JPS5917631A - Input device - Google Patents

Abstract

PURPOSE:To obtain a small-sized and unexpensive device with low power consumption by connecting one contact of respective switches in common through a diode in plural switch groups and a keyboard to be controlled by a microprocessor or the like. CONSTITUTION:Signals selecting switch groups 22-26 and a keyboard 46 is inputted from the microprocessor to a decoder 34 through an address and a data bus. Any one of signals V(-)-V6 is outputted from the decoder 34. If the signal V(-) is outputted, the signal is inputted only to the switch group 22 and a signal corresponding to the state of the switch is inputted to a buffer 42 through diodes 36-phi-36-3 and then inputted to the microprocessor through data buses D(-)-D3. Since only one buffer 42 satisfies the operation of many switch groups and a key group, the structure of the device can be simplified and reduced in size.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an input device for electronic equipment controlled by a microprocessor or the like.

2. Description of the Related Art Electronic devices including processing devices such as microprocessors (hereinafter simply referred to as μP) have become commonplace.

Such an electronic device includes a μP connected to a path 10 (including data, address and control buses) as shown in FIG.
12. Random access memory (hereinafter simply (-RAM)
) 14, read-only memory (hereinafter simply (-R)
OM) 16 and input device i1Bfm, for example, control various settings of the waveform storage device 20 and process measurement results.

Note that the RAM 14 operates as a temporary storage device for the μP12, and the ROM 16 stores programs for the μP12. A keyboard is generally used as the input device 18. This keyboard has multiple switches (keys) in a matrix (
The keyboard circuit is simplified by scanning each switch in a predetermined order and detecting the open/closed state of the switch. The switches on the keyboard are pressed (closed) only when the operator makes each setting, so the switches that are closed for the first setting are in the open state for another setting. Therefore, the closed state of the switch at the initial setting is maintained until the next setting, and the next setting is not adversely affected.

By the way, in electronic measuring devices such as the waveform storage device 20 and oscilloscope, it is better to use a rotary switch as the input device 18 for setting vertical sensitivity and horizontal sweep speed than a keyboard, which requires the same operation as in conventional measuring devices. It's convenient. However, in a device using μP, the output of the human-powered device 18 must be transmitted via the μP121m bus 10.
Furthermore, once an open/closed state of a switch such as a rotary switch is set, it remains open/closed until it is set next time.

FIG. 2 is a circuit diagram when such switches are connected to the bus 10 (-). Each of the switch groups 22 to 26 has a plurality of switches, and one contact of these switches is connected to the (floating) ground. and the other contact is connected to bus 10
connected to. That is, switch 22-0.24-0.2
6-0 is connected to the data line DH of the bus 10, and so on (2).Each switch is connected to each bus line (2) as shown.

Here, for example, switch groups 22 and 24 are for setting the vertical sensitivity of channels 1 and 2, respectively, and switch group 26 is for setting the horizontal sweep speed. First, if all the switches in the switch groups 24 and 26 are open, the open/closed state of each switch in the switch group 22 is transmitted to the μP 12 via the bus 10. That is, if the switch is open, a positive voltage (logic ``1'') is applied to the bus line through the resistor, and if the switch is closed, a ground voltage (logic ``0'') is applied to the bus line. Next, when setting the switch groups 24 and 26, the switch group 22
remain open and closed, the μP 12 cannot accurately detect the open and closed states of the switch groups 24 and 26. For example, if switches 22-K and 22-2 are closed, bus lines 10-0 and 10-2 are connected to switches 24-n and 24-2.
2. Open and closed states of 26-ga and 26-2 (normal without dimer)
This results in two ground voltages (rob).

Therefore, as shown in Figure 3, the bus IO and each switch group 2
2. It is conceivable to connect an enableable tri-state buffer 28 (a set of four buffers) between the buffers 24 and 26. To detect the open/closed state of each switch group, the address line A2 of 1, 0 and 0 energizes the decoder 30, and the address line input/and A2
1 logic signal is decoded to selectively set the lines SQ, 81 and S2 to "0". For example, the open/closed state of the switch group 22 is detected (= is μ according to the program in the ROM 16).
Due to the action of P12, the line SK becomes "0", the buffer 28-K is energized, and the logic level of each switch in the switch group 22 becomes the buffer 28-. 6' and the data lines Djll' to D3 of the bus 10 to the μP 12. On the other hand, the buffers 28-1 and 28-2 are not energized and their output terminals are tristated (high impedance state), so the open/closed states of the switch groups 24 and 26 are the same as those of the switch group 2.
Detection of 2 (no effect.

Similarly, when buffer 28-1 or 28-2 is energized, the other buffers are in the dry state.

In addition, in Figures 3 to 6, a bus consisting of multiple bus lines is shown as a single straight line, and when divided into each bus line (drawn out with diagonal lines, each bus line is associated with a symbol. In the circuit shown in the figure, each switch group does not interfere, but each switch in the switch group requires a buffer. Therefore, as the number of switches increases, the number of buffers increases and becomes expensive, resulting in large power consumption (2 At the same time, ('-1) a large installation space is required for the buffer.Furthermore, as the number of buffers increases, the number of decoders must also increase.

Assuming that the decoder 30 is removed from the circuit of FIG. 3,
As shown in FIG. 4, instead of the buffer 28, an energized buffer 32 having a multiplexer function (three buffers and one multiplexer make up a set and can be controlled in units of 2 m) can be used. Conceivable. A 74L8253 type IC can be used as such a buffer. That is, the buffer 32 also serves as the decoder 30 in FIG. 3, and performs the same operation as the circuit in FIG. However, this circuit of FIG. 4 also requires a buffer for each switch in the switch group, and the above-mentioned problems of high cost, large power consumption, and large installation space cannot be improved.

Also, it would be convenient if a switch such as a rotary switch and a keyboard could be used as a manual device, but the third
And the circuit shown in Figure 4 cannot be used also as a keyboard circuit.
A separate circuit had to be installed.

Accordingly, one of the objects of the present invention is to provide a novel input device using a switch that is maintained in an open or closed state.

Another object of the present invention is to provide an input device that has a simple configuration, is compact, inexpensive, and consumes low power.

Still another object of the present invention is to provide an input device that can also be used as a keyboard detection circuit.

A preferred embodiment of the present invention will be described below with reference to FIGS. 5 and 6. FIG. 5 is a circuit diagram of a preferred embodiment of the present invention. One contact of each switch in the switch groups 22, 24 and 26 is connected to each output terminal (two) of the decoder with latch function for each switch group.
, 24-K and 26-/ are each connected to a diode 36-Jr.

38-K and 40-y, the common connection point being connected to the bus 10 via a buffer 42 (a set of four buffers) which can be activated as line W/. Connected to the data line. Similarly, other switches 22-1 to 26
-3 is also commonly connected as shown through the diode b-1 toner dark~40-3,
These common connection points are connected to the bus 10 via a buffer 42. The lines W/-W3 each receive a positive voltage through a resistor 44. Note that as the decoder 34 and the buffer 42, for example, LSL, 37 type IC, and 4011244P type IC can be used, respectively.

Detects the open/closed state of each switch group (Secondly, ROM16
The μP 12 sends predetermined data to the data lines D and Dl of the bus 10 in accordance with the detection program of The output is latched. Now, if the decoder 34 outputs only the line (2)/ (-"0") and outputs "1" to the other lines Vl and (2), only the switch group 22 is energized.

Therefore, the decoder 34 operates as a biasing means.

Further, μP 12 outputs the address line Afll2 “0” to energize the buffer 42. Therefore, the "0" output of only the closed switches in the switch group 22 appears on the corresponding line W (-) via the corresponding diode 36. Note that the cathodes of the diodes 36 to 40 are connected to the switch group 22 to 26.
Note that the switch in the open state (the corresponding line W becomes ``1'' due to the positive voltage supplied through the resistor 44. Therefore, the switch group 22
The open/close state of is detected from μP12 (2) via the lines WE to W3, the buffer 42 and the bus 10. In this case, even if any switch of the switch groups 24 and 26 is in the closed state, the diode 38-y Since the switches 40-3 to 40-3 are off, the detection of the switch group 22 (2 has no effect. In other words, even if the switch 24-/ is in the closed state, the switch 22-J
If lll' is open, diodes 36-if and 38-
Both l are turned off and the line WO becomes "l". Also, if the switch 22-/ is in the closed state, the diode 36-7 is turned on and the line Wy becomes "0", but this "0" means that the diode 38-y is off, so the switch 24-〆 (= not supplied, The switch group 24 does not affect the detection of the open/closed state of the switch group 22.If the diode 38-y is not present (
If it is directly connected), “0” of the wire W/ is the switch 24-,
ff to the line V1, and the logic level of the lines W1 to W3 (= the effect of the switch group 24 occurs.
It is clear that the combinations with other switches are similar to those described above.

When detecting the open/closed state of the switches in the switch group 24,
The decoder 34 outputs only the line V1 (two "0"s, and the line Vl
and ■ Output "1" to 2. Further, when detecting the open/closed states of the switches in the switch group 26, the decoder 34 outputs "0" to the line V2, and outputs "1" to the lines ■/ and Vl. Other operations are similar to the above description regarding the switch group 22.

When the buffer 42 is composed of 0MO8 elements, the threshold voltage of “0” is approximately 1■, and the “0” of the decoder 34 is
The output is 0■. Therefore, as the diodes 36 to 40, inexpensive silicon diodes having a voltage drop of about 0.6V when turned on can be used. In addition, the buffer 42 is TTL
If it is composed of elements, germanium diodes may be used as the diodes 36 to 40.

FIG. 6 is a circuit diagram of another preferred embodiment of the present invention. This embodiment has a keyboard 46 added to the embodiment of FIG. 5, and the differences from FIG. 5 will be explained below. The keyboard 46 has key switches 4 arranged in 4 rows and 4 columns.
8-S to 54-3, one contact of the key switches 48-i to 48-3 is commonly connected, and the wire V
3 to the decoder 34. Similarly, the key
One contact of switches 50, 52 and 54, respectively, are also commonly connected and connected to lines V4. It is connected to the decoder 34 via V5 and v6. Key switch 48-g.

The other contacts of 50-g, 52-g and 54-g are connected in common and connected to line WQ via line Sy and diode 44-g.
connected to. Similarly, key switches 48-1 to 54-
1.48-2 to 54-2.4. The other contacts of 8-3 to 54-3 are also commonly connected to the lines W] to W3 via the lines 81 to S3 and the diodes 44-1 to 44-3. Connected. Since the decoder 34 has increased the number of output terminals to ■/～■6,
The number of input terminals has also increased to 3 bits, D$ to D2.

Detection of the open/closed states of the switch groups 22, 24 and 26 is performed by the fifth
The decoder 34 is similar to the embodiment shown, but the decoder 34
6t-11" is output. Therefore, even if any keyer switch of the keyboard 46 is pressed (closed) at this time, due to the action of the diodes 44-X to 44-3,
The detection of switch groups 22, 24 and 26 is not affected. To detect the open/closed state of the keyboard 46, the R2M17 program (2) Therefore, μP12 controls the data lines D@, Di, and D2, and sets the output lines (3) to (6) of the decoder 34 to "0" in sequence. The keyboard 46 is sequentially scanned.

If the scanned keyer switch is in the closed state, the corresponding line Sj! I to S3 become "0", and this "0" is transmitted to the buffer 42 via the corresponding diodes 44-/-44-3. At this time, the line V/~v2 is "l", and even if any switch in the switch groups 22-26 is closed, the keyboard 46 is detected (double-influenced) by the action of the diodes 36-l~40-3. do not.

As described above, according to the present invention, it is not necessary to provide an energized buffer for each switch that is maintained in an open/closed state. becomes easier and cheaper, and
Does not require large space. Furthermore, since the diode is a passive element, power consumption can be reduced. These effects become more pronounced as the number of switches increases. Furthermore, when used in conjunction with a keyboard, there is no need for a scanning circuit and a detection circuit dedicated to the keyboard; other circuits can be used as they are by simply increasing the number of diodes and the output of the decoder.

Although only the preferred embodiments of the present invention have been described above, those skilled in the art will understand that various changes and modifications can be made without departing from the gist of the present invention. For example, although the switch in the above embodiment is a rotary switch, it may also be a toggle switch, a push button switch, a slide switch, or the like, which maintains the open/closed state. Also, a separate decoder may be provided to energize the decoder 34 and buffer 42 of FIGS. 5 and 6. In the embodiment, μP and a ROM program are used to detect the open/closed state of the switch, but this detection function can also be realized by a combination of the logic circuit 12-.

[Brief explanation of the drawing]

Figure 1 is a block diagram of an electronic device using an input device, Figure 2 is a block diagram of an electronic device using an input device.
4 is a circuit diagram for explaining the input device, and FIGS. 5 and 6 are circuit diagrams of preferred embodiments of the input device of the present invention. 22-y to 26-3: switch 22.24, 26: switch group 34: energizing means 36-/-41-3: diode

Claims (1)

[Claims] In an input device comprising a plurality of switch groups each having a plurality of switches, and an energizing means for selectively energizing one contact of a switch of the plurality of switch groups for each of the switch groups, the plurality of switches The other contacts of the corresponding switches of the group are commonly connected via diodes, and the potential level of the common connection point of the diodes indicates the open/closed state of the two switches in each of the switch groups. Device.