JPS6134108B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an input section of an electronic timepiece with a calculator.

An object of the present invention is to miniaturize the input section of an electronic timepiece with a calculator.

A normal small calculator has a keyboard consisting of a reed switch or a contact spring, but the input keys of a calculator that generally perform four arithmetic operations are a numeric input key, a function key for addition, subtraction, multiplication, division, etc., a decimal point,
I need a lot of equals, clear keys, etc.
Furthermore, the more calculation functions are added, the more input keys are required. Proportionally reducing the size of this calculator to a size that could fit inside a wristwatch, for example, would not only be mechanically unreasonable, but would also be too large to be operated with one's fingers, which would impede operability. So it will have a bigger defect. That is, even if the user intends to input only one key, it is often impossible and the user ends up inputting multiple keys at the same time. In this case, the function as a calculator will be completely lost. In addition, in the case of an electronic wristwatch with a calculator, even if the display is a clock function, key input is performed and the computer circuit operates, which only increases the current consumption in the circuit even if it does not appear on the display.

The present invention relates to an electronic wristwatch with a calculator having a touch switch in the input section, which eliminates the above-mentioned drawbacks and further includes an alarm circuit for abnormal input.

This will be explained below using examples.

Embodiment In this embodiment, the input key group is composed of touch switches that detect the skin resistance of the human body, and the circuit configuration of this input switch section will be explained first. The reason why a touch switch was used in the embodiment is that, compared to a contact type switch, it has no moving parts or contact parts, so it solves problems related to waterproofness and reliability such as poor contact. In this switch, the key and the watch case are electrically insulated, and by touching one of the keys with a finger while the watch body is worn on the wrist, conduction is established between the two through skin resistance and switching is performed. However, since the size of the watch body is small and the keys cannot be spaced far apart, there is a risk of touching two or more keys at the same time. In this case, a different display will appear, so you must clear each entry and input carefully. The present invention solves the problem of preventing multiple inputs by controlling signals depending on the size of the contact area between a finger and a key, and the circuit diagram of the input section is shown in FIG. 1 and will be described in detail below. Touch plate and PNP field effect transistor (PNP-MOS) or NPN field effect transistor (NPN-MOS) or PNP-MOS and NPN-MOS
A touch switch detection section 1 consists of a CMOS inverter connected in a complementary manner, a multiple input prevention circuit 2 that prioritizes input of the signal that arrives first, and a key input signal
An encoder 3 that converts into a BCD code, a chattering prevention circuit 4, a BCD code conversion circuit 5 that inputs a bit time signal and represents one digit with 4 bits, a shift register section 6 to which a numeric value signal is sent, and a set signal in the chattering prevention circuit 4. and an input control section 7 for reading, which generates a 1-word cycle signal P (consisting of digit signals from D ₁ to D ₉ , for example, 448 Hz) which generates a reset signal and is generated once every time the input number is set. F/F8,
It is composed of a ROM 9, a judgment F/F 10, and a multiple input prohibition signal generation circuit 38 that generates a signal for prohibiting multiple inputs. The input section shown in FIG. 1 has a circuit configuration that can be applied to both an input key type and a key independent type. And a circuit 11 for determining whether it is a numeric value or a function.
It is equipped with Furthermore, one of the input keys is provided with a lamp 12 for internal illumination. Furthermore, if an unexpected input is made, the abnormal input alarm circuit 13 detects it. As an example of multiple input, a case will be described in which the user intends to touch only the touch board 14 but ends up touching the touch board 15 as well. (Touch plate 14 is
0001 or 1, touch plate 15 is 0010 or 2
). When the fingertip is not touching the touch board, the input sides of the CMOS inverters 26 and 27 are biased high via the high resistance _R1 . Resistor R ₂ is CMOS inverter 26 and 27
It is used to protect the CMOS gate from being damaged due to instantaneous abnormal voltage caused by static electricity, etc. (approximately 1MΩ). However, CMOS gates have very high input impedance and have a built-in protection circuit against instantaneous abnormal voltages, which consists of protection diodes and resistors, so they can withstand even abnormal voltages applied. Next, when the fingertips touch the touch boards 14 and 15, the voltage level at the input side of the CMOS inverters 26 and 27 will be RS/RS+R ₁・V _DD , where RS is the resistance between the ground and the fingertips (i.e., the skin resistance of the human body). Therefore, when RS≪R ₁ , it becomes almost 0V. (According to experiments, the skin resistance RS takes a value of approximately 10 MΩ or less, although there are individual differences. Therefore, R ₁ is
(set to 22MΩ). As mentioned above, it is the touch plate 14 that you consciously tried to touch, but if you also touch the touch plate 15, the contact area between the touch plate and your fingertip is larger on the touch plate 14 than on the touch plate 15. . Therefore, RS at touch plate 15 is larger than RS at touch plate 14 and becomes approximately 0V.
Figure 2 c and e because it takes a long time to reach
As shown in FIG. 2, the voltage waveforms at the inputs of CMOS inverters 26 and 27 lag behind CMOS inverter 27. When this waveform is shaped by a CMOS inverter, the waveforms become d and f in Fig. 2. OR this output
When connected, the waveform at 28 will be as shown in Figure 2g.
This is reversed with an inverter and reset priority is given to R-
It is input as the set signal of S flip-flop 7a and is synchronized with the 32Hz signal a shown in Figure 2b.
When the 32 Hz signal b (chattering can be prevented by synchronizing to 32 Hz, which has a larger period than possible chattering and external noise, etc.) as a reset signal, the data input 29 of the D-type flip-flop 7C becomes as shown in Fig. 2 h. Creates a clean waveform with no chattering. The Q output 30 of the D-type flip-flop 7C is shown in FIG. 2i, and the Q output of the D-type flip-flop 7d delayed by one word (448 Hz) is shown in FIG. 2j, and the output 31 of the NAND gate is shown in FIG. 2k. (CPC
(The signal is a signal in which a pulse is generated once per word.) This becomes a reset signal for an R-S flip-flop consisting of two NAND gates in the chattering prevention circuit 4. D type flip-flop 7d
From there, a one-word signal P43 is generated through a flip-flop. Here, when the function key and the decimal point key are pressed, the generation of the P signal 43 is cut off by the gate 7e. Also, Fk ₁ is a signal whose state changes to High or Low by inputting a function key, and CPA is a signal whose state changes to High or Low by inputting a function key.
This is the AND output of CPC and P. On the other hand, the 28 signals in the OR connection are the multiple input prohibition signal generation circuit 3.
8 and invert it to another R-S
The set signal of the flip-flop 7b is used as the set signal, and the reset signal k shown in FIG. 2 is input as the reset signal. Then, attach a capacitor to the inverter as shown in the figure, and R
-S flip-flop 7b signal (Fig. 2l)
When the waveform is rounded as shown in FIG. 2m and the two signals are input to an AND gate, the output becomes a multiple input prohibition signal having the waveform shown in FIG. 2n. The signal n that has passed through the delay circuit as described above is input to the NAND gates 2a and 2b, and the output 3
2 becomes o in FIG. 2, the output 33 of 2b remains high and the subsequent R-S flip-flops are not set. In other words, only the signal from the touch plate 14 is detected, and the signal from the touch plate 15 is cut off. In this way, by detecting the signal that comes first and using that signal to create a signal for prohibiting multiple inputs (n in FIG. 2), signals that arrive later than the first signal are cut out. The input signal 35 of the D-type flip-flop 34 becomes p in FIG.
The output 36 of the flip-flop 34 is shown in FIG.
Therefore, only the bit time signal of the 0001 signal _T1 is transferred, and no other signals are sent at all. This signal is taken out by one word (pulse width of P) and sent to the shift register 6. The above description also applies to other touch plates.

In wristwatches with conventional contact-type keyboards, the space is small, so multiple keys are touched at the same time, resulting in multiple signals being input. However, when a touch switch that detects the resistance of the human body is used as a keyboard, the difference in contact area results in a signal delay. By utilizing this delay, it has become possible to detect the earliest input signal in the circuit of FIG. 1 and to cut out other signals. Therefore, a large amount of input due to multiple keystrokes can be avoided, and a keyboard with fewer malfunctions can be obtained.

If there is a key input during the clock function, the circuit will operate even though it is not displayed, increasing current consumption. Therefore, in the present invention, each touch plate and CMOS
An NMOS transistor 37 is provided between the inverters, and by applying a signal 38 to the gate of each NMOS transistor 37, which is High for the clock function and Low for the calculation function, the NMOS transistor 37 is turned OFF during the clock function, and the key is not operated. However, the circuit will not operate and no current will flow. As an exception, the touch plate 14 is not provided with an NMOS transistor. This is because the watch functions as a changeover switch that switches between hours, minutes, seconds, and month and day.

Furthermore, if the touch switch keyboard is in the calculation function state and an input is made due to water or dirt, the input signal will be displayed. In such a case, R- in the abnormal input alarm circuit 13
The set signal 44 of the S flip-flop is generated, but the reset signal 45 is not generated, so the output 46 is
remains low. The signal is normally High, but when the continuation of the Low state is detected, this signal drives the decimal point on the display, and the decimal point lights up or blinks to notify the user of the abnormal state.

As described above, according to the present invention, the input terminal is configured with a touch switch keyboard, and double typing is completely prevented by the difference in contact area, so that even a small keyboard does not malfunction, and it can be used with an ultra-compact calculator. This made it possible to create an electronic clock.

[Brief explanation of the drawing]

FIG. 1 shows an input detection circuit for an electronic wristwatch with a calculator according to the present invention, and FIG. 2 shows its timing chart. 1...Touch switch detection section, 2...Multiple input prevention circuit, 3...Encoder, 4...Chattering prevention circuit, 5...BCD code conversion circuit, 6...
...Shift register section, 7...Input control section, 8...Reading F/F, 9...ROM, 10...
...Judgment F/F, 11...Function judgment circuit, 12...Lamp for internal illumination, 13...Abnormal input detection circuit, 14-25...Touch plate, 26,2
7...CMOS inverter, 37...NMOS transistor, 38...Multiple input prohibition signal generation circuit.

Claims (1)

[Claims] 1. In an electronic watch with a calculator that has a clock function and a calculation function, the input section is a touch switch detection section 1,
The touch switch detection unit 1 includes a multiple input prevention circuit 2 and a multiple input prohibition signal generation circuit 38 that generates a signal for prohibiting multiple input, and the touch switch detection unit 1 includes a plurality of touch plates, a resistor connected to the touch plate, and a CMOS.
The multiple input prevention circuit 2 OR-inputs the output of the CMOS inverter.
It consists of an OR gate, an output of the CMOS inverter, and a NAND gate for inputting the signal for prohibiting multiple inputs, and for prohibiting inputs other than the touch plate with the largest contact surface of the touch plate, and prohibits the multiple inputs. The signal generation circuit includes an R-S flip-flop inputting the output of the OR gate section, and a R-S flip-flop inputting the output of the OR gate section.
A calculator comprising: a capacitive component that blunts the output of a flip-flop; and an AND gate that inputs the output of the R-S flip-flop and a voltage at one end of the capacitive component and outputs a signal for prohibiting multiple inputs. electronic clock.