JPH0736595A - Switch circuit - Google Patents

Abstract

PURPOSE:To judge a switch which is turned on based on the level of a partial pressure outputted from a voltage dividing circuit accompanied with the turning-on of the switch by providing the voltage dividing circuit which outputs the partial pressure of the level corresponding to the switch which is turned on. CONSTITUTION:Prescribed dial keys 1-12 are pressed, and opening and closing switches SW1-SW12 corresponding to the operated dial keys 1-12 are turned on. A transmission line from a power source Vcc is a line passing through the opening and closing switches SW1-SW12 which are turned on. Voltages divided by resistors R1 and R2, and a resistor R3 arranged in the transmission line are outputted from a terminal P as output signals Vout, and inputted through an A/D converter 14 to a control circuit 15. The output signals Vout whose levels are different are outputted from a voltage dividing circuit according to the opening and closing switches SW1-SW12 which are turned on. Therefore, the operated dial keys can be judged based on the level of the inputted Vout by the control circuit 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch circuit for determining which operation key has been operated in, for example, a telephone or a facsimile machine.

[0002]

2. Description of the Related Art Generally, for example, a telephone or a facsimile machine is provided with various operation keys such as dial keys for inputting the telephone number of the other party. And
As a switch circuit for determining which operation key is operated when these operation keys are operated, conventionally, for example, a technique as shown in FIG. 3 or 4 is known. In the prior art shown in FIGS. 3 and 4,
A switch circuit for determining which of the plurality of dial keys has been operated is embodied.

First, in the former switch circuit shown in FIG. 3, a plurality of opening / closing switches SW1 to SW12 are provided corresponding to the dial keys 21 to 32, and these opening / closing switches SW1 to SW12 correspond to the dial keys 21. ~ 3
It is turned on by pressing 2. One end of each of the open / close switches SW1 to SW12 is connected to the control circuit 33 via the signal lines L1 to L12, and the other end of each of the open / close switches SW1 to SW12 is connected to the control circuit via one common signal line L0. It is connected to 33. When any one of the dial keys 21 to 32 is pressed, the open / close switches SW1 to SW12 corresponding to the pressed dial keys 21 to 32 are turned on, and the open / close switch S
A closed circuit is formed through W1 to SW12. As a result, the control circuit 33 determines which of the open / close switches SW1 to SW1.
12 is turned on, that is, which dial key 21 to 32
Dial key 1-
The dial pulse corresponding to 12 is transmitted.

In the latter switch circuit shown in FIG. 4, a plurality of signal lines Lx1 to Lx are provided to the control circuit 33.
4, Ly1 to Ly3 are connected, and the signal lines Lx1 to Lx4 and the signal lines Ly1 to Ly3 are arranged in an intersecting state. The open / close switches SW1 to SW12 are connected to the signal lines Lx1.
To Lx4 and signal lines Ly1 to Ly3, respectively. When any one of the dial keys 21 to 32 is pressed, the pressed dial key 2 is pressed.
The open / close switches SW1 to SW12 corresponding to 1 to 32 are turned on to connect the intersecting signal lines Lx1 to Lx4 and Ly1 to Ly3. Then, as in the case of the prior art shown in FIG. 3, a closed circuit is formed which passes through the on / off switches SW1 to SW12 that are turned on, whereby the control circuit 33 determines which of the on / off switches SW1 to SW12 is turned on, that is, It is possible to determine whether or not the dial keys 21 to 32 have been pressed.

[0005]

However, in the former one of the above prior arts, as shown in FIG. 3, the number of connection of the signal lines L0 to L12 to the control circuit 33 is the total number of the open / close switches SW1 to SW12. The number is the number obtained by adding 1 to N (13 in this conventional example). In the latter case, as shown in FIG. 4, open / close switches SW1 to SW
When the total number of 12 is N = N1 × N2, the number of connection of the signal lines Lx1 to Lx4 and Ly1 to Ly3 to the control circuit 33 is N1.
+ N2 (4 + 3 = 7 in this conventional example). Therefore, in any of the conventional techniques, as the total number of open / close switches increases, the number of signal lines connected to the control circuit 33 also increases, which complicates the wiring structure and increases the manufacturing cost. It was For example, when a large number of these signal lines and open / close switches are formed on a printed circuit board, it is necessary to form them using both front and back surfaces of the printed circuit board, which makes the manufacturing very complicated. Such a problem will occur.

In addition, in telephones and facsimile machines,
The dial keys 21 to 32 are arranged on the frame of the apparatus, and the open / close switches SW1 to SW12 which are turned on / off according to the operation of the dial keys 21 to 32 are arranged in the vicinity of the dial keys 21 to 32. . However, usually, the control circuit 33 is arranged inside the frame of the device relatively distant from the opening / closing switches SW1 to SW12. Therefore, if many signal lines extended from the open / close switches SW1 to SW12 are routed to the control circuit 33, there is a problem that the wiring structure becomes more complicated.

The present invention has been made to solve the above problems, and an object thereof is to provide a switch circuit which can simplify the wiring structure and reduce the manufacturing cost.

[0008]

In order to achieve the above-mentioned object, the present invention has at least a plurality of resistors connected in series and a switch having one end connected to each end of each resistor. A voltage dividing circuit that outputs a voltage division of a level corresponding to the turned-on switch is provided, and a judging means for judging the turned-on switch based on the voltage dividing level output from the voltage dividing circuit when the switch is turned on. It is provided.

[0009]

Therefore, according to the present invention, when the switch is turned on, the voltage dividing circuit outputs the voltage division of the level corresponding to the turned-on switch. Then, when the partial pressure is inputted, the judging means judges the switch that has been turned on based on the level of the partial pressure. That is, regardless of the total number of switches, the signal line connected to the determination means need only be one signal line for outputting the divided voltage, and therefore the wiring structure is simplified.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a switch circuit for determining which dial key is operated in a telephone will be described in detail with reference to the drawings.

As shown in FIG. 2, a plurality of dial keys 1
To 12 are arranged on the frame 13 of the telephone, and of the dial keys 1 to 12, predetermined dial keys 1 to 12 are provided.
The telephone number can be entered by sequentially pressing.

FIG. 1 shows a circuit configuration of a portion related to the switch circuit of the telephone of this embodiment. First to first
The two open / close switches SW1 to SW12 are provided corresponding to the dial keys 1 to 12, respectively.
It is turned on in response to the pressing operation of ~ 12. A plurality of resistors R1 are connected in series, and one end of each of the first to twelfth open / close switches SW1 to SW12 is connected to an end of each resistor R1. Further, one terminal of the first open / close switch SW1 is connected to the power supply Vcc via the signal line L1. With this configuration, each open / close switch SW1 to SW
Different numbers of resistors R are provided between 12 and the power supply Vcc.
1 are arranged in a state of being connected in series.

The first to twelfth open / close switches SW1 ...
One end of a resistor R2 is connected in series to the other terminal of SW12, and the other end of the resistor R2 is connected to a common terminal P. The resistor R3 has one end connected to the terminal P and the other end grounded through the signal line L2. In this embodiment, the first to twelfth open / close switches SW1 to SW1
The voltage dividing circuit 16 is composed of 2 and the resistors R1, R2 and R3.

The first to twelfth open / close switches SW
When any one of 1 to SW12 is turned on, the energization path from the power source Vcc is changed to the on / off switch SW1 to S which is turned on.
It will be a route through W12. Then, the voltage divided by the resistors R1 and R2 and the resistor R3 arranged in the energizing path is output from the terminal P to the signal line L3 as the output signal Vout, and is output via the A / D converter 14. Is input to the control circuit 15 as a determination means.

The control circuit 15 receives the output signal V
Based on the level of out, which open / close switch SW1 ~
Whether SW12 is turned on, that is, which dial key 1 to 1
It is determined whether 2 is pressed. And the control circuit 1
Reference numeral 5 controls a dial pulse sending circuit (not shown) so that dial pulses corresponding to the pressed dial keys 1 to 12 are transmitted.

In the telephone of this embodiment, when the predetermined dial keys 1 to 12 are pressed, the open / close switches SW1 to SW12 corresponding to the pressed dial keys 1 to 12 are turned on. Then, the energization path from the power source Vcc is changed to the on / off switch SW1 to S that is turned on.
It will be a route through W12. Then, the voltage divided by the resistors R1 and R2 and the resistor R3 arranged in the energization path is output from the terminal P as the output signal Vout, and A
It is input to the control circuit 15 via the / D converter 14.

For example, when the "2" dial key 2 is pressed and the second opening / closing switch SW2 is turned on,
The output signal Vout is expressed by the following equation (1). Vout = Vcc × R3 / (R1 + R2 + R3) (1) Further, for example, when the dial key 3 of "3" is pressed and the third opening / closing switch SW3 is turned on, the output signal Vout is expressed by the following equation. It becomes like (2).

Vout = Vcc × R3 / (R1 + R1 + R2 + R3) (2) Thus, in this embodiment, the open / close switch S turned on
Output signals Vout of different levels are output from the voltage dividing circuit 16 in accordance with W1 to SW12. Therefore, the control circuit 15 must surely determine which of the open / close switches SW1 to SW12 has been turned on, that is, which of the dial keys 1 to 12 has been pressed based on the level of the input output signal Vout. You can

Further, in this embodiment, a plurality of open / close switches S
Despite the provision of W1 to SW12, the signal line connected to the control circuit 15 is only one signal line L3 for outputting the output signal Vout, and its wiring structure is very large. It's easy. Therefore, unlike both the above-mentioned prior arts, the number of signal lines connected to the control circuit 15 does not increase as the total number of open / close switches increases, and the wiring structure for the control circuit 15 is simplified. Manufacturing costs can be reduced.

The open / close switches SW1 to SW12 are arranged in the vicinity of the dial keys 1 to 12 on the frame 13 of the apparatus, while the control circuit 15, the power supply Vcc, and the ground portion are open / close switches SW1 to SW12. It is often arranged inside the frame 13 relatively distant from. However, in the present embodiment, the signal lines connected to the voltage dividing circuit 16 including the open / close switches SW1 to SW12 include the signal line L3, the signal line L1 on the power source Vcc side, and the signal line on the ground side. Only 3 in total with L2. Therefore, even if the three signal lines L1, L2, L3 extending from the voltage dividing circuit 16 near the dial keys 1 to 12 are routed to the control circuit 15, there is almost no risk of the wiring structure becoming complicated.

Further, for example, even when the voltage dividing circuit 16 and the three signal lines L1, L2 and L3 are formed on a printed circuit board (not shown), the number of signal lines is small, so that they can be formed on the printed circuit board. It can be sufficiently formed by using only one side of, and its manufacture becomes easy.

The present invention is not limited to the above-described embodiments, and the configurations of the respective parts may be modified and embodied as follows, for example, without departing from the spirit of the present invention. (1) The present invention is embodied in various operation keys other than the dial keys 1-12. (2) The present invention is embodied in a facsimile device other than a telephone and various other electronic devices having a plurality of operation keys. (3) Change the configuration of the voltage dividing circuit 16 as appropriate. That is,
As the voltage dividing circuit 16, the open / close switch SW1 ...
Any configuration may be used as long as it can output a partial pressure of a level according to SW12. (4) The resistance values of the resistors R1, R2 and R3 are appropriately changed according to the voltage level of the power supply Vcc so that an appropriate output signal Vout can be obtained.

[0023]

As described in detail above, according to the present invention, the excellent effect that the wiring structure can be simplified and the manufacturing cost can be reduced is exhibited.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of a switch circuit embodying the present invention.

FIG. 2 is a partially cutaway perspective view showing dial keys on a frame of a telephone.

FIG. 3 is a circuit configuration diagram showing a conventional technique.

FIG. 4 is a circuit configuration diagram showing another conventional technique.

[Explanation of symbols]

1 to 12 ... Dial keys, 15 ... Control circuit as judging means, 16 ... Voltage dividing circuit, SW1 to SW12 ... First to twelfth
Open / close switches, R1 to R3 ... Resistance, Vout ... Output signal, L1 to L3 ... Signal line.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // H04M 1/00 J 7406-5K

Claims (1)

[Claims] 1. A voltage dividing circuit having at least a plurality of resistors connected in series and a switch having one end connected to the end of each resistor, and outputting a divided voltage at a level according to the turned-on switch. And a switch circuit provided with a determination unit that determines the switch that has been turned on based on the level of the voltage division output from the voltage divider circuit when the switch is turned on.