WRITING INSTRUMENT

Abstract: A writing instrument (10) with an advance-retract mechanism is operable by rotation of a knob (46) opposite the writing tip. The knob rotates a shaft (16) disposed in, and extending rearwardly from, the instrument body to advance and retract the writing tip when rotated. A retainer member (28) has a first cylindrical portion (32) with a plurality of inwardly extending tangs (33) into which the shaft is received and a larger cylindrical portion (34) having a surface (36) directed toward the instrument body.

Description: WRITING INSTRUMENT The present invention relates to writing instruments in general, and more particularly to a writing instrument having a mechanism for advancing and retracting the writing tip of the instrument wherein the mechanism is actuated by rotation of a knob disposed at the non-writing end of the pen barrel. Various writing instruments such as pencils or ball point pens are known in the art wherein the writing tip is advanced or retracted relative to the barrel by means of rotating or pushing the external element on the barrel of the instrument. Typical of such advance-retract devices are to be found in U.S. patent 3,679,318, issued July 25, 1972, to Thomas A. Liguori; U.S. patent 4,290,706, issued September 22, 1981, to Tatsuo Ariga; U.S. patent 4,786,197, issued November 22, 1988, to Harold E. Koeln et al.; French patent 1004813, published April 3, 1952, in the name of Poursier; and British patent specification 934160, published August 14, 1963, in the name of Ronald Hare. These, as well as other devices have been disclosed, and many mechanisms of this type have been produced, and have met with commercial success. It has been proposed to provide a writing instrument that includes an advance- retract mechanism serving to project the writing tip from within the barrel for employment of the writing instrument, and to retract the tip to a point within the barrel when the writing instrument is not in use. A plunger assembly includes a rotatable knob which is disposed at the rear of the barrel and is interconnected to a finger which contacts a cam surface of a slidable actuator. Rotation of the knob in one direction advances the writing tip from within the barrel, and opposite rotation of the knob is effective to retract the writing tip into the barrel. While such structure has proved successful in accomplishing its various objectives, it is considered that improvement of the knob attachment to the shaft of the plunger assembly may be accomplished by more firmly fixing the connection between the rotating knob assembly to the rotating shaft of the plunger assembly, while increasing the ease of rotation of the knob during the actuating process. It is therefore an object of the present invention to provide a writing instrument of the type described wherein the rotatable shaft portion of the actuating mechanism which extends into the rotatable knob is more firmly affixed to the knob while further providing a more easily rotatable knob for actuating the mechanism. A further object of the invention is to provide a retainer and bearing assembly which is mounted at the rear of the writing instrument barrel and is effective to firmly affix the shaft of the advance-retract mechanism onto the barrel while providing for ease of rotation of the actuating knob. A further object of the invention is to provide, in an alternative embodiment, a retainer which is mounted at the rear of the writing instrument barrel and is effective to firmly affix the shaft of the advance retract mechanism onto the barrel while providing for ease of rotation of the actuating knob, without the use of a bearing assembly. The above objects and other objectives which will become apparent as the description proceeds are accomplished by providing a writing instrument having a barrel and an advance- retract mechanism actuated by rotation of a knob disposed at the rear of the instrument barrel opposite the writing tip. The shaft extends rearwardly from within the barrel to receive the knob for rotation of said shaft, the shaft being effective to advance and retract the writing tip when so rotated. A retainer member having a first cylindrical portion enveloping the shaft and a plurality of rearwardly inwardly extending tangs contacts the surface of the shaft. The retainer member has a second cylindrical portion disposed forwardly of the retainer first cylindrical portion which has a forward facing surface in spaced relation with a rearwardly facing end surface of the barrel. Biasing means is provided to force the retainer member rearwardly, and is disposed between the second cylindrical portion forward facing surface and the rear surface of the barrel. The biasing means is effective to force the tangs into the shaft and also provides a bearing surface between the retainer member and the barrel. The biasing means disclosed herein comprises a unitary bearing member, the bearing member having a cylindrical body through which the shaft extends and having a surface contacting the end surface of the barrel. A radially outwardly extending flange is disposed on the bearing member for contacting the forward facing surface of the retainer member. The unitary bearing member is generally formed of a resilient plastic material and the radially outwardly extending flange is compressible between the end surfaces of the barrel and the forward facing surface of the retainer member, causing the biasing action to force the tangs into the shaft. The shaft is generally formed of plastic and the retainer member is formed of a metallic material to provide the locking action between the retainer and the shaft when the metallic tangs are forced into the plastic shaft. In an alternative embodiment the biasing means may be deleted from the apparatus, thereby eliminating one piece from and simplifying the assembly process. The foregoing and other features of the invention will be more particularly described in connection with the preferred embodiment, and with reference to the accompanying drawing, wherein: Figure 1 is a sectional elevational view showing a portion of a writing instrument constructed in accordance with the teachings of the present invention; Figure 2 is an elevational view showing the actuator shaft employed in the writing instrument of Figure 1; Figure 3 is an end elevational view showing the retaining rivet employed in the structure of Figure 1; Figure 4 is a side elevational view showing the rivet of Figure 3, the dot-dash lines indicating that portion of the rivet which has been set, as in Figure 1; Figure 5 is an elevational perspective view showing the retainer member employed in the structure of Figure 1; Figure 6 is an end elevational view showing details of the retainer member of Figure 5; Figure 7 is an elevational sectional view taken along the line VII-VII of Figure 6 showing further details of the structure of Figures 5 and 6; Figure 8 is an elevational perspective view showing the bearing member employed in the structure of Figure 1; Figure 9 is an end elevational view showing details of the structure of Figure 8; Figure 10 is an elevational sectional view taken along the line X-X of Figure 9 showing further details of the structure of Figures 8 and 9; Figure 11 is an elevational end view showing the sleeve member employed in the construction of Figure 1; Figure 12 is an elevational sectional view taken along the line XII-XII of Figure 11 showing details of the structure of Figure 11; Figure 13 is an end elevational view showing the cap member of Figure 1; Figure 14 is an elevational sectional view taken along the line XIV-XIV of Figure 13 showing details of the cap member; Figure 15 is a sectional elevational view of the alternative embodiment showing a portion of a writing instrument constructed in accordance with the teachings of the present invention, wherein the biasing member is deleted from the assembly; Figure 16 is an elevational view showing the actuator shaft employed in the writing instrument of Figure 15; Figure 17 is an elevational perspective view showing the retainer member employed in the structure of Figure 15; Figure 18 is an elevational sectional view taken along lines XVII-XVII of Figure 17, showing further details of the structure of Figure 17; Figure 19 is an isometric elevational view showing details of the alternative embodiment tang structure formed on the retainer; Figure 20 is a sectional elevational view showing a writing instrument; Figure 21 is a sectional plan view taken along the line II-II of Figure 20, taken on an enlarged scale for clarity showing details of the structure of Figure 20; Figure 22 is a sectional view taken along the line III-III of Figure 20 on an enlarged scale, showing.details of the elements of the structure ' of Figure 20; Figure 23 is a sectional view taken along the line IV-IV of Figure 20, taken on an enlarged scale showing further details of the elements of the structure of Figure 20; and Figure 24 is an exploded perspective view showing operative elements of the writing instrument of Figures 20 through 23. Referring now to the drawing, and particularly to Figure 1 there is shown a writing instrument 10 in the form of a ball point pen having an elongated writing assembly 12 disposed in a barrel 14. The various elements and the function of the writing assembly 12 are disclosed hereinafter with specific reference to Figures 20 through 24. The actuating member comprises a shaft 1 as shown in Figure 2, having a portion extending into the barrel 14, and a portion extending through an opening in the barrel for access by the user to rotate the shaft and thereby cause a finger 18 to manipulate those elements of the writing assembly 12, and move the writing tip into and out of the barrel 14. Referring still to Figure 1, taken with Figures 2 through 4, the barrel 14 has an opening 20 through which the shaft 16 extends, and a rivet 22 extends into the opening 20 having a planar surface 23 and a portion 24 which is peened over to encapsulate a clip 25. As best shown in Figure 1, the shaft 16 extends outwardly through the opening 20 to a point at which a shoulder 26 of the shaft contacts the surface 22 of the rivet. While the interface of the shoulder 26 of the shaft 16 with the peened portion 24 of the rivet is effective to retain the shaft from rearward movement, it is necessary to provide means for clamping the shaft in place such that it is held from movement either forwardly, or rearwardly, and yet is allowed to rotate freely for actuation of the writing assembly 12. Referring now to Figures 5 through 10 there is shown a novel retainer 28 and bearing 30 which combine to achieve both the clamping action, and produce the ease of rotation desired in the assembly. Referring particularly to Figures 5, 6 and 7 taken in conjunction with Figure 1 the retainer 28 is shown to comprise a first cylindrical portion 32 which is of a size to substantially envelop the shaft 16 when inserted therein, and three inwardly extending tangs 33 which project inwardly to contact the shaft in interfitting engagement with the outer surface of the shaft. A second cylindrical portion 34, of larger diameter than the cylindrical portion 32, is disposed forwardly of the portion 32 and comprises a forward facing surface 36 with the retainer mounted as shown in Figure 1, the surface 36 being disposed in spaced relation with the barrel 14 which has the rivet 22 set in place. It is well to note that the cylindrical portion 34 substantially forms a cup for retaining the bearing 30, however the forward edge of the retainer cylindrical portion 34 lies outside of the peened portion 24 of the rivet, thereby allowing only the bearing 30 to provide rotatable surfaces between the barrel 14 and the surface 36 of the retainer 28. With reference to Figures 8 through 10 the bearing 30 is of unitary construction and comprises a cylindrical body 38 through which the shaft 16 extends and a planar surface 40 which contacts the barrel 14 at the portion 24 of the rivet 22. A radially outwardly extending flange 42 is provided with a planar bearing surface 44 for contacting the forward facing surface 36 of the retainer 28. It will further be noted that the flange 42, in addition to extending radially outwardly, is canted rearwardly to, in effect, form a spring-like or biasing effect when compressed between the surface 36 of the retainer 28 and the barrel 14. In the construction of Figure 1, both the shaft 16 and the bearing 30 are manufactured of a resilient plastic material such as acetal. The retainer 28 is manufactured of a metallic material such as brass or the like, to provide tangs 33 which will pierce and enter the surface of the shaft 16 when forced rearwardly by the biasing action of the flange 42 of the bearing 30. Referring now to Figure 1 taken in conjunction with Figures 11 through 14 a knob 46 is provided at the rearwardmost end of the shaft 16 for rotation of the shaft to actuate the writing assembly 12. The elements of the knob 46 comprise a sleeve 48 and cap 50, the sleeve 48 being manufactured of a resilient plastic material and the cap 50 being formed of a metallic material. The sleeve 48 is provided with 4 inwardly directed projections 52 having arcuate surfaces which are spaced to provide an engagement with the rearwardmost end of the shaft 16. The sleeve 48 further has four outwardly projecting blocks 54 which extend outwardly from the body of the sleeve 48. As best shown in Figure 14, the cap 50 is a tubular member and has four slots 56 formed therein and positioned to receive the blocks 54 therein, the cap aiding to retain the resilient sleeve 48 into interfitting engagement with the shaft 16 when the cap is in place. In an alternative embodiment of the invention the biasing member i.e. bearing 30 is eliminated. Referring now to Figures 15-19, elimination of the bearing 30 (Figure 1) eases the assembly operation of the cap 50A, knob 46A and retainer 28A onto the shaft 16A. Since the bearing 30 has been eliminated, such that there is no longer an imposed force acting from the tang 33A to the shaft 16A, the tangs 33A are redesigned to engage the shaft in a more aggressive manner. Comparing the original tang design (Figure 5, Figure 7) with the revised tang design (Figure 18 and Figure 19) it can be seen that the new tang 33A includes a chevron side A 82 and a chevron side B 84 which merge at a chevron side A, B junction 86. The chevrons 82, 84 are forced sufficiently downward from the surface of the first cylindrical portion 32A of the retainer 28A, such that a definite tang opening 88 is formed between the exterior and interior surfaces of the retainer 28A. The retainer 28A, as before includes the forward facing surface 36A, the retainer second cylindrical portion outer surface 78, and the second cylindrical portion 34A. The shaft 16A as before includes a shoulder 26A and a main shaft shoulder 72, but also includes tang shoulder 70, and centralizer shoulder 74. The centralizer shoulder 74 is of smaller outer diameter than the tang shoulder 70, the tang shoulder 70 being of smaller outer diameter than the main shaft shoulder 72. The outer diameters of the shoulder 74, and 70 are selected such that the retainer 28A may first be centralized relative to the shaft 16A during assembly over the shaft 16A. As the assembly progresses, the tangs 33A drag over and securely engage with the tang shoulder 70, preventing the cap from being withdrawn from the shaft. The tang shoulder 70 in one embodiment has an outer diameter slightly less than the adjacent main shaft shoulder 72. It should be well understood that the tang shoulder, depending on the design of the tangs, may have an outer diameter equal to, or even greater than the main shoulder 72. Additionally, though the tangs are shown in Figure 18 located centrally from either end of the first cylindrical portion, they may be located toward either end of the first cylindrical portion, so as to cooperate with the tang shoulder 70. As can be seen from the new Figures 15-19, the second cylindrical portion outer surface 78 engages in an interference fit with the cap inner surface 76. The engagement force of the cap inner surface with the second cylindrical portion outer surface is designed to exceed the engagement force of the tangs with the centralizer shoulder and the tang shoulder, such that the cap remains fixed relative to the retainer when the tangs are engaged with the tang shoulder. In other words, during assembly, the knob 46A is first inserted into openings in cap 50A, and the retainer 28A is thereafter inserted into the cap 50A. The retainer 28A remains fixed relative to the cap 50A, by strong interference fit, even while the tangs are dragged upwardly over the centralizer shoulder and the tang shoulder. The selection of tang geometry, tang shoulder and centralizer shoulder dimensions, and the strength of the interference fit between the retainer 28A and cap 50A are such to create a strongly secured cap, retainer and knob system on the end of the shaft 16A. As can be seen from the drawings, inward motion of the shaft is prevented by the cap striking the end of the pen barrel 14A. Referring now to Figures 20 to 24, there is shown a writing instrument 110 in the form of a ball point pen having an elongated writing assembly 112 which in the present embodiment is a ball point pen cartridge having a writing tip 113 and an ink reservoir 114, the writing assembly being biased in the rearward direction by a helical spring 116. The writing instrument 110, further comprises a barrel 118 having a front opening 119 through which the writing tip 113 is extended and retracted, and a rear wall 120 having an opening 122 formed for receiving a plunger assembly 124. As best shown in Figure 24, the plunger assembly 124 comprises a rotatable knob 126 which in the present embodiment is formed of a plurality of rearwardly and outwardly extending legs 128. Each of the legs 128 has an outwardly protruding portion 130, and as shown in Figure 20, a cover 131, which may be fabricated of metal material such as brass, stainless steel, etc., having openings in the same number as the protruding portions 130 is snapped over the legs for appearance purposes in the finished product. Each of the legs 128 has a bearing surface 132 which serves to function in a manner which will be explained as the description proceeds. The plunger assembly 124 further comprises an elongated drive portion 134 extending forwardly into the barrel 118, the drive portion having a circular groove 136 formed forwardly of the bearing surfaces 132. An axial keyway 137 is formed in the elongated drive portion 134 and terminates adjacent the rear surface of the groove 136. Referring to Figures 23 and 24, a ring 138 which is split to form a pair of substantially flexible arcuate portions 139 and 140 is dimensioned to be received in the circular groove in interfitting engagement. A longitudinally extending finger 142 comprises an arcuate forwardly facing surface 143 and a longitudinal inwardly projecting key 144 which is dimensioned to be received in the axial keyway 137 when the ring 138 is mounted onto the drive portion 134 of the plunger assembly. As best shown in Figures 20, 22 and 24 a slidable actuator 146 comprises an exterior cylindrical surface onto which is formed a plurality of axially disposed outwardly projecting slide bars 147 which in the present embodiment are eight in number. The bars 147 extend from the forward end of the actuator 146 rearwardly, terminating a short distance from the rear surface of the actuator. As best seen in Figure 24, the rear surface of the actuator 146 is formed to produce a cam surface 148 which is disposed at a predetermined angle with respect to the longitudinal axis of the writing instrument 110. A notch 150 for receiving the arcuate surface 143 is formed in the cam surface 148 adjacent the rearwardmost portion of the actuator 146 and adjacent to a rearwardly extending stop 152. The actuator 146 further has a cavity 154 formed, therein to receive the rearward projection of the writing assembly 112, the cavity being of any suitable dimension and configuration which will accommodate a particular writing assembly for which the writing instrument is adapted. Referring now to Figures 20 through 23, assembly of the advance-retract portion of the writing instrument 110, which comprises the plunger assembly 124, ring 138 and actuator 146, is simply accomplished by inserting the drive portion 134 of the plunger assembly 124 through the opening 122 in the rear wall 120, prior to the rear portion of the barrel 118 being assembled to the forward portion at the screw threads 155. A clip 156 having a portion 157 with an opening formed therein will have been assembled between the knob 126 and the rear wall 120 by employment of a rivet 160, if a clip is to be desired in the final assembly. The ring 138 is now inserted through the forward end of the barrel 118 rear portion, the key 144 rotated into alignment with the axial keyway 137, and the arcuate portions 139 and 140 are spread by the chamfer on drive portion 134 to allow the ring to ride over the drive portion 134 until the ring is received in the circular groove 136. The location of the rear surface of the groove 136 and the bearing surfaces 132 are dimensioned such that with the ring 138 mounted onto the drive portion 134 there is a clamping of the ring and knob members either with the clip portion 157 and wall 120 therebetween, if a clip 156 is employed, or merely with the wall between the two if a clip is not to be employed. As best shown in Figures 22 and 23, a plurality of longitudinal grooves 158 are formed within the barrel 118 and the actuator 146 is entered into the barrel by aligning the slide bars 147 with the grooves 158 and moving the actuator rearwardly until the cam surface 148 contacts the arcuate surface 143 of the finger 142. The forward portion of the barrel 110 with the writing assembly 112 and helical spring 116 disposed therein is then assembled to the rear portion of the barrel 110 and the writing assembly rearwardmost extremity is received in the cavity 154 of the actuator 146. To complete the assembly, the cap 131 is placed over the knob 124 with the outwardly protruding portions 130 fitting through slots in the cover 131 to retain the cover onto the knob. It will be appreciated that the particular steps of the assembly procedure may vary somewhat from the above without departing from the spirit of the invention. For example, the ring 138 may first be inserted in the barrel 118 and the drive portion 134 then inserted through the opening 122 while the ring is held in place. It should further be understood that although the longitudinal grooves 158 are shown herein as being formed in the structure of the barrel 118, a separate sleeve (not shown) embodying the grooves may be inserted in the barrel, the sleeve having the grooves formed and retained therein, which grooves function in the same manner as when formed in the barrel. In operation, with the finger 142 disposed on the low or forwardmost part of the cam surface 148, the helical spring 116 forces the writing assembly 112 against the actuator 146 and the writing tip 113 is maintained within the barrel 118 of the writing instrument 110. Rotation of the knob 126 is effective through the axial keyway 137 and key 144 to rotate the arcuate surface 143 of the finger along the cam surface 148 moving the actuator forwardly into the barrel 118 with the subsequent forward movement of the writing assembly 112 until the tip 113 lies beyond the front opening in the barrel. The finger 142 is rotated until it reaches the stop 152 at which point the arcuate surface 143 of the finger 142 falls into the notch 150 and maintains the writing tip 113 in the writing position outside of the barrel 118. It should be evident that when the finger 142 is rotated with the arcuate surface 143 in contact with the cam surface 148, the motion would have a tendency to rotate the actuator 146, however, due to the slide bars 147 being retained in the longitudinal groove 158 the actuator is free to move in the longitudinal direction without rotation. To retract the writing tip 113, the knob 126 is rotated in the opposite direction and the helical spring 116 forces the writing assembly 112 back into the barrel 118 as the arcuate surface 143 moves to the lower or forwardmost portion of the cam surface 148. In operation, the writing tip 113 is moved forwardly by rotation of the knob 126 in one direction until the finger 142 reaches the stop 152, and moved rearwardly by counter rotation of the knob. If desired however, the stop 152 may be deleted from the cam surface 148, in which instance the tip 113 will be advanced forwardly by rotation of the knob 126 until the arcuate surface of the finger 142 is received in the notch 150, and further rotation of the knob in the same direction will serve to cause rearward movement of the tip into the barrel 118. It should also be understood that while in the preferred embodiment the cam surface 148 is shown to be formed on the actuator 146 and the finger 142 is disposed on the ring 138, the device may be constructed with the cam surface formed on the ring 138 and the finger disposed on the actuator 146.

Claims: C L A I M S 1. A writing instrument having a barrel and an advance-retract mechanism actuated by rotation of a knob disposed at the rear of the instrument barrel opposite the writing tip, comprising: a shaft extending rearwardly from within said barrel to receive a knob for rotation of said shaft, and said shaft being effective to advance and retract said writing tip when so rotated; and a retainer member having a first cylindrical portion enveloping said shaft and having a plurality of rearwardly inwardly extending tangs contacting the surface of said shaft; said retainer member having a second cylindrical portion disposed forwardly of said retainer first cylindrical portion and having a forward facing surface in spaced relation with a rearwardly facing end surface of said barrel. 2. The writing instrument of claim 1, wherein said shaft is formed of a plastic material and said retainer member is formed of a metallic material. 3. The writing instrument of claim 1, wherein said retainer member second cylindrical portion further comprises wall structure extending substantially from said forward facing surface to form a forwardly facing cup. 4. The writing instrument of claim 1, wherein said retainer member includes a second cylindrical portion outer surface, and said cap includes a cap inner surface, wherein said second cylindrical portion outer surface engages in an interference fit with said cap inner surface. 5. The writing instrument of claim 4, wherein said shaft includes a centralizer shoulder and an adjacent tang shoulder located on the distal end of said shaft, and wherein the engagement force of said cap inner surface with said second cylindrical portion outer surface exceeds the engagement force of said tangs with said centralizer shoulder and said tang shoulder, such that said cap remains fixed relative to said retainer when said tangs are engaged with said tang shoulder.

Inventors: PENNEL EVAN K, WACHA MARTIN E, PENNEL, EVAN, K., WACHA, MARTIN, E.
Applicants: PARKER PEN IP LTD, PARKER PEN (I.P) LIMITED
Application year: 1995
Main classification: B43K24
IPC codes: B43K24