JPWO2001001203A1 - Mechanical watch with balance rotation angle control mechanism - Google Patents

Abstract

(57) [Abstract] A mechanical timepiece having a balance rotation angle control mechanism that generates static electricity when the rotation angle of the balance (140) exceeds a predetermined threshold, and does not generate static electricity when the rotation angle of the balance (140) does not exceed the predetermined threshold. The control mechanism can control the oscillation angle of the balance so that it falls within a certain range. This mechanical timepiece has good accuracy because there is little change in the rate even as time passes from the time of full winding.

Description

[Detailed Description of the Invention] Mechanical Watch with Balance Rotation Angle Control Mechanism [Technical Field] The present invention relates to a mechanical watch with a balance rotation angle control mechanism configured to apply a force to the balance that suppresses its rotation.

[Background technology]

In a conventional mechanical timepiece, as shown in FIGS. 12 and 13, the movement (mechanical body) 1100 of the mechanical timepiece has a main plate 1102 that forms the base of the movement. A winding stem 1110 is rotatably mounted in a winding stem guide hole 1102a of the main plate 1102. A dial 1104 (shown in phantom lines in FIG. 13) is attached to the movement 1100.

Generally, the side of the main plate with the dial is referred to as the "back" of the movement, and the side opposite the dial is referred to as the "front" of the movement. The gear train installed on the "front" side of the movement is referred to as the "front gear train," and the gear train installed on the "back" side of the movement is referred to as the "back gear train."

The axial position of the winding stem 1110 is determined by a switching device including a setting pin 1190, a pulley 1192, a yoke spring 1194, and a backing 1196. A winding pinion 1112 is rotatably mounted on the guide shaft portion of the winding stem 1110. When the winding stem 1110 is rotated while it is in the first winding stem position (0th position), which is closest to the inside of the movement along the rotation axis, the winding pinion 1112 rotates via the rotation of the clutch wheel. The crown wheel 1114 rotates due to the rotation of the winding pinion 1112.

The ratchet wheel 1116 rotates due to the rotation of the crown wheel 1114. The rotation of the ratchet wheel 1116 winds the mainspring 1122 housed in the barrel complete 1120. The center wheel & pinion 1124 rotates due to the rotation of the barrel complete 1120. The escape wheel & pinion 1130 rotates via the rotation of the second wheel & pinion 1128, the third wheel & pinion 1126, and the second wheel & pinion 1124. The barrel complete 1120, the center wheel & pinion 1124, the third wheel & pinion 1126, and the fourth wheel & pinion 1128 constitute the front train wheel.

The escapement and speed regulating device for controlling the rotation of the front train wheel includes a balance 1140, an escape wheel 1130, and an anchor 1142. The balance 1140 includes a balance stem 1140a, a balance wheel 1140b, and a hairspring 1140c. Based on the rotation of the center wheel & pinion 1124, the cannon pinion 1150 rotates simultaneously. A minute hand 1152 attached to the cannon pinion 1150 displays the minutes. The cannon pinion 1150 is provided with a slip mechanism for the center wheel & pinion 1124. Based on the rotation of the cannon pinion 1150, the hour wheel 1154 rotates via the rotation of the minute wheel. An hour hand 1156 attached to the hour wheel 1154 displays the hours.

The barrel complete 1120 is supported rotatably relative to the main plate 1102 and the barrel bridge 1160. The center wheel & pinion 1124, the third wheel & pinion 1126, the fourth wheel & pinion 1128, and the escape wheel 1130 are supported rotatably relative to the main plate 1102 and the train wheel bridge 1162. The pallet fork 1142 is supported rotatably relative to the main plate 1102 and the pallet fork bridge 1164. The balance 1140 is supported rotatably relative to the main plate 1102 and the balance bridge 1166.

The hairspring 1140c is a spiral (helical) flat spring with multiple turns. The inner end of the hairspring 1140c is fixed to a collet 1140d fixed to the balance shaft 1140a, and the outer end of the hairspring 1140c is fixed by a screw through a stud 1170a attached to a stud holder 1170 fixed to the balance bridge 1166.

A regulator pin 1168 is rotatably mounted on the balance bridge 1166. A balance bridge 1340 and a balance pin 1342 are attached to the regulator pin 1168. A portion of the balance spring 1140c near its outer end is located between the balance bridge 1340 and the balance pin 1342.

In a typical conventional mechanical watch, as shown in Figure 8, the mainspring torque decreases as the time elapses from the fully wound state (fully wound state) to the unwound state. For example, in the case of Figure 8, the mainspring torque is approximately 27 g·cm when fully wound, decreases to approximately 23 g·cm after 20 hours from the fully wound state, and decreases to approximately 18 g·cm after 40 hours from the fully wound state.

Generally, in a typical conventional mechanical timepiece, as the mainspring torque decreases, the oscillation angle of the balance also decreases, as shown in Figure 9. For example, in the case of Figure 9, when the mainspring torque is 25 to 28 g cm, the oscillation angle of the balance is approximately 240 to 270 degrees, and when the mainspring torque is 20 to 25 g cm, the oscillation angle of the balance is approximately 180 to 240 degrees.

Referring to Figure 10, the change in instantaneous rate (a numerical value indicating the accuracy of a watch) versus the oscillation angle of the balance wheel in a typical conventional mechanical watch is shown. Here, "instantaneous rate" refers to the rate value indicating the gain or loss of a mechanical watch after one day, assuming that the mechanical watch is left for one day while maintaining the conditions and environment, such as the oscillation angle of the balance wheel, that were present when the rate was measured. In the case of Figure 10, the instantaneous rate is slow when the oscillation angle of the balance wheel is 240 degrees or more or 200 degrees or less.

For example, in a typical conventional mechanical watch, as shown in FIG. 10, when the oscillation angle of the balance is approximately 200 to 240 degrees, the instantaneous rate is approximately 0 to 5 seconds per day (gaining approximately 0 to 5 seconds per day), but when the oscillation angle of the balance is approximately 170 degrees, the instantaneous rate is approximately -20 seconds per day (losing approximately 20 seconds per day).

Referring to Figure 11, the graph shows the change in instantaneous rate over time when the mainspring is unwound from a fully wound state in a typical conventional mechanical timepiece. Here, in a conventional mechanical timepiece, the "rate," which indicates the gain or loss of the watch per day, is obtained by integrating the instantaneous rate over 24 hours with respect to the elapsed time since the mainspring was unwound from a fully wound state, as shown by the very thin line in Figure 11.

Generally, in conventional mechanical watches, as the mainspring is unwound from a fully wound state and time passes, the spring torque decreases and the balance's oscillation angle also decreases, causing the instantaneous rate to slow. For this reason, conventional mechanical watches were adjusted in advance to anticipate the timepiece's loss after 24 hours of operation, by advancement of the instantaneous rate when the mainspring is fully wound, so that the "rate," which indicates the timepiece's gain or loss per day, would be positive.

For example, in a typical conventional mechanical watch, as shown by the very thin lines in Figure 11, when fully wound, the instantaneous rate is approximately 3 seconds per day (gaining approximately 3 seconds per day), but after 20 hours from the fully wound state, the instantaneous rate becomes approximately -3 seconds per day (losing approximately 3 seconds per day), after 24 hours from the fully wound state, the instantaneous rate becomes approximately -8 seconds per day (losing approximately 8 seconds per day), and after 30 hours from the fully wound state, the instantaneous rate becomes approximately -16 seconds per day (losing approximately 16 seconds per day).

A conventional balance swing angle adjustment device is disclosed in, for example, Japanese Utility Model Application Laid-Open Publication No. 54-41675, which includes a swing angle adjustment plate that generates an overcurrent each time the magnet of the balance swings close to the balance, thereby applying a braking force to the balance.

An object of the present invention is to provide a mechanical timepiece equipped with a balance rotation angle control mechanism that can control the oscillation angle of the balance so that it falls within a certain range.

Another object of the present invention is to provide a mechanical timepiece that exhibits good accuracy and exhibits little change in rate even after time has passed since the watch was fully wound.

DISCLOSURE OF THE INVENTION

This invention relates to a mechanical timepiece that includes a mainspring that constitutes the power source of the mechanical timepiece, a top train wheel that rotates due to the torque generated when the mainspring is unwound, and an escapement/governing device for controlling the rotation of the top train wheel. The escapement/governing device includes a balance that alternates between clockwise and counterclockwise rotation, an escape wheel that rotates based on the rotation of the top train wheel, and an anchor that controls the rotation of the escape wheel based on the operation of the balance. The mechanical timepiece is characterized by having a balance rotation angle control mechanism that generates static electricity when the balance rotation angle exceeds a predetermined threshold value and does not generate static electricity when the balance rotation angle does not exceed the predetermined threshold value.

In the mechanical timepiece of the present invention, the balance rotation angle control mechanism includes a balance insulating plate provided on the balance and a base insulating plate disposed relative to the base plate, with a gap provided between the balance insulating plate and the base insulating plate.

In addition, in the mechanical timepiece of the present invention, it is preferable that the balance rotation angle control mechanism includes a switch lever rotatably attached to the balance bridge, a hairspring switch member rotatably attached to the switch lever and provided to come into contact with the hairspring and operate, and a stop member for determining the position of the hairspring switch member, and that the rotation of the hairspring switch member is capable of controlling the generation of static electricity between the balance insulating plate and the main plate insulating plate.

By using a balance rotation angle control mechanism configured in this way, the rotation angle of the balance of a mechanical watch can be effectively controlled, thereby improving the accuracy of the mechanical watch.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a plan view showing the general shape of the front side of the movement of the mechanical timepiece of the present invention (some parts are omitted in Figure 1, and the bridge member is shown by phantom lines).

FIG. 2 is a schematic partial cross-sectional view of the movement of the mechanical timepiece of the present invention (some components are omitted in FIG. 2).

FIG. 3 is an enlarged partial plan view showing the general shape of the balance portion of the mechanical timepiece of the present invention when the circuit is closed.

FIG. 4 is an enlarged partial cross-sectional view showing the general shape of the balance portion of the mechanical timepiece of the present invention when the circuit is closed.

FIG. 5 is an enlarged partial plan view showing the general shape of the balance portion of the mechanical timepiece of the present invention when the circuit is open.

FIG. 6 is an enlarged partial cross-sectional view showing the general shape of the balance portion of the mechanical timepiece of the present invention when the circuit is open.

FIG. 7 is a block diagram showing the operation of the mechanical timepiece of the present invention when the circuit is open and when the circuit is closed.

Figure 8 is a graph showing the relationship between the elapsed time from fully wound to unwound and the spring torque in a mechanical watch.

FIG. 9 is a graph showing the relationship between the oscillation angle of the balance and the torque of the mainspring in a mechanical watch.

FIG. 10 is a graph showing the relationship between the oscillation angle of the balance and the instantaneous rate of a mechanical watch.

FIG. 11 is a graph showing the relationship between the elapsed time from full winding to unwinding and the instantaneous rate of movement in the mechanical timepiece of the present invention and a conventional mechanical timepiece.

FIG. 12 is a plan view showing a schematic shape of the front side of a movement of a conventional mechanical timepiece (in FIG. 12, some parts are omitted and the bridge member is shown by an imaginary line).

Figure 13 is a schematic partial cross-sectional view of a conventional mechanical watch movement (some components are omitted in Figure 13).

BEST MODE FOR CARRYING OUT THE INVENTION

Below, an embodiment of the mechanical watch of the present invention is described based on the drawings.

1 and 2, in an embodiment of a mechanical timepiece of the present invention, a movement (mechanical body) 300 of the mechanical timepiece has a main plate 102 that constitutes the base of the movement. A winding stem 110 is rotatably mounted in a winding stem guide hole 102a of the main plate 102. A dial 104 (shown in phantom lines in FIG. 2) is attached to the movement 300.

The winding stem 110 has a corner portion and a guide shaft portion. A clutch wheel (not shown) is assembled to the corner portion of the winding stem 110. The clutch wheel has the same axis of rotation as the axis of rotation of the winding stem 110. That is, the clutch wheel has a square hole that fits into the corner portion of the winding stem 110, so that the clutch wheel rotates based on the rotation of the winding stem 110. The clutch wheel has teeth A and B. Tooth A is provided at the end of the clutch wheel closest to the center of the movement 300. Tooth B is provided at the end of the clutch wheel closest to the outside of the movement 300.

The movement 300 is equipped with a switching device for determining the axial position of the winding stem 110. The switching device includes a setting rod 190, a yoke 192, a yoke spring 194, and a back support 196. The position of the winding stem 110 along its rotational axis is determined based on the rotation of the setting rod 190. The position of the clutch wheel along its rotational axis is determined based on the rotation of the yoke 192. Based on the rotation of the setting rod 190, the yoke 192 is positioned in two rotational directions.

A pinion 112 is rotatably mounted on the guide shaft portion of the winding stem 110. When the winding stem 110 is rotated while in the first winding stem position (0th position), which is closest to the inside of the movement 300 along the direction of the rotation axis, the pinion 112 rotates via the rotation of the clutch wheel. The crown wheel 114 is configured to rotate by the rotation of the pinion 112. The ratchet wheel 116 is configured to rotate by the rotation of the crown wheel 114.

The movement 300 is powered by a mainspring 122 housed in a barrel 120. The mainspring 122 is made of an elastic material with spring properties, such as iron. The mainspring 122 is wound by the rotation of the ratchet wheel 116.

The center wheel & pinion 124 is configured to rotate with the rotation of the barrel wheel 120. The third wheel & pinion 126 is configured to rotate based on the rotation of the center wheel & pinion 124. The fourth wheel & pinion 128 is configured to rotate based on the rotation of the third wheel & pinion 126. The escape wheel & pinion 130 is configured to rotate based on the rotation of the fourth wheel & pinion 128. The barrel wheel & pinion 120, the center wheel & pinion 124, the third wheel & pinion 126, and the fourth wheel & pinion 128 form the front train wheel.

The movement 300 is equipped with an escapement/governing device for controlling the rotation of the front train wheel. The escapement/governing device includes a balance 140 that rotates clockwise and counterclockwise at a constant cycle, an escape wheel 130 that rotates based on the rotation of the front train wheel, and an anchor 142 that controls the rotation of the escape wheel 130 based on the operation of the balance 140.

The balance 140 includes a balance stem 140a, a balance wheel 140b, and a hairspring 140c. The hairspring 140c is made of an elastic material with spring properties, such as Elinvar. In other words, the hairspring 140c is made of a metallic conductive material.

The cannon pinion 150 rotates simultaneously based on the rotation of the center wheel & pinion 124. A minute hand 152 attached to the cannon pinion 150 is configured to display the minutes. The cannon pinion 150 is provided with a slip mechanism that has a predetermined slip torque relative to the center wheel & pinion 124.

A minute wheel (not shown) rotates based on the rotation of the cannon pinion 150. The hour wheel 154 rotates based on the rotation of the minute wheel. The hour hand 156 attached to the hour wheel 154 is configured to display the hours.

The barrel complete 120 is supported so as to be rotatable relative to the main plate 102 and the barrel bridge 160. The center wheel & pinion 124, the third wheel & pinion 126, the fourth wheel & pinion 128, and the escape wheel 130 are supported so as to be rotatable relative to the main plate 102 and the train wheel bridge 162. The pallet fork 142 is supported so as to be rotatable relative to the main plate 102 and the pallet fork bridge 164.

The balance 140 is rotatably supported relative to the main plate 102 and the balance bridge 166. That is, the upper pivot 140a1 of the balance stem 140a is rotatably supported relative to a balance upper bearing 166a fixed to the balance bridge 166. The balance upper bearing 166a includes a balance upper hole jewel and a balance upper jewel. The balance upper hole jewel and the balance upper jewel are made of an insulating material such as ruby.

The bottom pivot 140a2 of the balance shaft 140a is rotatably supported by a balance lower bearing 102b fixed to the main plate 102. The balance lower bearing 102b includes a balance lower hole jewel and a balance lower jewel. The balance lower hole jewel and the balance lower jewel are made of an insulating material such as ruby.

The hairspring 140c is a spiral-shaped flat spring with multiple turns. The inner end of the hairspring 140c is fixed to the collet 140d, which is fixed to the balance shaft 140a, and the outer end of the hairspring 140c is fixed by a screw via a stud 170a attached to a stud 170, which is rotatably fixed to the balance bridge 166. The balance bridge 166 is made of a conductive metal material such as brass. The stud 170 is made of a conductive metal material such as iron.

Next, the balance rotation angle control mechanism of the mechanical timepiece of the present invention will be explained.

1 to 4, the switch lever 168 is rotatably attached to the balance bridge 166. A first stop member 340 and a second stop member 342 are attached to the switch lever 168. The switch lever 168 is attached to the balance bridge 166 and is rotatable about the center of rotation of the balance 140.

The switch lever 168 is formed from an insulating plastic material such as polycarbonate. A switch reed substrate 310 is disposed on the switch lever 168. The switch reed substrate 310 has a switch pattern 310a. The switch reed substrate 310 is, for example, a double-sided substrate having copper foil patterns on both sides, and the switch pattern 310a is formed by through-hole plating to electrically connect the copper foil patterns on both sides. As a modified example, a switch pin made of a conductive material such as brass may be provided instead of the switch pattern 310a.

A first stop member 340 and a second stop member 342 pass through the switch reed substrate 310 and are fixed to the switch lever 168. The first stop member 340 and the second stop member 342 are preferably made of a metal such as brass. The first stop member 340 and the second stop member 342 may also be made of plastic.

A hairspring switch member 312 is attached to the switch lever 168 .

The hairspring switch member 312 is made of a conductive material, preferably a metal such as brass. The hairspring switch member 312 is rotatably attached to the switch lever 168 so that it can be in two states: one in which it is electrically connected to the switch pattern 310a of the switch lead board 310, and one in which it is not electrically connected to the switch pattern 310a of the switch lead board 310. In other words, when the hairspring switch member 312 rotates and contacts the first stop member 340 or the second stop member 342, the hairspring switch member 312 is not electrically connected to the switch pattern 310a of the switch lead board 310.

The hairspring switch member 312 has a hairspring receiving portion 312h formed in a groove shape to receive the portion 140ct of the hairspring 140c near its outer end. The portion 140ct of the hairspring 140c near its outer end is positioned within the groove of the hairspring receiving portion 312h. The portion 140ct of the hairspring 140c near its outer end is in contact with the hairspring switch member 312.

A base insulating substrate 320 is fixed by adhesive or the like to the front surface of the base plate 102, with a portion thereof facing the base plate side surface of the balance wheel 140b. The base insulating substrate 320 is made of an insulating material such as polyimide. A base insulating plate 322 is attached by adhesive or the like to the front surface of the base insulating substrate 320, with a portion thereof facing the base plate side surface of the balance wheel 140b. The base insulating plate 322 has a ring-shaped planar shape and is made of an insulating material such as polyimide, polycarbonate, or polyethersulfone. The base insulating plate 322 is formed in a shape that allows it to shield the escape wheel 130 and the pallet fork 142.

Balance insulating plate 324 is attached to the bottom side of balance wheel 140b so as to face the front surface of bottom insulating plate 322. Balance insulating plate 324 has a ring-shaped planar shape and is made of an insulating material such as polyimide, polycarbonate, or polyethersulfone. The planar shape of balance insulating plate 324 is approximately the same as the planar shape of bottom insulating plate 322 or is smaller than the planar shape of bottom insulating plate 322. Balance insulating plate 324 is fixed by adhesive or the like to the bottom side surface of balance wheel 140b, with one surface in contact with the ring-shaped rim portion of balance wheel 140b and the other surface facing the front surface of bottom insulating plate 322.

A gap is provided between the base insulating plate 322 and the balance insulating plate 324. The gap between the base insulating plate 322 and the balance insulating plate 324 is determined so that static electricity can be generated between the base insulating plate 322 and the balance insulating plate 324 as the balance wheel 140b rotates.

A resistor 326 is attached to the front surface of the insulating base plate substrate 320 by adhesive or the like.

Resistor 326 has a resistance of, for example, 100 ohms to 1 kiloohm. If the resistance is too small, sparks will fly, and if the resistance is too large, the braking will be too strong. Therefore, the resistance value can be calculated from the electrostatic force and the required braking force.

A first lead wire 330 is provided to connect one terminal of resistor 326 to switch pattern 310a of switch lead substrate 310. Switch pattern 310a is electrically connected to hairspring switch member 312 when the rotation angle of balance 140 is smaller than a predetermined angle. A second lead wire 332 is provided to connect base insulating plate 322 to stud 170a. A third lead wire 334 is provided to connect base insulating plate 322 to the other terminal of resistor 326.

Note that in Figures 2, 4, and 6, the thickness of the hairspring 140c (thickness in the radial direction of the balance) is exaggerated, but is, for example, 0.021 mm. The balance insulating plate 324 has, for example, an outer diameter of approximately 9 mm, an inner diameter of approximately 7 mm, and a thickness of approximately 1 mm. The base insulating plate 322 has, for example, an outer diameter of approximately 10 mm, an inner diameter of approximately 6 mm, and a thickness of approximately 1 mm. The gap STC between the base insulating plate 322 and the balance insulating plate 324 is, for example, approximately 0.4 mm.

Next, with reference to Figures 3, 4 and 7, the operation of balance 140 when the circuit is closed will be described.

Hairspring 140c expands and contracts in the radial direction of hairspring 140c depending on the rotation angle of balance 140. For example, in the state shown in Figure 3, when balance 140 rotates clockwise, hairspring 140c contracts in the direction toward the center of balance 140, and conversely, when balance 140 rotates counterclockwise, hairspring 140c expands in the direction away from the center of balance 140.

For this reason, in FIG. 4, when the balance 140 rotates counterclockwise, the portion 140ct near the outer end of the hair spring 140c operates to contact the outside of the groove in the hair spring receiving portion 312h of the hair spring switch member 312. On the other hand, when the balance 140 rotates clockwise, the portion 140ct near the outer end of the hair spring 140c operates to contact the inside of the groove in the hair spring receiving portion 312h of the hair spring switch member 312.

When the rotation angle (oscillation angle) of the balance 140 is less than a certain threshold value, for example, 180 degrees, the amount of radial expansion and contraction of the hairspring 140c is small, so that the hairspring 140c comes into contact with the groove in the hairspring receiving portion 312h of the hairspring switch member 312, and the hairspring switch member 312 remains electrically connected to the switch pattern 310a of the switch lead board 310.

Therefore, when the oscillation angle of the balance 140 is within a range exceeding 0 degrees and less than 180 degrees, the outer portion of the hairspring receiving portion 312h of the hairspring switch member 312 does not come into contact with either the first stop member 340 or the second stop member 342.

In this state, the base insulating plate 322 is electrically connected to the hairspring 140c and balance stud 170a via resistor 326. As a result, the base insulating plate 322 is in a short-circuited state, so that even if the balance 140 rotates, no static electricity is generated between the base insulating plate 322 and the balance insulating plate 324.

Next, the operation of the balance 140 when the circuit is open will be described with reference to Figures 5, 6, and 7. That is, Figures 5 and 6 show the state when the oscillation angle of the balance 140 is 180 degrees or more.

In FIG. 6, the thickness of the hairspring 140c (thickness in the radial direction of the balance) is exaggerated.

When the rotation angle (oscillation angle) of the balance 140 is equal to or greater than a certain threshold value, for example, 180 degrees, the amount of radial expansion and contraction of the hairspring 140c becomes sufficiently large that the hairspring 140c presses the groove in the hairspring receiving portion 312h of the hairspring switch member 312 outward or inward, causing the hairspring switch member 312 to rotate and lose electrical continuity with the switch pattern 310a of the switch lead board 310. The outer portion of the hairspring receiving portion 312h of the hairspring switch member 312 then contacts and is positioned with the first stop member 340 and the second stop member 342.

In this state, the base insulating plate 322 is not shorted, so static electricity is generated between the base insulating plate 322 and the balance insulating plate 324. This static electricity exerts a force on the balance 140 that inhibits the rotation of the balance 140. This action then applies a balance braking force that inhibits the rotation of the balance 140, reducing the oscillation angle of the balance 140.

When the oscillation angle of the balance 140 decreases beyond 0 degrees and falls below 180 degrees, the rotation angle of the hairspring switch member 312 decreases, and the hairspring switch member 312 becomes conductive with the switch pattern 310a of the switch reed board 310. As a result, as shown in Figures 3 and 4, the base insulating plate 322 is shorted, and therefore, even if the balance 140 rotates, no static electricity is generated between the base insulating plate 322 and the balance insulating plate 324.

In the mechanical timepiece of the present invention configured in this manner, the rotation angle of the balance 140 can be efficiently controlled.

As explained above, the present invention relates to a mechanical timepiece that includes an escapement/governing device that alternates between clockwise and counterclockwise rotation, an escape wheel that rotates based on the rotation of the front train wheel, and an anchor that controls the rotation of the escape wheel based on the operation of the balance. Because the invention is configured with a balance rotation angle control mechanism, the accuracy of the mechanical timepiece can be improved without reducing the running time of the mechanical timepiece.

In other words, this invention focuses on the correlation between instantaneous rate and oscillation angle, and by maintaining a constant oscillation angle, it is possible to suppress changes in instantaneous rate and adjust the watch to reduce gains and losses per day.

In contrast, in conventional mechanical watches, the relationship between the duration and the oscillation angle causes the oscillation angle to change over time. Furthermore, the relationship between the oscillation angle and the instantaneous rate causes the instantaneous rate to change over time. This makes it difficult to extend the duration of a watch while maintaining a consistent level of accuracy.

Next, we will explain the results of a simulation of instantaneous rate accuracy conducted on the mechanical watch of the present invention, which was developed to solve these problems with conventional mechanical watches.

Referring to Figure 11, in the mechanical timepiece of the present invention, the instantaneous rate of the timepiece is first adjusted to an advanced state, as indicated by the x-marked plot and thin line in Figure 11. In the mechanical timepiece of the present invention, when the balance 140 rotates more than a certain angle, the outer portion of the hairspring receiving portion 312h of the hairspring switch member 312 is positioned in contact with the first stop member 340 and the second stop member 342, shortening the effective length of the hairspring 140c, and therefore the instantaneous rate is further advanced.

In the mechanical timepiece of the present invention, when the outer portion of the hairspring receiving portion 312h of the hairspring switch member 312 is separated from the first stop member 340 and the second stop member 342, as shown by the x plot and thin line in FIG. 11, when the mainspring is fully wound, the rate is approximately 18 seconds per day (gaining approximately 18 seconds per day), after 20 hours from the fully wound state, the instantaneous rate is approximately 13 seconds per day (gaining approximately 13 seconds per day), and after 30 hours from the fully wound state, the instantaneous rate is approximately -2 seconds per day (losing approximately 2 seconds per day).

Assuming that the balance rotation angle control mechanism is not activated in this mechanical timepiece of the present invention, as shown by the triangular plots and bold lines in FIG. 11, when the outer portion of the hairspring receiving portion 312h of the hairspring switch member 312 is positioned in contact with the first stop member 340 and the second stop member 342, the rate is approximately 25 seconds per day (gaining approximately 25 seconds per day) when the mainspring is fully wound, and after 20 hours from the fully wound state, the instantaneous rate is approximately 20 seconds per day (gaining approximately 20 seconds per day), and after 30 hours from the fully wound state, the instantaneous rate is approximately 5 seconds per day (gaining approximately 5 seconds per day).

In contrast, in the mechanical timepiece of the present invention, when the balance rotation angle control mechanism is activated, as shown by the black circle and thick line in Figure 11, the instantaneous rate can be maintained at approximately 5 seconds per day (maintaining a gain of approximately 5 seconds per day) until 27 hours have passed since the balance rotation angle control mechanism was activated, i.e., from the state in which the mainspring is fully wound, and after 30 hours have passed since the fully wound state, the instantaneous rate becomes approximately -2 seconds per day (losing approximately 2 seconds per day).

A mechanical timepiece having a balance rotation angle control mechanism of the present invention controls the oscillation angle of the balance, thereby suppressing changes in the instantaneous rate of the timepiece. Therefore, compared to a conventional mechanical timepiece shown by the square plot and phantom line in Figure 11, the time elapsed from full winding at which the instantaneous rate is approximately 0 to 5 seconds per day can be extended.

That is, the mechanical timepiece of the present invention has a duration of approximately 32 hours during which the instantaneous rate remains within approximately plus or minus 5 seconds per day. This duration is approximately 1.45 times the duration of approximately 22 hours during which the instantaneous rate remains within approximately plus or minus 5 seconds per day for a conventional mechanical timepiece.

Therefore, the simulation results show that the mechanical timepiece of the present invention is extremely accurate compared to conventional mechanical timepieces.

[Industrial Applicability]

The mechanical watch of the present invention has a simple structure and is suitable for realizing a highly accurate mechanical watch.

───────────────────────────────────────────────────── (Note) This publication is based on the publication published internationally by the International Bureau of Patents (WIPO). The effect of the international publication of the Japanese patent application (Japanese utility model registration application) related to this publication arises pursuant to Article 184-10, Paragraph 1 of the Patent Act (Article 48-13, Paragraph 2 of the Utility Model Act) and is unrelated to this publication.

Claims (4)

[Claims] 1. A mechanical timepiece comprising a mainspring that constitutes the power source of the mechanical timepiece, a top train wheel that rotates due to the torque generated when the mainspring is unwound, and an escapement/governing device for controlling the rotation of the top train wheel, wherein the escapement/governing device includes a balance that alternately rotates clockwise and counterclockwise, an escape wheel that rotates based on the rotation of the top train wheel, and an anchor that controls the rotation of the escape wheel based on the operation of the balance, characterized in that the mechanical timepiece has a balance rotation angle control mechanism (322, 324, 326) that generates static electricity when the rotation angle of the balance (140) exceeds a predetermined threshold value and does not generate static electricity when the rotation angle of the balance (140) does not exceed the predetermined threshold value. 2. The mechanical timepiece according to claim 1, wherein the balance rotation angle control mechanism (322, 324, 326) includes a balance insulating plate (324) provided on the balance (140) and a main plate insulating plate (322) disposed relative to the main plate (102), with a gap provided between the balance insulating plate (324) and the main plate insulating plate (322). 3. The mechanical timepiece according to claim 2, wherein the balance rotation angle control mechanism (322, 324, 326) includes a switch lever (168) rotatably attached to the balance bridge (166), a hairspring switch member (312) rotatably attached to the switch lever (168) and provided to come into contact with the hairspring for operation, and a stop member (340, 342) for determining the position of the hairspring switch member (312), and wherein the rotation of the hairspring switch member (312) is configured to control the generation of static electricity between the balance insulating plate (324) and the main plate insulating plate (322). 4. The mechanical timepiece according to claim 3, wherein the balance rotation angle control mechanism (322, 324, 326) includes a resistor (326) provided to short-circuit the main plate insulating plate (322) and connected to the main plate insulating plate (322) and the hairspring switch member (312).