TWI636900B - Writing utensil and grip member - Google Patents

Abstract

The writing instrument of the present invention includes a shaft barrel and a grip member that surrounds the shaft barrel in the circumferential direction, and the thickness of the grip member varies in the circumferential direction, and the wall thickness of the barrel varies in the circumferential direction, and the thickness of the grip member is thicker than The large area surrounds the area of the shaft tube with a small wall thickness, and the area of the grip member having a small wall thickness surrounds the area of the shaft barrel having a large wall thickness.

Description

Writing utensil and grip member

The present invention relates to a writing instrument and a grip member.

A writing instrument that surrounds the outer surface of the barrel by a resilient grip member such as rubber has been known (for example, Japanese Patent No. 4043305 (Patent Document 1)). The grip member is attached to the writing instrument when the user holds the writing instrument, and absorbs the force applied to the user's finger by the elastic force to reduce fatigue, thereby providing a large friction between the shaft barrel and the finger to prevent The user's finger slides undesirably for the barrel. By these, the grip and writing feeling of the writing instrument are improved. However, the extent to which the elastic force of the grip member is felt is superior to the grip of the writing instrument having the grip member, which varies depending on the user's preference. That is, there is a user who feels that the grip member is softer and has a better grip feeling, and a user who feels that the grip member is harder has a better grip. Therefore, although it is desired to develop a writing instrument having a grip member that allows a majority of users to feel a better grip, it is difficult to implement. [Prior Art Document] [Patent Document 1] [Patent Document 1] Japanese Patent No. 4043305 The inventors of the present invention have repeatedly found out that the grip member is provided with a soft grip and provides a hard grip. The area can solve the above problems. The present invention is based on the above findings. That is, an object of the present invention is to provide a writing instrument having a grip member which allows a majority of users to feel a better grip. Or the object of the present invention is to provide a grip member which can make a grip feel better for most users.

The writing instrument of the present invention includes: a shaft cylinder; and a grip member that surrounds the shaft cylinder in a circumferential direction; and a thickness of the grip member varies in the circumferential direction; and a thickness of the shaft cylinder varies along the circumferential direction The region of the above-mentioned grip member having a large wall thickness surrounds a region where the wall thickness of the shaft cylinder is small; and the region of the grip member having a small wall thickness surrounds a region of the shaft cylinder having a large wall thickness. According to the present invention, since the wall thickness of the grip member is large to provide a soft grip to the user, the user can provide a hard grip to the user in a region where the wall thickness of the grip member is small, so A writing instrument having a grip member that allows most users to feel a better grip. Preferably, the inner surface of the shaft barrel has a substantially circular cross section. In this case, the barrel does not interfere with the writing body housed in the barrel, and the assembly of the writing instrument is also easy. Further, it is preferable that the outer surface of the grip member has a substantially circular cross section. In this case, the user can hold the writing instrument without any sense of discomfort. Preferably, the outer surface of the barrel surrounded by the grip member has a chamfered portion. The chamfered portion corresponds to a region where the wall thickness of the barrel is small. In this case, if the grip member is gripped by the region corresponding to the chamfered portion, the region of the grip member having a large wall thickness is compressed and deformed, and thus the gripping region where the chamfered portion is not provided, that is, the grip A softer grip can be provided when the wall thickness of the shank member is smaller. Further, the chamfered portion can be engaged with the region of the grip member having a large wall thickness to prevent undesired relative rotation of the grip member relative to the barrel. More preferably, the chamfered portions are provided at three equal intervals in the circumferential direction of the barrel. In this case, the chamfered portion of the barrel and the region where the wall thickness of the grip member is large can be positioned at a position where the three fingers (thumb, forefinger, and middle finger) holding the writing instrument contact the grip member. That is, it is possible to effectively arrange the region where the wall thickness of the grip member is large, that is, the region which provides a soft grip. The grip member of the present invention is a tubular member surrounding the barrel of the writing instrument, and has a region having a large wall thickness and a region having a small wall thickness, and a plurality of blocks surrounded by the groove on the outer surface are formed on the outer surface. . According to the present invention, the region having a large wall thickness has a large deformation, and the region having a small wall thickness is slightly deformed. Specifically, in a region having a large wall thickness, the entire block is largely compressed and deformed by the presence of the wall thickness and the grooves on the four sides, and on the other hand, in the region having a small wall thickness, the block Less compression deformation. Therefore, the user can provide a soft grip to the user in a region with a small wall thickness, and provide a hard grip to the user in a region with a small wall thickness, so that most users can feel the grip feeling. Grip member. Further, since the block surrounds the four sides by the groove, it is possible to suppress undesired sliding in the circumferential direction of the grip member by the user's finger resting on the groove. Furthermore, by the user's finger resting on the groove, it is possible to suppress undesired sliding in the axial direction of the grip member. Preferably, the block has a larger wall thickness in a region where the wall thickness is larger, and a smaller wall thickness in a region where the wall thickness is smaller. In this case, since the compression deformation of the block of the grip member in the region where the wall thickness is large becomes particularly easy, a softer grip can be provided in this region. Further, preferably, the grip member is attached to an inner region where the groove is not formed, and has an inner region having a large wall thickness and an inner region having a small wall thickness; and the region having a larger wall thickness corresponds to the larger wall thickness. The inner region; the region having the smaller wall thickness corresponds to the inner region having the smaller wall thickness. In this case, especially in a region where the wall thickness is large, the balance between the compression deformation and the flexural deformation is good, and a grip member which can make the grip feel better for most users can be provided.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 1A is a schematic plan view showing a writing instrument 100 according to an embodiment of the present invention, and FIG. 1B is a schematic side view showing the writing instrument 100 of FIG. 1A, showing that the writing portion 51 of the writing body 50 extends from the front end of the barrel 10. A schematic side view of the state of the out. Figure 2 is a schematic longitudinal cross-sectional view showing the writing instrument 100 of Figure 1A. As shown in FIG. 1A, FIG. 1B and FIG. 2, the writing instrument 100 of the present embodiment includes a shaft cylinder 10 having a front axle 20 and a shaft 30 connected to the front axle 20 by, for example, a socket fitting; a handle The member 40 surrounds the outer surface of the front axle 20 in the circumferential direction, and the writing body 50 is housed in the shaft cylinder 10 in abundance. As an example, the front axle 20 and the rear axle 30 are made of resin, and the grip member 40 is made of rubber. In the illustrated example, the writing instrument 100 is a ballpoint pen. The shaft barrel 10 (front shaft 20) is formed with a first opening portion 21 at the distal end where the writing portion 51 of the writing body 50 protrudes. Further, the barrel 10 (front shaft 20) has a first engaging portion 22 on the inner surface of the front region. The writing body 50 has a second engaging portion 52 on the outer surface (the right side in FIG. 2 ) of the first engaging portion 22 of the front shaft 20 . Further, the coil springs 60 are disposed in a compressed state between the first and second engaging portions 22 and 52. The coil spring 60 is for energizing the writing body 50 toward the rear of the axial direction of the barrel 10 (the right side in FIGS. 1A to 2). The rear end 50e of the writing body 50 abuts against the rotary cam 23 provided in the rear region of the rear axle 30, and restricts the relative movement rearward in the axial direction of the shaft cylinder 10, thereby maintaining the compressed state of the coil spring 60. The pressing member 70 is a member for causing the writing body 50 to protrude from the first opening portion 21 of the front shaft 20 against the ability of the coil spring 60 to be engaged. The pressing member 70 is movable in a state in which the writing body 50 is moved forward in the axial direction of the barrel 10 (the left side in FIGS. 1A to 2) and the writing portion 51 of the writing body 50 protrudes outward from the first opening portion 21. The protruding position (see FIG. 1B) moves between the immersed position (see FIG. 1A) corresponding to the state in which the writing portion 51 of the writing body 50 is immersed in the front shaft 20. As shown in FIG. 1A and FIG. 1B, the rear end 70e of the pressing member 70 protrudes outward from the second opening portion 31 at the rear end of the rear axle 30 in both the protruding position and the immersed position. Further, the writing instrument 100 of the present embodiment is provided with a cam mechanism having a rotary cam 23 for switching the writing of the writing core 51 of the writing body 50 in the barrel 10, and a cam groove for engaging with the rotating cam 23 ( Not shown). As will be described later, when the pressing member 70 is pressed (in the pressing operation) in a state where the writing portion 51 of the writing body 50 is immersed in the front shaft 20 (refer to FIG. 1A), the rotating cam 23 slides along the cam groove, and the writing is performed. The writing portion 51 of the body 50 protrudes outward from the first opening portion 21 of the front shaft 20, and further, the rotating cam 23 is rotated by the action of the cam mechanism, thereby preventing the relative movement of the writing body 50 toward the rear of the shaft cylinder 10 in the axial direction. This protruding state is also maintained after the end of the pressing operation. Further, when the pressing member 70 is pressed again (pressing operation) in the protruding state, the writing body 50 is allowed to relatively move rearward in the axial direction of the barrel 10 by the action of the cam mechanism, and by the coil spring 60 The ability to push the writing body 50 and the pressing member 70 rearward in the axial direction is restored to the initial state. Next, Fig. 3 is a partial perspective view showing a state in which the shaft 20 and the grip member 40 are assembled before the writing instrument 100 of Fig. 1A is assembled. 4 is a schematic perspective view showing the front shaft 20 of the writing instrument 100 of FIG. 1A, FIG. 5 is a schematic longitudinal cross-sectional view showing the front shaft 20 and the grip member 40 of FIG. 3, and FIG. 6 is a front view showing the shaft 20 and the grip member 40 of FIG. A schematic cross-sectional view. As shown in FIG. 3, the outer surface of the front shaft 20 of the writing instrument 100 of the present embodiment is surrounded by the grip member 40. The grip member 40 can be fabricated with the front axle 20 by, for example, 2-color shaping. On the outer surface of the grip member 40, 16 slots extending in the axial direction at one of the slots extending in the axial direction and 18 slots extending from the slot at equal intervals in the orthogonal direction are respectively formed. 42. That is, the outer surface of the grip member 40 of the present embodiment is divided into a plurality of rectangular regions (blocks 40b) surrounded by one groove 41 and the other groove 42 on the four sides. As shown in FIGS. 4 and 5, in the present embodiment, the shaft 20 has a front end region 24 which is not surrounded by the grip member 40, and a covering region 25 which is surrounded by the grip member 40. The front end region 24 has an annular cross section and is tapered toward the front (lower left in Fig. 4). The outer diameter of the rear end of the front end region 24 is larger than the outer diameter of the front end of the covering region 25, and the thickness of the grip member 40 is increased. In the state where the covering region 25 is surrounded by the grip member 40, the rear end portion of the front end region 24 is gripped. There is no step difference between the front ends of the shank members 40. Further, as shown in FIGS. 4 and 5, the outer surface of the covering region 25 has a chamfered portion 26. The chamfered portion 26 is an elongated circular region formed by excavation of the outer surface of the cylindrical coating region 25. Only two chamfered portions 26 are shown in Fig. 4, but actually, the chamfered portions 26 are provided at three equal intervals in the circumferential direction of the front axle 20. In Fig. 5, the cross section of the covering region 25 of the front axle 20 is visually recognized, but the chamfered portion 26 is not shown in the cross section 25a of the upper portion, and the wall thickness of the covering region 25 is fixed in the axial direction. On the other hand, the chamfered portion 26 is formed in the lower portion 25b of the lower portion, and the wall thickness of the front shaft 20 is varied in the axial direction (reduced in the chamfered portion 26). As shown in Fig. 6, the inner surface of the front axle 20 has a substantially circular cross section. Further, the outer surface of the grip member 40 has a substantially circular cross section. Here, the substantially circular shape means that when the irregularities existing on the inner surface of the front axle 20 are ignored, the outline of the inner surface is circular, or the groove 41 formed on the outer surface of the grip member 40 is ignored. The outline (ridge line) of each block 40b of the recess formed by the groove 42 is circular. Further, as shown in FIG. 6, the inner surface of the grip member 40 and the outer surface of the covering region 25 of the front axle 20, in particular, the inner surface of the grip member 40 and the chamfered portion 26 provided in the covering region 25, have no gap. Ground contact. That is, the thickness of the grip member 40 varies at a portion corresponding to the chamfered portion 26. Further, the thickness of the covering region 25 of the front axle 20 varies in the circumferential direction due to the presence of the chamfered portion 26. Further, the region 43 of the grip member 40 having a large wall thickness surrounds the region where the wall thickness of the front axle 20 is small, that is, the outer surface of the chamfered portion 26, and the region 44 of the grip member 40 having a small wall thickness is surrounded. The outer surface of the region 27 of the front axle 20 having a large wall thickness. Here, the configuration of the front axle 20 and the grip member 40 will be described in detail with reference to FIGS. 7 to 9 . Fig. 7 is a sectional view taken along line VII-VII of Fig. 1A, Fig. 8 is a sectional view taken along line VIII-VIII of Fig. 1A, and Fig. 9 is a sectional view taken along line IX-IX of Fig. 1A. In FIGS. 7 to 9, the illustration of the writing body 50 in the front axle 20 is omitted. As shown in FIGS. 7 and 8, at the position of the line VII-VII of FIG. 1A and the position of the line VIII-VIII, the chamfered portion 26 is present in the covered region 25 of the front axle 20, and the wall thickness of the front axle 20 is small. The region 27, which is a region where the chamfered portion 26 and the front axle 20 are thick, alternates at equal intervals in the circumferential direction. Further, as described above, the region 43 of the grip member 40 having a large wall thickness surrounds the outer surface of the chamfered portion 26, and the region 44 of the grip member 40 having a small wall thickness surrounds the region of the front axle 20 having a large wall thickness. 27 outside the surface. Further, as shown in Fig. 7, the wall thickness of the block 40b (rectangular region) formed on the outer surface of the grip member 40 varies. Specifically, the block 40b is in the region 43 where the wall thickness of the grip member 40 is large, and the wall thickness of the block 40b is large (thickness d1), and is in the region 44 of the region 44 where the wall thickness of the grip member 40 is small. The wall thickness of the block 40b is small (thickness d2). The thickness variation of such a block 40b is particularly remarkable in FIG. The line VIII-VIII of Fig. 1A corresponding to Fig. 8 corresponds to the position where the thickness of the chamfered portion 26 is the largest and the width of the circumferential direction is the largest. Therefore, the chamfered portion 26 of Fig. 8 has the smallest wall thickness of the front axle 20, and the grip member 40 surrounding the outer surface of the chamfered portion 26 has the largest wall thickness. As shown in Fig. 8, in the region 43 where the wall thickness of the grip member 40 is large, the maximum thickness of the block 40b is d1' (> d1). On the other hand, in the region 44 where the wall thickness of the grip member 40 of Fig. 8 is small, the maximum thickness of the block 40b is d2, which is substantially the same as that of Fig. 7. As shown in FIG. 7 and FIG. 8 , the handle member 40 has an outer region 45 formed with a groove 41 extending in the axial direction and another groove 42 extending from the groove 41 in the orthogonal direction; And the inner region 46 (the region closer to the inner side in the radial direction than the outer region 45), which does not form a groove 41 and another groove 42. The inner region 46 has an inner region 46a having a large wall thickness and an inner region 46b having a small wall thickness. Further, the region 43 of the grip member 40 having a large wall thickness corresponds to the inner region 46a having a large wall thickness, and the region 44 having a small wall thickness of the grip member 40 corresponds to the inner region 46a having a small wall thickness. Here, "corresponding" means that they exist at substantially the same position in the circumferential direction of the grip member 40. On the other hand, as shown in Fig. 9, in the region of the covering region 25 of the front axle 20 which is further rearward than the chamfered portion 26, the thickness of the front axle 20 is fixed, and the wall thickness of the grip member 40 is also fixed. Furthermore, the thickness of the block 40b is also fixed. Next, the action of the writing instrument 100 of the present invention will be described. First, the pressing member 70 presses the pressing member 70 against the barrel 10 (pressing operation). Thereby, the writing body 50 compresses the coil spring 60 and relatively moves forward in the axial direction of the barrel 10, and the writing portion 51 of the writing body 50 is exposed to the outside from the opening 21 at the front end of the front shaft 20. At the time of this relative movement, the writing body 50 cannot be relatively moved rearward in the axial direction of the barrel 10 by the cam mechanism 23, and the protruding state of the writing portion 51 is maintained even when the pressing operation (pressing operation) is completed. Further, the user holds the grip member 40 to write a writing surface such as a paper surface. When the grip member 40 of the present embodiment is held by a user, different grip feelings are provided according to the region pressed by the finger of the user. Specifically, when the user's finger is pressed against the region 43 of the grip member 40 having a large wall thickness, the user is provided with a soft grip. On the other hand, when the user's finger is pressed against the region 44 of the grip member 40 having a small wall thickness, the user is provided with a firm grip. As described above, the region 43 having a large wall thickness of the grip member 40 and the region 44 having a small wall thickness of the grip member 40 are alternately arranged at three intervals in the circumferential direction, so that the user is When a finger (for example, a thumb) is pressed against a region 43 having a large wall thickness of the grip member 40, normally, other fingers (for example, the index finger and the middle finger) are also pressed against the region 43 having a large wall thickness of the remaining two portions. Similarly, if a finger (for example, a thumb) of the user is pressed against the region 44 of the grip member 40 having a small wall thickness, generally, other fingers (for example, the index finger and the middle finger) are also pressed against the remaining 2 portions to have a smaller wall thickness. Area 44. At the time of the grip, the grip member 40 is compressively deformed in the radial direction by the force applied by the user's finger. In particular, if the user's finger is pressed against the region 43 of the grip member 40 having a large wall thickness, it is more compressively deformed than when the user's finger is pressed against the region 44 having a small wall thickness with the same force. Further, as described above, in the region 43 where the wall thickness of the grip member 40 is large, since the wall portion 44 having a smaller wall thickness than the grip member 40 sets the wall thickness of the block 40b to be thicker, it is When the user's finger is pressed, each of the blocks 40b of the grip member 40 that surrounds the four sides by the groove is easily deformed on the four sides. By virtue of this, in the region 43 where the wall thickness of the grip member 40 is large, the user is provided with a soft grip. On the other hand, if the user's finger is pressed against the region 44 of the grip member 40 having a small wall thickness, the user's finger is pressed against the region 43 having a large wall thickness, and the deformation is smaller. Further, in the region 44 where the wall thickness of the grip member 40 is small, the wall thickness of the block 40b is the smallest, and thus the block 40b is only slightly flexed and deformed. Therefore, in the region 44 where the wall thickness of the grip member 40 is small, a firm grip is provided to the user. Further, in the present embodiment, the outer surface of the chamfered portion 26 of the front axle 20 is in contact with the inner surface of the region 43 of the grip member 40 having a large wall thickness, and the cross section of the contact surface is non-perforated. It is circular, thereby preventing relative rotation of the grip member 40 with respect to the front axle 20 (refer to Figs. 7 and 8). When the writing of the writing instrument 100 is completed, the user presses the pressing member 70 (pressing operation) forward in the axial direction of the barrel 10 again. Thereby, the writing body 50 relatively moves toward the front of the barrel 10 against the ability of the coil spring 60. At the time of this relative movement, the writing body 50 is in a state of being relatively movable toward the rear in the axial direction of the barrel 10 by the cam mechanism 23. When the pressing operation (pressing operation) is completed, the coil spring 60 is relatively moved toward the rear in the axial direction of the barrel 10, and the initial state is restored, that is, the writing portion 51 of the writing body 50 is not inserted into the barrel 10. State. According to the present embodiment as described above, since the region 43 having a large wall thickness of the grip member 40 provides a soft grip to the user, the region 44 having a small wall thickness of the grip member 40 is provided to the user. With a stiff grip, it is possible to provide a writing instrument 100 having a grip member 40 that allows most users to feel better grip. Since the inner surface of the shaft cylinder 10 (front shaft 20) of the present embodiment has a circular cross section, the shaft cylinder 10 does not interfere with the writing body 50 housed in the shaft cylinder 10, and the assembly of the writing instrument 100 is also easy. . Further, since the outer surface of the grip member 40 has a substantially circular cross section, the user can hold the writing instrument 100 without any sense of discomfort. The outer surface of the covered region 25 of the front shaft 20 surrounded by the grip member 40 has a chamfered portion 26 as a region where the front wall 20 has a small wall thickness. Therefore, if the grip member 40 is gripped by the region corresponding to the chamfered portion 26, the region 43 of the grip member 40 having a large wall thickness is largely compressed and deformed, and thus the chamfered portion 60 is not provided with the grip. The region, i.e., the region 44 of the grip member 40 having a small wall thickness, provides a softer grip. Further, the chamfered portion 26 can be engaged with the region 43 of the grip member 40 having a large wall thickness to prevent undesired relative rotation of the grip member 40 relative to the front axle 20. The chamfered portions 26 are provided at equal intervals in three portions in the circumferential direction of the covering region 25 of the front axle 20, so that the chamfered portion 26 of the front axle 20 and the region 43 having a large wall thickness of the grip 40 can be positioned and held. The three fingers (thumb, index finger, and middle finger) of the writing instrument 100 contact the position of the grip member 40. That is, the region 43 of the grip member 40 having a large wall thickness can be effectively disposed, that is, a region providing a soft grip. Further, in the present embodiment, the block 40b (rectangular region) is formed by the groove 41 extending in the axial direction and the other groove extending from the groove in the orthogonal direction, but in other embodiments, The block 40b (circular area) surrounded by the grooves can be formed by a groove formed in an annular shape. Further, in the present embodiment, the thickness of the block 40b is set such that the maximum thickness thereof is the thickness of the block when the thickness is not fixed. Further, in the present embodiment, the writing instrument 100 has been described by taking a ball pen as an example, but the present invention is not limited thereto. The present invention can be applied to various writing instruments such as a mechanical pencil, a signature pen, and a correction pen by appropriately selecting the writing body 50.

10‧‧‧ shaft tube

20‧‧‧ front axle

21‧‧‧1st opening

22‧‧‧1st buckle

23‧‧‧Rotating cam

24‧‧‧ front end area

25‧‧‧covered area

25a‧‧‧ profile

25b‧‧‧ section

26‧‧‧Chamfering

27‧‧‧Area

30‧‧‧ rear axle

31‧‧‧2nd opening

40‧‧‧Handle member

40b‧‧‧ Block

41‧‧‧ slots

42‧‧‧ slots

43‧‧‧Area

44‧‧‧Area

45‧‧‧Outer area

46‧‧‧ inside area

46a‧‧‧ inside area

46b‧‧‧ inside area

50‧‧‧ writing body

50e‧‧‧ backend

51‧‧‧ writing department

52‧‧‧2nd buckle

60‧‧‧ coil spring

70‧‧‧Pressing components

70e‧‧‧ backend

100‧‧‧ writing utensils

D1‧‧‧ thickness

D1'‧‧‧ thickness

D2‧‧‧ thickness

Fig. 1A is a schematic plan view showing a writing instrument according to an embodiment of the present invention. Fig. 1B is a schematic side view showing the writing instrument of Fig. 1A, and is a schematic side view showing a state in which the writing portion of the writing body protrudes from the front end of the barrel. Figure 2 is a schematic longitudinal cross-sectional view showing the writing instrument of Figure 1A. Fig. 3 is a partially schematic perspective view showing the state of the shaft and the grip member before the writing instrument of Fig. 1A is assembled. Figure 4 is a schematic perspective view showing the axis of the writing instrument of Figure 1A. Figure 5 is a schematic longitudinal cross-sectional view of the front shaft and the grip member of Figure 3. Figure 6 is a schematic cross-sectional view of the front shaft and the grip member of Figure 3. Fig. 7 is a sectional view taken along line VII-VII of Fig. 1A, and the writing body in the barrel is omitted. Fig. 8 is a sectional view taken along line VIII-VIII of Fig. 1A, and the writing body in the barrel is omitted. Fig. 9 is a sectional view taken along line IX-IX of Fig. 1A, and the writing body in the barrel is omitted.

Claims (10)

A writing instrument comprising: a shaft cylinder; and a grip member that surrounds the shaft cylinder in a circumferential direction; and a thickness of the grip member varies along the circumferential direction; a thickness of the shaft barrel along the circumferential direction a region in which the wall thickness of the grip member is large is surrounded by a region having a small wall thickness of the shaft cylinder; and a region having a small wall thickness of the grip member surrounds a region having a large wall thickness of the shaft cylinder; The handle member is formed with a plurality of slots extending in an axial direction of the shaft cylinder and another slot extending in a direction orthogonal to the slot; each slot is orthogonal to an axial direction of the shaft cylinder The other surface has the same depth under the cut surface; the other groove is deeper in the region where the wall thickness of the handle member is larger under the cut surface, and is shallower in a region where the thickness of the handle member is smaller. The writing instrument of claim 1, wherein the depth of the other groove at the shallowest position of the other groove is equal to the depth of the one groove under the cut surface. The writing instrument of claim 1 or 2, wherein the depth of the other groove and the outer diameter of the barrel are changed together in the circumferential direction of the barrel, under the cut surface. The writing instrument of claim 1 or 2, wherein the inner surface of the shaft barrel has a substantially circular cross section. The writing instrument of claim 1 or 2, wherein the outer surface of the handle member has a substantially circular cross section. The writing instrument of claim 1 or 2, wherein the outer surface of the barrel surrounded by the grip member has a chamfered portion. The writing instrument of claim 6, wherein the chamfered portions are provided at three equal intervals in the circumferential direction of the shaft cylinder. A grip member characterized in that it is a tubular body surrounding a shaft barrel of a writing instrument, and the grip member has a region having a large wall thickness and a region having a small wall thickness, and is formed on the outer surface by a groove. a plurality of blocks on the four sides; the handle member is formed with a plurality of grooves extending in an axial direction of the shaft barrel, and another groove extending in a direction orthogonal to the groove; each groove is The cut surface having the same direction as the axial direction of the shaft cylinder has the same depth; and the other groove is deeper than the cut surface, and the depth of the grip member is deep, and the grip member is The above-mentioned area having a small wall thickness is shallow. The handle member of claim 8, wherein the plurality of blocks are thicker in a region having a larger wall thickness, and the wall thickness is greater The smaller the area, the smaller the wall thickness. The handle member of claim 8 or 9, wherein the grip member has an inner region having a larger wall thickness and an inner region having a smaller wall thickness in an inner region where the groove is not formed; and the region having a larger wall thickness corresponds to In the inner region having a large wall thickness; the region having a small wall thickness corresponds to the inner region having a small wall thickness.