JPH0519759B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a display device, and particularly to a display device that prevents erroneous display when a power switch is turned on.

[Prior art]

Generally, a sequencer has an input device for inputting a signal from an external device, and the input device is equipped with a display means, and the display means lights up when a signal is input from the external device to the input device. It is now possible to display a message to that effect.

FIG. 1 shows an input device for a sequencer according to the prior art.

In the figure, reference numeral 1 denotes a photocoupler as a switching means using electrical insulation. The photocoupler 1 is composed of a light emitting diode 2 and a phototransistor 3. A power source 4 and a switch 6 of an external device 5 are connected in series to the light emitting diode 2. When the switch 6 is turned on, the phototransistor 3 is turned on.

Further, 7 is a power source equipped with a power switch 8, 9 is a buffer, and 10 is the power switch 8 and buffer 9.
The delay circuit 10 includes resistors 11 and 12 connected in parallel to the collector side of the phototransistor 3, one side connected to the input side of the buffer 9, and the other side connected to the input side of the buffer 9. It consists of a capacitor 13 whose side is grounded.

Reference numeral 14 is an LED serving as a display means, one side of which is connected to the output side of the buffer 9, and the other side of the LED 14 is connected to the power switch 8.

Next, the operation of the conventional input device configured as described above will be explained.

First, when the power switch 8 of the external device 5 is turned on with the switch 6 turned off, the capacitor 13
Electric charge accumulates in . However, at this time, the buffer 9 inputs the H level and outputs the H level, so that the LED 14 is in the off state.

Next, when you turn on the switch 6 of the external device 5,
Since the charge accumulated in the capacitor 13 is discharged via the phototransistor 3, the buffer 9 inputs the L level and outputs the L level, and as a result, the switch 6 of the external device 5 is turned on. When a signal is input to the input device, the LED 14
will light up to indicate this.

By the way, in the input device according to the prior art configured in this way, the switch 6 of the external device 5
When the capacitor 13 is not turned on and the power switch 8 is not yet turned on, the capacitor 13 is in a discharged state.

Thereafter, when the power switch 8 is turned on, an H level is input to the buffer 9 with a delay of the time constant of the delay circuit 10, and an H level is output. However, at the moment when the power switch 8 is turned on, the buffer 9 inputs the L level and outputs the L level, and as a result, the LED 14 momentarily malfunctions and lights up. was.

[Summary of the invention]

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and the other side of the capacitor and the display means are commonly connected to the power supply side, and the switch means is provided between the delay circuit and the ground, or , the other side of the capacitor and the display means are connected to ground, and the switch means is provided between the delay circuit and the power switch, thereby preventing erroneous display when the power switch is turned on. This is what we provide.

An embodiment in which a display device according to the present invention is applied to an input device of a sequencer will be described below with reference to FIGS. 2 and 3. FIG. 2 shows a first embodiment of the invention. Note that the same components as those in the prior art are given the same reference numerals, and the description thereof will be omitted.

However, in the present invention, a capacitor 21 is provided in place of the capacitor 13 in the prior art. One side of the capacitor 21 is connected to the input side of the buffer 9, and the other side is connected to the power source 7 side.

Next, to explain its function, the power switch 8
When the switch 6 of the external device 5 is turned on, the buffer 9 inputs the L level and outputs the L level after a delay time determined by the capacitance of the resistor 12 and capacitor 21 as in the conventional technology. Therefore, the input device includes the switch 6 of the external device 5.
The adverse effects caused by chattering at the moment the switch is turned on are prevented. In this case, the LED 14 lights up to indicate that there is an input from the external device 5.

On the other hand, when the switch 6 of the external device 5 is in the off state and the moment the power switch 8 is turned on, the buffer 9 inputs the H level and outputs the H level, so the LED 14 does not light up and remains in the off state. It remains as it is. Thus, when the power switch 8 is turned on, the LED 14 will not turn on due to malfunction.

Further, FIG. 3 shows a second embodiment of the present invention.

The feature of this embodiment is that the phototransistor 32 constituting the photocoupler 31 is an emitter follower, and resistors 33 and 34 are connected in parallel to the emitter side of the phototransistor 32, and one side is connected to the input side of the buffer 9. The delay circuit 3 is constituted by the capacitor 35, which is grounded on the other side, and one side of the LED 14 is connected to the output side of the buffer 9, and the other side is grounded.

Next, the operation of the second embodiment will be explained.

First, assume that the power switch 8 is turned on. In this state, when the switch 6 of the external device 5 is turned on, the phototransistor 32 is turned on, so that the buffer 9 is delayed for a certain period of time by the time constant of the delay circuit 36, inputs an H level, and outputs an H level. Therefore, the input device is not adversely affected by chattering when the switch 6 of the external device 5 is turned on, as in the prior art. In addition,
In this case, when the buffer 9 outputs an H level, the LED 14 lights up to indicate that there is an input from the external device, as in the conventional case.

On the other hand, it is assumed that the switch 6 of the external device 5 is in the off state, and the power switch 8 is turned on in this state. In this case, since the phototransistor 32 is in an off state and the capacitor 35 is in a discharged state, the buffer 9 receives an L level and outputs an L level, and as a result, the LED 14 does not light up.
Thus, even in the case of the second embodiment, when the power switch 8 is turned on, the LED 14 will not be turned on due to malfunction. It goes without saying that the present invention can be applied to various other input devices for sequencers.

〔Effect of the invention〕

As explained above, according to the present invention, the other side of the capacitor and the display means are commonly connected to the power supply side, and the switch means is provided between the delay circuit and the ground, or the capacitor and the display means are By connecting the other side of the means to ground and providing the switch means between the delay circuit and the power switch, it is possible to prevent erroneous display when the power switch is turned on.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional input device for a sequencer, FIG. 2 is a block diagram showing a first embodiment in which a display device according to the present invention is applied to an input device for a sequencer, and FIG. FIG. 3 is a block diagram showing a second embodiment. 1, 31...Switch means, 5...External device, 7...
Power supply, 8...Power switch, 9...Buffer, 10,
36... Delay circuit, 13, 21, 35... Capacitor, 14... LED (display means). In the drawings, the same reference numerals are used for the same or corresponding parts.

Claims (1)

[Claims] 1. A switch means that is controlled on and off by an external device, a power source equipped with a power switch, a buffer, and a capacitor having one side connected to the buffer input side, and connecting the buffer input side to the power switch or ground. a delay circuit disposed between the switch means and outputting the output to the buffer with a fixed time delay when the switch means is turned on; and one side connected to the buffer output side, the light is turned on with a fixed time delay when the switch means is turned on In a display device comprising a display means, the other side of the capacitor and the display means are commonly connected to the power supply side, and the switch means is provided between the delay circuit and ground, or the capacitor and the display A display device characterized in that the other side of the means is connected to ground, and the switch means is provided between the delay circuit and a power switch.