JPS584486B2 - Sentaxado Cairo - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a selection operation circuit suitable as a channel selection device for a television receiver or the like.

In conventional television receivers, a lock-type switch selects a predetermined voltage from voltages preset for each broadcast channel, and supplies it to a variable capacitance diode whose capacitance changes depending on the applied voltage. A so-called electronic tuner that tunes to the broadcast channel of

In order to facilitate channel selection, this electronic tuner has a plurality of switches mechanically connected to each other, so that when one switch is turned on, the previously on switch is turned off.

However, in such conventional switching devices, when multiple switches are operated at the same time, all of the switches must be kept on or all of them are turned off. was considered incomplete.

Furthermore, in any case, a plurality of switches are mechanically connected to each other, resulting in a very complicated structure.

Due to the shortcomings of this mechanical switching device, channel selection devices using a combination of a diode matrix and a flip-flop, or a ring counter, etc., are being considered, but these devices use a large number of semiconductor elements, making the devices extremely expensive. It is difficult to employ this method in consumer equipment such as John receivers.

This invention was made in view of the above drawbacks.
This provides an economical selective operation circuit that utilizes the hysteresis characteristics of neon tubes.

Hereinafter, the present invention will be explained in detail with reference to the drawings which are one embodiment.

The figure is a circuit configuration diagram showing a channel selection device to which the selection operation circuit of the present invention is applied.
A, 1b, 1c, and 1d have a so-called hysteresis characteristic in which the discharge stop voltage is lower than the discharge start voltage.

2a, 2b, 2c, 2d are neon tubes 1a, 1b, respectively
, 1c, 1d from the DC power source 3 via the resistor 4, and also serves as a channel selection switch.

These switches 2a, 2b, 2C, and 2d are each provided independently and are turned on only when operated.

Also, common resistors 5, 6 and resistors 7a, 7b, 7c,
7d, and is configured to supply a voltage lower than the discharge start voltage and higher than the discharge stop voltage (hereinafter referred to as discharge holding voltage).

Note that a capacitor 8 is inserted between one end A of the resistor 4 and one end B of the resistor 5, and in a steady state, the voltage of the DC power supply 3 and the resistor 5,
It is charged by the potential difference with the voltage divided by 6.

Furthermore, the cathodes of the neon tubes 1a, 1b, 1c, and 1d are grounded via resistors 9a, 9b, 9c, and 9d, respectively.

10a, 10b, 10c, 10d are resistors 11a, respectively.
, 1lb, 11c, 11d through neon tubes 1a, 1b
, 1c and 1d are connected to the cathodes of the switching transistors; 12a, 12b, 12c and 12d are preset resistors inserted into the collector circuits of the transistors 10a, 10b, 10c and 10d, respectively; 13 is the transistor 1;
DC power supply for operating 0a, 10b, 10c, 10d, 14a, 14b, 14c, 14d are diodes connected to preset resistors 12a, 12b, 12c, 12d, 15 are diodes 14a, 14b, 14c, 14
d bias DC power supply, 21 each diode 1
Variable capacitance diodes connected to 4a, 14b, 14c, and 14d, 23 a capacitor, and 22 a resonant coil form a tuning circuit 20 together with the variable capacitance diode 21 and the capacitor 23.

With the above configuration, when the switch 2a is closed, a discharge starting voltage is applied to the neon tube 1a through the resistor 4, and the neon tube 1a performs a discharging operation.

At this time, the resistance 7a is also applied to the other neon tubes 1b, 1c, and 1d.
A voltage is applied through each of the resistors 7b, 7C, and 7d, but the voltage is divided by the resistor 7a and each of the resistors 7b, 7c, and 7d, and the voltage becomes lower than the discharge start voltage, so that no discharge operation is performed.

Note that even if the switch 2a is opened, the discharge holding voltage is applied to the neon tube 1a through the resistors 5 and 7a, so that the discharge operation continues.

Due to this operation of the neon tube 1a, a base bias is applied to the transistor 10a via the resistor 11a, and the transistor 10a is turned on.

Therefore, a voltage preset by the preset resistor 12a is applied to the variable capacitance diode 21 via the diode 14a, and the tuning frequency (reception channel) of the tuning circuit 20 is held at a constant value.

Next, when the switch 2b is closed, a discharge starting voltage is applied to the neon tube 1b through the resistor 4 and the switch 2b, and the neon tube 1b starts discharging.

When a current flows through the neon tube 1b circuit, the voltage at point A causes a voltage drop due to the resistor 4. Therefore, the voltage at point B is lowered by the voltage drop at point A by the capacitor 8, and is applied to the neon tube 1a. The voltage applied is lowered below the discharge holding voltage.

Therefore, the discharge operation of the neon tube 1a is stopped, and only the neon tube 1b is operated.

Note that regardless of the operation of switch 2b, the voltage at point B immediately returns to the steady state voltage due to the charging time constant of capacitor 8, and even if switch 2b is opened, neon tube 1b
maintains the discharge operation.

This operation of the neon tube 1b turns on the transistor 10b, and a voltage from the preset resistor 12b is applied to the variable capacitance diode 21, thereby switching the receiving channel.

Furthermore, even if the other channel selection switches 2c and 2d are closed, the corresponding channels can be received in the same way.

As described above, it is possible to obtain an extremely inexpensive channel selection device by utilizing the hysteresis characteristics of neon tubes, and it is also possible to use neon tubes as reception channel indicators, making it possible to separate the channel selection device and channel display circuit. It is possible to eliminate the uneconomical effects of conventional devices configured with

Although the above description has been made regarding the case where the present invention is applied to a channel selection device for a television receiver, the present invention can also be applied to a device equipped with two or more selection elements, such as a wind speed selection device for an electric fan. can.

As explained above, this invention utilizes the hysteresis characteristic of neon tubes in which the discharge start voltage and discharge stop voltage are different, thereby omitting a complicated switch mechanism and realizing a selective operation circuit with excellent operability at a low cost. be able to.

[Brief explanation of the drawing]

The figure is a circuit diagram showing a channel selection device for a television receiver, which is an embodiment of the present invention. In addition, in the figure, 1a, 1b, 1c, 1d... neon tube, 2a, 2b, 2C, 2d... channel selection switch, 3 7d, 9a, 9b, 9c, 9d... ...Resistance, 8.
...Capacitor, 10a, 10b, 10c, 10
d...Switching transistor, 12a, 1
2b, 12C, 12d... Preset resistance, 2
1... It is a variable capacitance diode.

Claims (1)

[Claims] 1. A plurality of neon tubes, a selection switch provided corresponding to each neon tube, and two types of voltages, a discharge starting voltage and a discharge holding voltage, in the neon tubes,
A power supply circuit that applies a discharge holding voltage to each of the plurality of neon tubes via a resistor and a discharge starting voltage via the selection switch, and a terminal between a discharge holding voltage supply terminal and a discharge starting voltage supply terminal in this power supply circuit. and a plurality of output circuits each generating an output according to the operation of the neon tube, which corresponds to the selection switch when the selection switch is closed. A discharge starting voltage is supplied to the neon tube to cause it to discharge, and a voltage drop due to this energization is transmitted to the discharge holding voltage supply terminal side via the capacitor, and the discharge holding voltage supplied to the neon tube is lower than the discharge holding voltage. A selection actuation circuit characterized in that the voltage is lowered to a lower level.