Timepiece

Patent metadata

Field	Value
Publication number	US-9904252-B2
Application number	US-201615279847-A
Country	US
Kind code	B2
Filing date	Sep 29, 2016
Priority date	Apr 1, 2014
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

Whether a bright state or a dark state is established is determined each time a motor is driven one step, based on a presence or absence of a passing of light through a detection hole disposed in a detection wheel that rotates associated with rotations of a hand wheel coupled with the motor. A switching position X is identified at which the dark state is switched to the bright state when the dark state is determined and thereafter the bright state is determined. A position one step after the identified switching position X is set to be a reference position X+1 of the hand wheel. The reference positions X+1 and X−1 can thereby be set after a driving mechanism is assembled.

First claim

What is claimed is:

1. A timepiece comprising:
a hand wheel configured to rotate around an axial center thereof;
a motor coupled with the hand wheel and configured to rotate the hand wheel;
a detection wheel configured to rotate around an axial center thereof, associated with rotation of the hand wheel;
a detection hole that penetrates the detection wheel in a direction along the axial center;
a photo sensor including:
a light emitting element that emits light to a detection position on an orbit along which the detection hole moves associated with the rotation of the detection wheel, and
a light receiving element that is disposed facing the light emitting element with the detection wheel therebetween; and

a control unit configured to drive and control the motor, wherein
the control unit determines one of a first state and a second state different from the first state, based on an amount of light received by the light receiving element each time the motor is driven a predetermined number of steps,
the control unit identifies a switching position at which the first state is switched to the second state when the control unit consecutively determines the first state for a first number of steps and thereafter consecutively determines the second state for a second number of steps, and
the control unit sets a position one step shifted from the identified switching position to be a reference position and stores information concerning the reference position to a storage unit.

2. The timepiece according to claim 1 , wherein
the control unit determines one of the first state and the second state in a state where a detection sensitivity of the photo sensor is set to be two or more different sensitivities.

3. The timepiece according to claim 2 , wherein
the control unit sets the detection sensitivity of the photo sensor by adjusting at least one of a light emission intensity of the light emitting element and a light receiving sensitivity of the light receiving element.

4. The timepiece according to claim 1 , wherein
the control unit determines a bright state in which the amount of light received is equal to or greater than a predetermined amount as the first state, and a dark state with which the amount of light received is less than the predetermined amount as the second state,
the control unit determines one of the bright state and the dark state based on the amount of light received by the light receiving element each time the motor is driven a predetermined number of steps,
the control unit identifies a switching position at which the second state is switched to the first state when the control unit consecutively determines the second state for the first number of steps and thereafter consecutively determines the first state for the second number of steps, and
the control unit sets a position one step after the identified switching position to be a reference position and stores information concerning the reference position to the storage unit.

5. The timepiece according to claim 1 , wherein
the control unit identifies the switching position and the reference position in a state where the detection sensitivity of the photo sensor is set to be a first sensitivity that is higher than a sensitivity used during normal movement of hands,
the control unit determines whether the second state is established at a position one step before the switching position and determines whether the first state is established at the reference position in a state where the detection sensitivity of the photo sensor is set to be a second sensitivity that is equal to the sensitivity used during normal movement of the hands or that is lower than the sensitivity used during normal movement of the hands, and
the control unit stores to the storage unit, information concerning a phase of the motor at the reference position when the second state is established at the position one step before the switching position and the first state is established at the reference position.

6. The timepiece according to claim 5 , wherein
the control unit determines a dark state in which the amount of light received is less than a predetermined amount as the first state, and a bright state in which the amount of received light is equal to or greater than the predetermined amount as the second state,
the control unit determines one of the bright state and the dark state, based on the amount of light received by the light receiving element each time the motor is driven the predetermined number of steps,
the control unit identifies a switching position at which the second state is switched to the first state when the control unit consecutively determines the second state for the first number of steps and thereafter consecutively determines the first state for the second number of steps, and
the control unit sets a position one step before the identified switching position to be a reference position and stores information concerning the reference position to the storage unit.

7. The timepiece according to claim 1 , wherein
the control unit identifies the switching position and the reference position in a state where the detection sensitivity of the photo sensor is set to be a first sensitivity that is higher than a sensitivity used during normal movement of hands,
the control unit determines whether the first state is established at a position one step after the switching position and determines whether the second state is established at the reference position in a state where the detection sensitivity of the photo sensor is set to be a second sensitivity that is equal to the sensitivity used during normal movement of the hands or that is lower than the sensitivity used during normal movement of the hands, and
the control unit stores to the storage unit, information concerning a phase of the motor at the reference position when the first state is established at the position one step after the switching position and the second state is established at the reference position.

8. The timepiece according to claim 5 , wherein
the control unit identifies the switching position and the reference position by rotating forward the motor in a state where the first sensitivity is set, and
the control unit, after identifying the switching position and the reference position, positions the detection wheel at a position one step or more before a detection position by rotating backward the motor and thereafter executes determination using the second sensitivity.

9. The timepiece according to claim 5 , further comprising
a time counting unit that counts time, wherein
the control unit, when identifying the phase of the reference position, determines during normal movement of hands, one of the first state and the second state at a timing of the identified phase using a third sensitivity that is lower than the first sensitivity and that is equal to the second sensitivity or higher than the second sensitivity, and counts time using the time counting unit in a state where a determination result at a position at least one step before the switching position and a determination result at a position one step after the switching position differ.

10. The timepiece according to claim 5 , wherein
the control unit identifies a non-detection level at which the photo sensor does not detect the bright state, the control unit identifying the non-detection level by varying stepwise the detection sensitivity of the photo sensor at two or more different sensitivities and determining one of the first state and the second state in a state where the control unit sets the detection sensitivity at each of the sensitivities,
the control unit identifies as the first sensitivity and

Assignees

• Citizen Watch Co Ltd

Inventors

• Kato Akira
• Imamura Kazuya
• Morita Shoichiro
• Yano Yuji

Classifications

• G04C3/14

  incorporating a stepping motor (G04C3/02 - G04C3/12 take precedence {; generating commutating pulses in primary clocks G04C13/0463}) · CPC title

• G04R20/00

  Setting the time according to the time information carried or implied by the radio signal · CPC title

• G04B19/24

  Clocks or watches with date {or week-day} indicators {, i.e. calendar clocks or watches}; Clockwork calendars · CPC title

• G04C3/143 Primary

  Means to reduce power consumption by reducing pulse width or amplitude and related problems, e.g. detection of unwanted or missing step · CPC title

• G04R20/08

  the radio signal being broadcast from a long-wave call sign, e.g. DCF77, JJY40, JJY60, MSF60 or WWVB · CPC title