Electric Pencil Sharpener

Abstract

An electric pencil sharpener comprises a cylindrical cutter and a rotary shaft having a pencil-feeding hole. A slider is disposed at the rear inner portion of the hole and connected with a rod extending through an axial hole in the rear portion of the shaft and adapted to be moved in axial direction integrally with the slider. The rear end of the rod projecting from the shaft is kept in contact with a pivoted operation plate. As the plate is moved backward by the point of pencil lead which is being sharpened, a lamp on the arm of the plate is moved upward. The degree of sharpness of the lead is indicated by the position of upwardly moving light which can be inspected through windows in the front panel.

Description

The present invention relates to an electric pencil sharpener, more particularly to a device for indicating the degree of sharpness of the lead sharpened to see to what extent the pencil point has been sharpened while it is being sharpened.

In order to indicate the sharpness of the lead in an electric pencil sharpener, a certain type of device has been proposed in which a lamp for indicating the sharpness is turned on and off. However, in indicating the degree of sharpness of the lead stagewise as in two or three stages with this type of device, there is a need to provide a required number of indication lamps in accordance with the number of the stages and contacts to open or close the circuits of the indicating lamps, so that the structure becomes inevitably complicated. The electric sharpener is therefore quite disadvantageous in that the more complex the structure becomes, the more likely it is that the sharpener is susceptible to troubles, since the sharpener is rotated at an extremely high speed.

An object of the present invention is to eliminate above-mentioned disadvantages of conventional electric pencil sharpeners.

Another object of the present invention is to provide a device to be used in an electric pencil sharpener for indicating the degree of sharpness of the lead which is simple in structure and free from troubles.

Still another object of the present invention is to enable a single indication lamp to provide stagewise indications in two, three or more stages of sharpness of the lead which is being sharpened so that useless over-sharpening of the pencil may be precluded.

The features of the present invention will become apparent in an embodiment shown in the accompanying drawings, in which:

FIG. 1 is a perspective view of an electric pencil sharpener in accordance with the present invention, part of the casing being broken away to show the interior structure;

FIG. 2 is a front view of FIG. 1 showing a pencil feeding portion and an indicator of sharpness of the lead which are provided in the front panel of the casing;

FIG. 3 is a side elevation in section taken along the line III -III in FIG. 2; and

FIG. 4 is an electrical circuit diagram for driving a motor and turning on an indication lamp.

As shown in the drawings, the casing of an electric pencil sharpener comprises two upper and lower portions 1 and 2 which are integrally joined together by means of screws (not shown). In the front of the upper portion 1 is provided a pencil holder 4 having a pencil-feeding inlet 3 and in the lower portion, a suitable number of support legs 5 made of rubber or the like attached to the under surface. In the front of the lower portion 2 is mounted a drawerlike receptacle 6 for chips which is adapted to be pulled out. In the interior of the casing is fixed a frame 7 which is integral with the lower portion 2 and to which is fixedly secured, by means of bolts (not shown), a bracket 8 for supporting a motor M and an operation mechanism to be later described.

A rotary shaft 10 formed with a pencil feeding hole 9 in conical shape is rotatably supported on the bracket 8. A follower gear 11 secured to the rotary shaft 10 at the rear end meshes with a pinion 12 keyed to the shaft of a motor M and through this meshing engagement the rotary shaft is driven. The pencil feeding hole 9 in the rotary shaft 10 is coaxial with the pencil-feeding inlet 3 of the pencil holder 4 and it is also coaxially disposed with the axis of rotation of the rotary shaft 10. Provided inside the front panel 13 of the bracket 8 is a sliding member 14 which is adapted to be pushed in the radial direction upon insertion of the pencil to close the switch of motor M.

The rotary shaft 10 further supports a cylindrical cutter 15 by an axis 16 in rotatably manner while allowing the same to orbitally rotate around the axis of the shaft 10, the cylindrical cutter 15 being provided with screwlike cutting edges exposed to the slanting surface of the conical hole 9 for receiving the pencil. Integrally formed with the cylindrical cutter 15 at its tail end is a planetary gear 17 which is in meshing engagement with an internal gears 18 fixed to the bracket 8, so that the cylindrical cutter 15, while being orbitally rotated, is rotated on its own axis to cut the forward end portion of the pencil pushed into the conical pencil feeding hole 9 and to sharpen the lead. Since the rotary shaft 10 rotates while supporting the cylindrical cutter 15, the rotary shaft 10 is provided with a balancer to ensure rotation in balanced condition. Designated at 20 is a cord connected to a power source.

When the pencil is pushed in through a pencil-feeding inlet 3 of the pencil holder 4, the sliding member 14 turns on the switch of motor M, and upon the rotary shaft 10 being brought into high speed rotation of the cylindrical cutter 15 is rotated orbitally while being driven on its own axis to sharpen the pencil point in already known manner.

In addition to the foregoing structure, in the most inner portion of the conical pencil-feeding hole 9 of the rotary shaft 10 there is disposed a slider 21 which is free to move forward and backward along the axis of the rotary shaft 10. This slider 21 is attached to the rotary shaft 10 with a portion thereof engaged with a guide groove 22 formed in the rotary shaft 10 and adapted to be pushed backward toward the rear of rotary shaft 10 by the point of pencil lead which has been sharpened with the cylindrical cutter 15.

It will be seen in the drawings that in the backward portion of the rotary shaft 10 is formed an axial hole 23, the shaft thus being formed as a hollow cylinder. The back of the slider 21 is connected with a front end of a rod 24 which extends through the hole 23 so as to move freely in the axial direction, with the rear end of the rod backwardly projected out of the rotary shaft 10. Behind the rotary shaft 10 is provided an operation plate 25 to be brought into abutting contact with the tail end of the rod 24. The lower end of the operation plate 25 is pivoted on a shaft 26 which is transversely supported on the bracket 8, the plate thereby being adapted to be pivotally moved back and forth on the shaft 26. Integrally formed with the operation plate 25 at a side portion thereof is an arm 27 extending forward and provided with an indicating lamp L at its forward end. As shown in FIG. 4, the indication lamp L IS INSERTED IN THE CIRCUIT OF THE MOTOR M in parallel therewith. The lamp is so adapted that it is turned on simultaneously with the closure of the switch S.

When the slider 21 is pushed backward by the point of pencil lead, the operation plate 25 is pivoted backward with the end of the arm 27 moved upward. That is to say, the indication lamp L is raised in accordance with the degree of sharpness of the pencil lead. The upward and downward movement of the arm 27 is guided by a vertical groove 28 formed beside the bracket 8.

In the front panel of the upper portion 1 of the casing at a portion corresponding to the position of the upward and downward movement of the indication lamp L, a suitable number of windows 29 are arranged in vertical row. To the windows 29 are fitted transparent plates 30 colored in appropriate colors as in red, yellow, blue, etc. Accordingly, as the indication lamp L is brought upwards, the light of indication lamp L, as it is moved upwards from the lowermost position, can be observed through the windows 29 in the front panel of the electric pencil sharpener. Thus, the sharpness of the lead can be inspected. In order to provide more distinct indication, mark 31 showing the sharpness of lead is printed beside the windows 29.

It will be understood from the foregoing description that the sharpness indicator is very simple in structure and is very simply in structure and is well fit for high speed rotation of the electric pencil sharpener. The indicator is therefore perfectly free from troubles and there is no need to employ more than one indication lamp. Furthermore, the light passing through the colored transparent plates serves to provide better indication of the lead sharpness.

When the pencil which has been sharpened to a desired degree is taken out of the feeding hole 9, the sliding member 14 projects into the feeding inlet 3 to open the switch S for the motor M and indication lamp L. The motor M is thus brought to a halt and the indication lamp is turned off. Due to the weight of the arm 27, the operation plate 25 is pivotally moved forward and the indication lamp is thereby lowered. At the same time, the rod 24 is pushed to move the slider 21 forward along the axis of the rotary shaft 10. The movement of the slider is guided by the groove 22.

Claims

1. In an electric pencil sharpener having a rotary shaft provided with a pencil-feeding hole in conical form and a cylindrical cutter supported on said rotary shaft and adapted to be rotated orbitally and on its own axis, said cutter being disposed along the slanting surface of the pencil-feeding hole, a structure comprising a slider disposed in the inner rear portion of said pencil-feeding hole and adapted to be freely moved along the axis of said rotary shaft, a rod extending through an axial hole in the rear portion of said rotary shaft and having a forward end connected to said slider and a rear end projecting backward from said rotary shaft so as to move integrally with said slider in the axial direction, an operation plate kept in abutting contact with the rear end of said rod all the time due to the weight of an arm supporting an indication lamp to be moved up and down, and windows provided in the front panel of a casing for inspecting from the front of the casing the indication lamp attached to the forward end of the arm which is integral

2. The electric pencil sharpener as claimed in claim 1 wherein said windows are arranged in an appropriate number in vertical row along the direction of upward and downward movement of said indication lamp so as to provide stagewise indications of the position of said lamp, each of said windows

3. The electric pencil sharpener as claimed in claim 1 wherein along the row of said windows are provided marks for indicating the degree of sharpness of the pencil lead.