JPH08179058A - Hand position detecting device - Google Patents

Abstract

PURPOSE: To provide a detecting device by the optical detecting method with few number of part items without enlarging the size of a module so much by forming a light receiving element on the same surface as a hand driving integrated circuit. CONSTITUTION: A through hole 4 is provided on a gear 1 to transmit light. An LED 5 emitting infrared rays is fixed to a substrate 6. A hand driving integrated circuit 7 is fixed to a substrate 8, and it is sealed by a mold 9 transmitting infrared rays. When the LED 5 is located on the same axis as a diode 701 formed on the integrated circuit 7, the emitted infrared rays are radiated to the diode 701 via the through hole 4. Regarding the positional relation between the through hole 4 and a second hand 3, the second hand 3 is located at the position of 12 o'clock when the through hole 4 is located on the same axis as the LED 5 and the diode 701 formed on the integrated circuit 7. When the second hand 3 is located at the position of 12 o'clock, the infrared rays emitted from the LED 5 are radiated to the diode 701 via the through hole 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to detection of a pointer position of a pointer type electronic timepiece, and more particularly to an optical detection method.

[0002]

2. Description of the Related Art Conventionally, a through hole is formed in a gear of a pointer drive system wheel train for the purpose of detecting a pointer position of a pointer type electronic timepiece,
It is said that the light emitting element and the light receiving element are arranged facing each other on both sides of the through hole, and the light emitted from the light emitting element is detected by the light receiving element through the through hole to detect that the pointer is at a specific position. The proposal is, for example, JP-A-61-118.
683 publication.

[0003]

However, the above-mentioned proposal requires a light emitting element and a light receiving element in addition to the integrated circuit for operating the electronic timepiece. There is a problem that the light emitting element or the light receiving element must be arranged on the same plane as the integrated circuit, the module becomes large in the thickness direction and the plane direction, and the manufacturing cost rises due to an increase in the number of parts.

It is an object of the present invention to provide a hand position detecting device for a pointer type electronic timepiece by an optical detecting method with a small number of parts without increasing the size of the module so much.

[0005]

[Means for Solving the Problems] A structure for achieving the above object is to provide a gear of a wheel train of a pointer drive system in which a through hole through which light can be transmitted is formed, and light is emitted on both sides of the through hole of the gear. In a needle position detecting device including an element and a light receiving element, the light receiving element is formed on the same surface of an integrated circuit for driving a pointer. Further, the light receiving element formed on the same surface of the driving integrated circuit is a diode having a pn junction provided on a semiconductor substrate forming the driving integrated circuit. Furthermore, the periphery of the light receiving element formed on the same surface of the driving integrated circuit is covered with a metal wiring layer.

[0006]

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view of the structure of an embodiment of the needle position detecting device according to the present invention. Reference numeral 1 is a gear, and the second hand 3 has a second hand shaft 2
Is fixed through. The gear 1 is provided with a through hole 4 for transmitting light. 5 is LE which emits infrared rays
D, which is fixed to the substrate 6. Reference numeral 7 is an integrated circuit for driving a pointer, and a circuit for driving the pointer and a diode 701 which is a light receiving element described later are formed. Integrated circuit 7
Is fixed to the substrate 8 and further sealed by a mold 9 that transmits infrared rays. LED5 is an integrated circuit 7
The infrared rays emitted from the LED 5 are arranged so as to face the diode 701 formed on the gear 1 and the through hole 4 provided in the gear 1 is on the axis facing the diode 701 through the through hole 4. Is irradiated.

FIG. 2 is a top view of the gear 1 in which a through hole 4 is arranged. Since the gear 1 is fixed to the second hand 3, it rotates by 6 ° per second. Similarly, the through hole 4 is also rotated by 6 ° per second. The positional relationship between the through hole 4 and the second hand 3 is that the through hole 4 is the LED 5 and the integrated circuit 7
The second hand is located at the 12 o'clock position when the second hand is on the axis directly facing the diode 701 formed in FIG. Therefore, the second hand 3
In the 2 o'clock position, infrared rays emitted from the LED 5 are applied to the diode 701 of the integrated circuit 7 through the through hole 4.

Next, the diode 7 provided in the integrated circuit 7
01 will be described in detail. FIG. 3 is a cross-sectional view of the periphery of a diode 701 having the semiconductor substrate 70 formed in the integrated circuit 7 as a cathode and the diffusion layer 71 as an anode. FIG. 4 is a top view of the periphery of the diode 701 of the integrated circuit 7. The metal wiring layer 73 is an insulating layer 72 from the semiconductor substrate 70.
And is in contact with the diffusion layer 71 to form an anode electrode. The metal wiring layer 75 is provided with an opening 77 above the diffusion layer 77 and covers the entire integrated circuit 7 except the periphery of the diffusion layer 71. The protective film 76 covers the upper surface of the integrated circuit 7 and protects the entire integrated circuit 7. LED5
When the infrared light emitted from the semiconductor device is applied to the integrated circuit 7 through the through hole 4, the mold 9, the protective film 76, the insulating layer 74,
Since 72 transmits infrared rays but does not transmit the metal wiring layer 75, only the diode 701 in the circuit formed in the integrated circuit 7 is irradiated with the infrared rays. Therefore, the infrared rays affect only the diode 701 and do not affect other circuits.

FIG. 5 is a block diagram of a detection circuit for detecting the infrared rays with which the diode 701 is irradiated. Since the cathode of the diode 701 is the N-type semiconductor substrate 70, V
The DD potential is applied. The anode is an operational amplifier 70
3 is connected to the inverting terminal. The inverting terminal of the operational amplifier 703 is connected to the cathode of the diode 701 and the resistor R described above.
One side of f is connected, and the other side of the resistor Rf is connected to the output. The reference voltage Vcom is applied to the non-inverting terminal of the operational amplifier 703. Therefore, the VDD voltage is applied to the cathode of the diode 701 and the reference voltage Vcom is applied to the anode thereof. When the diode 701 is not irradiated with light, the reverse leakage voltage Id of the diode 701 is almost 0, so that the output of the operational amplifier 70 becomes approximately Vcom. When the diode 701 is irradiated with light, the reverse leak voltage Id increases, and the output of the operational amplifier 703 is Vcom-I.
It becomes d × Rf. The voltage detection circuit 704 receives the output of the operational amplifier 703 as input, detects that the voltage level exceeds a certain value, and determines whether or not the diode 701 is irradiated with light.

The operation of the needle position detecting device having the above structure will be described with reference to FIGS. When the second hand 3 is not at the 12 o'clock position, the through hole 4 of the gear 1 does not directly face the LED 5, so that the light emitted from the LED 5 is blocked by the gear 1 and is not applied to the diode 701 of the integrated circuit 7.
Therefore, the reverse leakage current Id of the diode 701 is almost 0, the output of the operational amplifier 703 is almost Vcom, and the voltage level detection circuit 704 detects that the light is emitted from the diode 70
It is judged that it has not been irradiated to 1.

When the second hand 3 is at the 12 o'clock position, the through hole 4 of the gear 1 directly faces the LED 5, so that the light emitted from the LED 5 passes through the through hole 4 of the gear 1 and the diode 701 of the integrated circuit 7. Is irradiated. Therefore, the diode 7
The reverse leakage current Id of 01 is generated, and the operational amplifier 70
The output of No. 3 is Vcom-Id × Rf, and the voltage level detection circuit 704 determines that light is applied to the diode 701.

As a method of using the needle position detecting circuit according to the present invention, it is possible to know that the needle position has reached the 12 o'clock position by monitoring the output of the voltage level detecting circuit each time the hand is normally moved. Since it is possible to correct the time, it is possible to prevent the time from being changed due to a jump in the needle due to vibration or a strong magnetic field. Further, the initial position adjustment of hands such as a clock using a microcomputer can be performed without bothering the user.

In the present invention, the method of detecting the hand position of the second hand has been described, but the present invention can also be used to detect the positions of the hour hand, minute hand, date plate and the like.

[0014]

As described above, according to the present invention, it is possible to provide the hand position detecting device of the pointer type electronic timepiece by the optical detecting method having a small number of parts without increasing the size of the module too much.

[Brief description of drawings]

FIG. 1 is a sectional view of a structure of an embodiment of a needle position detecting device according to the present invention.

2 is a top view of the gear 1 of FIG. 1.

3 is a cross-sectional view around a diode 701 of the integrated circuit 7 of FIG.

4 is a top view of the periphery of a diode 701 of the integrated circuit 7 of FIG.

5 is a block diagram of a detection circuit that detects infrared rays with which a diode 701 is irradiated. FIG.

[Explanation of symbols]

 1 Gear 2 Second Hand Axis 3 Second Hand 4 Through Hole 5 LED 7 Integrated Circuit 701 Diode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Miyasaka 6-12 Hommachi, Tanashi City, Tokyo Citizen Watch Co., Ltd. Tanashi Factory (72) Inventor Masahiro Kasaya 6-12 Hommachi, Tanashi City, Tokyo Issue Citizen Watch Co., Ltd. Tanashi Factory

Claims (3)

[Claims] 1. A needle position detecting device comprising a gear of a wheel train of a pointer drive system having a through hole through which light can pass and a light emitting element and a light receiving element on both sides of the through hole of the gear.
A pointer position detecting device characterized in that the light receiving element is formed on the same surface of an integrated circuit for driving a pointer. 2. The light receiving element formed on the same surface of the driving integrated circuit is a pn junction diode provided on a semiconductor substrate forming the driving integrated circuit. The needle position detecting device according to claim 1. 3. The needle position according to claim 1, wherein a periphery of the light receiving element formed on the same surface of the driving integrated circuit is covered with a metal wiring layer. Detection device.