JPS63257352A - Signal circuit switching device - Google Patents

Abstract

PURPOSE:To use plural terminal equipments without line contact at one set of an electronic computer main body by devising the titled switch such that a signal line of other terminal equipment is not connected when the signal line of one terminal equipment is connected to an output terminal of a signal circuit switch. CONSTITUTION:When a tri-state gate 13a(13b) is conductive and a switch SW1(SW2) is closed, the output terminal of the tri-state gate 13a(13b) goes to an L level and the output terminal goes to an H level in other case. The output terminal of the tri-state gates 13a, 13b is connected to the input terminal of an R-S flip-flop 14 and connected also to the control input terminal and an input terminal of an AND gate 15 for control signal of the other tri-state gate 13. The output terminal of the AND gate 15 of the control signal is connected to an output terminal C0 connected to a control signal line 5 of the electronic computer main body. Thus, plural terminal equipments are connected optionally even to a small sized and any type of computer.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a signal circuit that is provided between a computer main body and a plurality of terminal devices, and automatically switches signal lines connected to the computer main body. This relates to switching devices.

[Prior art] Li number of terminals are combined into one T1! It has been practiced for a long time to make effective use of a computer by connecting it to the main body of the computer. In this case, if a plurality of terminals are used at the same time, each terminal must be connected in priority order according to the performance of the computer itself.

Conventionally, control of such terminal connections was done exclusively by
It was processed by the in's own software and a signal circuit switcher equipped with advanced functions.

[Problems to be Solved by the Invention] As mentioned above, conventionally, when a plurality of terminals are connected to the main body of the M/'B machine, the connection state is controlled by the software etc. of the main body of the Den'Ba machine. Not only did complex software have to be created for each model, but the devices were not compatible, and unless the computer was a medium-sized or large-sized computer with a certain capacity or more, it was necessary to create multiple The disadvantages were that it was not possible to use other terminals, and that the configuration of the signal circuit switch was complicated and expensive.

This invention eliminates such drawbacks and has a simple structure.
An object of the present invention is to provide a signal circuit switching device which can be used by arbitrarily connecting a plurality of terminals to any small-sized computer.

[Means for Solving the Problems] In order to solve the above-mentioned problems, a signal circuit switching device according to the present invention has a terminal to which a signal line from a terminal is connected and a line control line from the L terminal. A plurality of pairs of input terminals are provided, including a pair of terminals to which the computer is connected, one output terminal is connected to a signal line going to the main body of the computer, and a plurality of input terminals are provided between the output terminal and the plurality of input terminals. It is operated by an input signal from the line control line to selectively connect one of the plurality of signal lines to the output terminal, and when that signal line is connected to the output terminal, other signal lines are connected to the output terminal. The present invention is characterized in that it includes a connection control circuit that controls the connection state so that it is not connected to the output terminal.

[Operation: One of the signal lines from a plurality of terminals is selectively connected to the output terminal toward the main body of the calculator by an input signal from the line control line, and that signal line is connected to the output terminal. When the output terminal is connected, the connection control circuit controls the connection state so that other signal lines are not connected to the output terminal.

[Example] An example of the present invention will be described based on FIGS. 1 and 2.

FIG. 2 is a block diagram schematically showing the overall configuration of the embodiment, where 1 is a computer main body, such as a personal computer, and 2... are terminals. 2a and 2b are the first and second terminals, 2a is a card reader, and 2b is a barcode reader, for example. 3 is
This is a δ circuit switch that switches signal lines from multiple terminals.

4... are signal lines for transmitting signals from each terminal 2 to the computer main body 1; 5... are control signal lines for transmitting control signals for controlling the operation of the signal circuit switch; 6. ... is a return line that transmits a signal from the computer main body l to each terminal device 2.

FIG. 1 shows the signal circuit switching device 3 of this embodiment, in which the control signal line 5 is connected to the terminal T I * 72 to which the signal line 4 from the first and second terminals 2a and 2b is connected. Two input terminals are provided with a pair of terminals c, , c2. In addition, in FIG. 1, for convenience of illustration, C1 and T
1, C2, and T2 are shown separately, but in reality, as shown in FIG.
2 are arranged side by side.

sw, sw2 are provided in the first and second terminals 2a, 2b and connected to the control signal line 5.5.
It is a switch. These switches sw, , sw2 are grounded, and when the switches are closed, the control signal line 5 becomes L level. In addition, these switches sw,
sw2 is linked to a main switch (not shown) of each terminal 2a, 2b, and when the switch is open, no signal is output from that terminal.

In addition, the terminal Hl * H2 to which the return line 6 is connected is also provided in pairs with each input terminal, and these terminals H
, , H2 are connected to the output ends of the buffer amplifiers 12, and the input ends of these buffer amplifiers 12 are connected to the terminal H, to which the return line 6 from the computer main body 1 is connected. Therefore, a signal from the computer main body 1 is transmitted to the terminals 112a and 2b via the return line 6 and the buffer amplifier 12, so that mutual communication can be performed.

The terminals cl and c2 to which the control signal line 5 is connected are connected to the input ends of the first and second three-state gates 13a and 13b, and both input and output ends of the three-state gates 13a and 13b are connected to resistors 20 and 13b. It is connected to the H level source via... Therefore, when the three-state gate 13a (or 13b) is conductive and the switch SW1 (or sw2) is closed, the output terminal of the three-state gate 13a (or 13b) is at the L level; otherwise, the output terminal is at the H level. become the level. The output terminals of these three-state gates 13a and 13b are connected to the input terminal of the R-S flip-flop 14, and also to the control input terminal of the other three-state gate 13 and the input terminal of the AND gate 15 for control signals. There is. A for this control signal
The output end of the ND gate 15 is connected to the control signal line 5 on the computer main body side.
It is connected to the output terminal co which is connected to the output terminal co.

The output terminals of the flip-flop 14 are connected to the first and second (
7) Terminals T, , T2 are connected to the AND gates 16a, 16b (7) input terminals, and the other input terminals of these AND gates 16a, 16b are connected to the signal lines 4...
is connected. And these AND gates 16a,
The output terminal of 16b is connected to the input terminal of OR gate 18,
The output end of this OR gate 18 is connected to an output terminal To to which the signal line 4 toward the computer main body l is connected.

Next, the operation of the embodiment L will be explained with reference to the time chart of FIG.

When both the switch SW1 of the first terminal fi2a and the switch SW2 of the second terminal 2b are open, the three-state game)1
3a and 13b are both conductive, the input terminals S and R of the flip-flop 14 are both at H level, and the output terminals Q and Q maintain the previous state Iγ. However, S
When W and SW2 are open, no signal is input to TI and T2, so no signal is output to To. Further, both inputs of the control signal AND gate 15 become H level, and an H level signal indicating switch open is outputted from the output terminal CO to the next signal circuit switch.

When SW is closed, the input/output terminal of the first three-state gate 13a becomes L level, and the control input terminal of the second three-state gate 13b becomes L level and becomes non-conductive. Therefore, the input terminal S of the flip-flop 14 becomes L level and R becomes H level, the output terminal Q becomes L level and Q becomes H level, and the first AND gate 16a becomes conductive according to the signal from the input terminal T1. 2 AND gate 16b becomes non-conductive. As a result, the signal from the first terminal 2a is outputted from the output terminal TO via the AND gate 16a and the OR gate 18 of the input terminals T, il. Then, even if SW2 is closed next time, the first three-state gate 13
As long as a remains conductive, the second three-state game)
Since 13b is non-conductive, no matter how SW2 opens or closes, the effect is entirely on the second three-state gate 13b.
will be cut. Further, since one of the inputs to the control signal AND gate L5 becomes L level, the output terminal Co becomes L level indicating a connected state.

Next, when SW1 is opened while SW2 is closed, the output terminal of the first three-state gate 13a becomes H level, and the control input terminal of the second three-state gate 13b becomes H level. , S2's king state gates 13b are conductive. therefore,
The input terminal S of the flip-flop 14 is at H level, and the input terminal R is at L level.

The output terminal Q becomes L level, Q becomes H level, and the second
The first AND gate 16b becomes conductive in accordance with the signal from the input terminal T2, and the first AND gate 16a becomes non-conductive.

As a result, the input terminal T2, the second AND gate 16b
The signal from the second terminal @2b is outputted from the output terminal To via the OR gate 18. And firstly SWl
Even if the switch is closed, as long as the second three-state gate 1-13b remains conductive, the first three-state gate 13a remains non-conductive. However, the influence is all cut off by the first three-state gate 13a. Furthermore, since one of the inputs to the control AND gate 15 is at the L level, the output terminal Co maintains the L level, which means the TA state.

Then, when both SWI and SW2 are opened, the state returns to the initial state.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and may be implemented, for example, by a circuit that does not use a three-state gate or a flip-flop.

In addition, an A-D converter and a D-
By arranging an A converter, etc., it is possible to support analog circuits, and it can also be used, for example, in monitoring systems using terminals such as television cameras and various safety devices in buildings.

[Effects of the Invention] According to the signal circuit switch of the present invention, when the signal line of one terminal is connected to the output terminal of the signal circuit switch, the signal lines of other terminals are not connected. Multiple terminals can be used on a single computer without interference, and no software is required to control the connection status. No calculator function is required, and the signal circuit switch itself has a simple structure.Furthermore, by combining multiple signal circuit switchers, a single computer can be used with many terminals. Moreover, it has excellent effects such as being able to implement this using an inexpensive personal computer or the like.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a signal circuit switcher according to an embodiment of the present invention;
FIG. 2 is a block diagram showing the overall configuration of the embodiment, and FIG. 3 is a time chart showing the operation of the embodiment. ■... Electric/B machine body, 2... Terminal, 3... Signal circuit switch, 4... Signal line, 5... Control signal line.

Claims (1)

[Claims] A plurality of pairs of input terminals, including a terminal to which a signal line from the terminal is connected and a terminal to which a line control line from the terminal is connected, are connected to a signal line to the computer main body. one output terminal, which is provided between the output terminal and the plurality of input terminals, and is operated by an input signal from the line control line to selectively connect one of the plurality of signal lines to the output terminal. 1. A signal circuit switching device comprising a connection control circuit for controlling the connection state so that when the signal line is connected to the output terminal, other signal lines are not connected to the output terminal.