JP2003303719A - Transformer and stroboscopic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a floating capacity appearing in a secondary winding. <P>SOLUTION: An electric wire 6 is wound a plurality of times of turns between both edges of the outer face 2a of a drum of a bobbin 1, to be formed into the secondary winding of a transformer. The electric wire 6 is so wound as to form a prescribed a layer space between adjacent turns in the axial direction of the drum 2 of the bobbin 1. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer and a strobe device using the transformer as a power transformer.

[0002]

2. Description of the Related Art A winding structure of a secondary winding of a transformer conventionally used as a power transformer of a strobe device will be described with reference to a sectional view of FIG.

In the figure, 1 is a bobbin. The bobbin 1 is composed of a cylindrical body portion 2 and a pair of flange portions 3 and 4 integrally formed at both ends thereof. A rod-shaped core 5 is fitted and fixed to the body 2.

Reference numeral 6 denotes an electric wire (for example, copper wire) which constitutes a secondary winding. As shown in the drawing, the secondary winding is provided between both ends of the outer peripheral surface 2a of the body portion 2, that is, the pair of flange portions 3,
The electric wire 6 is wound a plurality of times between the inner surfaces 3a and 4a of the wire 4. The winding method is indicated by arrow A in FIG.
Since a transformer used as a power transformer of a strobe device needs to generate a high voltage of about 300 V (volt), it requires a secondary winding of several hundred turns. Therefore, first, from the inner surface 3a side of the one flange portion 3 toward the inner surface 4a side of the other flange portion 4, the electric wire 6 is fed at a feed pitch substantially equal to or slightly larger than the outer diameter of the outer peripheral surface 2a of the body portion 2. To form the first layer. Next, from the inner surface 4a side of the other flange portion 4 toward the inner surface 3a side of the one flange portion 3, the electric wire 6 is superposed on the first layer of electric wire 6 and wound at a similar feed pitch to form the second layer. Form. Next, again from the inner surface 3a side of the one flange portion 3 toward the inner surface 4a side of the other flange portion 4, the second-layer electric wire 6 is stacked and the electric wire 6 is wound at the same feed pitch to form the third-layer. To form. After that, in the same manner, the electric wire 6 is laminated in multiple layers such that the fourth layer, the fifth layer, ...

[0005]

By the way, conventionally, the wire 6 is wound around the body portion 2 of the bobbin 1 at a feed pitch substantially equal to the outer diameter of the wire 6 to form a secondary winding. The electric wires 6 adjacent to each other in the axial direction of the portion 2 were in contact with or close to each other. Therefore, large stray capacitance is generated in the secondary winding. When there is a switching element such as an oscillation transistor on a circuit including a transformer, this stray capacitance causes a ringing voltage 7 in the off voltage of this switching element, as shown in FIG. If the ringing voltage 7 exceeds the rated voltage of the switching element, the switching element may be destroyed.

Therefore, the present invention is intended to provide a transformer and a strobe device capable of reducing the stray capacitance generated in the secondary winding and suppressing the influence of the stray capacitance.

[0007]

According to a first aspect of the present invention, there is provided a transformer in which an electric wire is wound a plurality of times between both ends of an outer peripheral surface of a bobbin to form a secondary winding. An electric wire forming a winding is wound around an outer peripheral surface of a bobbin body with an interval of a predetermined value or more provided between the electric wires adjacent to each other in the axial direction of the bobbin body.

According to a second aspect of the present invention, in the first aspect of the invention, the interval between the electric wires adjacent to each other in the axial direction of the body of the bobbin, the feed pitch between the adjacent electric wires, and the outer diameter of the electric wire The interval is set to 1.5 times to 2.5 times.

The invention according to claim 3 of the present application is a strobe device using the transformer according to claim 1 or 2 as a power transformer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, the transformer of the present invention is applied to the power transformer of the strobe device.

FIG. 3 is a circuit diagram showing a main configuration of the strobe device. The strobe device includes a power supply circuit 10 and a flash circuit 20.

The power supply circuit 10 includes a choke coil 11, first to fourth capacitors 12-1 to 12-4, and a primary winding 13-.
A power transformer 13 having a primary and secondary winding 13-2 and a feedback winding 13-3, an NPN type oscillation transistor 14 constituting a switching element, first and second resistors 15-1 and 15-2.
And the first and second diodes 16-1 and 16-2.

That is, the power supply circuit has a power supply voltage input terminal 3
A series circuit of the choke circuit 11 and the first capacitor 12-1 is connected between 0 and the ground terminal 31. At the connection point between the choke circuit 11 and the first capacitor 12-1, the primary winding 13- in the power transformer 13
The winding end portion of 1 is connected, the winding start portion of the primary winding 13-1 is connected to the collector of the oscillation transistor 14, and the emitter of the oscillation transistor 14 is connected to the ground terminal 31.

Further, the power supply circuit includes a first capacitor 12-1.
A series circuit of a first resistor 15-1 and a second capacitor 12-2 is connected in parallel with the. And this first
At the connection point between the resistor 15-1 and the second capacitor 12-2,
The base of the oscillating transistor 14 is connected and the cathode of the first diode 16-1 is connected.
The anode of the diode 16-1 is connected to the ground terminal 31.

In the power supply circuit, the winding start portion of the secondary winding 13-2 in the power supply transformer 13 is connected to the second diode 16
-2 anode and connect the cathode of this second diode 16-2 to the third capacitor (electrolytic capacitor) 12-3
And the negative electrode of the third capacitor 12-3 and the winding end of the secondary winding 13-2 are connected to the ground terminal 31, respectively. Further, the winding end portion of the secondary winding 13-2 and the winding start portion of the feedback winding 13-3 are connected to each other, and the winding end portion of the feedback winding 13-3 is connected to the fourth capacitor 12-4. It is connected to the base of the oscillation transistor 14 via a series circuit with the second resistor 15-2.

In the power supply circuit 10 having such a configuration, when the power supply voltage Vin is applied to the power supply voltage input terminal 30, the oscillation transistor 14 turns on. When the oscillation transistor 14 is turned on, a primary current flows in the primary winding 13-1 of the power transformer 13. As a result, a secondary voltage is induced in the secondary winding 13-2. Then, a reverse voltage is generated in the feedback winding 13-3. As a result, the oscillation transistor 14 is turned off. When the oscillation transistor 14 is turned off, the primary current stops. When the primary current stops, the secondary voltage is no longer induced, and the reverse voltage of the feedback winding 13-3 also disappears. Therefore, the oscillation transistor 14 is turned on again. After that, the oscillation transistor 14 is repeatedly turned on and off while the power supply voltage is applied to the power supply voltage input terminal Vin. As a result, the secondary voltage is charged in the third capacitor 12-3 and is stably supplied to the flash circuit 20.

On the other hand, the flash circuit 20 includes a xenon tube 21, which constitutes a stroboscopic light emitting section, a transformer winding 22 for generating a high voltage, a trigger capacitor 23, and a main capacitor 2.
4, a thyristor 25 and a resistor 26.

In other words, the flash circuit 20 is provided between the electrodes of the third capacitor 12-3, which is the output of the power supply circuit 10,
A series circuit of a resistor 26 and a thyristor 25 is connected. The thyristor 25 has its anode connected to the resistor 26,
The cathode is connected to the ground terminal 31. Also, the resistor 2
6 is connected to the thyristor 25 at the trigger capacitor 23.
, One end of the primary winding 22-1 in the transformer winding 22 is connected in series to the trigger capacitor 23, and the other end of the primary winding 22-1 is connected to the ground terminal 31. There is.

In the flash circuit 20, a xenon tube 21 and a main capacitor 24 are connected in parallel between both electrodes of the third capacitor 12-3. Reference numeral 27 is a high-voltage electrode plate arranged near the xenon tube 21. The high-voltage electrode plate 27 is connected to one end of the secondary winding 22-2 of the transformer winding 22, and the other end of the secondary winding 22-2 is connected to the ground terminal 31.

In the flash circuit 20 having such a configuration, the thyristor 25 is in the non-conducting state in the steady state of the strobe. Therefore, the power supply voltage (secondary voltage of the power supply transformer 13) supplied from the power supply circuit 10 is applied to the trigger capacitor 23 via the resistor 26, and the trigger capacitor 23 is charged. When a trigger voltage is applied to the trigger terminal T of the thyristor 25 from an optical device such as a camera, the anode and the cathode of the thyristor 25 are electrically connected at that moment. As a result, the trigger capacitor 2
3 discharges rapidly. Then, a primary current flows through the primary winding 22-1 of the transformer winding 22, and this primary current induces a high voltage in the secondary winding 22-2 of the transformer winding 22. This high voltage is applied between the high voltage electrode plate 27 and the cathode of the xenon tube 21, and the xenon tube 21 lights up. When the xenon tube 21 lights up, the discharge current is rapidly supplied from the main capacitor 24. This allows the xenon tube 21
Flashes.

The output voltage of the power supply circuit 10, which is the secondary voltage of the power supply transformer 13, is about 300 V.
The voltage of about 00V is 5000V in the transformer winding 22.
It is boosted to a high voltage of ˜7000V.

Now, the winding structure of the secondary winding 13-2 of the power transformer 13 in this embodiment will be described with reference to the sectional view of FIG. The same parts as those in FIG. 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in the figure, in this embodiment, the electric wire 6 is provided a plurality of times between both ends of the outer peripheral surface 2a of the body portion 2 of the bobbin 1, that is, between the inner surfaces 3a and 4a of the pair of flange portions 3 and 4. The secondary winding 13-2 is formed by winding the windings around the same as the conventional one, but the wire 6 adjacent to the axial direction of the body 2 of the bobbin 1 is spaced by a predetermined value or more. It is different in that it is wound around the body outer peripheral surface 2a of the bobbin 1.

Here, the interval between the electric wires 6 adjacent to each other in the axial direction of the body portion 2 of the bobbin 1 is determined by the feed pitch p of the electric wires 6.
Is an interval when set to be about 1.5 times larger than the outer diameter of the electric wire 6.

In this way, the feed pitch p of the electric wires 6 is expanded about 1.5 times the outer diameter of the electric wires 6, so that the electric wires 6 adjacent to each other in the axial direction of the body portion 2 of the bobbin 1 can be made. Since the space can be widened, the stray capacitance generated in the secondary winding 13-2 becomes small. Therefore, it is possible to prevent adverse effects on the circuit due to the stray capacitance.

For example, in a strobe device, if the secondary winding 13-2 of the power transformer 13 has a large stray capacitance, the collector,
A ringing voltage is generated in the voltage generated between the emitters.

FIG. 5 shows a conventional transformer (see FIG. 4) in which the electric wire 6 is wound around the body portion 2 of the bobbin 1 at a feed pitch substantially equal to its outer diameter to form a secondary winding (see FIG. 4). 6 is a graph showing a transition of a voltage (V) generated between a collector and an emitter when the oscillation transistor 14 is turned off when used as the power transformer 13 of the power supply circuit 10 in FIG. As shown in the figure, a large ringing voltage 7 is generated in the voltage between the collector and the emitter when the oscillation transistor 14 is turned off.
Exceeds the rated voltage of the oscillation transistor 14, the oscillation transistor 14 may be destroyed.

On the other hand, in FIG. 2, the secondary winding is constructed by winding the electric wire 6 around the body 2 of the bobbin 1 at a feed pitch of about 1.5 times the outer diameter. Transformer (Fig. 1
Is used as the power transformer 13, the collector, when the oscillation transistor 14 is turned off,
5 is a graph showing a change in voltage (V) generated between emitters. As shown in the figure, almost no ringing voltage is seen in the voltage between the collector and the emitter when the oscillation transistor 14 is turned off. Therefore, there is no possibility that the oscillation transistor 14 is destroyed due to the ringing voltage, so that the reliability can be improved.

In the above embodiment, the electric wire 6 is wound around the body 2 of the bobbin 1 at a feed pitch of about 1.5 times its outer diameter to form a secondary winding. Even if the feed pitch is set, the stray capacitance is reduced, and the same effect as that of the above-described embodiment can be obtained. However, in order to generate a high voltage of, for example, 300 V as a secondary voltage within a limited winding width between both ends of the body portion 2 of the bobbin 1, that is, between the inner surfaces 3a and 4a of the pair of flange portions 3 and 4. Requires a winding of several hundreds of turns as a secondary winding, so the feed pitch between the adjacent electric wires 6 cannot be made very wide, and the outer diameter of the electric wires 6 is 1.5 times to 2 times. It is desirable to set it to about 5 times.

The present invention can be applied not only to the transformer used as the power transformer 13 of the power supply circuit 10 in the strobe device but also to transformers in general, and has the effect of reducing the stray capacitance of the secondary winding. Is.

[0031]

As described in detail above, according to the present invention,
It is possible to provide a transformer and a strobe device that can reduce the stray capacitance generated in the secondary winding and suppress the influence of the stray capacitance.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining a winding structure of a secondary winding of a transformer that is an embodiment of the present invention.

FIG. 2 is a diagram showing an off-voltage shift graph of the oscillation transistor when the transformer having the secondary winding structure of the same embodiment is used.

FIG. 3 is a circuit diagram showing a main configuration of a strobe device.

FIG. 4 is a sectional view for explaining a winding structure of a secondary winding of a conventional transformer.

FIG. 5 is a diagram showing an off-voltage shift graph of an oscillation transistor when a transformer having a conventional secondary winding structure is used.

[Explanation of symbols]

1 ... Bobbin 2 ... Body 3, 4 ... Flange part 6 ... Electric wire 10 ... Power supply circuit 13 ... Power transformer (transformer) 14 ... Oscillation transistor (switching element) 20 ... Flash circuit 21 ... Xenon tube 22 ... Transformer winding

Claims (3)

[Claims] 1. A transformer comprising a secondary winding formed by winding an electric wire a plurality of times between both ends of an outer peripheral surface of a bobbin body, wherein the electric wire forming the secondary winding is a bobbin body. A transformer characterized in that it is wound around the outer peripheral surface of the body of the bobbin with a gap of a predetermined value or more between adjacent electric wires in the axial direction of the part. 2. The spacing between the electric wires adjacent to each other in the axial direction of the body of the bobbin is such that the feed pitch between the adjacent electric wires is 1.5 times to 2.5 times the outer diameter of the electric wires. The transformer according to claim 1, wherein the interval is a set interval. 3. A strobe device using the transformer according to claim 1 as a power transformer.