JP4417177B2 - Knock-type writing instrument - Google Patents

Description

  The present invention relates to a knock type writing instrument provided with a feeding mechanism composed of a rotating cam.

  Conventionally, with respect to the center of gravity position of a writing instrument, for example, as in Japanese Patent Application Laid-Open No. 2001-270281 “writing instrument”, the main body cylinder is composed of a front region, an intermediate region, and a rear region, and the center of gravity position is located in the intermediate region. A writing instrument that can perform a stable and minute rotational movement during writing is disclosed.

  As a result of the study of the writing instrument capable of performing a stable and minute rotational movement at the time of writing, the present inventor has found that the rotation axis P in the minute rotational movement at the time of writing as shown in FIG. It was found that the moment was the smallest.

  It is well known that this moment of inertia is the magnitude of the ability of an object to continue to move. In general, the moment of inertia of a straight bar is the same as when rotating from the center of the straight bar. When turning at the end of the rod, turning at the center of the straight bar is easier to turn because the diameter of the circle drawn by the rotation is smaller, so the moment of inertia when turning at the center is smaller. This is because the position of the center of gravity is closely related to the moment of inertia, and when the mass and the total length are the same, the moment of inertia is the smallest if the position of the center of gravity and the rotation axis are the same. The moment is also high.

The moment of inertia dI of each writing instrument part is the rotation axis, that is, the distance from the center of gravity of the writing instrument to the center of gravity of each writing instrument part, part A = r ₁ , part B = r ₂ , part C = r ₃ ,. , The mass of each writing instrument part, parts A = dm ₁ , part B = dm ₂ , part C = dm ₃ ,..., Density of each writing instrument part: part A = ρ ₁ , part B = ρ ₂ , Part C = ρ ₃ ,..., Assuming that the volume of each writing instrument part is part A = dv ₁ , part B = dv ₂ , and part C = dv ₃ , the moment of inertia dI of each writing instrument part with respect to the rotation axis of the writing instrument However, it can obtain | require with a following formula.
Component A has dI ₁ = r ₁ ² dm ₁ (dm ₁ = ρ ₁ dv ₁ )
Component B is dI ₂ = r ₂ ² dm ₂ (dm ₂ = ρ ₂ dv ₂ )
Component C has dI ₃ = r ₃ ² dm ₃ (dm ₃ = ρ ₃ dv ₃ )

Since the inertia moment I of the writing instrument is the sum of the inertia moments of the respective parts, it can be obtained by adding the inertia moments of the parts constituting the writing instrument, which are obtained in advance, as shown in the following equation.
I = (r ₁ ² ρ ₁ dv ₁ + r ₂ ² ρ ₂ dv ₂ + r ₃ ² ρ ₃ dv ₃ +...)
"JP 2001-270281 A"

  However, in order to set the middle area of the writing instrument to the position of the center of gravity, it can be set in consideration of the total mass of the writing instrument and the mass of each writing instrument part. It is not something that can be done.

  As a result, even if the mass of the writing instrument parts located at the front end and the rear end of the writing instrument is heavy, the intermediate region can be set as the center of gravity, but as described above, the minute rotational motion is This is influenced by the moment of inertia, and the mass of the writing instrument parts located at the front end and the rear end separated from the center of gravity of the writing instrument is heavy when a small rotational movement is performed with this center of gravity as the rotation axis. This is because the moment of inertia of the writing instrument itself increases.

  Certainly, having the center of gravity and the rotation axis at the same position is likely to cause minute rotational movements, that is, a factor that reduces the moment of inertia. Considering that the moment is composed of the sum of the moments of inertia of the parts for each writing instrument, it is not easy to make a minute rotational motion just by making the rotational axis and the center of gravity the same.

  In particular, in the knock type writing instrument provided with the feeding mechanism composed of the rotating cam, the rotating cam and the push rod are arranged at the rear end portion of the shaft tube, and therefore the rear end side of the writing instrument becomes heavy. In addition, a knock type writing instrument having a feeding mechanism composed of such a rotating cam needs to increase the mass on the tip end side of the shaft cylinder in order to position the center of gravity in the intermediate region, and performs a minute rotational motion as described above. It was not easy.

  By the way, the writing instrument holds the writing instrument by attaching a fingertip to the gripping part of the shaft cylinder, such as attaching a grip member to the shaft cylinder or forming an uneven shape, and the inter-finger part abutting another shaft cylinder. ing. For this reason, it has been found that if the center of gravity is located at the gripping portion of the shaft cylinder and the mass is concentrated near the center of gravity, the sense of stability when gripping is good and the moment of inertia is reduced.

  Specifically, the overall length of writing instruments such as general pencils, ballpoint pens, fountain pens, and markers in the writing state, such as the protruding state of the ballpoint pen tip, is 120 to 180 mm, and such writing instruments visually recognize the tip of the writing body. In order to make it easy to do, the diameter is reduced from the gripping portion of the shaft tube toward the writing tip. Further, the contact portion between the thumb and the middle finger is slightly different depending on the size of the hand or the like, but is located on the rear end side from about ½ of the entire length of the writing instrument. Therefore, the gripping part of the shaft tube is formed between about 20 mm from the tip of the writing body and about ½ of the entire length of the writing instrument.

  In view of these problems, the present invention is to provide a writing instrument that has a good stability when grasped and has a low moment of inertia.

In the present invention, a cam groove for sliding and rotating the rotating cam back and forth is formed on the inner surface of the shaft cylinder, and the rotating cam is slidably disposed in the cam groove, and at the rear end of the rotating cam, A push rod having a cam portion at the tip for sliding the rotation cam and imparting rotation is disposed, and the knock body is pressed to bias the shaft barrel toward the rear end by a spring. And in the knock type writing instrument comprising a feeding mechanism consisting of a rotating cam that can be projected and retracted from the axial tube tip opening, the writing tip of the writing body that is slidably arranged, with the writing tip protruding, The gripping part is formed between a position of 20 mm from the tip of the writing body and ½ of the entire length of the writing instrument at the time of writing, and at the position corresponding to the gripping part of the shaft tube, the entire center of gravity of the knock type writing instrument and the rotation The center of gravity of the cam and the center of the push rod are located, and the grip To, with mounting the high grip member specific gravity than the barrel, characterized that mass and more than 50% of the total weight writing instrument between the half of the writing instrument the total length from the tip of the grip portion.

  Further, the center of gravity of the knock type writing instrument is located in the vicinity of the center of gravity of the rotating cam and the center of gravity of the push rod.

  Further, the overall center of gravity of the knock type writing instrument, the center of gravity of the rotary cam, and the center of gravity of the push rod are at positions corresponding to the rear end side of the shaft cylinder that bisects the grip portion.

  Further, the grip portion of the shaft tube is formed to have a diameter larger than the diameter of the other shaft tube.

  The shaft tube is transparent at the tip, opaque at the grip, and transparent at the rear.

  The present invention can provide a writing instrument having a good stability when grasped and a low moment of inertia.

  Next, examples of the writing instrument of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.

The knock type writing instrument 1 of Example 1 shown in FIGS. 1 to 5 first obtains a shaft cylinder body by screwing together a transparent shaft cylinder 2 and a transparent tip member 5 formed of PC resin. The gripping portion 3 of the shaft cylinder 2 has a larger diameter than the other shaft cylinders 2 and is positioned between a position 20 mm from the tip of the writing tip of the knock-type writing tool and a half of the writing tool total length L at the time of writing. Further, it is formed integrally with the shaft cylinder 2. A grip member 4 such as silicone rubber or polyurethane elastomer is attached to the grip portion 3. A stainless steel ballpoint pen tip 10 (writing tip), which rotatably holds a tungsten carbide ball, is mounted on the tip of the PP resin inside the shaft tube 2, and a ballpoint refill 9 containing oil-based ink inside. The (writing body) is energized and stored in the rear end direction of the shaft cylinder by a coil spring 12 disposed in the shaft cylinder. Further, the rotating cam 7 and the push rod 8 are also urged by the coil spring 12 through the ball pen refill 9 in the rear end direction of the shaft tube.

  A cam groove (not shown) for sliding and rotating the rotating cam 7 back and forth is formed on the inner wall surface corresponding to the grip portion 3 of the shaft cylinder 2, and the rotating cam formed of POM resin is formed in the cam groove. 7 is engaged. At the rear end of the rotating cam 7, a push rod 8 made of a resin such as POM having a cam portion for sliding the rotating cam 7 to impart rotation is opened by a coil spring 13 at the end of the shaft cylinder. It is urged in the direction of the portion 2a.

  A through hole is formed in the rotary cam 7 and the push rod 8, and the writing body 9 communicates with the through hole 7a of the rotary cam 7 and extends from the rear end 2b of the shaft cylinder. At this time, the protrusion 9 a formed on the cursive body 9 is in contact with the step 7 b formed on the inner wall of the rotating cam 7. At the rear end of the writing body 9, a knock body 6 formed of a low specific gravity resin such as polypropylene is disposed so as to protrude outward from the rear end 2 b of the shaft tube, and the knock type writing instrument 1 of the present invention is provided. It has gained.

  The entire center of gravity G of the knock type writing instrument 1 is located on the axis P of the writing instrument in a position corresponding to the gripping part 3 of the shaft cylinder, and the center of gravity J of the rotating cam and the center of gravity K of the push rod are also the gripping part of the shaft cylinder. It is in a position corresponding to 3. Further, the center of gravity J of the rotary cam and the center of gravity K of the push rod are positioned in the vicinity of the center of gravity G of the entire writing instrument.

  Specifically, the center of gravity G of the entire writing instrument is A (55 mm) from the writing tip with respect to the writing instrument total length L (140 mm) at the time of writing, and from the position of 20 mm from the tip of the writing tip of the knock type writing instrument at the time of writing. It is located between ½ (70 mm) of the writing instrument overall length L and is located at a position corresponding to the gripping portion 3 of the shaft cylinder. The center of gravity J of the rotating cam is C (48 mm) from the tip of the writing, and the center of gravity K of the push rod. Is B (53 mm) from the tip of the writing, and the center of gravity J of the rotating cam, the center of gravity K of the push rod, and the center of gravity G of the entire writing tool are at positions corresponding to the gripping portion 3 of the shaft tube.

  At this time, it is preferable that the center of gravity J of the rotating cam and the center of gravity K of the push rod are positioned in the vicinity of the center of gravity G of the entire writing instrument. The vicinity of the center of gravity G of the entire writing instrument is most preferably the same position as the center of gravity G of the entire writing instrument. However, if it is within 10% of the total length, the increase in the moment of inertia is small. ± 10% of the total length in the axial direction, specifically within ± 14 mm in the axial direction from the center of gravity G of the entire writing instrument, preferably ± 5% of the total length in the axial direction from the center of gravity G of the entire writing instrument, specifically Is ± 7 mm in the axial direction from the center of gravity G of the entire writing instrument.

  By positioning the center of gravity J of the rotating cam and the center of gravity K of the push rod in the vicinity of the center of gravity G of the entire writing instrument, the mass concentrates in the vicinity of the position of the center of gravity. it can.

  Further, generally, the abutment portion between the thumb and the middle finger of the grip portion 3 of the shaft tube divides the grip portion 3 into two equal parts, ie, a shaft tube tip side 3a and a shaft tube rear end side 3b. 3a, the overall center of gravity G of the knock type writing instrument, the center of gravity J of the rotating cam and the center of gravity K of the push rod are set to positions corresponding to the rear end side 3b of the barrel that divides the grip portion 3 into two equal parts. As a result, the sense of stability when gripped is improved.

  The shape of the gripping part 3 of the axial tube in the present invention is not particularly limited as long as it is formed between a position of 20 mm from the tip of the writing body and a half of the entire length of the writing instrument at the time of writing. It is preferable to make the diameter larger than the diameter of the cylinder because it is easy to dispose the rotating cam and the push rod and it is easy to increase the weight. Similarly, it is preferable to attach a grip member having a specific gravity higher than that of the shaft tube to the grip portion, because an anti-slip effect can be obtained and the weight of the grip portion can be increased.

Moreover, it is preferable to make the mass between 1/2 of the writing instrument full length at the time of writing from the position of 20 mm from the front-end | tip of a writing body into 50% or more of the total mass of a writing instrument. As shown in FIG. 5 , the center of gravity G of the writing instrument is located between the abutting portion a of the thumb and the middle finger and the abutting portion b between the thumb and the middle finger. When the mass between the contact part a and the contact part b between the thumb and middle finger is 50% or more of the total mass of the writing instrument, the mass becomes the heaviest of all knock type writing instruments. Even if the knock type writing instrument is tilted, the mass is concentrated between the contact part a of the thumb and the middle finger and the contact part b between the thumb and the middle finger. The feeling becomes good and the mass is concentrated near the center of gravity G, so the moment of inertia can be reduced.

  The structure of the knock type writing instrument of the present invention is not particularly limited as long as the center of gravity J of the rotating cam, the center of gravity K of the push rod, and the total center of gravity G of the knock type writing instrument are at positions corresponding to the gripping portion 3 of the shaft cylinder. However, the writing body 9 communicates with the through-hole 7a formed in the rotating cam 7 and reaches the vicinity of the rear end 2b of the shaft tube, and the writing body 9 contacts the stepped portion 7b formed on the inner wall of the rotating cam 7. With the contact structure, the arrangement positions of the rotating cam 7 and the push rod 8 can be set as appropriate, and the center of gravity J of the rotating cam and the center of gravity K of the push rod can be easily set near the entire center of gravity G of the knock type writing instrument.

  Further, as in the present embodiment, an opaque grip member 4 is attached to the grip portion 3 of the transparent shaft tube 2, and the tip member 5 located at the tip of the shaft tube is transparent, and the rotary cam and the push rod are positioned. The gripping portion to be mounted is fitted with an opaque grip member 4 and the rear end portion of the shaft tube 2 is made transparent so that the rotary cam 7 and the push rod 8 are hardly visible from the outside, and the knock operation is performed without visually checking the feeding mechanism. Because it can, it can attract the user's interest.

  A clip member 11 is integrally formed at the rear end portion of the shaft tube 2. When the clip member 11 is provided at the rear end portion of the shaft tube 2, the center of gravity position G is easily located on the rear end side of the shaft tube 2 and the moment of inertia is increased as the mass of the clip member 11 is increased. Therefore, the effect of the present invention is particularly remarkable.

  In the present embodiment, for the sake of convenience, it is exemplified as a knock-type ballpoint pen.

The knock-type writing instrument of the present invention exhibits excellent performance and can be widely used as a knock-type writing instrument having a feeding mechanism composed of a rotating cam, such as a ballpoint pen, a marker, and an applicator.

It is a longitudinal cross-sectional view which shows the knock type writing instrument which made the writing front-end | tip part the protrusion state in this invention. It is the longitudinal cross-sectional view which made the writing front-end | tip part in FIG. 1 immersed. It is the figure which showed the distance from the writing tip in FIG. FIG. 2 is an enlarged vertical cross-sectional view of a main part, partially omitted in FIG. 1. It is explanatory drawing which shows the state hold | gripped by the writing instrument. It is explanatory drawing which shows the fine reciprocating rotational motion of a writing instrument.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Knock type writing instrument 2 Shaft cylinder 3 Holding part 3a Shaft cylinder front end side 3b Shaft cylinder rear end side 4 Grip member 5 Tip member 6 Knock body 7 Rotating cam 8 Push rod 9 Ink storage cylinder 9a Clipping 10 Ball-point pen tip 11 Clip member 12, 13 Coil spring G Center of gravity J of the knock type writing instrument J Center of gravity K of the rotating cam K Center of gravity P of the push rod Rotating shaft

Claims (5)

A cam groove is formed on the inner surface of the shaft cylinder for sliding and guiding the rotating cam back and forth, and the rotating cam is slidably disposed in the cam groove. The rotating cam is disposed at the rear end of the rotating cam. A push rod having a cam portion at the tip for sliding and imparting rotation is disposed, and by pushing the knock body, the shaft is urged by the spring toward the rear end of the shaft and slides. In a knock type writing instrument comprising a feeding mechanism comprising a rotating cam capable of projecting and retracting a writing tip portion of a freely arranged writing body from a shaft tube tip opening portion, the gripping portion is held in a state where the writing tip portion protrudes. It is formed between the position of 20 mm from the tip of the writing body and half of the entire length of the writing instrument at the time of writing, and at the position corresponding to the grip portion of the shaft cylinder, the center of gravity of the knock type writing instrument, the center of gravity of the rotating cam, and The center of gravity of the push rod is located, With mounting the high grip member of remote gravity, knock-type writing instrument, wherein that mass and more than 50% of the total weight writing instrument between the half of the writing instrument the total length from the tip of the grip portion. The knock-type writing instrument according to claim 1, wherein the center of gravity of the knock-type writing instrument is positioned in the vicinity of the center of gravity of the rotating cam and the center of gravity of the push rod. The center of gravity of the entire knock-type writing instrument, the center of gravity of the rotary cam, and the center of gravity of the push rod are located at positions corresponding to the rear end side of the shaft cylinder that bisects the grip portion. 2. Knock type writing instrument according to 2. The knock type writing instrument according to any one of claims 1 to 3, wherein a grip portion of the shaft cylinder is formed to have a diameter larger than that of another shaft cylinder. The knock type writing instrument according to any one of claims 1 to 4, wherein the shaft tube has a transparent front end portion, an opaque grip portion, and a transparent rear end portion.

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