JPH08261759A - Time-limited lighting device for level - Google Patents

Abstract

PURPOSE: To provide a low cost and small-sized time-limited lighting device for lighting a level for a prescribed time interval in the leveling operation of a universal head and a tripod. CONSTITUTION: A MOS FET to which a CR circuit is inserted between the gate and the source is serially connected to the DC lighting circuit of an LED. When a press button switch disposed between a power source and the gate is closed, the LED is illuminated and a capacitor is simultaneously charged. As a result, even when the switch is opened, the LED continues to be illuminated until the voltage of the gate is lowered to a prescribed level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a timed illumination device for illuminating a level such as a tripod or a tripod head.

[0002]

2. Description of the Related Art When a camera, an astronomical telescope, a surveying instrument, etc. is mounted on a tripod or other pan head on which it is to be used, it is horizontal while observing the level provided on the pan head when the tripod is installed Need to issue. At night or in low light,
Lighting is provided to make it easier to observe the spirit level, but it is necessary to turn off the lighting after the installation is completed, as it interferes with the original camera work. For this reason, conventionally, two operations of lighting and extinguishing are performed, or a time switch or the like is provided, and the light is automatically extinguished after a lapse of a predetermined time from the lighting.

[0003]

[Problems to be Solved by the Invention]
The two operations of turning off the lights are troublesome, and there is a problem that the user forgets the turning off operations and wins. Moreover, when the platform is small, it is structurally difficult or expensive to incorporate a time switch or a timing device using a timing IC or the like. SUMMARY OF THE INVENTION It is an object of the present invention to solve these problems and to provide a timed illumination device that is inexpensive and easily miniaturized.

[0004]

In order to achieve the above object, a MOS field effect transistor (hereinafter referred to as "MO") is connected in series to a DC lighting circuit of a light emitting diode (hereinafter referred to as "LED").
SFET) and connect C between its gate and source.
An R circuit is inserted and a push button switch is provided between the power supply and the gate to form a timed illumination circuit.

[0005]

When the pushbutton switch is closed and a voltage is applied between the gate and the source of the MOSFET, the capacitor of the CR circuit is charged, and at the same time, a current path is formed between the drain and the source, so that the LED is turned on. Even if the switch is opened here, the above state is maintained until the capacitor is discharged and the potential of the gate drops to a certain level, and the LED is turned off when the discharge is completed. This lighting time, that is, the discharge time can be arbitrarily set by appropriately selecting the capacitor capacity or resistance of the CR circuit.

[0006]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a perspective view showing a camera platform incorporating an apparatus according to the present invention, FIG. 2 is a partial cross-sectional explanatory view of FIG. 1, and FIG. 3 is a circuit diagram of this apparatus.

FIG. 1 shows the rear surface of a small camera platform for a camera. A camera mounting portion 2 is rotatably mounted on a horizontal axis of a main body 1. The bottom portion 3 of the main body 1 is spherical and is fitted to a spherical seat of a tripod, and the level body 4 is observed and fixed to the tripod with a fastener (not shown) so that the platform body is horizontal.
FIG. 2 is a cross-sectional explanatory view showing the structure of a leveling device, in which a push button switch 5 and an LED 6 are attached to a circuit board 7, and a battery 8 and a lead wire 9 are connected to each other. In addition, 10 is a side plate of the main body, 11 is a lid of the battery housing portion, and the circuit components are housed in a recess formed in the side plate 10.

FIG. 3 shows a circuit of this device, in which a MOSFET is connected in series to an LED direct current lighting circuit composed of a battery-a resistor Ro-LED, and a resistor is provided between its gate (G) and source (S). R consisting of (R) and capacitor (C)
Insert C circuit. A push button switch (SW) is provided between the battery and the gate (G).

The operation of this device will be described below. When the push button switch (SW) is closed in the circuit of FIG.
A positive voltage is applied between the gate (G) and the source (S) of the FET to form a current path between the drain (D) and the source (S), And the DC lighting circuit of the LED are connected, and the LED lights up.

At the same time as the above, the capacitor (C) of the RC circuit
Since a voltage is applied to the gate to charge it, even if the push button switch (SW) is opened at this point, a positive voltage is still applied to the gate (G) of the MOSFET, and the current path between D and S is It is maintained and the LED remains lit. In this state, discharge proceeds through the resistance (R) of the RC circuit,
The voltage at the gate (G) of the MOSFET drops to a certain level and continues until the current path between D and S is cut off.

Since the lighting duration time of the LED by this circuit, that is, the discharge time of the capacitor (C) is determined by the capacity of the capacitor (C) or the size of the resistor (R), for example, the capacity of the capacitor is appropriately selected. By doing so, the LED lighting time can be arbitrarily determined.
By the way, the leveling work is 3 by setting the camera platform.
0 seconds is enough.

[0012]

As described above, since the timed lighting device can be made with the simplest circuit by using the MOSFET, it can be manufactured at low cost and can be easily incorporated in the small platform. . In addition, since the forward voltage (operating power supply) of the LED is about 2 volts (V) as a standard, 3 volts (V) is sufficient for the battery used. There is almost no power consumption other than the light emission of the LED, so that a timed lighting device having an extremely long life can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of a camera platform incorporating the present invention.

FIG. 2 is a cross-sectional explanatory view of a part of FIG.

FIG. 3 is a circuit diagram of the present invention.

[Explanation of symbols]

 1 Head platform 4 Level 5 Push button switch 6 Light emitting diode 7 Circuit board 8 Battery

Claims (2)

[Claims] 1. A direct current lighting circuit for a light emitting diode is connected in series with a MOS field effect transistor, a CR circuit is inserted between the gate and source, and a push button switch is provided between the power supply and the gate. The featured timed lighting device. 2. The timed illumination device according to claim 1, wherein a level such as a tripod or a platform is illuminated for a certain period of time.