United States Patent (19) 11 4,148,591 Tomura 45) Apr. 10, 1979 (54) WRITING UNIT LOCKING MECHANISM IN A MULTIPLE-POINT WRITING FOREIGN PATENT DOCUMENTS IMPLEMENT INCLUDING AMECHANICAL 1561838 3/1967 Fed. Rep. of Germany ............. 401/32 PENCIL UNIT 1611793 3/1968 Fed. Rep. of Germany ............. 401/32 2137469 7/1971 Fed. Rep. of Germany ............. 4O1/33 75 Inventor: Yoshihiro Tomura, Omiya, Japan 48-4354 2/1973 Japan ......................................... 4O1/32 Primary Examiner-Edward M. Coven 73) Assignee: Pilot Man-Nen-Hitsu Kabushiki Kaisha, Tokyo, Japan Attorney, Agent, or Firm-Wenderoth, Lind & Ponack 57 ABSTRACT 21 Appl. No.: 824,303 A writing unit locking mechanism in a writing imple ment having a mechanical pencil unit and a ball point (22 Filed: Aug. 12, 1977 pen unit both housed in a single holder cylinder. The locking mechanism has a writing unit selection member 51) Int. C.’.............................................. B43K 27/12 having a shift member shiftable under gravitational (52) U.S. C. ......................................... 401/32; 401/17 force to select one or the other writing unit and oper 58 Field of Search ....................... 401/17, 19, 20, 21, ated manually to actuate a chuck in the pencil unit and 401/29, 32, 33 a catch shoulder provided on a unit cylinder of the pencil unit and adapted to engage directly with the 56) References Cited holder cylinder or with an engagement member resil U.S. PATENT DOCUMENTS iently supported on the holder cylinder thereby to lock 2,505,267 4/1950 Weber .................................... 401/17 the pencil unit in its writing position. The pencil unit is 2,882,859 4/1959 Poritz ..... ... 401/29 released from its locked state simultaneously with the 3,152,578 10/1964 Hofmann ... 401/33 release of the selection member. 3,174,462 3/1965 Bross ...... ... 401/33 4,022,535 5/1977 Ritter ..................................... 401/32 8 Claims, 7 Drawing Figures U.S. Patent Apr. 10, 1979 Sheet 2 of 2 4,148,591 F. G. 4 NNs F G. 5 F G. 6 B F. G. 6 A 4,148,591 1. 2 ing units, and to move the same into the writing position WRITING UNIT LOCKING MECHANISM INA thereof wherein the writing end thereof projects out of MULTIPLE-POINT WRITING IMPLEMENT the writing end of the holder cylinder, an improved INCLUDING AMECHANCAL PENCIL UNIT writing unit locking mechanism comprising a writing unit selection means having a writing unit push member BACKGROUND OF THE INVENTION movable within the holder cylinder under gravitational This invention relates generally to writing imple force to select one of the writing units and operated ments such as ball point pens and mechanical pencils manually to actuate the chuck, said mechanism further and more particularly to a writing unit locking mecha comprising engagement means on the holder cylinder, a nism in a multiple-point writing implement including a 10 catch shoulder provided on the unit cylinder and mechanical pencil unit. adapted to engage with said engagement means thereby More specifically, the invention relates to a writing to lock the pencil unit in the writing position thereof, unit locking device in a multiple-point writing imple and means for causing release of the pencil unit from the ment comprising a mechanical pencil unit in which a locked state thereof simultaneously with that of the chuck connectable with a unit cylinder travels along the 15 writing unit selection means. axis of the unit cylinder thereby to feed a pencil lead out The nature, utility, and further features of this inven of the unit cylinder, at least one other writing unit such tion will be apparent from the following detailed de as, for example, a ball point pen unit, a single holder scription with respect to preferred embodiments of the cylinder for accommodating the pencil unit and the invention when read in conjunction with the accompa other writing unit, and a writing unit selection member 20 nying drawings, which are briefly described below, and for selecting any of the writing units as desired. throughout which like parts are designated by like ref. A great problem encountered in the design of a multi erence numerals and characters. ple-point writing implement of this kind has been the provision, together with a simple and expedient mecha BRIEF DESCRIPTION OF THE INVENTION nism for selecting writing units, of a simple and conve 25 In the drawings: nient mechanism for locking each of the writing units in FIG. 1 is a side view, with parts cut away and parts its writing position in relation with the writing unit shown in longitudinal section, showing a multiple-point selection mechanism. Particularly in the case of a me writing implement in which an embodiment of this chanical pencil, a requirement is that, when it is in its invention is incorporated; writing position and it is necessary to feed pencil lead 30 FIG. 2 is a side view of the writing implement illus out of it, it must remain in its writing position. For this trated in FIG. 1 with a mechanical pencil unit in its reason, the provision of a simple and convenient locking writing position; mechanism has been desired. FIG.3 is a side view showing another embodiment of Another requirement in a mechanical pencil unit of the invention and showing the mechanical pencil in its the instant kind is that the force with which the chuck 35 writing position; part holds the pencil lead be increased in order to resist FIG. 4 is a relatively enlarged side view, with parts the writing force imparted to the pencil lead. Accord cut away and parts shown in longitudinal section, show ingly, a simple and convenient solution for this require ing an example of the construction of a mechanical ment is also desired. pencil unit; FIG. 5 is an enlarged side view showing the relation SUMMARY OF THE INVENTION ship between a knob guide path and a knob in an exam It is an object of this invention to provide a multiple ple of the locking mechanism of the invention; and point writing implement including a mechanical pencil FIGS. 6A and 6B are cross sections showing differ in which the above described requirements are met by a ent states and showing the relationship between a first writing unit locking device having a simple construc 45 engagement part of an engagement member and a catch tion. part of a writing unit selection member in relation to In the multiple-point writing implement according to FIG. S. this invention, a desired writing unit is selected by means of a shifting member movable by gravitational DETALED DESCRIPTION force, whereby each of the writing units can be placed 50 Referring first to FIG. 1 showing the essential con in its writing position in a simple and convenient man struction of one example of a writing implement accord ner, and a catch part is formed on a unit cylinder of the ing to this invention, the writing implement has a holder mechanical pencil and caused to engage directly or cylinder 1 constituting an outer housing and accommo indirectly with the holder cylinder of the implement in dating therein a mechanical pencil unit 6 and a ball point a writing cylinder. By these provisions, the locking of 55 pen unit 6a disposed side-by-side separated by a case the mechanical pencil unit in the writing position can be partition 2 interposed therebetween. The holder cylin simply attained, and, at the same time, the pencil lead der comprises a front cylinder 1a and a rear cylinder 1b, holding force is increased by this locking mechanism so which are connected coaxially by a threaded cylinder 3. that it can withstand a relatively large writing force. The threaded cylinder 3 is fixedly secured to the rear According to this invention, briefly summarized, cylinder 1b, and the front cylinder 1a is detachably there is provided, in a multiple-point writing implement screwed onto the threaded cylinder 3. The threaded comprising a mechanical pencil unit having a unit cylin cylinder may be replaced by any other member which der and a chuck adapted to connect with the unit cylin can detachably hold the front cylinder 1a. der and to shift along the axis thereof thereby to feed a The front cylinder 1a has a bullet-like front end, at pencil lead out of the unit cylinder, at least one other 65 the extreme front tip of which an aperture 4 is defined writing unit, a single holder cylinder for accommodat and encompassed by a rim formed by the front cylinder. ing the pencil unit and the other writing unit, and a This rim is shaped to have a stop part 4a against which pressing member to be pressed to select one of the writ a stepped shoulder 9c of the mechanical pencil unit 6 4,148,591 3 4. described hereinafter abuts. Coil springs 5 and 5a are A unit selection member 19 is provided at the rear respectively provided around parts of the mechanical end of the rear cylinder 1b and comprises the above pencil unit (hereinafter referred to as the "pencil unit”) mentioned knob 20 having a projecting lug 20b adapted 6 and the ball point pen unit (hereinafter referred to the to slide in and along the guide path G and a push rod 21 "pen unit”) 6a and resiliently urge the respective units 6 5 engaged in a loose-fit state with the forward end part and 6a axially toward the rear of the holder cylinder 1. 20a of the knob and adapted to shift in accordance with The resilient force exerted by the coil spring 5 on the gravitational force.