JPS60173492A - Electronic timepiece - Google Patents

Abstract

PURPOSE:To facilitate incorporation during manufacture and attain high-accuracy temperature correction by providing masked ROM for storing data on the temperature coefficient of a crystal oscillator, etc., and nonvolatile memory for storing variance in temperature characteristics of the crystal oscillator, etc. CONSTITUTION:The temperature coefficient of secondary curve characteristics of the crystal oscillator which is stored in the masked ROM8 is read out according to detected temperature from a temperature detection part 4 and supplied to a logical operation part 5 together with variance of temperature characteristics of the crystal oscillator read out of the PROM9. Then, an arithmetic part 5 generates a temperature correcting signal through RAM6, a temporary register 7, etc., and impresses it to a logical control part 3, which controls a frequency divider 2 to make a rate adjustment. Consequently, the electronic timepiece which facilitates the incorporation during the manufacture and attain high-accuracy temperature correction is obtained.

Description

[Detailed description of the invention] The object of the present invention is to relate to a highly accurate and inexpensive electronic timepiece.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic timepiece that corrects the temperature characteristics of a crystal oscillator, in which manufacturing variations in the crystal oscillator or variations in the temperature detection circuit can be easily adjusted.

BACKGROUND OF THE INVENTION In conventional electronic watches, especially wristwatches, a crystal oscillation circuit using a tuning fork type flexural mode crystal oscillator with an iron loss frequency of 52.7.68 KHz is widely used as a reference time source. However, the disadvantages of this bent crystal resonator include poor temperature characteristics and large changes over time, and conventional methods have been considered to solve these problems from the circuit side. For example, there is a method of improving the reliability of the oscillation frequency of a crystal using a capacitor with temperature characteristics, or a method of correcting the beat by using two crystals. However, these methods require too much effort to make adjustments, have limitations on the type of crystals and capacitors that can be used, and have to meet strict specifications for the crystals, resulting in poor productivity, high costs, and limited number of parts. There are many cases where this happens, and it is also a factor that deteriorates the design of watches.

The present invention solves this drawback by using a temperature detection circuit and rate adjustment means that can be incorporated into an IC, and provides a circuit for creating a new hot water temperature correction signal for temperature correction. The purpose is to facilitate the adjustment of variations in the crystal oscillator and temperature detection circuit to improve the accuracy of temperature correction.

FIG. 1 is an example of a basic block diagram in the present invention. After the output of the oscillator 1 is divided into a certain frequency by the frequency divider 2, this is used as a clock to operate the arithmetic processing circuit.The arithmetic processing circuit consists of the following blocks. In other words, the PL generates addresses and outputs the control bus, which is the control circuit of each block, according to the program.
A logic control unit 5, RA consisting of
M (Random Access Memory) 6, Temperature register 7 for calculations, ROM (read memory) that stores part of the data of the temperature characteristics of the crystal resonator and sets constants in addition to the program for calculations.・Honoori Memory) 8. PR
It is OIII (programmer full ROM) 9. Data signals are exchanged through common buses 14 and 15, and circuit 4FifM! 10 is a temperature detection circuit that serves to convert the temperature sensed by the sensor into a digital signal and transfer it to the data bus, and 10 is a pROM write control circuit. 12 is a display drive circuit;
+5 is a display device. This is an interrupt control signal for controlling the division ratio of the 2117-j frequency divider 20.

FIG. 2A shows typical salinity characteristics of a crystal resonator. B is a correction curve for this characteristic, first detect the milling rate 1. B
The lines are twisted by the circuit block 4 to form the curve. Figure 5 shows a specific example of this circuit, which consists of a temperature detector constituted by a MOS transistor and a temperature signal converter constituted by a MOS transistor.

In this circuit, MOS) transistors 51 to 5554 to
Reference numeral 57 denotes an identical voltage generating circuit.

The MOS transistors 50 and 54 are formed by an ion implantation process or the like so that their key values are different from those of other MOS transistors. At this time, each output Vs, , Vs.

The difference between this 50.54 and the other MOS transistors' 11u appears, and the MOS transistor 50.3
1 and 54.55 with the same conductance coefficient (β
Then, the output becomes a reference voltage that has no dependence on power supply voltage or temperature. Appropriately varying this β results in a voltage output that is dependent on the surrounding m degrees and dependent on the power source. In the example of the present invention, VS.

V8. has a salinity characteristic and has an output voltage with extremely little barging. Is a lot of people f! This is a reference voltage with extremely small variations in i and o. In this specific example, the temperature coefficient of the conductance of the transistor, which is controlled by the seven key values of the transistor and the temperature characteristics of the mobility, is used. Further, according to the present invention, the temperature coefficient of mobility in the bulk as well as the surface of the MOS transistor may be mainly used. At a rate of once per minute, 1~
The pulse width (sampling time) is 10m5ec,
First, when φB goes to the L level, sampling starts and the gate 60 opens and the clock input OL is transferred to the register 61.
is input. Then, as the register values change sequentially, transistors 49 to 56 are turned on sequentially, and VB
, are sequentially divided by different common ratios by the resistors aO-, 46 and inputted to the comparator 57 as Vθ'2. On the other hand, to the other input of the comparator 57, a voltage divided by VB by resistors 58 and 39 is input. clock signal c
LKJ: Succeeding direct comparison of Vθ'2 (-1 direction'1 and V
When s/ match, an output is made from the comparator 57, the gate 6o is closed, and the data in the register 61 at this time is stored, converted into a binary code by the decoder 62, and output to the pass line. That is, 40-62 is A
- Operating as a TJ converter. Moreover, this decoder 62 can directly use the output as a square decoded output as the interrupt control signal 2o without performing any logical operation. The example φ in Figure 5. -6 is used for 8-level detection, that is, the density is divided into 87 f times, but it goes without saying that a can be made coarser if necessary.

Next, the salinity characteristic of a crystal resonator has a quadratic characteristic as shown in Fig. 2, but the coefficient of the quadratic and the internal temperature are determined by the settings at the time of manufacturing. The temperature coefficient of the crystal resonator, which changes due to manufacturing variations, is stored as binary data in the ROM 8, which is a mask ROM area. Furthermore, in order to make the adjustment more precise and increase the correction accuracy, in order to completely cancel out the variations in the coefficients of the temperature detector and the temperature coefficient of the vibrator, etc., we have created FROM9 and write control for each clock. The optimal numerical value of the external area is stored through the circuit 10. lol
, p is a write pulse, and FAM OEL (FLOAT Engineering NG-GATK) is an example of a FROM device.
AVALANO) IK INJECTION MOS
), 20 to 50V is required. Other non-volatile memory elements such as fuse type memo II-, diodes, and dielectric breakdown types (mechanical switches,
(Section bond, Laser bond) Anything is fine. In this way, as long as the data on the temperature characteristics of the vibrator and the temperature signal are available, the correction value can be determined according to a mathematical formula that requires only the CPU block 3, logic operation section 5, and memory 6.7. First, square the temperature signal (straight line and temporary addition),
After setting it as a quadratic characteristic, if an appropriate coefficient is applied, the result is as shown in FIG. 4C. Here, the coefficient applied to the quadratic curve is determined based on the temperature coefficient of the crystal resonator stored in FIOM8 or FROM9. ,, Next, when the interrupt control signal 20, which is a correction signal, is output according to the value of C,
A pulse is inserted into the frequency divider 2 to compensate for changes in rate due to temperature. '(a) in Figure 5 is when there is no interrupt (
b) 1 and (c) are examples when interrupts are performed at 1° and 2, respectively. There are various concrete methods for this interrupt method, so I will not give examples of each one, but it is absolutely The logical correction of the rate (a method in which the f. of the crystal is corrected by adjusting the dividing ratio of the frequency divider without using the capacitor of the oscillation circuit) and the logical correction in the temperature correction of the present invention are completely the same. What can be achieved with circuits is a great advantage in reducing the number of elements. Moreover, this temperature correction can be performed not only by controlling the frequency division ratio of the frequency divider, but also by the oscillator, for example, by logically selecting the capacitor of the crystal oscillator inside the IC.

Figure 6 shows the actual rate temperature characteristics of the above-mentioned method as a specific example of the present invention, and although there are ripples, the accuracy is much higher than that in Figure 2A, considering the average temperature change of the clock. Rise. Also, the crystal and IC are useful for maintaining a constant temperature inside the watch.
The temperature difference is so small that it can be ignored, so it's not a problem.

As described above, the present invention provides a mask ROM that stores data such as the temperature coefficient of a crystal resonator, and a non-volatile memory that stores variations in individual crystal resonators or temperature detection circuits. It is possible to easily adjust the temperature, thereby making it possible to improve the accuracy of temperature correction.

[Brief explanation of drawings]

FIG. 1 shows an example of a temperature-compensated timepiece according to the present invention. 5 is a logic control section, 4 is a temperature detection circuit, W and P are write pulses. FIG. B...
A diagram showing a correction curve. FIG. 6 shows a specific example of a temperature detection section and a signal conversion section. Figure 4 shows an example of correction in the present invention. FIGS. 5(a) to 5(c) are examples of interrupt signals for rate correction, and C is the correction curve thereof. FIG. 6 is an example of the temperature characteristic of the temperature-corrected rate of the present invention, and D is its rate curve. Applicant Suwa Seikosha Co., Ltd. Agent Mogami Patent Attorney Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A temperature detection circuit for detecting temperature in an electronic watch comprising a crystal oscillator using a crystal oscillator having a second-order Yamaga coefficient, a frequency divider for dividing the signal of the crystal oscillator, and a time display means; a calculation means for inputting the detection output of the quartz crystal to form a temperature correction signal, a correction means for correcting the rate based on the output of the calculation flat film, and a storage means, the storage means storing information on the temperature characteristics of the crystal resonator. Mask R
An electronic timepiece comprising a nonvolatile memory element that stores values related to variations in temperature characteristics of the OM and the crystal sensor or variations in the temperature detection circuit.