Mechanical pencil

Abstract

A mechanical pencil 3 includes: a shaft cylinder 4; a mechanical pencil mechanism 10 having a lead case capable of storing a writing lead; an electronic component 20 including a pressure sensor 24 for detecting writing pressure applied to the writing lead; and a cover member 6 which is removably disposed with respect to a rear end part of the shaft cylinder 4 and is configured to be removed when replenishing the writing lead into the lead case. The cover member 6 does not include the electronic component.

Description

mechanical pencil

[0001] The present invention relates to a mechanical pencil.

[0002] Mechanical pencils are known that have a mechanical pencil mechanism with a lead case that can store a writing lead, and electronic components that include a power source, a writing pressure sensor, etc. (See, for example, Patent Documents 1 and 2.) The electronic components perform, for example, communication processing and information processing related to data in response to user operations.

[0003] JP 2021-49681 A JP 2022-546544 A

[0004] In the mechanical pencil described in Patent Document 1, the mechanical pencil mechanism is located in the front shaft, and the electronic components are located in the rear shaft. Therefore, when refilling the lead, the rear shaft containing the electronic components must be removed, which makes refilling the lead difficult. Furthermore, the electronic components, particularly those containing heavy components such as a power supply, are heavier than the mechanical pencil mechanism. Therefore, the center of gravity of the mechanical pencil is located behind the shaft, which makes it difficult to perform a stable writing operation.

[0005] The mechanical pencil described in Patent Document 2 has a first body and a second body that is detachable from the rear end of the first body, and a mechanical pencil mechanism and electronic components are arranged in parallel inside the first and second bodies. Some components, including the wiring of the electronic components, are arranged in the second body and are removed together with the second body when refilling the lead. Therefore, when attaching the second body to the first body after refilling the lead, a reliable electrical connection must be established, which makes it difficult to refill the lead.

[0006] Furthermore, in the mechanical pencil described in Patent Document 2, the mechanical pencil mechanism and electronic components are arranged in parallel within the first body, so the tip of the writing lead is eccentric with respect to the central axis of the barrel and the center of gravity is biased to one side. A user can write stably by holding the mechanical pencil so as to support the center of gravity. However, as a result, the user always writes while holding the mechanical pencil in the same position, which causes uneven wear of the tip surface of the writing lead. In other words, with a typical mechanical pencil, the angle at which the tip surface of the writing lead abuts against the writing surface can be changed by re-gripping the mechanical pencil while rotating it around the central axis, thereby preventing uneven wear. In the mechanical pencil described in Patent Document 2, because the center of gravity is biased to one side, there is a problem in that re-gripping the mechanical pencil while rotating it around the central axis makes it difficult to write stably.

[0007] An object of the present invention is to provide a user-friendly mechanical pencil equipped with electronic components.

[0008] According to one aspect of the present invention, there is provided a mechanical pencil comprising a barrel, a mechanical pencil mechanism having a lead case capable of accommodating a writing lead, electronic components including a writing pressure sensor that detects the writing pressure applied to the writing lead, and a cover member that is removably arranged at the rear end of the barrel and configured to be removed when the writing lead is refilled into the lead case, wherein the cover member does not include the electronic components.

[0009] The mechanical pencil mechanism may be arranged parallel to the electronic component within the barrel and eccentric to the central axis of the mechanical pencil, and the mechanical pencil mechanism may have a chuck unit that allows the writing lead to move forward and prevents it from moving backward, and a rotation drive mechanism with a rotor, and the rotation drive mechanism may be configured to rotate the rotor in one direction in response to the axial backward movement caused by writing pressure applied to the writing lead held by the chuck unit and the axial forward movement caused by releasing the writing pressure. Part or all of the cover member may be an erasing part that can erase handwriting made with the writing lead.

[0010] According to another aspect of the present invention, there is provided a mechanical pencil comprising a barrel, a mechanical pencil mechanism having a lead case capable of accommodating a writing lead, and an electronic component including a writing pressure sensor that detects the writing pressure applied to the writing lead, wherein the mechanical pencil mechanism is arranged in parallel with the electronic component within the barrel and is arranged eccentrically with respect to the central axis of the mechanical pencil, the mechanical pencil mechanism having a chuck unit that allows the writing lead to move forward and prevents it from moving backward, and a rotation drive mechanism with a rotor, wherein the rotation drive mechanism is configured to rotate the rotor in one direction in response to the axial backward movement caused by the writing pressure applied to the writing lead held by the chuck unit and the axial forward movement caused by the release of the writing pressure.

[0011] The rotary drive mechanism may be retracted by the writing pressure applied to the writing lead, and the retraction of the rotary drive mechanism may cause the writing pressure sensor to detect the writing pressure.

[0012] According to the aspects of the present invention, a common effect is achieved in that a user-friendly mechanical pencil equipped with electronic components is provided.

[0013] FIG. 1 is a perspective view of a mechanical pencil according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional perspective view of the mechanical pencil of FIG. 1. FIG. 3 is an exploded perspective view of the mechanical pencil of FIG. 1. FIG. 4 is a longitudinal cross-sectional view of the mechanical pencil of FIG. 1. FIG. 5 is a functional block diagram of the barrel. FIG. 6 is an enlarged cross-sectional view of the front end of the mechanical pencil of FIG. 1. FIG. 7 is an enlarged cross-sectional view of a portion of the rotation drive mechanism. FIG. 8 is a schematic diagram illustrating the rotation drive of a rotor of the rotation drive mechanism. FIG. 9 is a schematic diagram illustrating the rotation drive of the rotor following FIG. 8. FIG. 10 is a perspective view of the rear end of the mechanical pencil of FIG. 1 with the cover member removed. FIG. 11 is an enlarged cross-sectional view of the front end of the mechanical pencil of FIG. 1.

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Corresponding components throughout the drawings are designated by common reference numerals.

[0015] FIG. 1 is a perspective view of a mechanical pencil 3 according to an embodiment of the present invention, FIG. 2 is a partial cross-sectional perspective view of the mechanical pencil 3 of FIG. 1, FIG. 3 is an exploded perspective view of the mechanical pencil 3 of FIG. 1, and FIG. 4 is a vertical cross-sectional view of the mechanical pencil 3 of FIG. 1.

[0016] The mechanical pencil 3 and the communication terminal 2 constitute a communication system 1. The communication terminal 2 is an information processing device such as a mobile phone, a smartphone, a PC (Personal Computer), a tablet terminal, or a portable game console that is owned by a user of the mechanical pencil 3. The communication terminal 2 is an example of a communication device external to the mechanical pencil 3.

[0017] In response to detecting the user's action, the mechanical pencil 3 transmits a signal to the communication terminal 2 to initiate communication with the communication terminal 2. The predetermined action is, for example, the application of writing pressure to the writing lead due to the writing action, or a knock operation on the mechanical pencil 3 to advance the writing lead. The mechanical pencil 3 can collect information related to the writing action and transmit it to the communication terminal 2 until the series of writing actions is completed. The communication terminal 2 can perform predetermined information processing using the information related to the writing action to generate information to assist the user in writing. The information to assist the user in writing is, for example, digital data indicating the characters written by the user. In this case, the predetermined information processing is processing to generate digital data indicating the characters written by the user based on the information related to the writing action.

[0018] The mechanical pencil 3 has a cylindrical barrel 4, a tip member 5 that fits into the front end of the barrel 4, and a cover member 6 that is located at the rear end of the barrel 4. The tip member 5 may also be referred to as the barrel 4. The mechanical pencil 3 is configured so that a writing part 13a protrudes from a tip opening 5a of the tip member 5. In this specification, in the axial direction of the mechanical pencil 3, the side of the writing part 13a is defined as the "front" side, and the side opposite the writing part 13a is defined as the "rear" side.

[0019] As shown in FIG. 3 , the barrel 4 is divided vertically into a first half 4a and a second half 4b. Three rod-shaped connecting protrusions 4c that protrude radially are provided on the inner surface of the first half 4a. Three insertion holes 4d are provided on the side of the second half 4b that face each of the three connecting protrusions 4c. The first half 4a and the second half 4b are connected to each other by fitting the connecting protrusions 4c into the corresponding insertion holes 4d, thereby forming the barrel 4. The inner surfaces of the first half 4a and the second half 4b are further provided with a plurality of support ribs 4e. The support ribs 4e are spaced apart in the axial direction. One of the support ribs 4e constitutes a sensor support plate 4f, which serves as a sensor fixing member that supports the pressure sensor 24 (described later).

[0020] The mechanical pencil mechanism 10 and the electronic component 20 are arranged in parallel within the barrel 4. The central axis of the mechanical pencil mechanism 10 is arranged eccentrically with respect to the central axis of the mechanical pencil 3, i.e., with respect to the central axis of the barrel 4. In other words, the mechanical pencil mechanism 10 is arranged offset to one side within the barrel 4. The mechanical pencil mechanism 10 and the electronic component 20 are supported within the barrel 4 by a support rib 4e so that lateral movement is restricted.

[0021] The tip member 5 is formed in a generally conical or frusto-conical shape. The tip opening 5a of the tip member 5 is also provided eccentrically to accommodate the mechanical pencil mechanism 10, which is arranged eccentrically within the barrel 4. The cover member 6 is formed in a cylindrical shape with one end closed. A receiving opening 6b extending in the axial direction and formed in a generally cylindrical shape is defined in a portion of the front end opening 6a of the cover member 6. A support protrusion 6c extending forward is provided on the bottom of the receiving opening 6b, i.e., the inner surface of the closed end of the cover member 6.

[0022] A part or all of the cover member 6 may be configured as an erasing portion capable of erasing handwriting made with a writing lead. When the writing lead is a normal writing lead containing graphite, the erasing portion is made of eraser components. The writing lead used in the mechanical pencil 3 may be a thermochromic writing lead. In this case, the mechanical pencil 3 is a thermochromic writing implement, and the handwriting made with the mechanical pencil 3 can be thermochromic due to the frictional heat generated when rubbed with the friction body that is the erasing portion.

[0023] Here, a thermochromic writing lead refers to an 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 the original color (first color) when cooled to a predetermined temperature (e.g., -5°C). In a mechanical pencil 3 using a thermochromic writing lead, the second color is rendered colorless, and "erasing" refers to heating a line drawn with the first color (e.g., red) to make it colorless. Therefore, the frictional portion serving as the erasing portion rubs against the writing surface on which the line was drawn, generating frictional heat, which changes the drawn line to colorless, i.e., erases it. Naturally, the second color may be a color other than colorless.

[0024] The mechanical pencil mechanism 10 includes a first lead case 11 and a second lead case 12 capable of housing a lead, a chuck unit 13 fitted to the front end of the first lead case 11 and equipped with a writing portion 13a at its tip, a coil spring 31, and a rotation drive mechanism 30 disposed between the first lead case 11 and the second lead case 12. The first lead case 11 is disposed in front of the rotation drive mechanism 30, and the second lead case is disposed behind the rotation drive mechanism 30. The writing portion 13a sequentially dispenses the mechanical lead (not shown) housed in the first lead case 11. An annular flange portion 11a is provided on the outer surface of the rear of the first lead case 11. The front end of the coil spring 31 is supported by the flange portion 11a of the first lead case 11. A support protrusion 6c of the cover member 6 is inserted into the rear opening of the second lead case 12.

[0025] The electronic component 20 has an electronic board 21, a power source 22 which is a secondary battery, a charging unit 23, and a pressure sensor 24. Current is supplied to the electronic board 21 from the power source 22. The charging unit 23 is configured to charge the power source 22. The charging unit 23 includes a connection unit 23a for connecting terminals, and a power supply circuit for supplying current from the connection unit to the power source 22 to charge the power source 22. The connection unit 23a is formed so that a terminal conforming to a standard such as USB-C (Universal Serial Bus Type C) can be connected.

[0026] The pressure sensor 24 has a through-hole 24a through which the second lead case 12 can be inserted. The pressure sensor 24 functions as a writing pressure sensor for detecting the writing pressure applied to the writing lead. The pressure sensor 24 is a pressure sensor that has a strain gauge that deforms in response to pressure applied to its detection surface and a resistance element, such as a piezoresistor or conductive ink, disposed on the strain gauge. The pressure sensor 24 detects pressure by detecting changes in resistance value due to deformation of the strain gauge. The pressure sensor 24 is disposed on the electronic board 21 so that its detection surface is perpendicular to the axial direction of the barrel 4. The pressure sensor 24 is disposed so that its rear surface abuts against the sensor support plate 4f of the barrel 4. The sensor support plate 4f restricts the rearward movement of the pressure sensor 24, allowing the pressure sensor 24 to accurately detect pressure.

[0027] Various sensors 101, including a pressure sensor 24, are arranged on the electronic board 21. The other sensors 101 are, for example, magnetic field sensors and inertial sensors. The magnetic field sensors are sensors that detect magnetic fields, such as Hall sensors. The inertial sensors are sensors that detect three-axis acceleration and angular velocity acting on the barrel 4, and include, for example, acceleration sensors and gyro sensors. The sensors 101 can generate information about the operation of the barrel 4 on a regular or irregular basis.

[0028] 5 is a functional block diagram of the barrel 4. The barrel 4, specifically the electronic board 21, is provided with a sensor 101, a switch 102 for receiving user operations, a notification unit 103 for issuing predetermined notifications to the user, a memory unit 104, a communication unit 105, and a processing unit 110.

[0029] The storage unit 104 is configured to store programs and data, and includes, for example, a semiconductor memory. The storage unit 104 stores programs such as an operating system program, driver programs, and application programs used in processing by the processing unit 110. The programs are installed into the storage unit 104 from a computer-readable, non-transitory, portable storage medium such as a CD-ROM (Compact Disc Read Only Memory) or a DVD-ROM (Digital Versatile Disc Read Only Memory).

[0030] The communication unit 105 is a component that enables the mechanical pencil 3 to communicate with other devices such as the communication terminal 2, and includes a communication interface circuit. The communication interface circuit is an interface circuit for a short-range wireless communication method such as BLE (Bluetooth Low Energy) (registered trademark). The communication unit 105 transmits data supplied from the processing unit 110 to other devices, and also supplies data transmitted from other devices to the processing unit 110.

[0031] The processing unit 110 is configured to comprehensively control the operation of the mechanical pencil 3 and includes one or more processors and their peripheral circuits. The processing unit 110 includes, for example, a CPU (Central Processing Unit). The processing unit 110 may also include a DSP (Digital Signal Processor), an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), etc. The processing unit 110 controls the operation of each component and executes various processes so that the various processes of the mechanical pencil 3 are executed in an appropriate order based on the programs stored in the storage unit 104.

[0032] The processing unit 110 has a determination unit 111, a transmission unit 112, a notification control unit 113, an acquisition unit 114, and a correction unit 115. Each of these units is a functional module realized by the processing unit 110 executing a program. Each of these units may be implemented in the barrel 4 as a dedicated processing circuit.

[0033] Figure 6 is an enlarged cross-sectional view of the front end of the mechanical pencil 3 in Figure 1. The chuck unit 13 includes a cylindrical chuck holder 11b, a cylindrical connecting member 14, a coil spring 15, a cylindrical slider 16, a cylindrical fastener 17, a chuck main body 18, and a holding chuck 19. The inner surface of the rear end of the chuck holder 11b fits into the outer surface of the front end of the first lead case 11. The outer surface of the rear end of the chuck main body 18 fits into the inner surface of the front end of the chuck holder 11b. At least the front half of the chuck main body 18 is divided into three chuck pieces along the axial direction, and a through hole for the writing lead is formed along the central axis. The chuck pieces are formed so that their front ends are spaced apart from each other.

[0034] The connecting member 14 is slidably disposed on the outer surface of the front end of the chuck holding member 11b. The coil spring 15 is disposed on the outer surface of the chuck holding member 11b. The inner surface of the rear end of the slider 16 is fitted onto the outer surface of the front end of the connecting member 14. The outer surface of the fastener 17 is fitted onto the inner surface of the slider 16. The rear end surface of the fastener 17 abuts against the front end surface of the connecting member 14. The fastener 17 is disposed so as to surround the front end of the chuck main body member 18. The inner surface of the fastener 17 is tapered, with the inner diameter decreasing toward the rear. A holding chuck 19, which has a through hole formed in the center, is fitted onto the inner surface of the front end of the slider 16. The through hole of the holding chuck 19 makes sliding contact with the outer surface of the writing lead, acting to temporarily hold the writing lead. A ring-shaped, stepped first locking portion 16a is provided on the outer surface of the slider 16. The tip member 5 has an inner surface provided with a second engagement portion 5b that is annular and stepped.

[0035] The coil spring 15 biases the chuck body member 18, together with the chuck holding member 11b, rearward against the connecting member 14, and thus against the slider 16 and fastener 17. The rearward-biased chuck body member 18 is housed within the fastener 17, causing the front ends to approach each other and maintaining a grip on the lead. When writing pressure is applied to the lead, the lead is gripped by the chuck body member 18 and prevented from retracting. On the other hand, when a force acts to pull the lead forward, the chuck body member 18 is not affected by the fastener 17, allowing the lead to be pulled forward without resistance. In other words, the chuck unit 13 acts to allow the lead to advance and prevent it from retracting. The chuck unit 13 may be a chuck unit other than a ball chuck, as long as it performs this function.

[0036] A brief description of the knocking operation of the mechanical pencil mechanism 10 will be given. By performing a knocking operation that presses the cover member 6 forward, the first lead case 11, and therefore the chuck holding member 11b and chuck body member 18, advance via the second lead case 12 and the rotation drive mechanism 30. As the chuck holding member 11b advances, the connecting member 14 and slider 16 advance via the coil spring 15. The advancement of the slider 16 is restricted by the engagement between the first locking portion 16a of the slider 16 and the second locking portion 5b of the tip member 5. Further advancing the chuck holding member 11b and the chuck body member 18 pushes the chuck body member 18 forward and escapes from the fastener 17. Accordingly, the writing lead held by the chuck body member 18 also advances, releasing the grip of the writing lead by the chuck body member 18. In short, the chuck unit 13 is capable of gripping and releasing the writing lead, thereby acting to advance the writing lead from the front end of the slider 16 .

[0037] When the pressure caused by the knocking operation is released, the chuck holding member 11b and the chuck body member 18 move backward due to the biasing force of the coil spring 15. Meanwhile, the writing lead is held by a holding chuck 19 disposed within the slider 16. As a result, the writing lead is advanced from the slider 16, and therefore, each time the knocking operation is repeated, the writing lead can be advanced by a predetermined amount.

[0038] 7 is an enlarged cross-sectional view of the rotation drive mechanism 30. The rotation drive mechanism 30 is connected to the rear end of the first lead case 11. The rotation drive mechanism 30 is biased rearward by a coil spring 31. That is, the front end of the coil spring 31 is supported by the flange portion 11a of the first lead case 11, and the rear end of the coil spring 31 is supported by the front end face of the rotation drive mechanism 30, thereby biasing the rotation drive mechanism 30 rearward.

[0039] The rotation drive mechanism 30 has a rotor 40 formed in a cylindrical shape, an upper cam forming member 41 which is a first cam forming member formed in a cylindrical shape, a lower cam forming member 42 which is a second cam forming member formed in a cylindrical shape, a cylinder member 43 formed in a cylindrical shape, a torque canceller 44 which is also formed in a cylindrical shape, and a coil-shaped cushion spring 45. The rotation drive mechanism 30 is a unit formed by integrating these members.

[0040] The front end of the rotor 40 is provided with a fitting portion 40c that extends forward, penetrating the lower cam forming member 42. The inner surface of the rear end of the first lead case 11 fits into the outer surface of the fitting portion 40c of the rotor 40. The central portion of the rotor 40 has a flange-shaped portion with a slightly larger diameter, and a first cam surface 40a is formed on the rear end surface of this portion, and a second cam surface 40b is formed on the front end surface of this portion.

[0041] The upper cam forming member 41 rotatably surrounds the rotor 40 behind the first cam surface 40a of the rotor 40. The lower cam forming member 42 is fitted to the outer surface of the front end portion of the upper cam forming member 41. A first fixed cam surface 41a is formed on the front end surface of the upper cam forming member 41 that faces the first cam surface 40a of the rotor 40. A second fixed cam surface 42a is formed on the inner surface of the front end portion of the lower cam forming member 42 that faces the second cam surface 40b of the rotor 40.

[0042] A cylindrically shaped cylinder member 43 is fitted onto the outer surface of the rear end of the upper cam forming member 41. An insertion hole is formed in the rear end of the cylinder member 43, through which the second lead case 12 can be inserted. A cylindrically shaped torque canceller 44 that is movable in the axial direction is disposed within the cylinder member 43. A cushion spring 45 is disposed between the inner surface of the front end of the torque canceller 44 and the inner surface of the rear end of the cylinder member 43. The cushion spring 45 biases the rotor 40 forward via the torque canceller 44. The outer surface of the second lead case 12 is fitted onto the inner surface of the front end of the torque canceller 44.

[0043] Here, the first lead case 11 transmits the backward and forward motion (cushioning motion) of the writing lead based on the writing action to the rotation drive mechanism 30, i.e., the rotor 40, and also transmits the rotational motion of the rotor 40 in the rotation drive mechanism 30 caused by the cushioning motion to the chuck unit 13 that is gripping the writing lead. Therefore, when the first lead case 11 rotates, the writing lead held by the chuck unit 13 also rotates.

[0044] When not writing with the mechanical pencil 3, i.e., when no writing pressure is being applied to the writing lead, the rotor 40 is positioned forward by the biasing force of the cushion spring 45 via the torque canceller 44. Therefore, the second cam surface 40b of the rotor 40 abuts against the second fixed cam surface 42a and is in an engaged state. When writing with the mechanical pencil 3, i.e., when writing pressure is being applied to the writing lead, the chuck unit 13 moves backward against the biasing force of the cushion spring 45, and the rotor 40 also moves backward accordingly. Therefore, the first cam surface 40a of the rotor 40 abuts against the first fixed cam surface 41a and is in an engaged state. The writing lead and rotor 40 move forward, backward, or rotate together.

[0045] Fig. 8 is a schematic diagram illustrating the rotational drive of rotor 40 of rotation drive mechanism 30, and Fig. 9 is a schematic diagram illustrating the rotational drive of rotor 40 subsequent to Fig. 8. In Figs. 8 and 9, a first cam surface 40a having a continuous sawtooth shape along the circumferential direction is formed in an annular shape on the rear end surface, which is the upper surface of rotor 40, and a second cam surface 40b having a continuous sawtooth shape along the circumferential direction is formed in an annular shape on the front end surface, which is the lower surface of rotor 40.

[0046] A first fixed cam surface 41a having a continuous sawtooth shape along the circumferential direction is also formed on the annular end face of the upper cam forming member 41 facing the first cam surface 40a of the rotor 40, and a second fixed cam surface 42a having a continuous sawtooth shape along the circumferential direction is also formed on the annular end face of the lower cam forming member 42 facing the second cam surface 40b of the rotor 40. The cam surfaces of the first cam surface 40a and the second cam surface 40b formed on the rotor 40 and the cam surfaces of the first fixed cam surface 41a formed on the upper cam forming member 41 and the second fixed cam surface 42a formed on the lower cam forming member 42 are formed so that the pitches are substantially the same.

[0047] 8(A) shows the relationship between the advanced rotor 40, upper cam forming member 41, and lower cam forming member 42 when no writing pressure is applied to the writing lead. In this state, the second cam surface 40b formed on the rotor 40 abuts against the second fixed cam surface 42a of the lower cam forming member 42 due to the biasing force of the cushion spring 45. At this time, the first cam surface 40a of the rotor 40 and the first fixed cam surface 41a of the upper cam forming member 41 are set so as to be shifted by half a phase (half a pitch) with respect to one tooth of the cam in the axial direction.

[0048] 8(B) shows the initial state in which writing pressure is applied to the writing lead for writing with the mechanical pencil 3. In this state, the rotor 40 retracts by contracting the cushion spring 45 as the chuck unit 13 retracts. As a result, the rotor 40 moves toward the upper cam forming member 41 and abuts against the first fixed cam surface 41a.

[0049] 8(C) shows a state in which further writing pressure is applied to the writing lead, causing the rotor 40 to slide back while abutting against the first fixed cam surface 41a of the upper cam forming member 41. In other words, the rotor 40 is subjected to a rotational drive equivalent to half the phase (half the pitch) of one tooth of the first cam surface 40a. In this state, the first cam surface 40a of the rotor 40 is engaged with the first fixed cam surface 41a of the upper cam forming member 41.

[0050] 8 and 9, the circle drawn in the center of the rotor 40 indicates the amount of rotational movement of the rotor 40. In the state shown in Fig. 8(C), the second cam surface 40b of the rotor 40 and the second fixed cam surface 42a of the lower cam forming member 42 are set to have a relationship in which they are shifted by half a phase (half a pitch) with respect to one tooth of the cam in the axial direction.

[0051] 9(D) shows the initial state after writing with the mechanical pencil 3 has finished and the writing pressure on the writing lead has been released. In this state, the rotor 40 moves forward due to the biasing force of the cushion spring 45. As a result, the rotor 40 moves toward the lower cam forming member 42 and abuts against the second fixed cam surface 42a.

[0052] 9(E) shows a state in which the rotor 40 advances while sliding against the second fixed cam surface 42a of the lower cam forming member 42 due to the biasing force of the cushion spring 45. That is, the rotor 40 is again subjected to a rotational drive equivalent to half the phase (half the pitch) of one tooth of the second cam surface 40b. In this state, the second cam surface 40b of the rotor 40 is engaged with the second fixed cam surface 42a of the lower cam forming member 42.

[0053] 8 and 9, as the rotor 40 reciprocates in the axial direction, i.e., moves back and forth, under writing pressure, the rotor 40 is rotationally driven by a distance equivalent to one tooth (one pitch) of the first cam surface 40a and the second cam surface 40b, and the writing lead held therein is similarly rotationally driven via the chuck unit 13. Therefore, with one axial movement of the rotor 40 back and forth due to writing, the rotor 40 undergoes a rotational movement corresponding to one tooth of the cam, and by repeating this process, the writing lead is sequentially rotationally driven. This prevents uneven wear of the writing lead as writing progresses, and prevents large changes in the thickness and darkness of the drawn lines.

[0054] The torque canceller 44, which pushes the rotor 40 forward by receiving the biasing force of the cushion spring 45, generates slippage between its front end face and the rear end face of the rotor 40, preventing the rotational motion of the rotor 40 from being transmitted to the cushion spring 45. In other words, the torque canceller 44 prevents the rotational motion of the rotor 40 from being transmitted to the cushion spring 45, thereby preventing the cushion spring 45 from twisting back (torque) which would hinder the rotational movement of the rotor 40.

[0055] During the knocking operation, the advancement of the cover member 6 causes the second lead case 12 to advance, which in turn causes the entire rotation drive mechanism 30 to advance via the torque canceller 44 and the rotor 40. As a result, the first lead case 11 also advances, and the writing lead is advanced as described above.

[0056] The front surface of the pressure sensor 24 is disposed so as to abut against the rotation drive mechanism 30, specifically the rear end surface of the cylinder member 43. During a writing operation, the chuck unit 13 retracts, causing the entire rotation drive mechanism 30 to retract via the rotor 40 and torque canceller 44. As a result, the rear end surface of the rotation drive mechanism 30, specifically the rear end surface of the cylinder member 43, presses against the pressure sensor 24 supported by the sensor support plate 4f. At this time, the entire rear end surface of the cylinder member 43 abuts against the front surface of the pressure sensor 24, allowing for more accurate and reliable pressure detection.

[0057] The sensor support plate 4f, which is the sensor fixing member, may be configured as desired, as long as it can fix the pressure sensor 24 so that the rear end surface of the cylinder member 43 can press the pressure sensor 24 evenly and reliably. For example, although the sensor support plate 4f is provided integrally with the barrel 4, the sensor fixing member may be a separate plate-like or column-like member that can be fixed to the barrel 4.

[0058] The pressure or reaction force that the writing lead receives against the writing surface, i.e., the writing pressure, is transmitted to the pressure sensor 24 via the chuck unit 13 and the rotation drive mechanism 30, specifically via the coil spring 31 and cushion spring 45. Furthermore, the rotation drive mechanism 30 is biased backward by the coil spring 31, and the pressure sensor 24 is constantly subjected to a pressure equivalent to that biasing force. Therefore, the detection value of the pressure sensor 24 needs to be corrected to take into account the influence of the coil spring 31, cushion spring 45, etc.

[0059] Specifically, since the detected value output from the pressure sensor 24 is information indicating the resistance value of a resistive element deformed by pressure, the correction unit 115 converts the output from the pressure sensor 24 into a numerical pressure value. The correction unit 115 uses a pre-calculated correction table stored in the storage unit 104 to convert the pressure into a numerical pressure value. The correction table is a table for correcting the output from the pressure sensor 24 and stores resistance and pressure in correlation with each other. Generally, the resistance output from the pressure sensor 24 has a nonlinear relationship with the pressure applied to the detection surface, and therefore requires correction. However, since the relationship between resistance and pressure is unique to each sensor, pre-storing the relationship between resistance and pressure makes it possible to correct the output from the pressure sensor 24 and easily calculate the pressure applied to the detection surface. The calculated pressure is transmitted to the communication terminal 2 by the communication unit 105, where further processing is performed using the received pressure.

[0060] Figure 10 is a perspective view of the rear end of the mechanical pencil 3 in Figure 1 with the cover member 6 removed. When the cover member 6 is removed from the barrel 4, the rear end opening of the second lead case 12 and the charging unit 23 are exposed. When a lead is inserted through the rear end opening of the second lead case 12, the lead can be delivered to the first lead case 11 via the rotation drive mechanism 30, specifically, via the hollow torque canceller 44 and rotor 40. Therefore, the mechanical pencil 3 allows for easy refilling of the lead. Furthermore, because the connection portion 23a of the charging unit 23 is exposed in this state, the terminal of another power source can be easily connected to the connection portion to charge the power source 22.

[0061] In the mechanical pencil 3, the rear end of the second lead case 12 extends further rearward than the rear end of the barrel 4 in the axial direction, but may be housed within the barrel 4 as long as it allows for refilling of the lead. The rear end of the charging part 23 extends further axially than the rear end of the barrel 4, but may be housed within the barrel 4 as long as it allows for connection to the terminal of another power source.

[0062] Figure 11 is an enlarged cross-sectional view of the front end of the mechanical pencil 3 in Figure 1. Figure 11(A) shows the chuck unit 13 in a state where it holds the writing lead 7, and Figure 11(B) shows the chuck unit 13 in a state where it does not hold the writing lead 7. In the state of the chuck unit 13 holding the writing lead 7 shown in Figure 11(A), the chuck body member 18 expands radially outward and is held by the fastener 17. In other words, the fastener 17 engages with the chuck body member 18, thereby restricting the forward movement of the slider 16. In this state, the first locking portion 16a and the second locking portion 5b are separated by a distance d as an axial gap.

[0063] On the other hand, in the state of the chuck unit 13 shown in Fig. 11(B) where no writing lead is being held, the chuck body member 18 contracts radially inward due to the absence of the writing lead 7, and is not completely held by the fastener 17. In other words, because the fastener 17 does not completely engage with the chuck body member 18, the slider 16 advances further due to the biasing force of the coil spring 15 compared to the chuck unit 13 shown in Fig. 11(A). The advancement of the slider 16 is restricted by the first locking portion 16a engaging with the second locking portion 5b of the tip member 5. In other words, the slider 16 advances by a distance d compared to the slider 16 shown in Fig. 11(A).

[0064] If there were no axial gap as described above in the chuck unit 13 when it holds the lead 7, the chuck holding member 11b, and therefore the first lead case 11, would be urged backward by the biasing force of the coil spring 15 when the chuck unit 13 is not holding the lead 7. This would undesirably result in a biasing force constantly acting on the pressure sensor 24 via the rotation drive mechanism 30. In the mechanical pencil 3, by providing a gap of distance d in the axial direction between the first locking portion 16a and the second locking portion 5b when the chuck unit 13 is holding the lead 7, the biasing force acting on the pressure sensor 24 when the chuck unit 13 is not holding the lead 7 can be reduced.

[0065] According to the above-described embodiment, the mechanical pencil 3 includes a barrel 4, a mechanical pencil mechanism 10 having lead cases capable of accommodating a lead 7, i.e., a first lead case 11 and a second lead case 12, an electronic component 20 including a pressure sensor 24 that detects the writing pressure applied to the lead 7, and a cover member 6 that is removably arranged at the rear end of the barrel 4 and configured to be removed when refilling the first lead case 11 and the second lead case 12 with the lead 7. Since the cover member 6 does not include the electronic component 20, this has the effect of improving usability.

[0066] Ease of use means, for example, that the cover member 6 can be easily attached and detached without having to worry about the wiring of the electronic components 20, and that the writing lead 7 can be easily refilled. In particular, by configuring the rear end of the lead case to extend further rearward than the rear end of the barrel 4, refilling the writing lead 7 can be made even easier.

[0067] Furthermore, according to the above-described embodiment, the mechanical pencil 3 is provided with a barrel 4, a mechanical pencil mechanism 10 having lead cases capable of accommodating the lead 7, i.e., a first lead case 11 and a second lead case 12, and an electronic component 20 including a pressure sensor 24 that detects the writing pressure applied to the lead 7, wherein the mechanical pencil mechanism 10 is arranged in parallel with the electronic component 20 within the barrel 4 and is arranged eccentrically with respect to the central axis of the mechanical pencil 3, the mechanical pencil mechanism 10 having a chuck unit 13 that allows the lead 7 to move forward and prevents it from moving backward, and a rotation drive mechanism 30 equipped with a rotor 40, and the rotation drive mechanism 30 is configured to rotate the rotor 40 in one direction in response to the axial backward movement caused by the writing pressure applied to the lead 7 held by the chuck unit 13 and the axial forward movement caused by the release of the writing pressure, thereby achieving the effect of improving usability.

[0068] Ease of use means, for example, that the mechanical pencil 3 has a center of gravity that is biased to one side, so the user always holds the mechanical pencil 3 in the same position, but the writing lead 7 rotates as the user writes, preventing uneven wear. In other words, it is desirable to position electronic components, including heavy components such as power supplies, as far forward as possible to ensure stable writing. As a result, the mechanical pencil mechanism and electronic components must be arranged in parallel, making it difficult to configure the center of gravity to be aligned along the central axis. Therefore, by including the rotation drive mechanism 30 in the mechanical pencil 3, the user can prevent uneven wear of the writing lead 7 without having to re-grip the mechanical pencil 3 while rotating it around the central axis.

[0069] The rotation drive mechanism 30 may be omitted from the mechanical pencil 3. In this case, the mechanical pencil 3 may be configured so that a single lead case is used instead of the first lead case 11 and the second lead case 12, an annular flange portion is provided on the outer surface of the lead case, and the rear end face of the flange abuts against the pressure sensor 24. Furthermore, the pressure sensor 24 may be omitted from the mechanical pencil 3. In this case, a single lead case may be used instead of the first lead case 11 and the second lead case 12, and the lead case is configured so that the rotation drive mechanism 30 passes through it. The mechanical pencil 3 may be configured to detect the number of rotations or rotation speed of the rotor 40 using an inertia sensor, angle sensor, or the like.

[0070] REFERENCE SIGNS LIST 1 Communication system 2 Communication terminal 3 Mechanical pencil 4 Body tube 4f Sensor support plate 5 Tip member 6 Cover member 6a Front end opening 6b Receiving opening 7 Writing lead 10 Mechanical pencil mechanism 11 First lead case 11b Chuck holding member 12 Second lead case 13 Chuck unit 20 Electronic component 21 Electronic board 22 Power source 23 Charging unit 24 Pressure sensor 30 Rotation drive mechanism

Claims

1. A mechanical pencil comprising: a barrel; a mechanical pencil mechanism having a lead case capable of accommodating a lead; electronic components including a writing pressure sensor that detects the writing pressure applied to the lead; and a cover member that is removably positioned at the rear end of the barrel and configured to be removed when the lead case is refilled with the lead, wherein the cover member does not include the electronic components.

2. The mechanical pencil according to claim 1, wherein the mechanical pencil mechanism is arranged parallel to the electronic component within the barrel and eccentric to the central axis of the mechanical pencil, the mechanical pencil mechanism having a chuck unit that allows the writing lead to move forward and prevents it from moving backward, and a rotation drive mechanism equipped with a rotor, the rotation drive mechanism being configured to rotate the rotor in one direction in response to the axial backward movement caused by the writing pressure applied to the writing lead held by the chuck unit and the axial forward movement caused by the release of the writing pressure.

3. A mechanical pencil comprising: a barrel; a mechanical pencil mechanism having a lead case capable of accommodating a writing lead; and an electronic component including a writing pressure sensor that detects the writing pressure applied to the writing lead; wherein the mechanical pencil mechanism is arranged in parallel with the electronic component within the barrel and is arranged eccentrically with respect to the central axis of the mechanical pencil; the mechanical pencil mechanism has a chuck unit that allows the writing lead to move forward and prevents it from moving backward; and a rotation drive mechanism with a rotor; and the rotation drive mechanism is configured to rotate the rotor in one direction in response to the axial backward movement caused by the writing pressure applied to the writing lead held by the chuck unit and the axial forward movement caused by the release of the writing pressure.

4. A mechanical pencil as described in claim 2 or 3, wherein the rotary drive mechanism retracts due to the writing pressure applied to the writing lead, and the writing pressure sensor detects the writing pressure as the rotary drive mechanism retracts.

5. A mechanical pencil according to claim 1 or 2, wherein part or all of the cover member is an erasing portion capable of erasing handwriting made with the writing lead.

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