Retractable writing instrument

Abstract

To provide a knock type writing instrument having a simple mechanism for achieving a stable scratch operation or the like.SOLUTION: A knock type writing instrument 1 comprises: a barrel 4; an operation part 30; and a rotor 40, in which a writing state and a non-writing state can be switched, by performing a knock operation for forward pressing of the operation part 30. The writing instrument further comprises a knock lock member 50 capable of moving in a cross direction in the barrel by gravity force, and an engagement part 60 disposed on an inner face of the barrel 4 and capable of engaging to the knock lock member 50. When a front end of the barrel 4 is directed upward, the knock lock member 50 moves rearward and engages to the engagement part 60, and forward movement of the operation part 30 is inhibited.SELECTED DRAWING: Figure 12

Description

Technical Field

[0001] The present invention relates to a knock-type writing instrument.

Background Art

[0002] There is known a so-called knock-type writing instrument in which an operation portion is provided at the rear end portion of a shaft cylinder, and by performing a knock operation for pressing the operation portion forward against the biasing force of a spring disposed within the shaft cylinder, a writing state in which a writing portion, which is a pen tip, protrudes from the tip of the shaft cylinder and a non-writing state in which the writing portion is immersed within the shaft cylinder can be switched (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the writing instrument described in Patent Document 1, the operation portion also serves as a friction body for rubbing the thermochromic ink of the writing instrument. Therefore, during the rubbing operation, in order to perform a stable rubbing operation, it is necessary to rotate the operation portion in the circumferential direction to prevent movement in the front-rear direction. Such an operation is troublesome.

[0005] [[ID=There is provided a knock-type writing instrument having a simple mechanism that enables a stable rubbing operation and the like.

Means for Solving the Problems

[0006] According to one aspect of the present invention, a knock-type writing instrument is provided, comprising a barrel, an operating part, and a rotor, wherein a writing state and a non-writing state can be switched by performing a knock operation to press the operating part forward, and further comprising a knock-lock member that can move in the front-rear direction within the barrel by gravity, and a locking part provided on the inner surface of the barrel and capable of locking with the knock-lock member, wherein when the front end of the barrel is pointed upward, the knock-lock member moves backward and locks with the locking part, preventing the operating part from moving forward. Herein, "front" refers to the writing part side in the writing state, and the other end side is referred to as "rear".

[0007] In another embodiment, a retractable writing instrument is provided, characterized in that the retractable locking member is a cylindrical member.

[0008] Furthermore, according to another embodiment, a knock-type writing instrument is provided characterized in that the rotor or the operating part has a cam surface facing the knock-lock member, the knock-lock member has a cam receiving surface that cooperates with the cam surface, and when the knock-lock member moves backward, the cam surface and the cam receiving surface cooperate to rotate the knock-lock member in the circumferential direction, and the locking part and the knock-lock member become locked.

[0009] Furthermore, according to another embodiment, a retractable writing instrument is provided characterized in that the operating part has the cam surface facing the knock-lock member, and the rotor is disposed within the operating part.

[0010] Furthermore, according to another embodiment, a knock-type writing instrument is provided characterized in that the knock-lock member has a first projection and the locking portion has a second projection, and when the knock-lock member rotates in the circumferential direction, the first projection and the second projection engage with each other, thereby locking the knock-lock member and the locking portion.

[0011] Furthermore, a retractable writing instrument is provided, characterized in that a recess is formed on the side surface of the first projection or the second projection, and the first projection and the second projection are locked together by the recess.

[0012] Furthermore, a retractable writing instrument is provided, characterized in that two recesses are formed in front of and behind one of the first or second protrusions, and that the recesses can be locked with the other protrusion in both the writing state and the non-writing state.

[0013] Furthermore, a retractable writing instrument is provided, characterized in that two recesses are formed in front of and behind one of the second or first protrusions, and that the recesses can be locked to the other protrusion in both the writing state and the non-writing state.

[0014] Furthermore, a retractable writing instrument is provided, characterized in that the recess has a shape complementary to a part of the projection that engages with it.

[0015] Furthermore, a knock-type writing instrument is provided, characterized in that a plurality of first protrusions and a plurality of second protrusions are arranged at equal intervals in the circumferential direction, a guide groove extending in the front-rear direction is defined between one of the first protrusions or the second protrusions, and the other protrusion moves within the guide groove in accordance with the front-rear movement of the knock-lock member.

[0016] Furthermore, a retractable writing instrument is provided, characterized in that the recess has a slope that guides the locking projection into the guide groove.

[0017] Furthermore, according to another embodiment, a knock-type writing instrument is provided, characterized in that a window is provided on the side surface of the barrel, the knock-lock member can be seen through the window when it is positioned towards the rear end inside the barrel, and cannot be seen through the window when it is positioned towards the front end inside the barrel, or the knock-lock member can be seen through the window when it is positioned towards the front end inside the barrel, and cannot be seen through the window when it is positioned towards the rear end inside the barrel.

[0018] Furthermore, according to another embodiment, a retractable writing instrument is provided characterized in that the barrel and the portion of the knock-lock member visible through the window are formed in different colors.

[0019] Furthermore, according to another embodiment, a retractable writing instrument is provided characterized in that the forward movement of the knock-lock member is prevented by contact with a cushioning member.

[0020] Furthermore, it is desirable that the retractable writing instrument be characterized in that all or part of the operating section is an erasing section capable of erasing the writing of the retractable writing instrument.

[0021] Furthermore, according to another embodiment, a retractable writing instrument is provided which has thermochromic ink, and is characterized in that the writing made with the thermochromic ink can be thermochromic due to the frictional heat generated when it is rubbed by the erasing part. [Effects of the Invention]

[0022] According to aspects of the present invention, a common effect is to provide a retractable writing instrument equipped with a simple mechanism that enables stable scratching action. Furthermore, it provides a retractable writing instrument that makes it easy to determine whether or not stable scratching action is possible. [Brief explanation of the drawing]

[0023] [Figure 1]A longitudinal sectional view of the writing instrument according to the first embodiment of the present invention in a non-writing state with the front end facing upward. [Figure 2] A longitudinal sectional view of the writing instrument of FIG. 1 in a non-writing state with the front end facing downward. [Figure 3] A longitudinal sectional view of the writing instrument of FIG. 1 in a writing state with the front end facing downward. [Figure 4] An exploded assembly view of the knock mechanism of the writing instrument of FIG. 1. [Figure 5] A partial longitudinal sectional view of the inner cylinder of the writing instrument of FIG. 1. [Figure 6] A perspective view of the operation portion of the writing instrument of FIG. 1. [Figure 7] A perspective view of the rotor of the writing instrument of FIG. 1. [Figure 8] A perspective view of the knock lock member of the writing instrument of FIG. 1. [Figure 9] Another perspective view of the knock lock member of the writing instrument of FIG. 1. [Figure 10] A longitudinal sectional view of the rear shaft of the writing instrument of FIG. 1. [Figure 11] A rear view of the rear shaft of the writing instrument of FIG. 1. [Figure 12] A schematic diagram showing the switching of the knock mechanism of the writing instrument of FIG. 1 from the non-writing state to the writing state. [Figure 13] A longitudinal sectional view of the writing instrument according to the second embodiment of the present invention in a non-writing state with the front end facing upward. [Figure 14] A longitudinal sectional view of the writing instrument of FIG. 13 in a non-writing state with the front end facing downward. [Figure 15] A longitudinal sectional view of the writing instrument of FIG. 13 in a writing state with the front end facing downward. [Figure 16] A longitudinal sectional view of the writing instrument of FIG. 13 in a writing state with the front end facing upward. [Figure 17] A perspective view of the knock lock member of the writing instrument of FIG. 13. [Figure 18] Another perspective view of the knock lock member of the writing instrument of FIG. 13. [Figure 19] A longitudinal sectional view of the rear shaft of the writing instrument of FIG. 13. [Figure 20]Figure 13 is a rear view of the rear barrel of the writing instrument. [Figure 21] Figure 13 is a schematic diagram illustrating the switching of the writing instrument's knock mechanism from the non-writing state to the writing state. [Figure 22] This is a perspective view of a knock-lock member of a writing instrument according to a third embodiment of the present invention. [Figure 23] Figure 22 is another perspective view of the knock-lock component of the writing instrument. [Figure 24] This is a longitudinal cross-sectional view of the rear barrel of a writing instrument according to a third embodiment of the present invention. [Figure 25] Figure 24 is a rear view of the rear barrel of the writing instrument. [Figure 26] This is a side view showing a cover member of an erasing member in a different embodiment. [Figure 27] Figure 26 is a longitudinal cross-sectional view of the eraser with the cover member attached. [Figure 28] This is a side view of a writing instrument according to a fourth embodiment of the present invention. [Figure 29] Figure 28 is a longitudinal cross-sectional view of the writing instrument in a non-writing state with its front end facing upwards. [Figure 30] Figure 28 is a longitudinal cross-sectional view of the writing instrument in a non-writing state, with the front end facing downwards. [Figure 31] Figure 28 is a vertical cross-sectional view of the writing instrument in the writing position with the front end facing downwards. [Figure 32] Figure 28 is an exploded view of the knock mechanism of a writing instrument. [Figure 33] Figure 28 is a side view of the rear barrel of the writing instrument. [Figure 34] Figure 28 is a rear view of the rear barrel of the writing instrument. [Figure 35] This is a cross-sectional view along line AA of the rear axis in Figure 33. [Figure 36] Figure 28 is a perspective view of the knock-lock component of a writing instrument. [Figure 37] Figure 28 is another perspective view of the knock-lock component of the writing instrument. [Figure 38] Figure 28 is a schematic diagram illustrating the switching of the writing instrument's knock mechanism from the non-writing state to the writing state. [Figure 39]Figure 28 is a longitudinal cross-sectional view of the erasing component of a writing instrument. [Figure 40] This is a longitudinal cross-sectional view of a writing instrument according to the fifth embodiment of the present invention, in a non-writing state with the front end facing upward. [Figure 41] Figure 40 is a longitudinal cross-sectional view of the writing instrument in a non-writing state, with the front end facing downwards. [Figure 42] Figure 40 is a vertical cross-sectional view of the writing instrument with the front end facing downwards while the click mechanism is being operated. [Figure 43] Figure 40 is a vertical cross-sectional view of the writing instrument in the writing position with its front end facing downwards. [Figure 44] Figure 40 is a vertical cross-sectional view of the writing instrument in the writing position with its front end facing upwards. [Figure 45] Figure 40 is an exploded view of the knock mechanism of a writing instrument. [Figure 46] Figure 40 is a longitudinal cross-sectional view of the rear barrel of the writing instrument. [Figure 47] Figure 40 is a front view of the inner cylinder of a writing instrument. [Figure 48] Figure 47 is a cross-sectional view of the inner cylinder along line BB. [Figure 49] Figure 40 is a perspective view of the operating section of a writing instrument. [Figure 50] Figure 40 is a vertical cross-sectional view of the operating part of the writing instrument. [Figure 51] Figure 40 is a perspective view of the rotor of a writing instrument. [Figure 52] Figure 40 is a perspective view of the knock-lock component of a writing instrument. [Figure 53] Figure 40 is another perspective view of the knock-lock component of the writing instrument. [Figure 54] Figure 40 is a side view of the front barrel of the writing instrument. [Figure 55] Figure 40 is a perspective view of the erasing component of a writing instrument. [Figure 56] Figure 40 is a longitudinal cross-sectional view of the erasing component of a writing instrument. [Figure 57] Figure 40 is a schematic diagram illustrating the switching of the writing instrument's knock mechanism from the non-writing state to the writing state. [Figure 58]Figure 40 is a schematic diagram illustrating the switching of the writing instrument's knock mechanism from the writing state to the non-writing state. [Figure 59] This is a longitudinal cross-sectional view of a writing instrument according to the sixth embodiment of the present invention, in a non-writing state with the front end facing upward. [Figure 60] Figure 59 is a longitudinal cross-sectional view of the writing instrument in a non-writing state, with the front end facing downwards. [Figure 61] Figure 59 is a vertical cross-sectional view of the writing instrument in the writing position with its front end facing downwards. [Figure 62] Figure 59 is a vertical cross-sectional view of the writing instrument in the writing position with its front end facing upwards. [Figure 63] Figure 59 is a disassembled and assembled diagram of the knock mechanism of a writing instrument. [Figure 64] Figure 59 is a longitudinal cross-sectional view of the rear barrel of the writing instrument. [Figure 65] Figure 59 is a perspective view of the operating section of a writing instrument. [Figure 66] Figure 59 is a perspective view of the rotor of a writing instrument. [Figure 67] Figure 59 is a schematic diagram illustrating the switching of the writing instrument's knock mechanism from the non-writing state to the writing state. [Figure 68] Figure 59 is a schematic diagram illustrating the switching of the writing instrument's knock mechanism from the writing state to the non-writing state. [Modes for carrying out the invention]

[0024] Embodiments of the present invention will be described in detail below with reference to the drawings. Throughout all drawings, corresponding components are denoted by the same reference numerals.

[0025] Figure 1 is a vertical cross-sectional view of the writing instrument 1 according to the first embodiment of the present invention in a non-writing state with the front end facing upwards; Figure 2 is a vertical cross-sectional view of the writing instrument 1 of Figure 1 in a non-writing state with the front end facing downwards; Figure 3 is a vertical cross-sectional view of the writing instrument 1 of Figure 1 in a writing state with the front end facing downwards; and Figure 4 is an exploded assembly view of the knock mechanism 10 of the writing instrument 1 of Figure 1.

[0026] The writing instrument 1 comprises a barrel 4 formed in a cylindrical shape and having a front barrel 2 and a rear barrel 3; a refill 5 which is a writing body disposed inside the barrel 4 and having a writing section 5a at one end; a spring 6 which biases the refill 5 backward; and a knock mechanism 10 located at the rear end of the barrel 4, i.e., the rear end of the rear barrel 3. The knock mechanism 10 has a cylindrical inner cylinder 20, an operating section 30, and a rotor 40, each formed in a cylindrical shape. The front end of the front barrel 2 is tapered and has a through hole 2a for allowing the writing section 5a of the refill 5 to protrude. The rear end of the front barrel 2 is inserted into the front end of the rear barrel 3 and fitted by press-fitting. The inner cylinder 20 may be formed integrally with the rear barrel 3. The front barrel 2 and the rear barrel 3 may also be formed integrally.

[0027] In this specification, the inner cylinder 20, the front shaft 2, and the rear shaft 3 are collectively referred to as the barrel. In this specification, in the axial direction of the writing instrument 1, the side with the writing section 5a is defined as the "front" side, and the side opposite the writing section 5a is defined as the "rear" side. Furthermore, in the writing instrument 1, the refill 5 moves in the front-rear direction within the barrel 4 by the knock mechanism 10. At this time, the state in which the writing section 5a is retracted into the barrel 4 is referred to as the non-writing state (Figures 1 and 2), and the state in which the writing section 5a protrudes from the barrel 4 is referred to as the writing state (Figure 3). Furthermore, in Figures 1 to 3, the upper direction is vertically upward, and the lower direction is vertically downward. That is, gravity acts downward in each figure.

[0028] Within the shaft cylinder 4, the knock lock member 50 is positioned in front of the knock mechanism 10, that is, in front of the rotor 40. Therefore, within the shaft cylinder 4, the operating section 30, the rotor 40, and the knock lock member 50 are arranged in order from the rear end (Figure 4).

[0029] As will be described later, the knock-lock member 50 is movable in the front-rear direction within the barrel 4 by gravity. Therefore, although Figures 1 and 2 show the same non-writing state of the writing instrument 1, in Figure 1, the front end of the writing instrument 1, i.e., the front end of the barrel 4, is facing upward, so the knock-lock member 50 is positioned towards the rear end within the barrel 4. On the other hand, in Figure 2, the front end of the writing instrument 1, i.e., the front end of the barrel 4, is facing downward, so the knock-lock member 50 is positioned towards the front end within the barrel 4 compared to Figure 1.

[0030] Figure 5 is a partial longitudinal cross-sectional view of the inner cylinder 20 of the writing instrument 1 shown in Figure 1. In Figure 5, the top is the front of the writing instrument 1. Four outer cams 21 are provided on the inner surface of the inner cylinder 20 at equal intervals in the circumferential direction. Two adjacent outer cams 21 define four guide grooves 22 that extend in the front-rear direction. Each outer cam 21 consists of a first projection 23, a second projection 24, and a third projection 25 that extend in the front-rear direction and are arranged continuously in the circumferential direction. The second projection 24, located in the center, has a thinner radial thickness than the first projection 23 and the third projection 25. Therefore, a radial recess is formed between the first projection 23 and the third projection 25, and the projection 31 of the operating section 30, which will be described later, is housed between the first projection 23 and the third projection 25 at both ends, i.e., on the second projection 24.

[0031] Figure 6 is a perspective view of the operating part 30, also known as the knocking mechanism, of the writing instrument 1 shown in Figure 1. In Figure 6, the top is the front of the writing instrument 1. Eight protrusions 31 are provided at equal intervals in the circumferential direction on the outer circumferential surface of the front of the operating part 30. Each of the protrusions 31 is configured to move in the front-rear direction within the outer cam 21, more specifically within the recess between the first protrusion 23 and the third protrusion 25, or within the guide groove 22 between the outer cams 21, when the knocking operation is performed. A cam surface 32 is also formed on the front end surface of the operating part 30. The cam surface 32 has eight peaks 33 and valleys 34.

[0032] Furthermore, the operating section 30 has a cylindrical erasing member 35 that functions as an erasing unit. The erasing member 35 is attached to the other parts by adhesive or two-color molding. In other words, a part of the operating section 30 functions as an erasing unit.

[0033] Figure 7 is a perspective view of the rotor 40 of the writing instrument 1 shown in Figure 1. In Figure 7, the top is the front of the writing instrument 1. The rotor 40 consists of a small-diameter portion 41 inserted into the operating section 30 and used for lead alignment, a medium-diameter portion 42 formed in front of the small-diameter portion 41, and a large-diameter portion 43 formed in front of the medium-diameter portion 42. The medium-diameter portion 42 has a larger diameter than the small-diameter portion 41, and the large-diameter portion 43 has a larger diameter than the medium-diameter portion 42. A cam receiving surface 44 is formed on the rear end surface of the medium-diameter portion 42, with a shape complementary to the cam surface 32 of the operating section 30. The cam receiving surface 44 has eight peaks 45 and valleys 46, similar to the cam surface 32 of the operating section 30. Four internal cams 47 extending in the front-rear direction are provided at equal intervals in the circumferential direction on the outer circumferential surface of the medium-diameter portion 42. When the rotor 40 rotates circumferentially due to a knocking operation, the inner cam 47 engages with the outer cam 21 or is housed in the guide groove 22 between the outer cams 21. When the inner cam 47 is housed in the guide groove 22 between the outer cams 21, the outer cam 21 is housed in the groove 48 between the inner cams 47.

[0034] The cam surface 32 of the operating section 30 and the cam receiving surface 44 of the rotor 40 are configured such that when the inner cam 47 engages with the outer cam 21 or is housed in the guide groove 22 between the outer cams 21, the peaks 33 of the cam surface 32 are located on the slope between adjacent peaks 45 and valleys 46 of the cam receiving surface 44 in the circumferential direction. Therefore, when the slope of the cam surface 32 presses against the slope of the cam receiving surface 44 due to a knocking operation, the rotor 40 receives a circumferential force component due to this operating load and the biasing force of the spring 6 and rotates in the circumferential direction. On the other hand, the rotation of the operating section 30 is restricted in the circumferential direction by the projection 31 contacting the first projection 23 or the third projection 25 of the outer cam 21 in the circumferential direction.

[0035] A cam surface 49 is formed on the front end surface of the large-diameter portion 43 of the rotor 40. The cam surface 49 has four peaks 49a and four valleys 49b. In detail, the peaks 49a and four valleys 49b are configured such that the cam surface 49 has a slanted portion 49c that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction, and a vertical wall portion 49d that extends along the front-rear direction. The peaks 49a of the cam surface 49 of the rotor 40 are asymmetrical, unlike the peaks 33 of the cam surface 32 of the operating portion 30, but they may also have a similarly symmetrical shape.

[0036] Figure 8 is a perspective view of the knock-lock member 50 of the writing instrument 1 in Figure 1, and Figure 9 is another perspective view of the knock-lock member 50 of the writing instrument 1 in Figure 1. In Figures 8 and 9, the top is the front of the writing instrument 1. The knock-lock member 50 is a cylindrical member. The knock-lock member 50 is passed through by the refill 5 and is movable in the front-rear direction between the locking part 60 and the rotor 40, which will be described later.

[0037] The rear end surface of the knock-lock member 50 has a cam receiving surface 51 that has a shape complementary to the cam surface 49 of the rotor 40. The cam receiving surface 51 has four peaks 51a and valleys 51b, similar to the cam surface 49 of the rotor 40. That is, the peaks 51a and valleys 51b of the cam receiving surface 51 of the knock-lock member 50 are configured such that they have a slanted portion 51c that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction, and a vertical wall portion 51d that extends along the front-rear direction.

[0038] The front end surface of the knock-lock member 50 has four corner portions 52 that protrude forward as first projections. The four corner portions 52 are provided at equal intervals in the circumferential direction. The corner portions 52 also have a shape defined by rectangular notches 53 formed from the front end of the cylindrical member toward the rear. The tips of the corner portions 52 have inclined surfaces 54 that are inclined in the same direction as the slanted portion 51c of the cam receiving surface 51.

[0039] Figure 10 is a longitudinal cross-sectional view of the rear barrel 3 of the writing instrument 1 in Figure 1, and Figure 11 is a rear view of the rear barrel 3 of the writing instrument in Figure 1. In Figure 10, the top is the front side of the writing instrument 1. A notch 3a is formed at the rear end of the rear barrel 3 to prevent rotation when the inner cylinder 20 is fitted by press-fitting. A locking portion 60 is also provided in the middle of the inner surface of the rear barrel 3. The locking portion 60 has four projections 61 as second projections. The projections 61 extend in the front-rear direction and are arranged at equal intervals in the circumferential direction. Four guide grooves 62 extending in the front-rear direction are defined by adjacent projections 61.

[0040] A circumferential recess 63 is formed on the circumferential side surface 61a of the projection 61 of the locking portion 60, particularly on the rear end side surface 61a. The front inner surface of the recess 63 is an inclined surface 64 that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction. The bottom surface of the recess 63 is a side surface 65 that is parallel to the circumferential side surface 61a of the projection 61. Therefore, the inclined surface 64 is an inclined surface that connects the side surface 61a of the projection 61 and the side surface 65 of the recess 63 that is parallel to it. In addition, a rear end surface 66 perpendicular to the front-rear direction is formed at the rear end of the projection 61 of the locking portion 60. The side surface 65 of the projection 61 plays a role in restricting the circumferential rotation of the knock lock member 50, and the rear end surface 66 of the projection 61 plays a role in restricting the forward movement of the knock lock member 50.

[0041] Each of the corners 52 of the knock-lock member 50 is housed in the guide groove 62 of the corresponding locking portion 60 and moves back and forth within the guide groove 62. When the corners 52 of the knock-lock member 50 are housed in the guide groove 62 of the locking portion 60, the projection 61 of the locking portion 60 is housed in the notch 53 of the knock-lock member 50.

[0042] The cam surface 49 of the rotor 40 and the cam receiving surface 51 of the knock-lock member 50 are configured such that when the corner portion 52 of the knock-lock member 50 is housed in the guide groove 62 of the locking portion 60, the peak portion 49a of the cam surface 49 is positioned on the slanted portion 51c of the cam receiving surface 51 in the circumferential direction. For example, when the front end of the writing instrument 1 is turned upward as shown in Figure 1, the knock-lock member 50 comes into contact with the rotor 40 due to the action of gravity, but due to the weight of the knock-lock member 50, the knock-lock member 50 receives a circumferential component force and rotates in the circumferential direction. On the other hand, the rotation of the rotor 40 is restricted in the circumferential direction by the fact that the inner cam 47 is housed in the guide groove 22.

[0043] Figure 12 is a schematic diagram showing the switching of the knock mechanism 10 of the writing instrument 1 in Figure 1 from the non-writing state to the writing state. Specifically, Figure 12 is a schematic diagram showing the positional relationship between the outer cam 21, the operating part 30, the rotor 40, and the knock lock member 50. It shows the positions of the inner cam 47 and cam surface 49 of the rotor 40, the cam receiving surface 51 and corner portion 52 of the knock lock member 50, and the locking portion 60 of the rear shaft 3 with respect to the outer cam 21 unfolded in the circumferential direction. In the figure, the top is the front side of the writing instrument 1, and the bottom is the rear side of the writing instrument 1.

[0044] The rotor 40 is given rotational force by the cam mechanism between the cam surface 32 of the operating section 30 and the cam receiving surface 44 of the rotor 40, and moves from left to right in the figure with each knock operation. In Figure 12, for convenience, the first projection 23, second projection 24, and third projection 25 of the outer cam 21 are shown as a single unit, and the projection 31 of the operating section 30 is omitted.

[0045] Figure 12(a) is a schematic diagram of the knock mechanism 10 in the non-writing state and with the front end facing upward, as shown in Figure 1. Therefore, gravity is acting downward in the figure. At this time, the inner cam 47 of the rotor 40, which is biased rearward by the spring 6 via the refill 5, is housed in the guide groove 22 between the outer cams 21. Therefore, in this state, the writing section 5a is retracted into the barrel 4. Also, the cam surface 32 of the operating section 30 and the cam receiving surface 44 of the rotor 40 are engaged.

[0046] By pointing the front end of the writing instrument 1 upward, the knock lock member 50 moves backward and comes into contact with the rotor 40. As described above, the knock lock member 50 rotates circumferentially due to the circumferential component force caused by its own weight. That is, the cam surface 49 of the rotor 40 and the cam receiving surface 51 of the knock lock member 50 work together to rotate the knock lock member 50 circumferentially. As a result of this rotation, the knock lock member 50 locks with the locking part 60, preventing the rotor 40, and consequently the operating part 30, from moving forward.

[0047] In detail, the corner portion 52 of the knock-lock member 50 is housed within the recess 63 of the locking portion 60, thereby locking the knock-lock member 50 and the locking portion 60 together. In other words, the recess 63 of the locking portion 60 is configured to have a shape complementary to a part of the corner portion 52 of the knock-lock member 50, so that the corner portion 52 of the knock-lock member 50 is housed within the recess 63 of the locking portion 60. Therefore, the bevel 54 of the corner portion 52 has the same inclination as the bevel 64 of the recess 63. In this state, even if the operating portion 30 is pressed hard to move it forward, only the force in the direction that houses the corner portion 52 of the knock-lock member 50 within the recess 63 of the locking portion 60 will increase, and the locking state will not be released.

[0048] Figure 12(b) is a schematic diagram of the knock mechanism 10 in the non-writing state and with the front end facing downward, as shown in Figure 2. Therefore, gravity is acting upward in the figure. By pointing the front end of the writing instrument 1 downward, the knock lock member 50 becomes free in relation to the rotor 40. On the other hand, the knock lock member 50 presses the locking part 60 via the corner 52 due to its own weight. That is, due to the weight of the knock lock member 50, the inclined surface 54 of the corner 52 receives a circumferential component force from the inclined surface 64 of the recess 63 of the locking part 60. As a result, the knock lock member 50 rotates in the opposite circumferential direction to the case in Figure 12(a), and the corner 52 is guided into the guide groove 62. That is, the locking state between the knock lock member 50 and the locking part 60 is released, and the rotor 40, and consequently the operating part 30, becomes capable of moving forward.

[0049] Figure 12(c) is a schematic diagram of the knock mechanism 10 when the writing instrument 1 is transitioning to the writing state and its front end is facing downward. Therefore, gravity is acting upward in the figure. When the operating part 30 is pressed against the biasing force of the spring 6, and the operating part 30 and rotor 40 are moved forward, the rear end of the inner cam 47 passes the front end of the outer cam 21, i.e., the first projection 23, in the front-rear direction. At this time, the cam surface 32 and the cam receiving surface 44 coincide, and the restriction of the circumferential rotation of the rotor 40 by the side surface of the outer cam 21 is released. The knock lock member 50 does not prevent these operations.

[0050] Figure 12(d) is a schematic diagram of the knock mechanism 10 in the writing state of the writing instrument 1 shown in Figure 3, with the front end facing downwards. Therefore, gravity is acting upwards in the figure. When the pressure on the operating part 30 is released from the state shown in Figure 12(c), the operating part 30 and the rotor 40 retract due to the biasing force of the spring 6. At this time, since the circumferential rotation of the rotor 40 is not restricted by the side surface of the outer cam 21, the rotor 40 receives a component force from the inclined surface of the outer cam 21 and rotates in the circumferential direction (counterclockwise when viewed from the front). That is, the inner cam 47 of the rotor 40 moves along the inclined surface of the outer cam 21 until it contacts the side surface of the front end of the third projection 25. As a result, the inner cam 47 engages with the outer cam 21 and is prevented from retracting, and the writing part 5a, which is connected to the rotor 40 via the refill 5, is kept in a state where it protrudes from the barrel 4, so that writing is possible.

[0051] In this embodiment, as explained with particular reference to Figure 12(a), when not writing and with the front end facing upward, the forward movement of the operating part 30 is prevented, and the knocking operation cannot be performed. Therefore, for example, when erasing writing by the writing instrument 1 using the erasing member 35 of the operating part 30, a stable rubbing operation can be performed. That is, even if the writing instrument 1 is held differently and the operating part 30 is pressed against the writing surface to perform a rubbing operation, the operating part 30 does not rattle.

[0052] Figure 13 is a vertical cross-sectional view of the writing instrument 100 according to the second embodiment of the present invention in a non-writing state with the front end facing upward, and Figure 14 is a vertical cross-sectional view of the writing instrument 100 of Figure 13 in a non-writing state with the front end facing downward. Furthermore, Figure 15 is a vertical cross-sectional view of the writing instrument 100 of Figure 13 in a writing state with the front end facing downward, and Figure 16 is a vertical cross-sectional view of the writing instrument 100 of Figure 13 in a writing state with the front end facing upward.

[0053] The writing instrument 100 according to this embodiment differs from the writing instrument 1 according to the first embodiment only in the shape of the knock-lock member 150 and the locking part 160. Therefore, only the differences between this embodiment and the first embodiment will be described. In Figures 13 to 16, the upper direction is vertically upward, and the lower direction is vertically downward. That is, gravity acts downward in each figure.

[0054] The knock-lock member 150 is movable in the front-to-back direction within the barrel 4 by gravity. Therefore, although Figures 13 and 14 show the same non-writing state of the writing instrument 100, in Figure 13, the front end of the writing instrument 100, i.e., the front end of the barrel 4, is facing upward, so the knock-lock member 50 is closer to the rear end within the barrel 4. On the other hand, in Figure 14, the front end of the writing instrument 100, i.e., the front end of the barrel 4, is facing downward, so the knock-lock member 150 is closer to the front end within the barrel 4 compared to Figure 13. Similarly, although Figures 15 and 16 show the same writing state of the writing instrument 100, in Figure 15, the front end of the writing instrument 100, i.e., the front end of the barrel 4, is facing downward, so the knock-lock member 150 is closer to the front end within the barrel 4. On the other hand, in Figure 16, since the front end of the writing instrument 100, i.e., the front end of the barrel 4, is facing upward, the knock-lock member 150 is positioned closer to the rear end within the barrel 4 compared to Figure 15.

[0055] Figure 17 is a perspective view of the knock-lock member 150 of the writing instrument 100 shown in Figure 13, and Figure 18 is another perspective view of the knock-lock member 150 of the writing instrument 100 shown in Figure 13. In Figures 17 and 18, the top is the front side of the writing instrument 100. The knock-lock member 150 is a cylindrical member. The knock-lock member 150 is passed through by the refill 5 and is movable in the front-rear direction between the locking part 160 (described later) and the rotor 40.

[0056] The rear end surface of the knock-lock member 150 has a cam receiving surface 151 with a shape complementary to the cam surface 49 of the rotor 40. The cam receiving surface 151 has four peaks 151a and valleys 151b, similar to the cam surface 49 of the rotor 40. That is, the peaks 151a and valleys 151b of the cam receiving surface 151 of the knock-lock member 150 are configured such that the cam receiving surface 151 has a slanted portion 151c that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction, and a vertical wall portion 151d that extends along the front-rear direction.

[0057] The front end surface of the knock-lock member 150 has two corners 152 that protrude forward as first projections. The two corners 152 are provided at equal intervals in the circumferential direction. The corners 152 also have a shape defined by a rectangular notch 153 formed from the front end of the cylindrical member toward the rear. The tip of each corner 152 has a slope 154 that is inclined in the same direction as the slanted portion 151c of the cam receiving surface 151.

[0058] Figure 19 is a longitudinal cross-sectional view of the rear barrel 3 of the writing instrument 100 shown in Figure 13, and Figure 20 is a rear view of the rear barrel 3 of the writing instrument shown in Figure 13. In Figure 19, the top is the front side of the writing instrument 1. A locking portion 160 is provided in the middle of the inner surface of the rear barrel 3. The locking portion 160 has two projections 161 as second projections. The projections 161 extend in the front-rear direction and are arranged at equal intervals in the circumferential direction. Two guide grooves 162 extending in the front-rear direction are defined by adjacent projections 161.

[0059] A first circumferential recess 163 is formed on the circumferential side surface 161a of the projection 161 of the locking portion 160, particularly on the rear end side surface 161a. Furthermore, a second circumferential recess 164 is formed on the circumferential side surface 161a of the projection 161 of the locking portion 160 in front of the first recess 163. That is, the first recess 163 and the second recess 164 are spaced apart in the front-rear direction. The bottom surface of the first recess 163 is a side surface 165 parallel to the circumferential side surface 161a of the projection 161, and the bottom surface of the second recess 164 is a side surface 166 parallel to the circumferential side surface 161a of the projection 161. The front inner surface of the first recess 163 is a first inclined surface 167 that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction, and the front inner surface of the second recess 164 is a second inclined surface 168 that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction. The first recess 163 and the second recess 164 are formed in a stepped shape when viewed from the rear to the front of the projection 161. In addition, a rear end surface 169 perpendicular to the front-rear direction is formed at the rear end of the projection 161 of the locking portion 160. The side surfaces 165 and 166 of the projection 161 serve to restrict the circumferential rotation of the knock lock member 150, and the rear end surface 169 of the projection 161 serves to restrict the forward movement of the knock lock member 150.

[0060] Each of the corners 152 of the knock-lock member 150 is housed in the guide groove 162 of the corresponding locking portion 160 and moves back and forth within the guide groove 162. When the corners 152 of the knock-lock member 150 are housed in the guide groove 162 of the locking portion 160, the projection 161 of the locking portion 160 is housed in the notch 153 of the knock-lock member 150.

[0061] The cam surface 49 of the rotor 40 and the cam receiving surface 151 of the knock-lock member 150 are configured such that when the corner portion 152 of the knock-lock member 150 is housed in the guide groove 162 of the locking portion 160, the peak portion 49a of the cam surface 49 is positioned on the slanted portion 151c of the cam receiving surface 151 in the circumferential direction. For example, when the front end of the writing instrument 100 is turned upward as shown in Figures 13 and 16, the knock-lock member 150 comes into contact with the rotor 40 due to the action of gravity, but due to the weight of the knock-lock member 150, the knock-lock member 150 receives a circumferential component force and rotates in the circumferential direction. On the other hand, the rotation of the rotor 40 is restricted by the engagement of the inner cam 47 with the outer cam 21 or by housing it in the guide groove 22.

[0062] Figure 21 is a schematic diagram showing the switching of the knock mechanism 10 of the writing instrument in Figure 13 from the non-writing state to the writing state. Figure 21 is a schematic diagram similar to Figure 12, with the upper part of the diagram being the front side of the writing instrument 100 and the lower part being the rear side of the writing instrument 100.

[0063] Figure 21(a) is a schematic diagram of the knock mechanism 10 in the non-writing state and with the front end facing upward, as shown in Figure 13. Therefore, gravity is acting downward in the figure. At this time, the inner cam 47 of the rotor 40, which is biased rearward by the spring 6 via the refill 5, is housed in the guide groove 22 between the outer cams 21. Therefore, in this state, the writing section 5a is retracted into the barrel 4. Also, the cam surface 32 of the operating section 30 and the cam receiving surface 44 of the rotor 40 are engaged.

[0064] By pointing the front end of the writing instrument 100 upward, the knock lock member 150 moves backward and comes into contact with the rotor 40. As described above, the knock lock member 150 rotates circumferentially due to the circumferential component force caused by its own weight. That is, the cam surface 49 of the rotor 40 and the cam receiving surface 151 of the knock lock member 150 cooperate to rotate the knock lock member 150 circumferentially. As a result of this rotation, the knock lock member 150 locks with the locking part 160, preventing the rotor 40, and consequently the operating part 30, from moving forward.

[0065] In detail, the corner portion 152 of the knock-lock member 150 is housed within the first recess 163 of the locking portion 160, thereby locking the knock-lock member 150 and the locking portion 160. In other words, in the non-writing state, the first recess 163 of the locking portion 160 is configured to have a shape complementary to a part of the corner portion 152 of the knock-lock member 150, so that the corner portion 152 of the knock-lock member 150 is housed within the first recess 163 of the locking portion 160. Therefore, the bevel 154 of the corner portion 152 has the same inclination as the first bevel 167 of the first recess 163. In this state, even if the operating portion 30 is pressed hard to move it forward, only the force component in the direction that houses the corner portion 152 of the knock-lock member 150 within the first recess 163 of the locking portion 160 will increase, and the locking state will not be released.

[0066] Figure 21(b) is a schematic diagram of the knock mechanism 10 in the non-writing state and with the front end facing downward, as shown in Figure 14. Therefore, gravity is acting upward in the figure. By pointing the front end of the writing instrument 100 downward, the knock lock member 150 becomes free in relation to the rotor 40. On the other hand, the knock lock member 150 presses the locking portion 160 via the corner portion 152 due to its own weight. That is, due to the weight of the knock lock member 150, the inclined surface 154 of the corner portion 152 receives a circumferential component force from the first inclined surface 167 of the first recess 163 of the locking portion 160. As a result, the knock lock member 150 rotates in the opposite circumferential direction to that in Figure 21(a), and the corner portion 152 is guided into the guide groove 162. In other words, the locking state between the knock-lock member 150 and the locking part 160 is released, allowing the rotor 40, and consequently the operating part 30, to move forward.

[0067] Figure 21(c) is a schematic diagram of the knock mechanism 10 when the writing instrument 100 is transitioning to the writing state and its front end is facing downward. Therefore, gravity is acting upward in the figure. When the operating part 30 is pressed against the biasing force of the spring 6, and the operating part 30 and rotor 40 are moved forward, the rear end of the inner cam 47 passes over the front end of the outer cam 21, i.e., the first projection 23, in the front-rear direction. At this time, the cam surface 32 and the cam receiving surface 44 coincide, and the restriction of the circumferential rotation of the rotor 40 by the side surface of the outer cam 21 is released. The knock lock member 150 does not prevent these operations.

[0068] Figure 21(d) is a schematic diagram of the knock mechanism 10 in the writing state of the writing instrument 100 as shown in Figure 15, with the front end facing downwards. Therefore, gravity is acting upwards in the figure. When the pressure on the operating part 30 is released from the state shown in Figure 21(c), the operating part 30 and the rotor 40 retract due to the biasing force of the spring 6. At this time, since the circumferential rotation of the rotor 40 is not restricted by the side surface of the outer cam 21, the rotor 40 receives a component force from the inclined surface of the outer cam 21 and rotates in the circumferential direction (counterclockwise when viewed from the front). That is, the inner cam 47 of the rotor 40 moves along the inclined surface of the outer cam 21 until it contacts the side surface of the front end of the third projection 25. As a result, the inner cam 47 engages with the outer cam 21 and is prevented from retracting, and the writing part 5a, which is connected to the rotor 40 via the refill 5, is kept in a state where it protrudes from the barrel 4, so that writing is possible.

[0069] Figure 21(e) is a schematic diagram of the knock mechanism 10 in the writing position of the writing instrument 100 as shown in Figure 16, with its front end facing upward. Therefore, gravity is acting downward in the figure. By pointing the front end of the writing instrument 100 upward, the knock lock member 150 moves backward and contacts the rotor 40 again. As described above, the knock lock member 150 rotates circumferentially due to the circumferential component force caused by its own weight. That is, the cam surface 49 of the rotor 40 and the cam receiving surface 151 of the knock lock member 150 cooperate to rotate the knock lock member 150 circumferentially. As a result of this rotation, the knock lock member 150 locks with the locking part 160, preventing the rotor 40, and consequently the operating part 30, from moving forward.

[0070] In detail, the corner portion 152 of the knock-lock member 150 is housed within the second recess 164 of the locking portion 160, thereby locking the knock-lock member 150 and the locking portion 160. In other words, in the writing state, the second recess 164 of the locking portion 160 is configured to have a shape complementary to a part of the corner portion 152 of the knock-lock member 150, so that the corner portion 152 of the knock-lock member 150 is housed within the second recess 164 of the locking portion 160. Therefore, the bevel 154 of the corner portion 152 has the same inclination as the second bevel 168 of the second recess 164. In this state, even if the operating portion 30 is pressed hard to move it forward, only the force component in the direction that houses the corner portion 52 of the knock-lock member 50 within the first recess 163 of the locking portion 60 will increase, and the locking state will not be released.

[0071] The locking state between the knock lock member 150 and the locking portion 160 via the second recess 164 is released by bringing the front end of the writing instrument 100 downwards, similar to the case of the first recess 163. By performing a knock operation in this state, the writing instrument 100 can be switched from a writing state to a non-writing state.

[0072] In this embodiment, as described in the first embodiment, the forward movement of the operating part 30 is prevented when the writing is not in progress and the front end is facing upward, and similarly, the forward movement of the operating part 30 is prevented when the writing is in progress. Therefore, for example, when erasing writing by the writing instrument 100 using the erasing member 35 of the operating part 30, a stable rubbing operation can be performed whether the writing instrument 100 is in progress or not. In other words, even if the writing instrument 100 is held differently and the operating part 30 is pressed against the writing surface to perform a rubbing operation, the operating part 30 will never rattle.

[0073] Figures 22 to 25 are component diagrams of a writing instrument according to a third embodiment of the present invention. In this embodiment, the shape of the knock-lock member 250, the locking portion 260, and the cam surface 49 of the rotor 40 corresponding to the knock-lock member 250 differ from those of the writing instrument 1 according to the first embodiment. Therefore, only the differences between this embodiment and the first embodiment will be described.

[0074] Figure 22 is a perspective view of the knock-lock member 250 of a writing instrument according to a third embodiment of the present invention, and Figure 23 is another perspective view of the knock-lock member 250 of the writing instrument in Figure 22. In Figures 22 and 23, the top is the front side of the writing instrument. The knock-lock member 250 is a cylindrical member. The knock-lock member 250 is passed through by the refill 5 and is movable in the front-rear direction between the locking portion 260 and the rotor 40, which will be described later.

[0075] The rear end surface of the knock-lock member 250 has a cam receiving surface 251 formed thereon, which has a shape complementary to the cam surface 49 of the rotor 40. The cam receiving surface 251 has three peaks 251a and three valleys 251b. That is, the cam receiving surface 251 of the knock-lock member 250 is configured such that it has a slanted portion 251c that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction, and a vertical wall portion 251d that extends along the front-rear direction, with the peaks 251a and three valleys 251b. Similarly, the cam surface of the corresponding rotor 40 also has three peaks 49a and three valleys 49b.

[0076] The front outer circumferential surface of the knock-lock member 250 has three corners 252 that protrude forward. The three corners 252 are provided at equal intervals in the circumferential direction. Furthermore, the corners 252 have a shape defined by a rectangular notch 253 formed from the front end of the cylindrical member toward the rear. The tip of each corner 252 has a slope 254 that is inclined in the same direction as the slanted portion 251c of the cam receiving surface 251.

[0077] The three corners 252 are connected by a cylindrical portion 255 that protrudes forward from the front end surface of the knock-lock member 250. That is, the cylindrical portion 255 is positioned so that its outer surface abuts against the inner surfaces of the three corners 252. In other words, the corners 252 are first projections that protrude from the outer circumferential surface of the cylindrical portion 255. Furthermore, the outer diameter of the cylindrical portion 255 is smaller than the inner diameter of the locking portion 260, which will be described later. Since the cylindrical portion 255 connects the three corners 252, it plays a role in reinforcing the corners 252. As a result, the durability of the corners 252 against repeated operation over a long period of time can be improved.

[0078] Figure 24 is a longitudinal cross-sectional view of the rear barrel 3 of a writing instrument according to a third embodiment of the present invention, and Figure 25 is a rear view of the rear barrel 3 of the writing instrument in Figure 24. In Figure 24, the top is the front side of the writing instrument. A notch 3a is formed at the rear end of the rear barrel 3 to prevent rotation when the inner cylinder 20 is fitted by press-fitting. A locking portion 260 is also provided in the middle of the inner surface of the rear barrel 3. The locking portion 260 has three projections 261 as second projections. The projections 261 extend in the front-rear direction and are arranged at equal intervals in the circumferential direction. Three guide grooves 262 extending in the front-rear direction are defined by adjacent projections 261.

[0079] The rear end of the projection 261 of the locking portion 260 has a slope 263 that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction. The slope 263 can engage with the corner 252 of the knock-lock member 250, for example, similar to the recess 63 in the first embodiment. Therefore, the slope 263 plays a role in restricting the forward movement of the knock-lock member 250.

[0080] Each of the corners 252 of the knock-lock member 250 is housed within the guide groove 262 of the corresponding locking portion 260 and moves back and forth within the guide groove 262. When the corners 252 of the knock-lock member 250 are housed within the guide groove 262 of the locking portion 260, the projections 261 of the locking portion 260 are housed within the notches 253 of the knock-lock member 250. As described above, since the outer diameter of the cylindrical portion 255 is formed to be smaller than the inner diameter of the locking portion 260, the back and forth movement of the corners 252 of the knock-lock member 250 is not obstructed.

[0081] In this embodiment of the writing instrument, compared to the writing instrument 1 of the first embodiment, although a recess is not formed in the locking portion 260, the presence of a corresponding slope 263 allows the switching of the knock mechanism 10 from a non-writing state to a writing state to be the same as in the embodiment described with reference to Figure 12. Therefore, in the non-writing state and with the front end facing upward, the forward movement of the operating portion 30 is prevented, and the knock operation cannot be performed. For this reason, for example, when erasing writing with the writing instrument using the erasing member 35 of the operating portion 30, a stable rubbing operation can be performed. That is, even if the writing instrument is held differently and the operating portion 30 is pressed against the writing surface to perform a rubbing operation, the operating portion 30 does not rattle.

[0082] Figure 26 is a side view showing a cover member 70 of the erasing member 135 in another embodiment, and Figure 27 is a longitudinal cross-sectional view of the erasing member 135 of Figure 26 with the cover member 70 attached. The erasing member 135 and the cover member 70 are applicable to any of the above-described embodiments of the writing instrument.

[0083] The erasing member 135 has a smaller outer diameter than the erasing member 35 according to the above-described embodiment. That is, the erasing member 135 is formed in a cylindrical shape with an outer diameter smaller than the outer diameter of the operating section 30. The erasing member 135 is attached to the rear end of the operating section 30 by adhesive or two-color molding, etc. The tip is formed in a hemispherical shape.

[0084] The cover member 70 is a cylindrical cap member with an outer diameter approximately the same as that of the operating section 30 and a closed rear end. The inner diameter of the cover member 70 is set to be approximately the same as, or slightly smaller than, that of the eraser member 135. Therefore, the cover member 70 can be attached to the eraser member 135 in a detachable manner. Since the eraser member 135 is covered by the cover member 70 when not in use, it is possible to prevent the eraser member 135 from becoming dirty.

[0085] Figure 28 is a side view of the writing instrument 300 according to the fourth embodiment of the present invention; Figure 29 is a vertical cross-sectional view of the writing instrument 300 of Figure 28 in a non-writing state with the front end facing upwards; Figure 30 is a vertical cross-sectional view of the writing instrument 300 of Figure 28 in a non-writing state with the front end facing downwards; and Figure 31 is a vertical cross-sectional view of the writing instrument 300 of Figure 28 in a writing state with the front end facing downwards. Figure 32 is an exploded assembly view of the knock mechanism of the writing instrument 300 of Figure 28.

[0086] The shapes of the rear barrel 3, inner barrel 20, operating section 330, knock lock member 350, and eraser member 335 of the writing instrument 100 according to the second embodiment differ significantly from those of the rear barrel 3, inner barrel 20, operating section 30, knock lock member 150, and eraser member 35 of the writing instrument 100 according to the second embodiment. In other words, this embodiment has a configuration in which the roles of the first projection of the knock lock member and the second projection of the locking part in the above-described embodiment are reversed. The other configurations of the writing instrument 300 according to the fourth embodiment are generally the same as those of the writing instrument 100 according to the second embodiment. For example, the inner barrel 20 has a clip 20a, but like the inner barrel 20 of the writing instrument 100 according to the second embodiment, it has an outer cam on its inner surface. Therefore, only the points that differ significantly from the second embodiment will be described for this embodiment. In Figures 29 to 31, "up" is vertically upward, and "down" is vertically downward. That is, gravity acts downward in each figure.

[0087] The knock-lock member 350 is movable in the front-to-back direction within the barrel 4 by gravity. Therefore, although Figures 29 and 30 show the same non-writing state of the writing instrument 300, in Figure 29, the front end of the writing instrument 300, i.e., the front end of the barrel 4, is facing upward, so the knock-lock member 350 is closer to the rear end within the barrel 4. On the other hand, in Figure 30, the front end of the writing instrument 300, i.e., the front end of the barrel 4, is facing downward, so the knock-lock member 350 is closer to the front end within the barrel 4 compared to Figure 29. Figure 31 shows the writing state of the writing instrument 300, and since the front end of the writing instrument 300, i.e., the front end of the barrel 4, is facing downward, the knock-lock member 350 is closer to the front end within the barrel 4.

[0088] Figure 33 is a side view of the rear barrel 303 of the writing instrument 300 shown in Figure 28, Figure 34 is a rear view of the rear barrel 303 of the writing instrument 300 shown in Figure 28, and Figure 35 is a cross-sectional view of the rear barrel 302 along line AA in Figure 33. In Figures 33 and 35, the top is the front side of the writing instrument 300. A notch 303a is formed at the rear end of the rear barrel 303 to prevent rotation when the inner cylinder 20 is fitted by press-fitting. A locking portion 360 is also provided in the middle of the inner surface of the rear barrel 303. The locking portion 360 has four second projections 361 arranged at equal intervals in the circumferential direction. The cross-section of the second projections 361 is a parallelogram. The rear end surface of the second projections 361 is an inclined surface 362 that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction.

[0089] A window portion 303b is formed on the side of the rear shaft 303 behind the second projection 361, so that the inside of the shaft cylinder 4 can be seen from the outside. In this embodiment, the window portion 303b is a rectangular through hole, but it does not have to be a through hole as long as the inside can be seen, and it may be formed of a partially transparent or translucent material. That is, the shaft cylinder 4 may be formed of a transparent material, and then the window portion 303b may be formed by painting or wrapping a film around it, leaving the portion of the window portion 303b untouched. Furthermore, the shape and number of window portions 303b can be arbitrarily set. In addition, the shaft cylinder 4 and the portion of the knock lock member 350 that can be seen through the window portion 303b may be formed of different colors. Naturally, the configuration of the window portion 303b can be applied to the embodiment described above.

[0090] The writing instrument 300 has a window portion 303b, which allows the knock-lock member 350 to be seen through the window portion 303b, making it easy to confirm the position of the knock-lock member 350. That is, the knock-lock member 350 can be seen through the window portion 303b when it is located towards the rear end of the barrel 4, and cannot be seen through the window portion 303b when it is located towards the front end of the barrel 4. Alternatively, the knock-lock member 350 may be made visible through the window portion 303b when it is located towards the front end of the barrel 4, and not visible through the window portion 303b when it is located towards the rear end of the barrel 4. This makes it easier to determine whether or not stable scratching is possible. That is, if the knock-lock member 350 is visible through the window portion 303b, stable scratching is possible, and if the knock-lock member 350 is not visible, stable scratching is not possible. Naturally, the configuration of forming a window portion in the shaft cylinder 4 so that the inside can be seen is also applicable to other embodiments.

[0091] Figure 36 is a perspective view of the knock-lock member 350 of the writing instrument 300 shown in Figure 28, and Figure 37 is another perspective view of the knock-lock member 350 of the writing instrument 300 shown in Figure 28. In Figures 36 and 37, the top is the front side of the writing instrument 300. The knock-lock member 350 is a cylindrical member. The knock-lock member 350 is passed through by the refill 5 and is movable in the front-rear direction between the locking portion 360 and the rotor 40.

[0092] The rear end surface of the knock-lock member 350 has a cam receiving surface 351 with a shape complementary to the cam surface 49 of the rotor 40. The cam receiving surface 351 has four peaks 351a and valleys 351b, similar to the cam surface 49 of the rotor 40. That is, the peaks 351a and valleys 351b of the cam receiving surface 351 of the knock-lock member 350 are configured such that the cam receiving surface 351 has a slanted portion 351c that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction, and a vertical wall portion 351d that extends along the front-rear direction.

[0093] The outer circumferential surface of the cylindrical portion 350a of the knock-lock member 350 has four first protrusions 352, which are similar in shape to the protrusion 161 provided on the rear shaft 3 of the writing instrument 100 according to the second embodiment. The first protrusions 352 extend in the front-rear direction and are arranged at equal intervals in the circumferential direction. Four guide grooves 353 extending in the front-rear direction are defined by adjacent first protrusions 352.

[0094] A first recess 354 in the circumferential direction is formed on the circumferential side surface 352a of the first projection 352, particularly on the front end side surface 352a. Furthermore, a second recess 355 in the circumferential direction is formed on the circumferential side surface 352a of the first projection 352 rearward of the first recess 354. That is, the first recess 354 and the second recess 355 are spaced apart in the front-rear direction. The bottom surface of the first recess 354 is a side surface 356 parallel to the circumferential side surface 352a of the first projection 352, and the bottom surface of the second recess 355 is a side surface 357 parallel to the circumferential side surface 352a of the first projection 352. The rear inner surface of the first recess 354 is a first inclined surface 358 inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction, and the rear inner surface of the second recess 355 is a second inclined surface 359 inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction. The first recess 354 and the second recess 355 are formed in a stepped shape when viewed from the front to the rear of the first projection 352. The sides 356 and 357 of the first projection 352 serve to restrict the circumferential rotation of the knock lock member 350.

[0095] Each of the guide grooves 353 of the knock-lock member 350 accommodates the second projection 361 of the corresponding locking portion 360 of the rear axle 303, allowing it to move relatively back and forth within the guide groove 353.

[0096] The cam surface 49 of the rotor 40 and the cam receiving surface 351 of the knock-lock member 350 are configured such that when the second projection 361 of the locking portion 360 is housed in the guide groove 353 of the knock-lock member 350, the peak portion 49a of the cam surface 49 is located on the slanted portion 351c of the cam receiving surface 351 in the circumferential direction. For example, when the front end of the writing instrument 300 is turned upward as shown in Figure 29, the knock-lock member 350 comes into contact with the rotor 40 due to the action of gravity, but due to the weight of the knock-lock member 350, the knock-lock member 350 receives a circumferential force component and rotates in the circumferential direction. On the other hand, the rotation of the rotor 40 is restricted by the engagement of the inner cam 47 with the outer cam 21 or by housing it in the guide groove 22.

[0097] Figure 38 is a schematic diagram showing the switching of the knock mechanism 10 of the writing instrument 300 from the non-writing state to the writing state, as shown in Figure 28. Figure 38 is a schematic diagram similar to Figure 12, with the upper part of the diagram being the front of the writing instrument 300 and the lower part being the rear of the writing instrument 300.

[0098] Figure 38(a) is a schematic diagram of the knock mechanism 10 in the non-writing state and with the front end facing upward, as shown in Figure 29. Therefore, gravity is acting downward in the figure. At this time, the inner cam 47 of the rotor 40, which is biased rearward by the spring 6 via the refill 5, is housed in the guide groove 22 between the outer cams 21. Therefore, in this state, the writing section 5a is retracted into the barrel 4. Also, the cam surface 32 of the operating section 330 and the cam receiving surface 44 of the rotor 40 are engaged.

[0099] By pointing the front end of the writing instrument 300 upward, the knock-lock member 350 moves backward and comes into contact with the rotor 40. As described above, the knock-lock member 350 rotates circumferentially due to the circumferential component force caused by its own weight. That is, the cam surface 49 of the rotor 40 and the cam receiving surface 351 of the knock-lock member 350 work together to rotate the knock-lock member 350 circumferentially. As a result of this rotation, the knock-lock member 350 engages with the locking portion 360, preventing the rotor 40, and consequently the operating portion 330, from moving forward.

[0100] In detail, the second projection 361 of the locking portion 360 is housed within the first recess 354 of the first projection 352 of the knock-lock member 350, thereby locking the knock-lock member 350 and the locking portion 360. In other words, in the non-writing state, the first recess 354 is configured to have a shape complementary to a part of the second projection 361 of the locking portion 360, so that the second projection 361 of the locking portion 360 is housed within the first recess 354 of the first projection 352 of the knock-lock member 350. Therefore, the inclination 362 of the second projection 361 has the same inclination as the first inclination 358 of the first recess 354. In this state, even if the operating portion 330 is pressed hard to move it forward, only the force component in the direction that houses the second projection 361 of the locking portion 360 within the first recess 354 of the knock-lock member 350 will increase, and the locking state will not be released.

[0101] Figure 38(b) is a schematic diagram of the knock mechanism 10 in the non-writing state of the writing instrument 300 and with its front end facing downward, as shown in Figure 30. Therefore, gravity is acting upward in the figure. By pointing the front end of the writing instrument 300 downward, the knock lock member 350 becomes free in relation to the rotor 40. On the other hand, the knock lock member 350 presses the locking portion 360 via the first projection 352 due to its own weight. That is, due to the weight of the knock lock member 350, the first inclined surface 358 of the first recess 354 of the first projection 352 receives a circumferential component force from the inclined surface 362 of the second projection 361 of the locking portion 360. As a result, the knock lock member 350 rotates in the opposite circumferential direction to that in Figure 38(a), and the second projection 361 is guided into the guide groove 353. In other words, the locking state between the knock-lock member 350 and the locking part 360 is released, allowing the rotor 40, and consequently the operating part 330, to move forward. The forward movement of the knock-lock member 350 is stopped by the rear end surface of the front shaft 2.

[0102] Figure 38(c) is a schematic diagram of the knock mechanism 10 when the writing instrument 300 is transitioning to the writing state and its front end is facing downward. Therefore, gravity is acting upward in the figure. When the operating part 330 is pressed against the biasing force of the spring 6, and the operating part 330 and rotor 40 are moved forward, the rear end of the inner cam 47 passes the front end of the outer cam 21, i.e., the second projection 361, in the front-rear direction. At this time, the cam surface 32 and the cam receiving surface 44 coincide, and the restriction of the circumferential rotation of the rotor 40 by the side surface of the outer cam 21 is released. The knock lock member 350 does not prevent these operations.

[0103] Figure 38(d) is a schematic diagram of the knock mechanism 10 in the writing state of the writing instrument 300 as shown in Figure 31, with the front end facing downwards. Therefore, gravity is acting upwards in the figure. When the pressure on the operating part 330 is released from the state shown in Figure 38(c), the operating part 330 and the rotor 40 retract due to the biasing force of the spring 6. At this time, since the circumferential rotation of the rotor 40 is not restricted by the side surface of the outer cam 21, the rotor 40 receives a component force from the inclined surface of the outer cam 21 and rotates in the circumferential direction (counterclockwise when viewed from the front). That is, the inner cam 47 of the rotor 40 moves along the inclined surface of the outer cam 21 until it contacts the side surface of the front end of the third projection 25. As a result, the inner cam 47 engages with the outer cam 21 and is prevented from retracting, and the writing part 5a, which is connected to the rotor 40 via the refill 5, is kept in a state where it protrudes from the barrel 4, so that writing is possible.

[0104] Figure 38(e) is a schematic diagram of the knock mechanism 10 in the writing position of the writing instrument 300 with its front end facing upward (similar to Figure 16, though not shown). Therefore, gravity is acting downward in the figure. By pointing the front end of the writing instrument 300 upward, the knock lock member 350 moves backward and contacts the rotor 40 again. As described above, the knock lock member 350 rotates circumferentially due to the circumferential component force caused by its own weight. That is, the cam surface 49 of the rotor 40 and the cam receiving surface 351 of the knock lock member 350 work together to rotate the knock lock member 350 circumferentially. As a result of this rotation, the knock lock member 350 locks with the locking part 360, preventing the rotor 40, and consequently the operating part 330, from moving forward.

[0105] In detail, the second projection 361 of the locking portion 360 is housed within the second recess 355 of the first projection 352 of the knock-lock member 350, thereby locking the knock-lock member 350 and the locking portion 360. In other words, in the writing state, the second recess 355 is configured to have a shape complementary to a part of the second projection 361 of the locking portion 360, so that the second projection 361 of the locking portion 360 is housed within the second recess 355 of the first projection 352 of the knock-lock member 350. Therefore, the inclination 362 of the second projection 361 has the same inclination as the second inclination 359 of the second recess 355. In this state, even if the operating portion 330 is pressed hard to move it forward, only the force component in the direction that houses the second projection 361 of the locking portion 360 within the second recess 355 of the knock-lock member 350 will increase, and the locking state will not be released.

[0106] The locking state between the knock lock member 350 and the locking portion 360 via the second recess 355 is released by bringing the front end of the writing instrument 300 downwards, similar to the case of the first recess 354. By performing a knock operation in this state, the writing instrument 300 can be switched from a writing state to a non-writing state.

[0107] In this embodiment, as described in the second embodiment, in both the non-writing and writing states, if the front end is facing upward, the forward movement of the operating unit 330 is prevented. Therefore, for example, when erasing writing by the writing instrument 300 using the erasing member 335 of the operating unit 330, stable rubbing operation can be performed whether the writing instrument 300 is in the writing state or the non-writing state. In other words, even if the writing instrument 300 is held differently and the operating unit 330 is pressed against the writing surface to perform a rubbing operation, the operating unit 330 will never rattle.

[0108] Figure 39 is a longitudinal cross-sectional view of the erasing member 335 portion of the writing instrument 300 shown in Figure 28.

[0109] A hole 331 extending forward is formed at the rear end of the operating section 330. The hole 331 is defined by the side wall 332 of the operating section 330 and the bottom wall 333 which is connected to the side wall 332 almost perpendicularly. The inside of the hole 331 is filled with an erasing member 335. Two stepped sections 332a and 332b that reduce the inner diameter are formed on the inner surface of the side wall 332 of the hole 331, resulting in the formation of a small diameter section at the bottom, a large diameter section at the entrance, and a medium diameter section between them. A relatively small through hole 333a is provided in the center of the bottom wall 333 of the hole 331. In this embodiment, the cross-sectional shapes of the small diameter section, medium diameter section, and large diameter section are circular, but they may be elliptical, rectangular, or other shapes.

[0110] The erasing member 335 has a relatively small diameter base portion 336 that fills the hole portion 331, and an outer portion 337 that wipes away the writing, etc., and has a relatively large diameter outer portion 337 that has an outer shape approximately the same as the outer diameter of the operating portion 330. As a result, a shoulder-shaped portion 338 is formed on the outer portion 337 based on the difference in outer diameter between the base portion 336 and the outer portion 337. In addition, the base portion 336 of the erasing member 335 has a small diameter portion 336a, a medium diameter portion 336b, and a large diameter portion 336c formed therein, corresponding to the shape of the hole portion 331 of the operating portion 330.

[0111] The operating section 330 and the erasing member 335 are joined to each other by adhesive or by a two-color molding method. In this embodiment, the operating section 330 and the erasing member 335 are molded and joined to each other using a two-color molding method. When using a two-color molding method, the operating section 330 is first injection molded, and then the cavity of a mold for molding the erasing member 335 is combined with the core of the mold in which the molded operating section 330 remains, and a different material, such as a rubber-based material described later, is injected to add the erasing member 335 to the operating section 330. With the two-color molding method, the surfaces of the operating section 330 and the erasing member 335 are joined with relatively high strength, depending on the materials used.

[0112] Since a through hole 333a is provided in the bottom wall portion 333 of the operating section 330, a venting path is secured for the gas generated from the molding material when the eraser member 335 is injection molded during two-color molding. As a result, molding defects such as insufficient filling at the base portion 336 of the eraser member 335 can be prevented.

[0113] Furthermore, since two stepped portions 332a and 332b are formed on the side wall portion 332 of the operating portion 330, the edges of these steps lock the erasing member 335, improving the joint strength compared to when there are no stepped portions. In addition, it becomes possible to reduce the volume of the erasing member 335, which is often made of a more expensive material than the operating portion 330. Moreover, by making at least one of the cross-sectional shapes of the small diameter portion, medium diameter portion, and large diameter portion a non-circular shape such as an ellipse, a structural support portion is provided against the torsional moment acting on the erasing member 335 around its axis.

[0114] Based on the above, the operating section 330 and the erasing member 335 prevent the erasing member 335 from falling off the writing instrument body even when rubbed hard, and ensure that the retention force of the erasing member 335 is maintained over a long period of time.

[0115] Figure 40 is a vertical cross-sectional view of the writing instrument 400 according to the fifth embodiment of the present invention in a non-writing state with the front end facing upward, Figure 41 is a vertical cross-sectional view of the writing instrument 400 of Figure 40 in a non-writing state with the front end facing downward, Figure 42 is a vertical cross-sectional view of the writing instrument 400 of Figure 40 with the front end facing downward and the knocking operation being performed, Figure 43 is a vertical cross-sectional view of the writing instrument 400 of Figure 40 in a writing state with the front end facing downward, and Figure 44 is a vertical cross-sectional view of the writing instrument 400 of Figure 40 in a writing state with the front end facing upward. Also, Figure 45 is an exploded assembly view of the knocking mechanism 410 of the writing instrument 400 of Figure 40. In Figures 40 to 44, "up" is vertically upward, and "down" is vertically downward. That is, gravity acts downward in each figure.

[0116] In the knock mechanism of the writing instrument according to the embodiment described above, the operating part, rotor, and knock lock member were arranged in series inside the barrel, starting from the rear end (see, for example, Figure 4). As a result, the cam surface of the rotor and the cam receiving surface of the knock lock member cooperate to rotate the knock lock member in the circumferential direction, thereby locking the locking part and the knock lock member. The writing instrument 400 according to this embodiment has a different basic configuration. That is, in the knock mechanism 410 of the writing instrument 400, as shown in Figure 45, the rotor 440 is arranged inside the operating part 430 and moves in the front-rear direction inside the operating part 430. As a result, the cam surface 432 of the operating part 430 and the cam receiving surface 451 of the knock lock member 450 cooperate to rotate the knock lock member 450 in the circumferential direction, thereby locking the locking part 460 and the knock lock member 450. A detailed explanation follows below.

[0117] The knock lock member 450 is movable in the front-rear direction within the barrel 4 by gravity. Therefore, although Figures 40 and 41 show the same non-writing state of the writing instrument 400, in Figure 40, the front end of the writing instrument 400, i.e., the front end of the barrel 4, is facing upward, so the knock lock member 450 is closer to the rear end within the barrel 4. On the other hand, in Figure 41, the front end of the writing instrument 400, i.e., the front end of the barrel 4, is facing downward, so the knock lock member 450 is closer to the front end within the barrel 4 compared to Figure 40. Furthermore, Figure 42 shows the state in which the knock operation is performed with the front end of the writing instrument 400 facing downward, and because the front end of the writing instrument 400, i.e., the front end of the barrel 4, is facing downward, the knock lock member 450 is closer to the front end within the barrel 4 compared to Figure 40. Similarly, Figures 43 and 44 show the same writing state of the writing instrument 400, but in Figure 43, the front end of the writing instrument 400, i.e., the front end of the barrel 4, is facing downwards, so the knock-lock member 450 is positioned closer to the front end within the barrel 4. On the other hand, in Figure 44, the front end of the writing instrument 400, i.e., the front end of the barrel 4, is facing upwards, so the knock-lock member 450 is positioned closer to the rear end within the barrel 4 compared to Figure 43.

[0118] Figure 46 is a longitudinal cross-sectional view of the rear barrel 403 of the writing instrument 400 shown in Figure 40. In Figure 46, the top is the front side of the writing instrument 400. A notch 403a is formed at the rear end of the rear barrel 403 to prevent rotation when the inner cylinder 420 is fitted by press-fitting. A locking portion 460 is also provided in the middle of the inner surface of the rear barrel 403. The locking portion 460 has six second projections 461 arranged at equal intervals in the circumferential direction. In this embodiment, the second projections 461 have the same shape as the second projections 361 in the fourth embodiment. Therefore, the cross-section of the second projections 461 is a parallelogram. The rear end surface of the second projections 461 is a slope 462 that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction.

[0119] Figure 47 is a front view of the inner cylinder 420 of the writing instrument 400 shown in Figure 40, and Figure 48 is a cross-sectional view of the inner cylinder 420 of Figure 47 along line BB. In Figure 48, the top is the front of the writing instrument 400. The inner cylinder 420 is a cylindrical member. Outer cams 421 are provided at equal intervals in the circumferential direction on the inner surface of the central part of the inner cylinder 420. The outer cams 421 consist of three large projections 422 that protrude radially, and the front end of each large projection 422 has a slope that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction. Three small projections 423 are provided on the inner surface of the inner cylinder 420 in the center between the large projections 422 along the circumferential direction. The small projections 423 have a radial thickness that is thinner than the large projections 422. In addition, a number of ribs 424 extending toward the rear end are provided on the inner surface of the inner cylinder 420 behind the outer cams 421. The multiple ribs 424 reduce frictional resistance between the biasing spring 490, which will be described later and is located inside the inner cylinder 420, and the inner surface of the inner cylinder 420.

[0120] Figure 49 is a perspective view of the operating section 430 of the writing instrument 400 shown in Figure 40, and Figure 50 is a longitudinal cross-sectional view of the operating section 430 of the writing instrument 400 shown in Figure 40. In Figures 49 and 50, the top is the front side of the writing instrument 400. The operating section 430 is a cylindrical member. The operating section 430 has a cylindrical portion 431 with a smooth outer surface in the central part in the axial direction. Three elliptical protrusions 431a are provided on the inner surface of the cylindrical portion 431 at equal intervals in the circumferential direction. The front of the cylindrical portion 431 is formed with a slightly larger outer diameter, and a cam surface 432 is formed on its front end surface. The cam surface 432 has six peaks 432a and valleys 432b. In detail, the peaks 432a and valleys 432b are configured such that the cam surface 432 has a slanted portion 432c that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction, and a vertical wall portion 432d that extends along the front-rear direction. The peaks 432a of the cam surface 432 of the operating portion 430 are asymmetrical along the circumferential direction, but may also be symmetrical in shape.

[0121] Behind the cylindrical portion 431, a guide portion 433 is formed, having an outer diameter slightly smaller than the outer diameter of the cylindrical portion 431. A rear wall 433a is provided at the rear end of the guide portion 433. Three slits 433b are formed in the guide portion 433 along the axial direction. The three slits 433b are provided at equal intervals in the circumferential direction, penetrating all the way through to the interior. Thus, the three slits 433b define three columnar portions 434 with a substantially fan-shaped cross-section. Guide grooves 434a are formed on the outer surface of each columnar portion 434 along the axial direction. In addition, projections 434b are formed on the inner surface of each columnar portion 434, extending forward from the inner surface of the rear wall 433a. A V-shaped cam surface 435 is formed on the front end surface of each projection 434b. That is, three V-shaped cam surfaces 435 are formed on the inner surface of the guide portion 433.

[0122] Three fitting corners 436 extending toward the rear are formed on the rear end surface of the guide portion 433, that is, on the rear end surface of the rear wall 433a of the guide portion 433. The three fitting corners 436 are provided at equal intervals in the circumferential direction and are formed to be elastically deformable in the radial direction. A fitting projection 436a extending radially outward is formed on the outer surface of the tip of each fitting corner 436.

[0123] The operating section 430 is inserted into the inner cylinder 420 from the front. At this time, each of the large protrusions 422 of the inner cylinder 420 is positioned between the slits 433b of the operating section 430, and therefore, the column portion 434 of the operating section 430 is positioned between the large protrusions 422 of the inner cylinder 420. At this time, each of the small protrusions 423 formed on the inner cylinder 420 is positioned within the guide groove 434a formed on the corresponding column portion 434 of the operating section 430. By positioning the small protrusions 423 of the inner cylinder 420 within the guide groove 434a of the operating section 430, the operating section 430 is restricted from circumferential rotation relative to the inner cylinder 420, while remaining movable in the front-rear direction. In addition, each of the large protrusions 422 of the inner cylinder 420 protrudes into the guide portion 433 of the operating section 430 through the slits 433b, and the amount of protrusion is approximately the same as the amount of protrusion of the protrusion 434b from the inner surface of the column portion 434. Therefore, the large projection 422 of the inner cylinder 420 and the projection 434b of the operating section 430 work together to act on the inner cam 443 of the rotor 440, which will be described later.

[0124] Figure 51 is a perspective view of the rotor 440 of the writing instrument 400 shown in Figure 40. In Figure 51, the top is the front of the writing instrument 400. The rotor 440 is a cylindrical member. The rotor 440 has a cylindrical body portion 441 and a flange portion 442 provided at the front end of the body portion 441. The outer diameter of the flange portion 442 is set to be slightly smaller than the inner diameter of the cylindrical portion 431 of the operating portion 430 into which it is inserted. Three internal cams 443 extending in the front-rear direction are provided on the outer circumferential surface of the body portion 441 at equal intervals in the circumferential direction. A sawtooth-shaped cam receiving surface 444 is formed on the rear end surface of each internal cam 443, which cooperates with the V-shaped cam surface 435 of the operating portion 430.

[0125] The rotor 440 is inserted into the operating section 430 from the front. After the rotor 440 is inserted, it will not easily come off due to the locking between the flange portion 442 and the projection 431a formed on the inner surface of the operating section 430. When the rotor 440 rotates circumferentially due to a knocking operation, the inner cam 443 of the rotor 440 engages with or is positioned between the outer cams 421, which protrude into the operating section 430 through the slit 433b. When the inner cam 443 is positioned between the outer cams 421, the outer cams 421 are positioned between the inner cams 443.

[0126] The V-shaped cam surface 435 of the operating section 430 and the cam receiving surface 444 of the rotor 340 are configured such that when the inner cam 443 engages with or is positioned between the outer cams 421, the phase difference between the V-shaped cam surface 435 and the cam receiving surface 444 is offset. Therefore, when the inclined surface of the V-shaped cam surface 435 presses against the inclined surface of the cam receiving surface 444 due to the knocking operation, the rotor 440 receives a circumferential force component due to this operating load and the biasing force of the spring 6 and rotates in the circumferential direction. On the other hand, as described above, the rotation of the operating section 430 is restricted by the placement of the small projection 423 of the inner cylinder 420 within the guide groove 434a.

[0127] Figure 52 is a perspective view of the knock-lock member 450 of the writing instrument 400 in Figure 40, and Figure 53 is another perspective view of the knock-lock member 450 of the writing instrument 400 in Figure 40. In Figures 52 and 53, the top is the front side of the writing instrument 400. The knock-lock member 450 is a cylindrical member. The knock-lock member 450 is passed through by the refill 5 and is movable in the front-rear direction between the locking portion 460 and the operating portion 430.

[0128] The rear end surface of the knock-lock member 450 has a cam receiving surface 451 formed thereon, which has a shape complementary to the cam surface 432 of the operating section 430. The cam receiving surface 451 has six peaks 451a and valleys 451b, similar to the cam surface 432 of the operating section 430. That is, the peaks 451a and valleys 451b of the cam receiving surface 451 of the knock-lock member 450 are configured such that the cam receiving surface 451 has a slanted portion 451c that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction, and a vertical wall portion 451d that extends along the front-rear direction.

[0129] The outer circumferential surface of the cylindrical portion 450a of the knock-lock member 450 has six first projections 452, which have a shape similar to that of the knock-lock member 350 according to the fourth embodiment. The first projections 452 extend in the front-rear direction and are arranged at equal intervals in the circumferential direction. Six guide grooves 453 extending in the front-rear direction are defined by adjacent first projections 452.

[0130] A circumferential recess 454 is formed on the circumferential side surface 452a of the first projection 452, particularly on the front end side surface 452a. The bottom surface of the recess 454 is a side surface 455 parallel to the circumferential side surface 452a of the first projection 452. The rear inner surface of the recess 454 is a slope 456 inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction. The recess 454 is formed in a stepped shape when viewed from the front to the rear of the first projection 452. The side surface 455 of the first projection 452 plays a role in restricting the circumferential rotation of the knock lock member 450.

[0131] Each of the guide grooves 453 of the knock-lock member 450 accommodates the second projection 461 of the corresponding locking portion 460 of the rear axle 403, allowing it to move relatively back and forth within the guide groove 453.

[0132] The cam surface 432 of the operating section 430 and the cam receiving surface 451 of the knock-lock member 450 are configured such that when the second projection 461 of the locking section 460 is housed in the guide groove 453 of the knock-lock member 450, the peak 432a of the cam surface 432 is positioned on the slanted portion 451c of the cam receiving surface 451 in the circumferential direction. For example, when the front end of the writing instrument 400 is turned upward as shown in Figure 40, the knock-lock member 450 comes into contact with the operating section 430 due to the action of gravity, but due to the weight of the knock-lock member 450, the knock-lock member 450 receives a circumferential force component and rotates in the circumferential direction. On the other hand, the rotation of the operating section 430 is restricted by the placement of the small projection 423 of the inner cylinder 420 in the guide groove 434a.

[0133] Figure 54 is a side view of the front barrel 402 of the writing instrument 400 shown in Figure 40. A threaded portion 402a is formed at the rear of the front barrel 402, which screws into the rear barrel 403, and a cushioning member 402b is positioned at the rear end of the front barrel 402 behind the threaded portion 402a. When the writing instrument 400 is held with the front end facing upward, i.e., with the knock-lock member 450 closer to the rear end, and then the writing instrument 400 is changed so that the front end faces downward, the knock-lock member 450 moves forward due to the action of gravity. The forward movement of the knock-lock member 450 is stopped by contact with the rear end surface of the front barrel 402, i.e., by collision. At this time, the cushioning member 402b is provided at the rear end of the front barrel 402, which reduces the impact and sound during the collision. Therefore, the forward movement of the knock-lock member 450 is prevented by contact with the cushioning member 402b, particularly its rear end surface.

[0134] The cushioning member 402b may be formed from a material that can be selected as an eraser member, for example, as described later. In that case, the cushioning member 402b may be provided at the rear end of the front shaft 402 by bonding or two-color molding. Alternatively, a spring or sponge may be provided as the cushioning member 402b. In this embodiment, the cushioning member 402b is provided at the rear end of the front shaft 402, but it may also be provided at the front end of the knock lock member 450. These configurations are, of course, applicable to other embodiments as well.

[0135] Figure 55 is a perspective view of the erasing member 470 of the writing instrument 400 in Figure 40, and Figure 56 is a longitudinal cross-sectional view of the erasing member 470 of the writing instrument 400 in Figure 40. In Figure 56, the bottom is the front side of the writing instrument 400. The erasing member 470 is provided at the rear end of the holding member 471 and is attached to the rear end of the operating section 430 via the holding member 471. In other words, a part of the operating section 430 functions as an erasing section. The erasing member 470 is attached to the holding member 471 by adhesive or two-color molding, etc.

[0136] The retaining member 471 has a retaining body 472. The front part of the retaining body 472 is formed in a cylindrical shape that opens forward. Three rectangular openings 473 are formed on the outer circumferential surface of the cylindrical part. A flange portion 474 is also formed on the outer circumferential surface in front of the openings 473. The retaining member 471 is attached to the fitting corner portion 436 of the operating part 430 by fitting. That is, when attaching the retaining member 471, the fitting corner portion 436 of the operating part 430 elastically deforms radially inward, and the fitting projection 436a of the fitting corner portion 436 snaps into the opening 473 of the retaining body 472. The rear part of the retaining body 472, together with the erasing member 470, is formed as a whole in a tapered truncated triangular pyramidal shape.

[0137] A cover member 480 is attached to the erasing member 470, although it is omitted in Figures 40 and 44, as shown in Figures 41 to 43. Specifically, the cover member 480 is detachably fitted to the holding member body 472. The front end surface of the cover member 480 abuts against the rear end surface of the flange portion 474 of the holding member 471. Since the erasing member 470 is covered by the cover member 480 when not in use, it is possible to prevent the erasing member 470 from becoming dirty. An air hole is formed in the closed end surface of the rear end of the cover member 480.

[0138] Furthermore, as shown in Figures 40 to 44, a biasing spring 490 is positioned between the rear end faces of the three large protrusions 422 of the inner cylinder 420 and the front end face of the flange portion 474 of the retaining member 471, so as to surround the guide portion 433 of the operating portion 430. The biasing spring 490 biases the retaining member 471, and furthermore the operating portion 430 connected to the retaining member 471 and the eraser member 470 attached to the retaining member 471, toward the rear. Therefore, whether the writing instrument 400 is in writing mode or not, the eraser member 470 is always positioned in the same location in the axial direction.

[0139] Figure 57 is a schematic diagram showing the switching of the knock mechanism 410 of the writing instrument 400 in Figure 40 from the non-writing state to the writing state. Figure 57 is a schematic diagram similar to Figure 12, with the upper part of the diagram being the front of the writing instrument 400 and the lower part being the rear of the writing instrument 400.

[0140] Figure 57(a) is a schematic diagram of the knock mechanism 410 in the non-writing state of the writing instrument 400 as shown in Figure 40, with its front end facing upward. Therefore, gravity is acting downward in the figure. At this time, the inner cam 443 of the rotor 440, which is biased rearward by the spring 6 via the refill 5, is positioned between the outer cams 421. Therefore, in this state, the writing section 5a is retracted into the barrel 4. In addition, the V-shaped cam surface 435 of the operating section 430 and the cam receiving surface 444 of the rotor 440 are in contact, but there is a phase difference between the V-shaped cam surface 435 and the cam receiving surface 444.

[0141] By pointing the front end of the writing instrument 400 upward, the knock lock member 450 moves backward and comes into contact with the operating section 430. As described above, the knock lock member 450 rotates circumferentially due to the circumferential component force caused by its own weight. That is, the cam surface 432 of the operating section 430 and the cam receiving surface 451 of the knock lock member 450 cooperate to rotate the knock lock member 450 circumferentially. As a result of this rotation, the knock lock member 450 engages with the locking section 460, preventing the operating section 430 from moving forward.

[0142] In detail, the second projection 461 of the locking portion 460 is housed in the recess 454 of the first projection 452 of the knock-lock member 450, thereby locking the knock-lock member 450 and the locking portion 460. In other words, in the non-writing state, the recess 454 is configured to have a shape complementary to a part of the second projection 461 of the locking portion 460, so that the second projection 461 of the locking portion 460 is housed in the recess 454 of the first projection 452 of the knock-lock member 450. Therefore, the slope 462 of the second projection 461 has the same inclination as the slope 456 of the recess 454. In this state, even if the operating portion 430 is pressed hard to move it forward, only the force component in the direction that houses the second projection 461 of the locking portion 460 in the recess 454 of the knock-lock member 450 will increase, and the locking state will not be released.

[0143] Figure 57(b) is a schematic diagram of the knock mechanism 410 in the non-writing state of the writing instrument 400 as shown in Figure 41, with its front end facing downwards. Therefore, gravity is acting upwards in the figure. By pointing the front end of the writing instrument 400 downwards, the knock lock member 450 becomes free in relation to the operating part 430. On the other hand, the knock lock member 450 presses the locking part 460 via the first projection 452 due to its own weight. That is, due to the weight of the knock lock member 450, the inclined surface 456 of the recess 454 of the first projection 452 receives a circumferential component force from the inclined surface 462 of the second projection 461 of the locking part 460. As a result, the knock lock member 450 rotates in the opposite circumferential direction to that in Figure 57(a), and the second projection 461 is guided into the guide groove 453. In other words, the locking state between the knock-lock member 450 and the locking part 460 is released, allowing the operating part 430 to move forward. The forward movement of the knock-lock member 450 is stopped by the buffer member 402b of the front shaft 2.

[0144] Figure 57(c) is a schematic diagram of the knock mechanism 410 in the process of transitioning the writing instrument 400 to the writing state as shown in Figure 42, with its front end facing downwards. Therefore, gravity is acting upwards in the figure. When the operating part 430 is pressed against the biasing force of the spring 6 and the biasing spring 490, and the operating part 430 and rotor 440 are moved forward, the rear end of the inner cam 443 passes over the front end of the outer cam 421, i.e., the large projection 422, in the front-rear direction. As a result, the restriction on the circumferential rotation of the rotor 440 is released. At this time, because the phases of the V-shaped cam surface 435 of the operating part 430 and the cam receiving surface 444 of the rotor 440 are out of sync, the rotor 440 is subjected to a circumferential component force.

[0145] Figure 57(d) is a schematic diagram of the knock mechanism 410 in the writing position of the writing instrument 400 as shown in Figure 43, with the front end facing downwards. Therefore, gravity is acting upwards in the figure. When the pressure on the operating part 430 is released from the state shown in Figure 57(c), the rotor 440 retracts due to the biasing force of the spring 6. At this time, the circumferential rotation of the rotor 440 is not restricted by the side surface of the outer cam 421, so the rotor 440 rotates circumferentially by receiving a component force from the inclined surface of the outer cam 421. That is, the inner cam 443 of the rotor 440 moves along the inclined surface of the outer cam 421. As a result, the inner cam 443 engages with the outer cam 421, that is, the sawtooth-shaped cam receiving surface 444 engages with the large projection 422 of the outer cam 421, preventing it from retracting. The writing section 5a, which is connected to the rotor 440 via the refill 5, remains in a state where it protrudes from the barrel 4, thus enabling writing. The operating section 430 retracts due to the biasing force of the biasing spring 490 and returns to its original position.

[0146] Figure 57(e) is a schematic diagram of the knock mechanism 410 in the writing position of the writing instrument 400 as shown in Figure 44, with its front end facing upward. Therefore, gravity is acting downward in the figure. By pointing the front end of the writing instrument 400 upward, the knock lock member 450 moves backward and contacts the operating section 430 again. As described above, the knock lock member 450 rotates circumferentially due to the circumferential force component caused by its own weight. That is, the cam surface 432 of the operating section 430 and the cam receiving surface 451 of the knock lock member 450 cooperate to rotate the knock lock member 450 circumferentially. As a result of this rotation, the knock lock member 450 locks with the locking part 460, preventing the operating section 430 from moving forward.

[0147] In detail, the second projection 461 of the locking portion 460 is re-accommodated within the recess 454 of the first projection 452 of the knock-lock member 450, thereby locking the knock-lock member 450 and the locking portion 460. In this state, even if the operating portion 430 is pressed hard to move it forward, the force component in the direction that re-accommodates the second projection 461 of the locking portion 460 within the recess 454 of the knock-lock member 450 will only increase, and the locking state will not be released.

[0148] As described above, the locking state between the knock-lock member 450 and the locking portion 460 via the recess 454 is released by positioning the front end of the writing instrument 400 downwards. By performing a knock operation in this state, the writing instrument 400 can be switched from a writing state to a non-writing state. This will be briefly explained with reference to Figure 58.

[0149] Figure 58 is a schematic diagram showing the switching of the knock mechanism 410 of the writing instrument 400 in Figure 40 from the writing state to the non-writing state. Figure 58 is a schematic diagram similar to Figure 12, with the upper part of the diagram being the front of the writing instrument 400 and the lower part being the rear of the writing instrument 400.

[0150] Figure 58(a) is identical to Figure 57(d) and is a schematic diagram of the knock mechanism 410 in the writing position of the writing instrument 400 as shown in Figure 43, with its front end facing downwards. Therefore, gravity is acting upwards in the figure.

[0151] Figure 58(b) is a schematic diagram of the knock mechanism 410 when the writing instrument 400 is transitioning to a non-writing state and its front end is facing downward. Therefore, gravity is acting upward in the figure. When the operating part 430 is pressed against the biasing force of the spring 6 and the biasing spring 490, and the operating part 430 and rotor 440 are moved forward, the rear end of the inner cam 443 passes over the front end of the outer cam 421, i.e., the large projection 422, in the front-rear direction. As a result, the restriction on the circumferential rotation of the rotor 440 is released. At this time, because the V-shaped cam surface 435 of the operating part 430 and the cam receiving surface 444 of the rotor 440 are out of phase, the rotor 440 is subjected to a circumferential component force.

[0152] Figure 58(c) is a schematic diagram of the knock mechanism 410 when the writing instrument 400 is transitioning to a non-writing state and its front end is facing downward. Therefore, gravity is acting upward in the figure. When the pressure on the operating part 430 is gradually released from the state in Figure 58(b), the rotor 440 retracts due to the biasing force of the spring 6. Immediately after this, the circumferential rotation of the rotor 440 is not restricted by the side surface of the outer cam 421, so the rotor 440 rotates circumferentially by receiving a component force from the inclined surface of the outer cam 421. That is, the inner cam 443 of the rotor 440 moves along the inclined surface of the outer cam 421. As the operating part 430 retracts, the rotor 440 rotates circumferentially until the inner cam 443 of the rotor 440 is positioned between the outer cams 421. At this time, the circumferential rotation of the rotor 440 is restricted by the side surface of the outer cam 421.

[0153] Figure 58(d) is identical to Figure 57(b) and is a schematic diagram of the knock mechanism 410 in the non-writing state and with the front end facing downwards, as shown in Figure 41. Therefore, gravity is acting upwards in the figure. When the pressure on the operating part 430 is completely released from the state shown in Figure 58(c), the rotor 440 retracts further due to the biasing force of the spring 6. Since the inner cam 443 of the rotor 440 is located between the outer cams 421, the rotor 440 retracts until the writing part 5a, which is connected to the rotor 440 via the refill 5, is retracted into the barrel 4. As a result, the writing instrument 400 is in the non-writing state. The operating part 430 retracts due to the biasing force of the biasing spring 490 and returns to its original position.

[0154] Figure 59 is a vertical cross-sectional view of the writing instrument 500 according to the sixth embodiment of the present invention in a non-writing state with the front end facing upward, Figure 60 is a vertical cross-sectional view of the writing instrument 500 of Figure 59 in a non-writing state with the front end facing downward, Figure 61 is a vertical cross-sectional view of the writing instrument 500 of Figure 59 in a writing state with the front end facing downward, and Figure 62 is a vertical cross-sectional view of the writing instrument 500 of Figure 59 in a writing state with the front end facing upward. Figure 63 is an exploded assembly view of the knock mechanism 510 of the writing instrument of Figure 59. In Figures 59 to 63, "up" is vertically upward, and "down" is vertically downward. That is, gravity acts downward in each figure.

[0155] In the knock mechanism 510 of the writing instrument 500 according to this embodiment, as shown in Figure 63, the operating part 530 is formed to be longer in the axial direction than the knock lock member 450, so the knock lock member 450 is arranged to surround the operating part 530. The knock lock member 450 has the same shape as the knock lock member 450 of the writing instrument 400 according to the fifth embodiment. The operating part 530 extends forward through the knock lock member 450 and cooperates with the rotor 540. The cam surface 532 of the operating part 530 and the cam receiving surface 451 of the knock lock member 450 cooperate to rotate the knock lock member 450 in the circumferential direction, locking the locking part 560 and the knock lock member 450. A detailed explanation follows below. In this embodiment, the eraser member and the holding member are also the same as the eraser member 470 and the holding member 471 of the writing instrument 400 according to the fifth embodiment.

[0156] The knock-lock member 450 is movable in the front-rear direction within the barrel 4 by gravity. Therefore, although Figures 59 and 60 show the same non-writing state of the writing instrument 500, in Figure 59, the front end of the writing instrument 500, i.e., the front end of the barrel 4, is facing upward, so the knock-lock member 450 is closer to the rear end within the barrel 4. On the other hand, in Figure 60, the front end of the writing instrument 500, i.e., the front end of the barrel 4, is facing downward, so the knock-lock member 450 is closer to the front end within the barrel 4 compared to Figure 59. Also, although Figures 61 and 62 show the same writing state of the writing instrument 500, in Figure 61, the front end of the writing instrument 500, i.e., the front end of the barrel 4, is facing downward, so the knock-lock member 450 is closer to the front end within the barrel 4. On the other hand, in Figure 62, since the front end of the writing instrument 500, i.e., the front end of the barrel 4, is facing upward, the knock lock member 450 is positioned closer to the rear end within the barrel 4 compared to Figure 61.

[0157] Figure 64 is a longitudinal cross-sectional view of the rear shaft 503 of the writing instrument 500 shown in Figure 59. In Figure 64, the top is the front side of the writing instrument 500. A locking portion 560 is provided in the middle of the inner surface of the rear shaft 503. The locking portion 560 has three second projections 561 arranged at equal intervals in the circumferential direction. The rear end surface of the second projections 561 is an inclined surface 562 that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction. In addition, an outer cam 563 is formed in front of the second projections 561 via a large projection 564 that protrudes radially from the second projections 561. The front end surface of the outer cam 563 is an inclined surface that is inclined in the same direction as the inclined surface 562 of the second projections 561 with respect to a plane perpendicular to the front-rear direction.

[0158] Figure 65 is a perspective view of the operating section 530 of the writing instrument 500 shown in Figure 59. In Figure 65, the top is the front of the writing instrument 500. The operating section 530 is a cylindrical member. The operating section 530 has a cylindrical portion 531 with a smooth outer surface in the central part in the axial direction. The rear of the cylindrical portion 531 is formed to have a slightly larger outer diameter via a forward-facing stepped portion 531a, and a forward-facing cam surface 532 is formed. The cam surface 532 has six peaks 532a and valleys 532b. In detail, the peaks 532a and valleys 532b are configured such that the cam surface 532 has an inclined portion 532c that is inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction, and a vertical wall portion 532d that extends along the front-rear direction. The peaks 532a of the cam surface 532 of the operating section 530 are asymmetrical along the circumferential direction, but they may be symmetrical in shape.

[0159] Three guide grooves 531b are formed on the outer circumferential surface of the front of the cylindrical portion 531, extending in the front-rear direction to the front end. A cam surface 533 is formed on the front end surface of the cylindrical portion 531. The cam surface 533 has six peaks 534 and valleys 535.

[0160] At the rear end of the operating section 530, three fitting corners 536 are formed, which are identical to the fitting corners 436 of the operating section 430 of the writing instrument 400 according to the fifth embodiment, and which extend toward the rear. The three fitting corners 536 are provided at equal intervals in the circumferential direction and are formed to be elastically deformable in the radial direction. A fitting projection 536a extending radially outward is formed on the outer surface of the tip of each fitting corner 536.

[0161] The operating section 530 is inserted into the rear axle 503 from the front. At this time, each of the large protrusions 564 formed on the rear axle 503 is positioned within the corresponding guide groove 531b of the operating section 530. By positioning the large protrusions 564 of the rear axle 503 within the guide groove 531b of the operating section 530, the operating section 530 is restricted from rotating in the circumferential direction relative to the rear axle 503, while remaining movable in the front-rear direction.

[0162] Figure 66 is a perspective view of the rotor of the writing instrument 500 shown in Figure 59. In Figure 66, the top is the front of the writing instrument 500. The rotor 540 is a cylindrical member. The rotor 540 has a cylindrical body portion 541. Three internal cams 543 extending in the front-rear direction are provided on the outer circumferential surface of the body portion 541 at equal intervals in the circumferential direction. A sawtooth-shaped cam receiving surface 544 is formed on the rear end surface of each internal cam 543, which cooperates with the cam surface 533 of the operating portion 530.

[0163] When the rotor 540 rotates circumferentially due to a knocking operation, the inner cam 543 of the rotor 540 engages with or is positioned between the outer cams 563. When the inner cam 543 is positioned between the outer cams 563, the outer cams 563 are positioned between the inner cams 543.

[0164] The cam surface 533 of the operating section 530 and the cam receiving surface 544 of the rotor 540 are configured such that when the inner cam 543 engages with the outer cam 563 or is positioned between the outer cams 563, the phase difference between the cam surface 533 and the cam receiving surface 544 is offset. Therefore, when the inclined surface of the cam surface 533 presses against the inclined surface of the cam receiving surface 544 due to the knocking operation, the rotor 540 receives a circumferential force component due to this operating load and the biasing force of the spring 6 and rotates in the circumferential direction. On the other hand, as described above, the rotation of the operating section 530 is restricted by the position of the large projection 564 of the rear shaft 503 within the guide groove 531b.

[0165] As described above, the knock-lock member of the writing instrument 500 according to this embodiment has the same shape as the knock-lock member 450 of the writing instrument 400 according to the fifth embodiment. In this embodiment, the knock-lock member 450 is passed through by the operating part 530 and is movable in the front-rear direction between the locking part 560 and the operating part 530. The cam receiving surface 451 formed on the rear end surface of the knock-lock member 450 has a shape complementary to the cam surface 532 of the operating part 530. Each of the guide grooves 453 of the knock-lock member 450 accommodates the second projection 561 of the locking part 560 of the corresponding rear shaft 503 inside, allowing it to move relatively back and forth within the guide groove 453.

[0166] The cam surface 532 of the operating section 530 and the cam receiving surface 451 of the knock-lock member 450 are configured such that when the second projection 561 of the locking section 560 is housed in the guide groove 453 of the knock-lock member 450, the peak 532a of the cam surface 532 is positioned on the slanted portion 451c of the cam receiving surface 451 in the circumferential direction. For example, when the front end of the writing instrument 500 is turned upward as shown in Figure 59, the knock-lock member 450 comes into contact with the operating section 530 due to the action of gravity, but due to the weight of the knock-lock member 450, it receives a circumferential component force and rotates in the circumferential direction. On the other hand, the rotation of the operating section 530 is restricted by the placement of the large projection 564 of the rear shaft 503 within the guide groove 531b.

[0167] Furthermore, as shown in Figures 59 to 62, a biasing spring 590 is positioned between the rear end faces of the three large protrusions 564 of the rear shaft 503 and the front end face of the flange portion 474 of the retaining member 471, so as to surround the cylindrical portion 531 of the operating portion 530. The biasing spring 590 biases the retaining member 471, and furthermore the operating portion 530 connected to the retaining member 471 and the eraser member 470 attached to the retaining member 471, toward the rear. Therefore, whether the writing instrument 500 is in writing mode or not, the eraser member 470 is always positioned in the same location in the axial direction. The knock lock member 450 is positioned so as to surround the biasing spring 590.

[0168] Figure 67 is a schematic diagram showing the switching of the knock mechanism 510 of the writing instrument 500 in Figure 59 from the non-writing state to the writing state. Figure 67 is a schematic diagram similar to Figure 12, with the upper part of the diagram being the front of the writing instrument 500 and the lower part being the rear of the writing instrument 500.

[0169] Figure 67(a) is a schematic diagram of the knock mechanism 510 in the non-writing state and with the front end facing upward, as shown in Figure 59. Therefore, gravity is acting downward in the figure. At this time, the inner cam 543 of the rotor 540, which is biased rearward by the spring 6 via the refill 5, is positioned between the outer cams 563. Therefore, in this state, the writing section 5a is retracted into the barrel 4. In addition, the cam surface 533 of the operating section 530 and the cam receiving surface 544 of the rotor 540 are in contact, but there is a phase difference between the cam surface 533 and the cam receiving surface 544.

[0170] By pointing the front end of the writing instrument 500 upward, the knock lock member 450 moves backward and comes into contact with the operating section 530. As described above, the knock lock member 450 rotates circumferentially due to the circumferential component force caused by its own weight. That is, the cam surface 532 of the operating section 530 and the cam receiving surface 451 of the knock lock member 450 cooperate to rotate the knock lock member 450 circumferentially. As a result of this rotation, the knock lock member 450 engages with the locking section 560, preventing the operating section 530 from moving forward.

[0171] In detail, the second projection 561 of the locking portion 560 is housed in the recess 454 of the first projection 452 of the knock-lock member 450, thereby locking the knock-lock member 450 and the locking portion 560. In other words, in the non-writing state, the recess 454 is configured to have a shape complementary to a part of the second projection 561 of the locking portion 560, so that the second projection 561 of the locking portion 560 is housed in the recess 454 of the first projection 452 of the knock-lock member 450. Therefore, the slope 562 of the second projection 561 has the same inclination as the slope 456 of the recess 454. In this state, even if the operating portion 530 is pressed hard to move it forward, only the force component in the direction that houses the second projection 561 of the locking portion 560 in the recess 454 of the knock-lock member 450 will increase, and the locking state will not be released.

[0172] Figure 67(b) is a schematic diagram of the knock mechanism 510 in the non-writing state of the writing instrument 500 as shown in Figure 60, with its front end facing downwards. Therefore, gravity is acting upwards in the figure. By pointing the front end of the writing instrument 500 downwards, the knock lock member 450 becomes free in relation to the operating part 530. On the other hand, the knock lock member 450 presses the locking part 560 via the first projection 452 due to its own weight. That is, due to the weight of the knock lock member 450, the inclined surface 456 of the recess 454 of the first projection 452 receives a circumferential component force from the inclined surface 562 of the second projection 561 of the locking part 560. As a result, the knock lock member 450 rotates in the opposite circumferential direction to that in Figure 67(a), and the second projection 561 is guided into the guide groove 453. In other words, the locking state between the knock-lock member 450 and the locking portion 560 is released, allowing the operating portion 530 to move forward. The forward movement of the knock-lock member 450 is stopped by contact with the rear end surface of the large projection 564 of the rear shaft 503. Therefore, the large projection 564 of the rear shaft 503 may be formed as the buffer member described above.

[0173] Figure 67(c) is a schematic diagram of the knock mechanism 510 when the writing instrument 500 is transitioning to the writing state and its front end is facing downward. Therefore, gravity is acting upward in the figure. When the operating part 530 is pressed against the biasing force of the spring 6 and the biasing spring 590, and the operating part 530 and rotor 540 are moved forward, the rear end of the inner cam 543 passes the front end of the outer cam 563 in the front-rear direction. As a result, the restriction on the circumferential rotation of the rotor 540 is released. At this time, because the cam surface 533 of the operating part 530 and the cam receiving surface 544 of the rotor 540 are out of phase, the rotor 540 is subjected to a circumferential component force.

[0174] Figure 67(d) is a schematic diagram of the knock mechanism 510 in the writing state of the writing instrument 500 as shown in Figure 61, with the front end facing downwards. Therefore, gravity is acting upwards in the figure. When the pressure on the operating part 530 is released from the state shown in Figure 67(c), the rotor 540 retracts due to the biasing force of the spring 6. At this time, the circumferential rotation of the rotor 540 is not restricted by the side surface of the outer cam 563, so the rotor 540 rotates circumferentially by receiving a component force from the inclined surface of the outer cam 563. That is, the inner cam 543 of the rotor 540 moves along the inclined surface of the outer cam 563. As a result, the inner cam 543 engages with the outer cam 563, that is, the sawtooth-shaped cam receiving surface 544 engages with the outer cam 563, preventing retraction, and the writing part 5a, which is connected to the rotor 540 via the refill 5, is kept in a state where it protrudes from the barrel 4, thus enabling writing. Furthermore, the operating section 530 retracts due to the biasing force of the biasing spring 590 and returns to its original position.

[0175] Figure 67(e) is a schematic diagram of the knock mechanism 510 in the writing position of the writing instrument 500 as shown in Figure 62, with its front end facing upward. Therefore, gravity is acting downward in the figure. By pointing the front end of the writing instrument 500 upward, the knock lock member 450 moves backward and contacts the operating section 530 again. As described above, the knock lock member 450 rotates circumferentially due to the circumferential force component caused by its own weight. That is, the cam surface 532 of the operating section 530 and the cam receiving surface 451 of the knock lock member 450 cooperate to rotate the knock lock member 450 circumferentially. As a result of this rotation, the knock lock member 450 locks with the locking part 560, preventing the operating section 530 from moving forward.

[0176] In detail, the second projection 561 of the locking portion 560 is re-accommodated within the recess 454 of the first projection 452 of the knock-lock member 450, thereby locking the knock-lock member 450 and the locking portion 460. In this state, even if the operating portion 530 is pressed hard to move it forward, the force component in the direction that re-accommodates the second projection 561 of the locking portion 560 within the recess 454 of the knock-lock member 450 will only increase, and the locking state will not be released.

[0177] As described above, the locking state between the knock-lock member 450 and the locking portion 560 via the recess 454 is released by positioning the front end of the writing instrument 500 downwards. By performing a knock operation in this state, the writing instrument 500 can be switched from a writing state to a non-writing state. This will be briefly explained with reference to Figure 68.

[0178] Figure 68 is a schematic diagram showing the switching of the knock mechanism 510 of the writing instrument 500 in Figure 62 from the writing state to the non-writing state. Figure 68 is a schematic diagram similar to Figure 12, with the upper part of the diagram being the front of the writing instrument 500 and the lower part being the rear of the writing instrument 500.

[0179] Figure 68(a) is identical to Figure 67(d) and is a schematic diagram of the knock mechanism 510 in the writing position of the writing instrument 500 as shown in Figure 61, with its front end facing downwards. Therefore, gravity is acting upwards in the figure.

[0180] Figure 68(b) is a schematic diagram of the knock mechanism 510 when the writing instrument 500 is transitioning to a non-writing state and its front end is facing downward. Therefore, gravity is acting upward in the figure. When the operating part 530 is pressed against the biasing force of the spring 6 and the biasing spring 590, and the operating part 530 and rotor 540 are moved forward, the rear end of the inner cam 543 passes the front end of the outer cam 563 in the front-rear direction. As a result, the restriction on the circumferential rotation of the rotor 540 is released. At this time, because the cam surface 533 of the operating part 530 and the cam receiving surface 544 of the rotor 540 are out of phase, the rotor 540 is subjected to a circumferential component force.

[0181] Figure 68(c) is a schematic diagram of the knock mechanism 510 when the writing instrument 500 is transitioning to a non-writing state and its front end is facing downward. Therefore, gravity is acting upward in the figure. When the pressure on the operating part 530 is gradually released from the state in Figure 68(b), the rotor 540 retracts due to the biasing force of the spring 6. Immediately after this, the circumferential rotation of the rotor 540 is not restricted by the side surface of the outer cam 563, so the rotor 540 rotates circumferentially by receiving a component force from the inclined surface of the outer cam 563. That is, the inner cam 543 of the rotor 540 moves along the inclined surface of the outer cam 563. As the operating part 530 retracts, the rotor 540 rotates circumferentially until the inner cam 543 of the rotor 540 is positioned between the outer cams 563. At this time, the circumferential rotation of the rotor 540 is restricted by the side surface of the outer cam 563.

[0182] Figure 68(d) is identical to Figure 67(b) and is a schematic diagram of the knock mechanism 510 in the non-writing state and with the front end facing downwards, as shown in Figure 60. Therefore, gravity is acting upwards in the figure. When the pressure on the operating part 530 is completely released from the state shown in Figure 68(c), the rotor 540 retracts further due to the biasing force of the spring 6. Since the inner cam 543 of the rotor 540 is located between the outer cams 563, the rotor 540 retracts until the writing part 5a, which is connected to the rotor 540 via the refill 5, is retracted into the barrel 4. As a result, the writing instrument 500 is in the non-writing state. The operating part 530 retracts due to the biasing force of the biasing spring 590 and returns to its original position.

[0183] In the fifth and sixth embodiments, as described in the second and fourth embodiments, in both the non-writing and writing states, if the front end of the writing instrument is facing upwards, the forward movement of the operating unit is prevented. Therefore, for example, when erasing writing with the writing instrument 400 using the erasing member 470 of the operating unit 430, stable rubbing action can be performed whether the writing instrument 400 is in the writing state or the non-writing state. In other words, even if the writing instrument is changed and the operating unit is pressed against the writing surface to perform a rubbing action, the operating unit will never rattle.

[0184] Furthermore, in the fifth and sixth embodiments, since the operating unit and the erasing member are always biased to the rear, the amount of protrusion of the erasing member from the rear end of the barrel is the same in both the non-writing and writing states, unlike in the second and fourth embodiments. Therefore, when erasing handwriting with the writing instrument using the erasing member of the operating unit, the erasing member can be equally visible whether the writing instrument is in the writing state or the non-writing state. As a result, it is possible to easily target the intended area and perform a precise erasing action.

[0185] Furthermore, in the fifth embodiment, since the rotor 440 is located within the operating section 430, the overall length of the refill 5 can be made longer, and as a result, the writing distance can be made longer.

[0186] The knock-lock member may have any shape as long as it is movable in the front-to-back direction within the barrel. The number of first projections on the knock-lock member and the number of second projections on the corresponding locking part may be the same or different, and can be set arbitrarily. Therefore, there may be one or more of each. Furthermore, the shape of a part of the first projection on the knock-lock member and the recess of the second projection on the corresponding locking part may be any shape as long as they can lock together, even if they are not complementary.

[0187] The refill 5, which is the cursive writing instrument in the embodiment described above, may contain thermochromic ink. In this case, the writing instrument 1 is a thermochromic writing instrument, and the writing on the writing instrument 1 can change color due to the frictional heat generated when it is rubbed by the friction element, which is the erasing part. As the cursive writing instrument, a ballpoint pen containing thermochromic ink, a mechanical pencil containing a thermochromic lead, a pencil holder, etc. may also be used. Alternatively, a writing instrument containing eraser-erasable ink that can be erased with an eraser may also be used.

[0188] Here, thermochromic ink refers to ink that maintains a predetermined color (first color) at room temperature (e.g., 25°C), changes to a different color (second color) when heated to a predetermined temperature (e.g., 60°C), and then returns to its original color (first color) when cooled to a predetermined temperature (e.g., -5°C). In writing instrument 1 using thermochromic ink, the second color is made colorless, and the process of heating the line written with the first color (e.g., red) to make it colorless is referred to here as "erasing." Therefore, friction heat is generated by rubbing the writing surface on which the line is written with a friction element acting as an eraser, thereby changing the line to colorless, i.e., erasing it. Of course, the second color may be a color other than colorless.

[0189] Furthermore, in the case of a writing instrument containing an eraser-erasable ink that can be erased with an eraser, the eraser-erasable ink must contain water and at least 3 to 30% by weight of non-thermoplastic colored resin particles with an average particle diameter of 1.0 to 15 μm and 0.1 to 10% by weight of uncolored particles, based on the total amount of the ink composition. The colored resin particles used in the aqueous ink of the present invention consist of colored resin particles, are non-thermoplastic, and have an average particle diameter of 1.0 to 15 μm. Examples include colored resin particles in which a coloring agent consisting of a pigment is dispersed in the resin particles, colored resin particles in which the surface of the resin particles is coated with a coloring agent consisting of a pigment, and colored resin particles in which a coloring agent consisting of a dye is dyed onto the resin particles. In this embodiment, the structure (with or without hollow structure (dense)), shape (spherical, polygonal, flattened, fibrous), etc., of the colored resin particles are not particularly limited as long as they are non-thermoplastic and satisfy the above average particle diameter. However, preferably, from the viewpoint of exhibiting excellent eraserability, writing properties, and long-term stability as an ink, it is desirable to use spherical colored resin fine particles that have intramolecular crosslinking such that the glass transition temperature is 150°C or higher and close to the thermal decomposition temperature, and furthermore, the melt flow index value is less than 0.1, are not sticky, and have an average particle diameter of 1.0 to 15 μm. The "average particle diameter" as defined in the present invention (including examples, etc.) is the D50 value measured with a particle size analyzer (Microtrac HRA9320-X100 (manufactured by Nikkiso Co., Ltd.)).

[0190] The material used to form the erasing section, i.e., the erasing member 35, erasing member 135, or erasing member 335, is a rubber elastic material such as thermosetting rubber such as silicone rubber, nitrile rubber, ethylene propylene rubber, or ethylene propylene diene rubber, or thermoplastic elastomers such as styrene elastomer, olefin elastomer, or polyester elastomer, a mixture of two or more rubber elastic materials, or a mixture of a rubber elastic material and a synthetic resin, configured such that the Taber wear amount on the CS-17 wear wheel of the Taber wear tester is 10 mg or more under a load of 9.8 N and a 1000 rpm environment in the abrasion test (ASTM D1044) specified in JIS K7204. Furthermore, a phthalate-based plasticizer may be added to the material of the erasing member to increase its flexibility in order to adjust the Taber wear amount to 10 mg or more. By including a phthalate-based plasticizer in the erasing member, the erasing member becomes more easily abraded, making it possible to erase handwriting without damaging the paper surface or blurring printed characters. Furthermore, it is desirable that the erasing element has a durometer D hardness of 30 or higher as specified in JIS K6203. This ensures the required hardness and enables more stable swiping. The erasing element can also be used as a touch pen or stylus pen.

[0191] In this invention, "erasing" refers to removing written lines, characters, etc., by adsorption or scraping them off with an erasing part such as an eraser, even when using the above-mentioned thermochromic ink. Furthermore, the operating part may be configured to function as a capacitive touch pen by providing conductivity to a pressure-sensitive touch pen or barrel, instead of an erasing member. Therefore, this invention is applicable to any writing instrument that erases written lines using an erasing part. [Explanation of Symbols]

[0192] 1 writing implements 4 shaft cylinder 20 Inner cylinder 30 Control section 40 rotors 50 Knock lock member 60 Locking part

Claims

1. It comprises a barrel, an operating part positioned at the rear end of the barrel and functioning as a stylus, a rotor, and a writing body equipped with a writing section. A touch pen that can switch between a writing state in which the writing part protrudes from the barrel and a non-writing state in which the writing part is retracted into the barrel by performing a knock operation by pressing the operating part forward, The device further comprises a knock-lock member that can move in the front-rear direction within the shaft cylinder by gravity, and a locking portion provided on the inner surface of the shaft cylinder that can engage with the knock-lock member. When the front end of the shaft cylinder is pointed upward, the knock-lock member moves backward and engages with the locking portion, preventing the operating portion from moving forward. A stylus pen characterized in that the rotor or the operating part has a cam surface facing the knock-lock member, the knock-lock member has a cam receiving surface that cooperates with the cam surface, and when the knock-lock member moves backward, the cam surface and the cam receiving surface cooperate to rotate the knock-lock member in the circumferential direction, causing the locking part and the knock-lock member to lock together.

2. It comprises a barrel, an operating part positioned at the rear end of the barrel and functioning as a stylus, a rotor, and a writing body equipped with a writing section. A touch pen that can switch between a writing state in which the writing part protrudes from the barrel and a non-writing state in which the writing part is retracted into the barrel by performing a knock operation by pressing the operating part forward, The device further comprises a knock-lock member that can move in the front-rear direction within the shaft cylinder by gravity, and a locking portion provided on the inner surface of the shaft cylinder that can engage with the knock-lock member. When the front end of the shaft cylinder is pointed upward, the knock-lock member moves backward and engages with the locking portion, preventing the operating portion from moving forward. A stylus pen characterized in that the knock-lock member has a first projection and the locking portion has a second projection, and when the knock-lock member rotates in the circumferential direction, the first projection and the second projection engage with each other, thereby locking the knock-lock member and the locking portion.

3. It comprises a barrel, an operating part positioned at the rear end of the barrel and functioning as a stylus, a rotor, and a writing body equipped with a writing section. A touch pen that can switch between a writing state in which the writing part protrudes from the barrel and a non-writing state in which the writing part is retracted into the barrel by performing a knock operation by pressing the operating part forward, The device further comprises a knock-lock member that can move in the front-rear direction within the shaft cylinder by gravity, and a locking portion provided on the inner surface of the shaft cylinder that can engage with the knock-lock member. When the front end of the shaft cylinder is pointed upward, the knock-lock member moves backward and engages with the locking portion, preventing the operating portion from moving forward. A stylus pen characterized by having a window on the side of the barrel, which allows the knock-lock member to be seen through the window when it is positioned towards the front or rear end inside the barrel.

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