Writing instrument

Abstract: A writing instrument comprising a pen point receiver (4), a pen point (5) and an ink introducing core member. The tip end portion of the pen point (5) is formed to curve downwardly towards the tip end writing portion with respect to the base end portion of the pen point.

Description: This invention relates to a writing instrument which can draw fine lines without causing blur. Writing instruments such as fountain pens make it possible to write with a writing portion by having a structure that ink in an ink container installed in a penholder is percorated through a bunch of fibers in a pen point receiver which is inserted into a tip end opening portion of the penholder, and is supplied from a tip end of the bunch of fibers to the inner surface of the tip end portion of the pen point supported by the pen point receiver, and then is introduced to a writing end portion of the pen point through a split formed in the middle of the tip end portion of the pen point. In such writing instruments structed as mentioned above, the pen point is conventionally formed to curve downwardly from a center of the pen point in its width directions to both edges thereof to make an arc, to have a venthole at a predetermined length of interval from the writing end portion towards abase end portion of the pen point, and to have a straight split penetrating from the venthole to the center of the writing end portion. Examples of such type of fountain pen are known from US-A- 4 968 169 and EP-A-0 209 342. However, according to the above mentioned pen point, since both of side fragments of the end portion divided by the split, curve with respect to the width directions but they are straight in its longitudinal directions to have a two dimentional structure, a bend-resistance of the writing end portion against a strength of pen stroke at the time of writing is inferior, and when pressure is put on the pen point, the both of the side fragments easily warp upwards with the the venthole side as a fulcrum, by which the split is widened and there arises a problem that thickness of letters and lines become thicker. Therefore, although the conventional pen point may be suitable to write sentences and the like subtly adjusting thickness of letters by changing the strength of pen stroke, it is difficult to draw illustration with innumerable fine pieces of hair, for example. Further, since the writing end portion is easily warp upwards by a strong pen stroke, a gap is made between the writing end portion and the pen point receiver, and letters may blur because supply of ink from the tip end portion of a bunch of fibers for supplying ink to the pen point becomes insufficient. Futhermore, as the elastic restoration force of the writing end portion is impeded by repeatedly working bend force at the time of writing, there was a fear that the pen point cannot be used due to a distored state of the tip end portion of the pen point and the pen point receiver having a gap inbetween. Therefore, in order to maintainer the elastic restoration force for a long time resisting against such repeated load as bend force acting on the pen point at a time of writing, it is required to make a thickness of the pen point bigger, in which case it becomes necessarily impossible to draw extrafine lines. An object of the present invention is to provide a writing instrument having a pen point structure by which a lot of fine lines can be smoothly drawn without causing blur, and by which distortion and deformation of the pen point are rarely caused due to a strong elastic restoration force. To achieve the above object, the wri ting instrument according to this invention, comprises a pen point receiver inserted into a tip end opening of a penholder in which an ink container is received, a pen point having a split of a predetermined length from a writing end portion of the pen point, a base end portion of the pen point inserted into the tip end opening of the penholder in a state that the pen point is operlapped on the uppersurface of the pen point receiver, and an ink introducing core member provided in a center of the pen point receiver so that an ink may percolate through a base end portion of the ink introducing core member, a tip end portion of the ink introducing core member being tightly contacted with the undersurface of a pen point tip end portion of the pen point, said writing device characterized in that the tip end portion of the pen point is formed to curve downwardly towards the tip end writing portion with respect to the base end portion of the pen point. In the above mentioned writing instrument, it is preferable that the ink introducing core member comprises a bunch of fibers or an elastic porous material and the tip end portion of the core member is compressed elastically with squeezing pressure between the undersurface of the pen point tip end portion and the uppersurface of the tip end portion of the pen point receiver. Further, it is also preferable that the pen point is made of a thin steel plate having wear resistance and elasticity. According to the present invention, since the tip end portion of the pen point is formed to curve downwardly to have a three-dimention structure, it may obtain a great bending strength against a bending load loaded at the time of writing, and therefore even if a writing load is great, the pen point maintains a strong elastic force within a range of elastic limit. Therefore, it becomes possible to surely carry out a supply of ink by eliminating blur of letters or the like without interrupting supply of ink to the pen point in a state that the undersurface of the tip end portion of the pen point is always contacted with the tip end portion of the ink introducing core member under pressure. Further, it becomes possible to obtain a great elastic restoration force with respect to a writing load when the pen point is made thin, so that it may provide a pen point structure to draw extrafine lines continously without causing blur. Furthermore, since the tip end portion of the pen point is formed to curve downwardly, and a bunch of the fibers or the elastic porous material and the tip end portion of the core member is compressed elastically with squeezing pressure between the undersurface of the pen point tip end portion and the uppersurface of the tip end portion of the pen point receiver, even if the pen point is warped upwards and displaced due to a great writing pressure, the ink introducing core member is restored elastically according to its amount of displacement so as to maintain a state that the core member may be always contacted with the undersurface of the pen point under pressure. As a result, the ink, which is percorated through the ink introducing core member with capillarity, can be always introduced from the tip end portion of the core member to the tip end writing portion through the split of the pen point. Advantages of this invention are as follows. Since a writing instrument of this invention comprises a pen point receiver inserted into a tip end opening of a penholder in which an ink container is received, a pen point having a split of a predetermined length from a writing end portion of the pen point, a base end portion of the pen point inserted into the tip end opening of the penholder in a state that the pen point is operlapped on the uppersurface of the pen point receiver, and an ink introducing core member provided in a center of the pen point receiver so that an ink may percolate through a base end portion of the ink introducing core member, a tip end portion of the ink introducing core member being tightly contacted with the undersurface of a pen point tip end portion of the pen point, and said writing device is characterized in that the tip end portion of the pen point is formed to curve downwardly towards the tip end writing portion with respect to the base end portion of the pen point, the tip end portion of the pen point may display a great bending strength against a bending load due to a writing pressure which is caused at the time of writing, and it becomes possible to disperse bending stress to whole of the pen point which is curved downwardly without focusing bending stress on a portion, so that it may always maintain repeatedly a restoration force of elasticity within elastic limit of the pen point. Therefore, it becomes possible to use the pen point for a long time without occurring strain and to control the tip end portion of the pen point not to separate it from the pen point receiver under a great writing pressure so as to always contact the tip end of the ink introducing core member with the undersurface of the split of the pen point, so that it may smoothly and continously carry out a supply of ink from the ink introducing core member to the split. Further, since the tip end portion of the pen point is formed to curve downwardly so as to generate a great elastic repulsive power against a writing load, it becomes possible to produce the thin pen point which has not ever been obtained in a shape of the conventional pen point. Accordingly, the present invention may provide the pen point which draws extrafine lines without blur. Furtheremore, since the tip end portion of the pen point is formed to curve downwardly, and a bunch of fibers or an elastic porous material and the tip end portion of the core member is compressed elastically with squeezing pressure between the undersurface of the pen point tip end portion and the uppersurface of the tip end portion of the pen point receiver, even if the pen point is warped upwards and displaced due to a great writing pressure, the ink introducing core member is restored elastically according to its amount of displacement so as to maintain a state that the core member may be always contacted with the undersurface of the pen point under pressure. Therefore, the ink, which is percorated through the ink introducing core member with capillarity, can be always introduced from the tip end portion of the core member to the tip end writing portion through the split of the pen point. As a result, it becomes possible to carry out a continous supply of ink stablly so as to surely eliminate occurrence of blur even if fine lines are drawn. Other advantages of this invention will be apparent from the description of the embodiments with reference to the drawings. The drawings show an embodiment of a writing instrument according this invention in which: Fig. 1 is a brief sectional side view of the writing instrument, Fig. 2 is a brief perspective view of a pen point, Fig. 3 is a brief perspective view seeing from a rear side of the pen point, Fig. 4 is a sectional side view of a pen point receiver supporting the pen point, Fig. 5 is a plan view of the pen point receiver partially broken away, Fig. 6 is a sectional side view of a tip end portion of the pen point in a state of use, Fig. 7 is an enlarged sectional front view taken along lines X1-X1, Fig. 8 is a sectional side view of the tip end portion of the pen point in a state of drawing with a great writing pressure, and Fig. 9 is an enlarged sectional front view taken along lines X2-X2. Embodiments of the present invention will be described with reference to the drawings. In Fig. 1, a writing instrument A comprises a penholder 1 having a predetermined length, which receives therein an ink container 2 changablly, a pen point receiver 4 inserted into a tip end opening portion of the penholder 1 via a cylindrical holder 3, a pen point 5 suppurted on the uppersurface of the pen point receiver 4 and inserted with its base portion between the undersurface of the upper peripheral portion of the tip end portion of the cylindrical holder 3 and the uppersurface of the pen point receiver 4 in a squeezed state, and an ink introducing core member 6 which is made of a bunch of fibers such as felt and the like, and which is arranged in a center portion of the pen point receiver 4 in a state that a base portion of the core member is directed to the ink container 2 and its tip end portion is contacted with a center portion of the tip end portion of the pen point 5. By the way, as the ink introducing core member 6, it may be formed by using an elastic porous material such as sponge and porous resin which provides continous porous and capillarity. The pen point 5 is made of a thin steel plate having superior wear resistance, corrosion resistance and elasticity, and it is formed to curve downwardly from a center of the pen point in its width directions towards both edges thereof to make an arc, as is well known. And, the tip end portion of the pen point is formed to have a shape of a triangle in plan view that is gradually narrow towards its tip end so as to form a writing portion 5a of small width at its tip end. Further, a predetermined length of a split 5b is formed from the writing portion 5a towards a base portion of the pen point and a venthole 5c is opened with a base portion of the split 5b, so that both sides of the tip end portion of the pen point 5 may be divided into two pieces to make right and left side fragments. In the pen point 5 as formed above, as shown in Figs. 2 to 4, it takes a structure that the tip end poortion from a part of the venthole 5c to the writing portion 5a is curved downwardly towards the writing portion 5a with respect to the base portion of the pen point. Therefore, the right and left both side fragments 5h and 5d, which form the tip end portion of the pen point 5, is thus curved downwardly towards the outside ends from the split 5b to form an arc, and also with respect to its longitudinal directions, they are curved downwardly from the venthole 5c towards the writing portion 5a to form an arc so as to make a three dimentional structure. The said pen point 5 is formed by punching a thin steel plate having a width of about 0.15∼0.3mm to form a pen point main body of the pen point 5 which is unfolded, and thereafter, a pressing process is carried out by bending, by means of a press machine, the pen point main body from its center portion to the both side edges to form an arc, and then gently curving, with choking process, the main body downwardly from its center portion in the longitudinal directions thereof towards its tip end portion and further the split 5b of predetermined length from the writing portion 5a towards the base portionj thereof is formed together with the venthole 5c. As an extent of curve of the pen point by choking process, it is, for example, preferable that the pen point is curved from its center portion to its tip end with the radius of curvature of about 200mm and also it is preferable that an angle, which is formed with an extended horizontal line of the base portion and a straght line in the directions of its curving surfaces that crosses the extended horizontal line, may be about 4 to 5 degrees, but they are not limited particularly. The pen point receiver 4 supporting the pen point 5, has a rear part from its center portion to its base portion, which rear part is formed by a small diameter cylindrical portion 4a having a guide opening 4b into which the ink introducing core member 6 is inserted, and by a comb groove portion 4c comprising a number of disc scales which are projecting on the periphery of the small diameter cylindrical porion 4a, leaving a small distance between the disc scales in the longitudinal directions. On the other hand, a front part of the pen point receiver is formed to be narrow towards its tip end and its upper periphery is formed to be a shape which may contact the undersurface of the pen point 5 with the upper priphery of the pen point receiver, and further a guide groove 4d, which has a width equal to a diameter of the ink introducing core member 6, is formed to have a depth reaching a center portion of the pen point receiver from a center portion of the upper periphery. The lower end base portion (rear end) of the guide groove 4d is communicated with the guide opening 4b and the groove bottom of the guide groove 4d is inclined gently and upwardly towards the tip end (front end), so as to place the inclined upper end thereof to face the undersurface of the tip end portion of the pen point 5. Further, the ink introducing core member 6, which is formed by a bunch of fibers to form like a thin string having a circle in section, is inserted through the guide opening 4b to reach the tip end of the guide groove 4d, and its base end portion is made to project rearwardly from the guide opening 4b and its tip end is compressed to be flat by pressing between the tip end uppersurface of the pen point receiver 4 and the tip end undersurface of the pen point 5, so that the core member is elastically contacted under pressure wi th the undersurface of the pen point beneath the split 5b. By the way, as shown in Fig. 5, there is provided a thin groove 7 for ventilation on the peripheral portion of the comb groove portion 4c of the pen point receiver 4, to communicate its base end and the guide groove 4d. The pen point receiver 4 is inserted into the cylindrical holder 3 with its comb groove portion 4c in a state that the pen point 5 is overlapped on the uppersurface of the tip end portion of the pen point receiver, and the base end portion of the pen point 5 is squeezed and fixed by the the upper peripheral surface of the tip end portion of the comb groove portion 4c and the inner peripheral surface of the upper peripheral portion of the tip end portion of the cylindrical holder 3. The cylindrical holder 3 is inserted into the tip end opening portion of the penholder 1, and a samll diameter cylindrical portion 3a is formed integrally with the holder 3 at a center of the base end thereof, to project rearwardly. The tip end opening of the ink container 2 as a spare is connected to the small diameter cylindrical portion 3a, so as to supply ink of the ink container 2 to the base end portion of the ink introducing core member 6 via the small diameter cylindrical portion 3a, which faces the core member, so that ink may be pecorated through the ink introducing core member 6 with capillarity to reach its tip end. The penholder 1 receiving the ink container 2 is divided into two pieces as a forward half portion 1a and a rear half portion 1b which are connected separably by means of screw. By using the writing instrument A as mentioned above, the pen point 5 is put on a paper B , as shown in Fig. 6, and writing is carried out with its tip end writing portion 5a. Then, the tip end writing portion 5a receives a bending load of warp in a upward direction, but since the right and left side fragments 5b and 5d forming the tip end of the pen point 5, is curved downwardly from the split 5b towards its outer side to form an arc and also curved downwardly with respect to its longitudinal directions from the venthole 5c to the tip end writing portion 5a to form an arc so as to make a three dimensional structure, they display a great strength against bending stress in a direction of warp and it is possible to evade the bending stress to focus on the base portions of the right and left side fragments 5b and 5d, and to disperse the bending stress to whole of the right and left side fragments 5b and 5d, so that restoration force of these fragments may be always maintained repeatedly within an elastic limit thereof. Further, it may control separation of the pen point 5 from the pen point receiver 4 even if a great writing force is acting thereon, and contact the tip end portion of the ink introducing core member 6 with the undersurface of the pen point 5 beneath the split 5b, so as to continue supply of ink from the ink introducing core member 6 to the split 5b. Further, even if warp occurrs with the pen point 5 due to a strong bending load, as shown in Fig. 7, the ink introducing core member 6 is squeezed under pressure between the undersurface of the tip end portion of the pen point 5 and the uppersurface of the pen point receiver 4, and since the ink introducing core member 6 made of a bunch of fibers has an elastic restoration force, the ink introducing core member 6 may be extended elastically according to an amount of displacement of warp, to maintain a state that the tip end portion of the core member is always contacted with the undersurface of the tip end portion of the pen point 5 under pressure, so as to continue folow of ink smoothly with respect to the pen point 5 and to carry out writing of fine lines without causing blur. Next, examples of this invention will be described. Example 1 To form a pen point, a steel plate having a thickness of 0.27mm is punched by means of a press machine and then it is bent to have a bending radius of 3.5mm in a direction of width, and it is curved downwardly with a bending raidus of 200mm, so as to have an angle of 4.5 ° with respect to a center line of its tip end portion. Further, a split of a predetermined length is formed wi th the tip end wri ting portion of the pen point from its center portion to its base end and a venthole is formed with the base end portion of the split. By using the writing instrument having the pin point, it becomes possible to carry out contninous drawing with a fine line having a width of 0.25mm and a lenght of 1500m. Where writing pressure increases upto 150g, the width of the line becomes 0.36mm and when the writing pressure returns to 50g, the width of the line also returns to 0.25mm. Example 2 A steel plate having a thickness of 0.18mm is processed in the same manner as the above example 1 and then it has obtained a pen point with a writing portion having a width of 0.18mm. By using the writing instrument having the penpoint, continous drawing is carried out on a test pater under the same conditions as the above example 1. It becomes possible to draw continously a fine line having a width of 0.2mm. Where writing pressure increases upto 150g, the width of the line becomes 0.25mm and when the writing pressure returns to 50g, the width of the line also returns to 0. 2mm.

Claims: A writing instrument comprising a pen point receiver (4) inserted into a tip end opening of a penholder (1) in which an ink container (2) is received, a pen point (5) having a split (5b) of a predetermined length from a writing end portion (5a) of the pen point, the pen point having a downwardly curved profile transvesally to the direction of said split, a base end portion of the pen point inserted into the tip end opening of the penholder in a state that the pen point is overlapped on the uppersurface of the pen point receiver (4), and an ink introducing core member (6) provided in a center of the pen point receiver so that an ink may percolate through a base end portion of the ink introducing core member, a tip end portion of the ink introducing core member being tightly contacted with the undersurface of a pen point tip end portion of the pen point (5), said writing instrument being characterized in that : the tip end portion of the pen point (5) is formed to curve downwardly towards the tip end writing portion (5a) with respect to the base end portion of the pen point. The writing instrument as claimed in claim 1, wherein the ink introducing core member (6) comprises a hunch of fibers or an elastic porous material and the tip end portion of the core member is compressed elastically with squeezing pressure between the undersurface of the pen point tip end portion and the uppersurface of the tip end portion of the pen point receiver (4). The writing instrument as claimed in claims 1 or 2, wherein the pen point is made of a thin steel plate having wear resistance and elasticity.

Inventors: TACHIKAWA TOSHIKAZU, TACHIKAWA, TOSHIKAZU
Applicants: TACHIKAWA KABUSHIKI KAISHA
Application year: 1999
Main classification: B43K1
IPC codes: B43K1