediate ceasing of rotation thereof upon opening of the motor circuit.
Description (OCR text may contain errors)
July 25, 1972 United States Patent Imanishi et al.
Masakazu lmanishi; Kenzi Kondou; Ituo Suglura,.al1 of Nagoya, Japan Germany...............,.....:........
e G 1,] 66 99 Ill 35 96 2 21. h -l 0o .11. 1 1
Primary Examiner-Andrew R. Juhasz Assistant Examiner-James F. Coan Attorney-Flynn & Frishauf m L m C k u m E m 0. 8 i mm SL.
.k 3 a kw 0a TK a e n .w s s A M 7  Filed: March 2, 1970  ABSTRACT An electric pencil sharpener including a pencil holding unit  App]. No.:
 Ford!" Application Priority Data provided with a start switch, a motor circuit to which there are connected an electric motor and rotating sharpening mechanism operated by said motor, detecting means for detecting the sharpened condition of a pencil, switching means actuated by said detecting means whereby, upon completion of the sharpening of the pencil to a desired first degree, a lamp is illuminated, and upon completion of sharpening to a second sharper degree, the switching means is operated to open the 4 22 2 M 7.N&7. 8 8 R 3 2 4 I y 4 3M7 00 I n.2,; m m u 8 n 2 8 n M 2 m 4 m .4 ll "84 u ""2 u u u m n n u n m a U u P h a n J u m mum l mmu mm& h G m d 3 SLM M Umw. 11.1 2 8, 555 [.ll.
nmAmm a m B 58 e.1 .ISDDO ngea mm mm m m n. c mu 'm f 3y 0 8 w e m n a vme 0 d h .m c m m F he m n g o o S. n h e u .I .nn m w We Pm m chm D etf et-U00 1 0 8 1 tnmen 9 S i m o u E OC m n e I Onn L C tic O nlm 2 m ep m 1 Pudi er O C eecmf. thh O ttim dtdtm .nm e ee V Vh .n m mh cmPflPo 555 2 888 Run 444 44 44 1.11.4 ""1  References Cited UNITED STATES PATENTS 3,486,540 12/1969 2,561,438 7/1951 Duchesneau 2,408,767 10/1946 Fleming......... 3, l 25,994 3/1964 Ruskin Patented July 25, 1972 4 Sheets-Sheet 1' Patented July 25, 1972 3,678,975
4 Sheets-Sheet 2 Patented July 25, 1972 4 Shoots-Sheet 5 Patented July 25, 1972 4 Sheets-Sheet 4- The present invention relates to an electric pencil sharpener and more particularly to an improved pencil sharpener including means for indicating the sharpened condition of a pencil.
There have heretofore been proposed various types of electric pencil Sharpeners equipped with means for indicating the time at which there has been sharpened a pencil to a desired condition so as to prevent it from being excessively sharpened. With one type, when the operation of sharpening a pencil is brought to an end, a sliding member involved in a rotary sharpening mechanism is made to slide to actuate a switch interlocked therewith and there is lighted a lamp disposed in front of said pencil sharpening mechanism. Another type carries out said lamp indication in two stages according to the extent of sharpening, that is, the case where the core tip of a pencil is sharpened fine and the case where said tip is sharpened relatively thick. A third type indicates the position of the core tip of a pencil to the user by interlocking an indicator with a sliding member. However, the prior art pencil sharpeners indicate by visual means that the core tip of a pencil has been sharpened to a desired size. Accordingly, they have the drawbacks that the user must always watch for the time of such indication and that if he forces a pencil into a sharpener with said indication overlooked or unnoticed then there will be sharpened a pencil to an unnecessary extent. A further disadvantage is that there is a slight interval between the time said indication is given and the time a pencil is actually taken out, thus leading to excessive sharpening and waste.
An object of the present invention is to provide an electric pencil sharpener including means for indicating the completion of the pencil sharpening operation by stopping a motor so as to eliminate the above-mentioned shortcomings encountered with the prior art.
Another object of the invention is to provide an electric pencil sharpener including an improved switching unit for controlling the indication of a completed sharpening operation, and which provides a smoothly sharpened pencil.
This invention can be more fully understood from the following detailed description when taken in connection with the accompanying drawings, in which:
FIG. 1 is a longitudinal sectional view of an electric pencil sharpener according to an embodiment of the present invention;
FIG. 2 is a cross sectional view of a rotary sharpening mechanism involved in the electric pencil sharpener of FIG. 1;
FIGS. 3 and 4 jointly represent a pencil holding unit; FIG. 3 is a sectional view on line 3--3 of FIG. 4 and FIG. 4 is a sectional view on line 44 of FIG. 3;
FIG. 5 is a perspective view of the indicator switch assembly involved in the electric pencil sharpener of FIG. 1;
FIG. 6 is a sectional view of the upper portion of the indicator switch assembly of FIG. 5;
FIG. 7 is a perspective view of the front portion of the electric pencil sharpener of FIG. 1 when uncovered;
FIG. 8 is a sectional view on line 8-8 of the electric pencil sharpener of FIG. 1;
FIG. 9 is a cross sectional view of the sharpening mechanism of an electric pencil sharpener having a cutter holder molded from synthetic resin;
FIG. 10 is a schematic circuit diagram of the electric pencil sharpener of FIG. I; and
FIG. 11 is a cross sectional view of the electric pencil sharpener of FIG. 1, showing the manner in which a pencil is sharpened.
Referring to FIG. 1 showing an electric pencil sharpener, numeral 11 denotes a housing which consists of a base plate 12 and cover 13 disposed thereon. Said housing 11 is separated into a sharpening chamber 100 and mechanism chamber 101 by a partition plate 14 erected at the substantially central part of said base plate 12. In said sharpening chamber 100 are provided a rotary sharpening mechanism 15 and square mounting frame 16 surrounding it. In said mechanism chamber 101 is disposed a motor 17 for driving said rotary sharpening mechanism 15. In front of said mounting frame 16 is positioned a pencil holding unit 18 for clamping a pencil introduced into the sharpener, and behind said frame 16 is fixed an internal gear 19. Said mounting frame 16 is attached to a support member 20 projecting forward from said partition plate 14. Said pencil holding unit 18 contains, as later described, a start switch actuated upon insertion of a pencil, and is further provided with cylindrical members 22 and 23 extending forward and backward respectively from the substantially central part thereof. The front cylindrical member 22 has a screw socket formed on its peripheral surface and screwed to the cover 13 from the outside by a socket member 24. The rear cylindrical member 23 supports said rotary sharpening mechanism 15. Said pencil holding unit 18 has alamp socket 26 formed at the top to hold a lamp 25. At that part of said cover 13 which is disposed opposite to said lamp 25 is formed a lamp window 27 made of, for example, transparent glass or synthetic resin. The lighting of said lamp 25 indicates that the core tip of a pencil has been sharpened relatively thick. The rotary sharpening mechanism 15 consists of a cutter holder 28 shown in FIG. 2 and a cutter 30rotatably fitted to said cutter holder 28 by means of a support plate 29. Said cutter holder 28 has a cavity formed at the substantially central part, a balance weight 32 provided at the front part which is perforated with a threaded bore 31 for allowing said support plate 29 to be screwed in place, a cylindrical pencil entry portion 33 projecting to the front side and a Conical pencil receiving bore 34 coaxially formed in said cylindrical pencil entry portion 33 in a manner to extend up to the aforementioned cavity provided in the cutter holder 28. On the side wall 7 of said cutter holder 28 is cut out a depression 35 in which there are embedded two pins 36. To these pins 36 is slidably fitted a sliding member 37 in the coaxial direction of said pencil receiving bore 34 in such a manner that the front end of said sliding member 37 contacts the rear end of said bore 34 and the rear end of said member 37 contacts the front end of the latter described operating rod 38. At the rear end of said cutter holder 28 is disposed a rotatable shaft 39, which has an elongated bore 40 penetrating its axial center. Into said elongated bore 40 is slidably inserted said operating rod 38. Said rotatable shaft 39 engages a bearing 41 projecting to the rear side of said partition plate 14. Between said cutter holder 28 and partition plate 14 is interposed a thrust washer 42.
As shown in FIG. 2, said cutter 30 assumes a cylindrical shape and has a plurality of spiral blades 43 formed on its peripheral surface. To the rear end of said cutter 30 is tightly fitted coaxially therewith a cutter pinion 44 in engagement with said internal gear 19. Further, said cutter 30 is perforated with a shaft hole 45 penetrating its axial center. Into said shaft hole 45 is inserted a cutter shaft 46, the rear end of which fits into a shaft receiving hole 47 provided at the rear plane of the aforementioned cavity of the cutter holder 28 and the front end of which is supported by said support plate 29. This support plate 29 consists of a substantially elliptical metal plate, and has a hole 48 formed at the substantially central part and two support holes 49 and 50 disposed in an approximately symmetrical relationship with respect to said central hole 48. Said central hole 48 engages said pencil entry portion 33, and said support hole 49 supports one end of said cutter shaft 46 and said support hole 50 serves to fix said support plate 29 to said cutter holder 28 by means of a screw assembly 51 with a washer 52 interposed therebetween. Between said cutter 30 and support plate 29, and between said cutter pinion 44 and cutter holder 28 are disposed washers 53 and 54 respectively. To the rear end of said cutter holder shaft 39 is provided a speed reduction gear assembly which includes a spur gear 55 and pinion 56. The pinion 56 is fixed to the shaft of said motor 17. To said spur gear 55 is concentrically fitted a cylindrical fly wheel 57 in a manner to project forward. This fly wheel 57 serves to slow down the speed at which said sharpening mechanism 15 is brought to rest. Said fly wheel may be fitted to the sharpening mechanism. To a fitting stand 59 mounted on said motor 17 is fixed an indicator switching unit 58 actuated by said operating rod 38. Between the upper edge of said partition plate 14 and cover 13 is provided an elastic shielding member 60 madeof, for example, polyurethane rubber to prevent pencil shavings. from being carried into said mechanism chamber 101. In said sharpening chamber 100 right below said sharpening mechanism 15 is placed a waste case 61 which is free to be inserted into and taken out of theintervening space between said cover 13 and base plate 12.
The mounting frame 16 may assume a U-shape, with the closed end used in receiving said pencil holding unit 18 and both walls of the open end screwed to the partition plate 14. In this case, the internal gear 19 is fitted to the support stand (not shown) of said partition plate 14.
Said pencil holding unit 18 consists, as shown in FIGS. 3 and 4, of a cover 62 and body 63. To these components are projectingly fitted said cylindrical members 22 and 23. Said body 63 contains a cylindrical pencil receiving member 64 extending inward coaxially with saidcylindiical member 23 and is perforated with three arcuate slits 65 equally spaced in the circumferential direction. Into each of said three slits 65 is slidably inserted a pencil holding leg assembly 68 consisting of an arcuate member 66 and leg member 67 projecting inward from the inside of said arcuate member 66 insuch a manner that said arcuate member 66 is disposed around the outer periphery of said cylindrical pencil receiving member 64. At the end of that side of said leg member 67 on which there is inserted a pencil is formed an inclined plane 67a. In said arcuate member 66 is cut out an arcuate groove 69 having a common axial center with said cylindrical pencil receiving member 64. There is stretched a looped coil spring 70 through said arcuate grooves 69 fonned in the arcuate members 66 of said three pencil holding leg assemblies 68 inserted into said pencil receiving member 64 in such a manner that all said grooves 69 are connected to each other by said looped coil spring 70. This looped coil spring 70 is prepared by forming a coil spring into an annular shape and has a tendency to contract itself toward its axial center. Accordingly, said pencil holding leg assemblies 68 are always urged toward the axial center of said pencil receiving member 64. In the body 63 of said pencil holding member 18 is provided said start switch 21 in such a manner that its contact is located right on said pencil holding leg assemblies 68. Said start switch 21 is closed when said pencil holding leg assemblies 68 are displaced in position in the radial direction of said cylindrical pencil receiving member 64.
Theaforementioned pencil holding unit 18 supports a pencil inserted thereinto without eccentrically displacing it, because said pencil holding leg assemblies 68 are subjected to a uniform contracting force acting toward the axial center by looped coil spring 70.
Said pencil holding leg assemblies 68 need not consist of three units, but may be provided in a larger number with equal spacings therebetween around the outer peripheral surface of said pencil receiving member 64.
Said indicator switching unit 58 is used to light an indication lamp and stop the motor. This indicator switching unit 58 consists, as shown in FIGS. and 6, of a switch box 71 and actuating assembly 72. Said actuating assembly 72 consists of an armature lever 74 and a plate spring 75 supported by a common pivot 73. One end of said plate spring 75 is attached to one side wall of said switch box 71, and the other end to the side wall of said armature lever 74. Accordingly, said armature lever 74 is always urged to contact the rear end of said operating rod 38 by means of said plate spring 75. Said switch box 71 consists of a body 71a and cover 71b. Said body 710 contains a nonnally opened lamp switch 76 and normally closed stop switch juxtaposed with each other and switching lever 78 for actuating them. Each of these switches 76 and .77 has a stationary contact blade and movable contact blade. Said stop switch 77 has longer contact blades than those of said. lamp switch 76 and the movable contact blade. of said stop switch 77 has a protuberance 77a formed at the end. Said switching lever 78 is inserted into said body 71b in such a manner that one end of said switching lever 78 contacts the armature lever 74 and the other end contacts said lamp switch 76. Further there is formed at said other end a protuberance 79 which facesthe protuberance 78 of said stop switch 77 at right angles, and contacts the protuberance 77a of said stop switch 77 when said switching lever 78 is displaced. Said switching lever 78 and said lamp and stop switches 76 and 77 have such an operational interrelationship that when the other end of said switching lever 78 contacts said lamp switch 76 there is allowed a prescribed spacing between the protuberance 79 of said switching lever 78 and the protuberance 77a of said stop switch 77 and that when said switching lever 78 is displaced its protuberance 79 contacts the protuberance 77a of said stop switch 77 to open it.
The electric pencil sharpener of the present invention is further improved as described below. Since an electric pencil sharpener generally sharpens a pencil with a rapidly rotating cutter, it has the drawbacks that pencil shavings are scattered on all sides to be deposited on the upper surface of the mounting frame or waste case and that when said box is taken out of the sharpener the shocks caused by said removal allow shavings remaining in the sharpener to fall on a desk to contaminate its surface. To eliminate the aforementioned shortcomings, therefore, the electric pencil sharpener of the present invention has a shavings guide cover assembly 80 fitted to the mounting frame 16 shown in FIGS. 7 and 8. This cover assembly 80 consists of an upper cover member 800 having a semicircular cross section and two side plates 80b extending downward from the bottom of both side walls of said cover member 80a, each of said side plates having two holes 80c cut out on each side. Said upper cover member 804 has such a semicircular cross section as surrounds the revolving locus of the cutter 30 of said sharpening mechanism 15 and has a width at least equal to the axial length of said cutter 30. Said side plates 80b extend downward at least to the upper edge of said waste case 61. On each side of said mounting frame 16 are provided two hooked portions 81 prepared by bending up a cut piece of its side wall. Said cover assembly is fitted to said mounting frame 16 by allowing the holes 80c of said side plates 80b to be engaged from the outside by said hooked portions 81 of said frame 16. Said cover assembly 80 may be prepared from an integral combination of said upper cover member 80a and side plates 80b or by separately fabricating them, and also fitted to the inside of said mounting frame 16 instead of to the outside as practiced in the aforementioned case. Further, the fitting of said cover assembly 80 to the mounting frame 16 may be carried out by any other means than described above.-The provision of said cover assembly 80 enables scattering pencil shavings reliably to fall into said shavings box 61, thus avoiding the occurrence of the aforementioned inconvenience.
Furthermore, said electric pencil sharpener should preferably have a cutter holder molded from synthetic resin. The cutter holder of the prior art sharpener is made of die-cast aluminum. It will be apparent that replacement of said die-cast aluminum with synthetic resin molding will realize easy fabrication and appreciable reduction of cost.
There will now be described this second embodiment by reference to the appended drawings. The other parts of said sharpener than the cutter holder are the same as those of the preceding sharpener and description thereof is omitted. As shown in FIG. 9, the cutter holder 82 is molded from synthetic resin. When the cutter 20 is fitted to the cutter holder 82, the lightness of synthetic resin material results in unbalance between the weight of said material and that of the cutter 20 with the most likely occurrence of vibrations when the sharpener is operated. To prevent such an occurrence, there is embedded a heavy metal balance weight 83 in said cutter holder 82 in such a manner that one side of said weight 83 is made flush with the front surface of said cutter holder 82. Atthe central part of said balance weight 83 is formed a screw socket 84 which serves to allow the support plate 29 for rotatably There will now be described by reference to FIG. the circuit of an electric pencil sharpener according to the aforementioned embodiments. The first output terminal 86 of an AC source 85 is connected to the first input terminal 87 of a condenser motor 17 and the second output terminal 88 is connected to the second input terminal 89 of said condenser motor 17 through the start switch 21 and stop switch.77 connected in series. The indication lamp 25 and lamp switch 76 are connected in series. One end of said series connected assembly is connected to said first input terminal and the other end is connected to a line contacting both start switch 21 and stop switch 77.
There will now be described the operation of said electric pencil sharpener. When there is inserted a pencil from the socket member 24 into the sharpener, the start switch 21 is closed to supply current to said motor 17. Its rotating moment is transmitted to the rotary sharpening mechanism through the pinion 56 and spur gear 55. The resultant rotation of said cutter holder 82 causes the cutter gear 44 engaging the internal gear 19 to be rotated together with the cutter 30 fitted thereto while revolving around the periphery of said internal gear 19. When the pencil is further forced into the pencil receiving bore 34, it is gradually sharpened by said revolving and rotating cutter 30, and its core tip contacts the sliding member 37 to urge it backward and allow the operating rod 38 interlocked with said sliding member 37 also to slide backward (FIG. 11). The rear end of said operating rod 38 forcefully displaces said armature lever 74. When the sliding member 37 is brought to point D shown in FIG. 11, the extent of said displacement is transmitted to said switching lever 78 through said operating rod 38 and armature lever 74 to close said lamp switch 76. The closing of said lamp switch 76 leads to the formation of an electric circuit (FIG. 10) for said lamp 21 to light it, thereby indicating that the pencil has been sharpened. Indication at this stage announces that the pencil core is sharpened relatively thick. Where it is desired to sharpen the core tip to a finer size, it is only required further to push the pencil into the sharpener. When it is thus urged, said sliding member 37 is further displaced and the switching lever 78 is also shifted in position with said lamp switch 76 closed. When said sliding member 37 is brought to point E of FIG. 11 the protuberance 79 on said switching lever 78 presses the protuberance 77a of said stop switch 77 to open it. The open ing of said stop switch 77 opens the circuit of said motor. The stopping of said motor prevents any further sharpening of a pencil, indicating the completion of said sharpening operation. In this case, the rotary sharpening mechanism 15 does not suddenly stop its rotation, but is so slowly brought to rest as to prevent any further forceful sharpening of the pencil due to the rotation inertia of said fly wheel 57. During the time interval required for the complete stopping of said sharpening mechanism 15, the pencil is actually a little more sharpened without allowing the teeth of said cutter to bite into it, so that it is sharpened clean, free from any fine splits. When the pencil is drawn out of the sharpener, the operating rod 38 and sliding member 37 are urged backward by the plate spring 75 to extinguish the actuating force of said switching lever 78, causing the normally closed stop switch 77 to be brought back to its original closed position due to its own elastic force. Said withdrawal of the pencil again puts the motor in operation to actuate said rotary sharpening mechanism 15. This actuation is continued until the pencil is fully taken out of the sharpener, thus permitting its easy removal. Upon completion of the withdrawal of the pencil, said start switch 21 is opened to stop said motor 17.
Generally the cutter of a pencil sharpener is reduced in its cutting quality in a relatively short time, namely, when it has been used about 5,000 times, so that it has to be replaced with a new one once in a while. The pencil sharpener of the present invention is so arranged as to allow said replacement to be effected easily. Where it is necessary to replace the cutter 30, it can be removed simply by taking out said pencil holding unit 18 together with said cover 13 and pulling the screw 51 to remove said support member 29 and cutter shaft 46. When a new cutter is to be fitted, the aforementioned step has only to be reversed.
What we claim is:
1. An electric pencil sharpener comprising:
a pencil holding unit disposed on the front inside of said housing to receive and clamp a pencil to be sharpened, said holding unit including a start switch operated upon insertion of a pencil for supplying power to said sharpener;
a motor which is energized responsive to operation of said start switch;
a cutter holder for holding a cutter at a prescribed angle of inclination;
a fly wheel coupled to said cutter holder;
gear means coupled to the rear end of said cutter holder and engaging with a gear connected to said motor;
an operating rod slideably mounted in said cutter holder; the position of said operating rod being a function of the degree of sharpness of the pencil;
switching means operatively coupled to the rear end portion of said operating rod which is remote from said holding unit;
said switching means including a normally open contact which is closed to cause a lamp to illuminate when the position of said operating rod corresponds to a first degree of sharpness of the pencil being sharpened, and a normally closed contact which is opened when the position of said operating rod corresponds to a second degree of sharpness which is sharper than said first degree of sharpness, said motor being coupled to said switching means to turn said motor off when said normally closed contacts are opened.
2. The sharpener according to claim 1 including means for sliding said operating rod rearwardly relative to said cutter holder responsive to the insertion of the pencil in said sharpener, the degree of sliding being a function of the depth of insertion of said pencil in said sharpener.
3. The sharpener according to claim 2 wherein said means for sliding said operating rod includes a sliding member in said cutter holder for contacting the forward end portion of said operating rod and for contacting the sharpened point of the pencil inserted in said sharpener, said sliding member sliding rearwardly responsive to increasing insertion of said pencil.
4. The sharpener according to claim 1 wherein said gear means includes a spur gear coupled to the rear of said cutter holder which is engaged with a pinion gear coupled to said motor.
5. The sharpener according to claim 4 wherein said fly wheel is a cylindrical fly wheel coaxially coupled to said spur gear.
6. The sharpener according to claim 1 wherein said pencil holding unit has a bore therein through which a pencil passes, at last three spaced leg member located about the periphery of said bore .with a substantially equal spacing therebetween, said leg members being movable in a radial direction relative to said bore and each leg member having a groove therein, an annular spring arranged in said grooves for exerting a substantially equal pressure on each leg member to bias it toward the axial center of said bore, said leg members clamping the pencil inserted in said sharpener.
7. The sharpener according to claim 1 including a shavings guide cover provided in said housing to cover a planetary revolving locus of said cutter.
8. The sharpener according to claim 7 wherein said guide cover is approximately semicircular in shape.
9. The sharpener according to claim 1 wherein said cutter holder is a synthetic resin molding.
10. The sharpener according to claim 9 including a balance weight embedded in said molded synthetic resin cutter holder to eliminate vibrations upon operation hereof.
11. The sharpener according to claim 1 wherein said lamp remains illuminated when said normally closed contacts are caused to open and is extinguished upon removal of said pencil from said sharpener whereby said starting switch is rendered inoperative.
12. The sharpener according to claim 1 wherein said switching means includes a switching lever operably displaca- 3 23 C UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 678, 975 Dated July 25 1972 Inventods) Masakazu 'IMANISI-II, et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
i In the priority claim, Application No."4 4/2044" 1 should becorrected to 44/20443.
Signed and sealed this 9th day of January 1973.
EDWARD M.FLETCHER,JR. 7 ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents