JPS6325531Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power supply device for a video tape recorder (VTR), and particularly to a power supply device suitable for use in a portable VTR.

Generally, portable VTRs use rechargeable batteries when used outdoors, and connect an AC power adapter or a tuner unit with a built-in AC power adapter when used indoors.
Use AC power.

The above-mentioned AC power adapter and tuner unit require a power source to supply 12V DC to the VTR body, a power source to charge the rechargeable battery, and a power source to operate the heater to prevent condensation on the guide cylinder, which requires a large power transformer. , the entire device had become larger.

Furthermore, the number of terminals for connecting the AC power adapter or tuner unit to the VTR body is large, resulting in high costs.

This invention was made in view of the above points,
To provide a power supply device for a VTR in which the power transformer of an AC power adapter or tuner unit can be downsized and the number of terminals connected to the VTR main body can be reduced.

An embodiment of the present invention will be described below with reference to the drawings. The drawing is a schematic circuit diagram of the device of the present invention,
11 is AC input terminal, 12 is power transformer, 13
is a constant voltage DC power supply, _S1 is a first power switch that controls the operation of the constant voltage DC power supply, and 14 outputs DC12V which is the output of the constant voltage DC power supply 13.
A DC 12V output terminal, 15 a ground terminal, 16 a charging power supply terminal, and 17 a tuner section constitute the tuner unit 1.

21 is a DC 12V input terminal into which the DC 12V is input, 22 is a ground terminal, and 23 is a charging power input terminal into which the charging power is input, and each of these input terminals is connected to each of the output terminals in a corresponding manner.
S ₂ and S ₃ are first and second changeover switches that are switched in conjunction with the engagement and separation of the tuner unit 1, and one contact C of the first changeover switch S ₂ is connected to the DC12V input terminal 21. . 24 is a rechargeable battery connected to the other contact d of the first changeover switch _S2 , _S4 is a second power switch connected to the first changeover switch _S2 , and one contact g is connected to the VTR circuit 2.
5 is connected, and the second changeover switch _S3 is connected to the other contact h. T ₁ said on base
A first transistor to which the DC12V input terminal 21 is connected, the charging power input terminal 23 is connected to the collector, and the emitter is grounded; 26 is a heater that increases the temperature of the guide cylinder (not shown) to prevent condensation; T ₂ is the first transistor at the base
a second transistor to which the collector of _T1 is connected, the collector is connected to the charging power input terminal 23 via the heater 26, and the emitter is grounded;
T ₃ is a third transistor whose emitter is connected to the charging power input terminal 23 and whose collector is connected to the + terminal of the rechargeable battery 24; T ₄ is a third transistor whose base is connected to one contact e of the second changeover switch S ₃ ; The collector is connected to the base of the third transistor _T3 , and the emitter is grounded.These transistors constitute the VTR main body 2.

Next, the operation of the above-mentioned device will be explained. First, each output terminal 14, 16 of the tuner unit 1
When the input terminals 21, 23 and the ground terminal 22 of the VTR body 2 are connected to the ground terminal 15, the first and second changeover switches _S2 and _S3 are switched to the contacts c and e, respectively. Here, when the first and second power switches S ₁ and S ₄ are turned on by switching to contacts a and g, respectively, 12V DC, which is converted from AC input to DC, is supplied to the VTR circuit (not shown), and , is input to the base of the first transistor _T1 , turning on the first transistor and turning off the second transistor _T2 . Therefore, no current flows through the heater 26 and it does not operate. Furthermore, since the third and fourth transistors T ₃ and T ₄ are both off, charging power from the charging power input terminal 23 is not supplied to the charging battery 24 .

Next, when the second power switch _S4 is switched to the contact h side to turn it off, 12V DC is input to the base of the fourth transistor _T4 , turning on the fourth transistor and turning on the third transistor _T3. shall be. Therefore, charging power is supplied to the rechargeable battery 24 and the rechargeable battery 24 is charged. Furthermore, since the second transistor T ₂ is still off, the heater 26 also remains non-conductive.

Next, when the first power switch _S1 is switched to the contact b side to turn it off, power is not supplied to the DC12V input terminal 21, so regardless of whether the second power switch _S4 is on or off, the VTR main body 2 is DC12V is not supplied, but charging power is supplied, so the first
Since the transistor T ₁ is turned off and the second transistor T ₂ is turned on, the heater 26 is energized,
The temperature of the guide cylinder (not shown) is raised to maintain a dew-free state at all times. In this state, the third and fourth transistors T ₃ and T ₄ are both off, so no charging power is supplied to the rechargeable battery 24 .

Next, the operation when the tuner unit 1 and the VTR main body 2 are separated will be explained. When the tuner unit 1 is separated, the first and second
The changeover switches S ₂ and S ₃ are switched to the contacts d and f, respectively. Here, when the contact g side of the second power switch S ₄ is switched to the on state, the output of the rechargeable battery 24 is supplied to the VTR circuit 25 . At this time, since charging power is not supplied, the heater 26 does not operate.

Next, when the second power switch _S4 is switched to the contact h side to turn off, the output of the rechargeable battery 24 is not supplied to the VTR circuit 25 and all operations are stopped.

Therefore, when the power switch of the tuner unit is turned off with the tuner unit and the VTR body connected, that is, when the VTR is not in use, the heater is energized to keep the guide cylinder at a constant temperature, so the guide cylinder is always exposed when in use. It is in a state of no connection.

As mentioned above, according to the present invention, a portable VTR
In order to obtain power for the heater that prevents dew condensation on the guide cylinder from the charging power line, there is no need to provide a power supply section for the heater in the AC power adapter or the tuner unit that has a built-in AC power adapter. Since the rechargeable battery is not charged and the heater is not energized at the same time, the current consumption of the power transformer does not increase, and the AC power adapter can be made smaller. Furthermore, since the AC power adapter or tuner unit is connected to the VTR body using only three lines: the DC12V line, the charging power line, and the ground line, the configuration is simple and practical, reducing costs. .

[Brief explanation of drawings]

The drawing is a schematic circuit diagram of an embodiment of the present invention. Explanation of main drawing numbers, 13... Constant voltage DC power supply, 2
4...Rechargeable battery, 26...Heater, _S1 , _S4 ...First and second power switches, _S2 , _S3 ...First and second changeover switches, _T1 , _T2 , _T3 , T ₄ ... 1st, 2nd,
third and fourth transistors;

Claims (1)

[Scope of utility model registration request] In a video tape recorder in which the video tape recorder main body and the AC power supply section can be connected and separated,
The AC power supply section includes a constant voltage DC power source and a first power switch that controls turning on of the constant voltage DC power source.
A charging source, a constant voltage DC power output terminal, a charging source output terminal, and a ground terminal are provided, and the video tape recorder main body is provided with input terminals corresponding to the respective terminals, and charging is performed by the charging source. a selector switch that selects the constant voltage DC power supply output or the rechargeable battery output in conjunction with the connection or disconnection of the AC power supply section; and a switch connected to the selector switch and connected to the video tape recorder circuit a second power switch for controlling the power supply of the battery, and a heater operated by the charging source;
When connecting the AC power supply, turn on the first power switch,
By shutting off the second power switch, the rechargeable battery is charged by the charging source, and by shutting off the first power switch, the heater is operated by the charging source. By turning on the first and second power switches, the constant voltage DC power supply is supplied to the video tape recorder circuit, and the
A power supply device for a video tape recorder, characterized in that when the AC power source is disconnected, the rechargeable battery output is supplied to the video tape recorder circuit by turning on the second power switch.