JP3297451B2 - Strobe device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulated gate bipolar transistor which controls the light emitting operation of a flash tube in series with the flash tube.
r; G. FIG. B. T. In particular, the present invention relates to a strobe device having a feature in a voltage supply system to the flash discharge tube, which is effective when emitting light at high speed repeatedly.

[0002]

2. Description of the Related Art Conventionally, the I.D. G. FIG. B. T.
Japanese Patent Application Laid-Open No. 64-170
The device disclosed in Japanese Patent Publication No. 33 is well known.

[0003] As shown in FIG.
A DC high-voltage power supply 1 which is a C-DC converter circuit; a main capacitor 2 charged by the power supply 1; a constant voltage circuit 3 provided in parallel with the power supply 1 to supply a constant voltage to a light emission control circuit 7 described later; A known trigger circuit 4, which is connected to a control means 8 in the camera body, and which sends and receives various signals and generates various output signals such as a trigger signal for operating the trigger circuit 4; I. connected in series to the flash discharge tube 5 G. FIG. B. T. A flash control circuit 7 for controlling on / off of the flash discharge tube 5 to control light emission of the flash discharge tube 5 and a voltage doubler circuit 9 for applying a double voltage of the charging voltage of the main capacitor 2 to the flash discharge tube 5. ing.

When the switch Sw is turned on in the above apparatus, the DC high-voltage power supply 1 operates, and the main capacitor 2 and the voltage doubler capacitor 9a are charged with the high voltage output from the DC high-voltage power supply 1 as shown in the polarity. A power supply capacitor C that functions as a power supply for the control circuit 6 with the low-voltage power supply E
e is charged, and further, the capacitor 3a of the constant voltage circuit 3 is charged. Therefore, the control circuit 6 starts operating, and the light emission control circuit 7 enters a light emission preparation state.

In the state where each of the capacitors has been charged, when a light emission start signal is input from the control means 8 to the control circuit 6, the control circuit 6 operates and outputs a high level signal from the output terminal Oa to emit light. Transistor Q of control circuit 7
a, Qb are turned on.

When the transistors Qa and Qb are turned on, I.V. G. FIG. B. T. Is turned on, and the trigger circuit 4 also operates. As a result, the flash discharge tube 5 consumes the charge stored in the main capacitor 2 and emits light.

In the course of the light emission, when a light emission stop signal is input from the control means 8 to the control circuit 6, the control circuit 6 operates, and outputs a high level signal from the output terminal Ob to output the transistors Qc and Qc of the light emission control circuit 7. Turn on Qd. As a result, the transistor Qb which has been turned on until then,
I. G. FIG. B. T. Is turned off, and as a result, the flash discharge tube 5 stops emitting light.

The above operation is a basic operation of the conventional device shown in FIG.

[0009]

SUMMARY OF THE INVENTION G. FIG. B. T. A strobe device using a light emitting device is well known. Unlike a conventional device in which light emission is stopped by using a commutation capacitor, over-emission is eliminated, and high-speed repetitive light-emitting operation and downsizing of the device shape can be realized.

However, when the high-speed repetitive light emission operation is examined in detail, it still has the following problems.

That is, when the cycle of the high-speed repetitive light emission operation is a high cycle equal to or longer than a predetermined cycle, for example, a certain cycle band of several tens of Hz or more, in the configuration shown in FIG. It is conceivable that the next light emitting operation will be performed before the operation is performed. In such a case, the operation of the voltage doubler circuit 9 cannot be expected, so that the flash discharge tube 5 cannot be made to emit light, and light emission is lost. Has the following disadvantages.

More specifically, the voltage doubler 9
a indicates that the charging is started only when the cathode potential of the flash discharge tube 5 is set to the low level, in other words, that the charging is not performed while the cathode potential is at the high level, according to the circuit configuration shown in the drawing. it is obvious.

By the way, the cathode potential is set to a value corresponding to the flash discharge tube 5.
Once the light is emitted, the period until the ionization state ends and returns to the initial state even if the energy supply is stopped,
It is well known that the potential is maintained at a high potential, and the voltage doubler capacitor 9a has an appropriate charging time constant.
If the next light emitting operation is performed during the above-described period or at the time when the time constant has not elapsed even after the elapse of the above-described period, the charging capacitor 9a is not sufficiently charged, As a result, the operation of the voltage doubler 9 cannot be expected.

In the case of an extremely high period exceeding a certain period band, the operation for the next light emission is performed when the flash discharge tube 5 can emit light without being triggered. Therefore, it is well known that the flash discharge tube 5 emits light very easily, and does not cause the light emission omission described above.

On the other hand, in order to reduce the size of the flash discharge tube and increase the amount of emitted light, a method of increasing the internal gas pressure and increasing the impedance is well known. It is known that the starting voltage rises. In addition, considering the high-speed repetitive light emission operation, the heat radiation characteristic is deteriorated by miniaturization, and the heat accumulation characteristic is increased by increasing the impedance, and the light emission start voltage is further increased. In view of the above-mentioned situation, the fact that the operation of the voltage doubler circuit cannot be expected is disadvantageous to the light emission of the flash discharge tube.

The present invention has been made in consideration of the above disadvantages.
It is possible to reliably perform the next light emission operation at the time of high-speed repetition light emission operation of several tens of Hz or more ,
An object of the present invention is to provide a strobe device capable of employing a flash discharge tube having a small size and a high impedance.

[0017]

SUMMARY OF THE INVENTION A strobe device according to the present invention comprises a DC high-voltage power supply, a main capacitor connected to both ends of the DC high-voltage power supply, a flash discharge tube, a first diode and an I.D. G. FIG. B. T. Are sequentially connected in series, a first series connected body connected to both ends of the main capacitor, a first control switch element having a control pole, and a second diode are connected in series. G. FIG. B. T. And a second series-connected body connected to both ends of the series body, and one end connected to the anode of the second diode, and the other end connected via a second control switch element having a control pole. G. FIG.
B. T. , A third diode having an anode connected to the cathode of the first diode, a cathode connected to the other end of the doubler capacitor, and the second diode via the second diode. o a charging means for charging the pressure condenser, and operates in response to the supply of the light emission start signal, the first, the second control switch element
A switch control means allowed to down operation, the I. G. FIG. B.
T. The supply of the on-voltage to the control electrode of I. G. FIG.
B. T. A drive control circuit for turning on / off the
And a trigger circuit for exciting the flash discharge tube .

[0018]

Since the strobe device according to the present invention is constructed as described above, the voltage-doubler capacitor is connected to the third diode by the charging means, that is, through the third and first diodes. The other end connected to the cathode is charged via the second diode so as to have a high potential.

When the switch control means operates in response to the supply of the light emission start signal, and the first and second control switch elements are turned on, I.P. G. FIG. B. T. Is in the ON state, the charging voltage of the voltage doubler capacitor is changed to the second control switch element, I.I. G. FIG. B. T. The main capacitor and the first
The voltage is applied between the main electrodes of the flash discharge tube via the control switch element. Therefore, the voltage between the main electrodes of the flash discharge tube is controlled to a high voltage value which is about twice the charging voltage of the main capacitor.

As a result, the trigger circuit operates during the above operation, and when the flash discharge tube is excited, the flash discharge tube easily starts its light emission operation and consumes the charge of the main capacitor to emit light. I do.

On the other hand, I.I. G. FIG.
B. T. Is turned off, the discharge loop of the main capacitor and the doubler capacitor is cut off, the flash discharge tube is ionized, the light emission stops, and the doubler capacitor can be charged.

When the flash discharge tube is in an ionized state, its cathode potential becomes high. In the present invention, a third diode connecting one end of the voltage doubler capacitor and the cathode of the flash discharge tube via the first diode is used. A diode, so that the voltage-doubler capacitor is connected to the I.D. G. FIG. B. T. , The charging by the high potential of the cathode is started.

Note that this charging is performed via the flash discharge tube and the first, third, and second diodes in the ionized state, unlike the charging by the charging means, and the charging time constant is extremely reduced. It can be set smaller. That is, the doubler capacitor according to the present invention has the I.I. G. FIG. B.
T. Is turned off, charging is instantaneous. As a result, even when a high-frequency repetitive light-emitting operation is performed, the charging voltage of the voltage doubler capacitor can always be applied to the flash discharge tube, and the above-described repetitive light-emitting operation causes light emission loss. It can be realized without.

[0024]

FIG. 1 is an electric circuit diagram showing an embodiment of a strobe device according to the present invention. In FIG. 1, elements having the same reference numerals as those in FIG. 3 indicate elements having the same functions.

A main capacitor 2 is connected to both ends of a DC high-voltage power supply 1 composed of a well-known DC-DC converter circuit and a laminated power supply.

A flash discharge tube 5 is provided at both ends of the main capacitor 2.
, The first diode 12 and the I.D. G. FIG. B. T. And a first series-connected body 10 in which a series body 11 is connected in series.

I. G. FIG. B. T. Form switch control means together with an operation control circuit 20 described later. G. FIG. B. T. Is connected to the output terminal 13b of the drive control circuit 13 for controlling the conduction and non-conduction operations of the drive control circuit 13. In addition,
For example, a light emission stop signal is supplied to the input terminal 13a of the drive control circuit 13.

The drive control circuit 13 includes I.O.
G. FIG. B. T. Is turned on in response to the operation of the DC high-voltage power supply 1 and turned off when a light emission stop signal is supplied, or I. G. FIG. B.
T. Is controlled in response to a light emission start signal, that is, turned on only during a light emission operation, and turned off when a light emission stop signal is supplied.

At both ends of the series body 11, a second series connection body comprising a series connection of a transistor 15 as a first control switch element having a resistor and a control pole, which are not numbered, and a second diode 16. 14 are connected.

The voltage doubler capacitor 17 has one end connected to the anode of the second diode 16 and the other end connected to an I.V. capacitor 18 via an SCR 18 which is a second control switch element having a control pole. G. FIG. B. T. Connected to the collector. The other end of the voltage doubler capacitor 17 is connected to the first anode.
The diode 12 is connected to the cathode of the third diode 19 connected to the cathode of the flash discharge tube 5 via the diode 12.

The gate, which is the control pole of the SCR 18, forms a switch control means together with the drive control circuit 13, and operates in response to the supply of a light emission start signal to its input terminal 20a to turn on the SCR 18. It is connected to the output terminal 20b of the operation control circuit 20 that generates and outputs a voltage from the output terminal 20b.

Second diode 16 and transistor 1
5 is composed of resistors 22 and 23 , the voltage doubler capacitor 17 , the SCR 18 and the I.D. G. FIG. B. T. And a discharge circuit 21 serving as a switch control means for turning on the transistor 15 by supplying a voltage generated when the discharge loop is formed to the control electrode of the transistor 15. Have been. In addition,
Since the operation of the SCR 18 is controlled by the operation control circuit 20 which operates in response to the supply of the light emission start signal, the time of forming the discharge loop is a point in time in response to the supply of the light emission start signal. Needless to do.

The charging resistor 25 forms a charging means 24 for charging the voltage doubler capacitor 17 via the second diode 16.

Further, a trigger capacitor 27 and a trigger transformer 28 are provided.
G. FIG. B. T. Trigger capacitor 27 by turning on
Trigger circuit 26 that excites flash discharge tube 5 by discharging through SCR 18, trigger transformer 28, etc.
Are SCR18 and I. G. FIG. B. T. Are connected to both ends of a series body consisting of

Hereinafter, the operation of the embodiment of the flash device according to the present invention shown in FIG. 1 will be described in detail. It is assumed that the drive control circuit 13 employs a circuit based on the former of the two control methods described above.

When the DC high-voltage power supply 1 starts operating by turning on an appropriate power switch (not shown), the main capacitor 2 is charged to the indicated polarity by the high DC voltage output between its output terminals. At the same time, the drive control circuit 13 becomes active in response to the start of the operation of the DC high-voltage power supply 1, and I.P. G. FIG. B. T. Is output, so that at this point, I.V. G. FIG.
B. T. Is brought into the conduction preparation state.

At the same time, the charging of the doubler capacitor 17 and the trigger capacitor 27 to the illustrated polarity, that is, the terminal connected to the cathode of the flash discharge tube 5 via the first and third diodes 12 and 19 becomes high. The charging to the potential is performed via the charging resistor 25 and the second diode 16 as the charging means 24 or the charging resistor 25 and the trigger transformer 28, respectively.

When a light emission start signal is supplied to the input terminal 20a of the operation control circuit 20 at an appropriate point in time when the main capacitor 2 and the like are charged, the operation control circuit 20 operates, and the output terminal 20b of the operation control circuit 20 operates. The ON voltage of the SCR 18 is output and supplied to the gate of the SCR 18. Therefore, this SCR 18 is G. FIG. B. T. Are turned on when the above-mentioned ON voltage is supplied, since the drive control circuit 13 is in the conductive preparation state by the operation of the drive control circuit 13.

When the SCR 18 is turned on, the charge of the trigger capacitor 27 is changed to the SCR 18, I. G. FIG. B. T. And the flash discharge tube 5 is excited by the high voltage induced in the secondary winding of the trigger transformer 28, and the flash discharge tube 5 is excited. 17 is charged by the SCR 18, I.I. G. FIG. B. T. And discharged through the discharge circuit 21.

Accordingly, the voltage drop across the resistor 22 forming the discharge circuit 21 is applied to the base, which is the control pole of the transistor 15, and this transistor 1
5 turns on.

Therefore, between the main electrodes of the flash discharge tube 5,
SCR18, I.P. G. FIG. B. T. The voltage obtained by superimposing the charging voltage of the main capacitor 2 and the voltage doubler capacitor 17 via the main capacitor 2 and the transistor 15 is applied. As a result, the flash discharge tube 5 easily starts the light emission operation, That is, light is emitted by consuming the charge of the main capacitor 2 from the time when the SCR 18 is turned on.

When an emission stop signal is supplied to the input terminal 13a of the drive control circuit 13 at an appropriate time when the flash discharge tube 5 emits light, the drive control circuit 13 sets the I.D. G. FIG. B. T.
Off.

I. G. FIG. B. T. Is turned off, the discharge current flowing through the flash discharge tube 5 is interrupted, the flash discharge tube 5 stops emitting light, and returns to the initial state through the above-described ionized state.

At the same time, the I.D.
G. FIG. B. T. And a discharge loop via the discharge circuit 21 and the like, and the I.D. G. FIG. B.
T. The discharge loop through the etc. will be interrupted,
Therefore, the voltage doubler capacitor 17 and the trigger capacitor 27 can be charged.

As a result, the loop of the main capacitor 2, the flash discharge tube 5, the first diode 12, the third diode 19, the voltage doubler capacitor 17, and the second diode 16, the main capacitor 2, the flash discharge tube 5, and the first diode Current flows through the loop of the twelfth, third diode 19, trigger capacitor 27, and trigger transformer 28, and the voltage doubler capacitor 17 and the trigger capacitor 27 are instantaneously charged.

That is, even if the flash discharge tube 5 is in an ionized state and its cathode potential is high,
7. Since the trigger capacitor 27 is charged so that the terminal of the flash discharge tube 5 connected to the cathode side has a high potential as described above, the charging operation is performed by the flash discharge. The operation is performed without any trouble from the time when the tube 5 is in the ionized state. G. FIG. B. T. Will be started at the same time as turning off.

As a result, after a very short time, the supply of the light emission stop signal to the drive control circuit 13 is stopped and the light emission start signal is again supplied to the gate of the SCR 18 in order to perform the light emission operation at a high cycle of several tens Hz or more. Even if this is the case, the voltage doubler capacitor 17 and the like are connected to the I.D. G. FIG. B. T.
Is instantaneously charged during the OFF operation of
When the CR 18 is turned on, the flash discharge tube 5 can be excited at all times, and the charge voltage of the voltage doubler capacitor 17 can be applied between the main electrodes thereof superimposed on the charge voltage of the main capacitor 2. Can be prevented.

FIG. 2 is an electric circuit diagram showing another embodiment of a strobe device according to the present invention. In the drawing, components having the same reference numerals as those in FIG. 1 indicate the same components.

As is clear from FIG. 2, this embodiment uses the operation control system of the transistor 15 which is the control switch element of the embodiment shown in FIG. 1 without using the discharging operation of the voltage doubler capacitor 17. This is an example in which the configuration is such that it operates independently in response to the supply of a light emission start signal and outputs an ON signal for turning on the transistor 15.

That is, instead of the discharge circuit 21, an input terminal 29a to which a light emission start signal is supplied, a reference power supply terminal 29b to which an appropriate reference power is applied, and the input terminal 29
a first and second transistors 30 and 3 forming a switch circuit for supplying the reference power supply to a base, which is a control electrode of the transistor 15, in response to the supply of the light emission start signal to the transistor a.
This is an example in which a gate means 29 composed of 1, resistors 32, 33, 34, 35, 36, 37 is connected. It is clear that such a gate means 29 functions as a current amplifier circuit.

The operation of the embodiment shown in FIG. 2 will be described below. As described above, the only difference from the previous embodiment is the operation control system of the transistor 15. It goes without saying that the operation such as the increase of the voltage between the main electrodes of the flash discharge tube 5 is the same as that of the previous embodiment. The drive control circuit 1
As 3, it is assumed that a circuit that responds to the DC high-voltage power supply 1 is employed as in the previous embodiment.

When the DC high-voltage power supply 1 starts operating, the main capacitor 2, the doubler capacitor 17 and the trigger capacitor 27 are charged to the polarity shown in the drawing, and the drive control circuit 13 starts operating, as in the previous embodiment. And I. G. FIG.
B. T. Is turned on.

When a light emission start signal is supplied to the input terminal 20a of the operation control circuit 20 and the input terminal 29a of the gate means 29 in a state where the main capacitor 2 and the like are charged, the operation of the operation control circuit 20 is started. By SC
R18 is turned on, and the gate means 29 also starts operating, so that the first and second transistors 30, 31 are turned on.

Therefore, as in the previous embodiment, the trigger circuit 26 is connected to the SCR 18, I.
G. FIG. B. T. Perform a well-known operation by discharge through such as,
The flash discharge tube 5 is excited.

The reference power supply terminal 29 of the gate means 29
b is supplied to the base of the transistor 15 through the second transistor 31 which is turned on, so that the transistor 15 is turned on. As a result, the charge of the voltage doubler capacitor 17 is charged. As in the previous embodiment, SCR18, I.I. G. FIG. B. T. The voltage is applied between the main electrodes of the flash discharge tube 5 via the main capacitor 2 and the like.

As a result, the voltage between the main electrodes of the flash discharge tube 5 is boosted to almost twice the charging voltage of the main capacitor 2, and the flash discharge tube 5 starts emitting light very easily. Emits light by consuming the charged electric charge.

During the light emission of the flash discharge tube 5, a light emission stop signal is supplied to the input terminal 13a of the drive control circuit 13 and the I.S. G. FIG. B. T. Is turned off, the discharge loop of the main capacitor 2, the voltage doubler capacitor 17 and the trigger capacitor 27 is cut off as in the previous embodiment, so that the flash discharge tube 5 stops emitting light and changes the ionized state described above. After returning to the initial state, the voltage doubler capacitor 17 and the trigger capacitor 27 can be charged.

As a result, a loop of the main capacitor 2, the flash discharge tube 5, the first diode 12, the third diode 19, the voltage doubler capacitor 17, and the second diode 16 and the main capacitor 2, the flash discharge tube 5, the first diode Current flows through the loop of the twelfth, third diode 19, trigger capacitor 27, and trigger transformer 28, and the voltage doubler capacitor 17 and the trigger capacitor 27 are instantaneously charged as in the previous embodiment.

That is, the charging operation of the capacitors 17 and 27 is performed at the time when the flash discharge tube 5 is in the ionized state. G. FIG. B. T. Will be performed without any trouble from the time of turning off.

As a result, I.I. G. FIG. B. T. A very short time after the OFF point of the above, the supply of the light emission stop signal to the drive control circuit 13 is stopped, and at the same time, the light emission start signal is supplied to the gate of the SCR 18;
The flash discharge tube 5 can be always excited, and the charging voltage of the voltage doubler capacitor 17 can be applied between the main electrodes thereof so as to be superimposed on the charging voltage of the main capacitor 2. Can be performed stably without light emission loss.

Although the two embodiments of the strobe device according to the present invention have been described above, in any of the embodiments, the I.V. G. FIG. B. T. As a drive control circuit 13 which employs a circuit of a type which outputs an ON voltage, a circuit of a type similar to the conventional device shown in FIG. G. FIG. B. T. Is controlled to be in an off state, and operates only during the light emission operation to control the I.V. G. FIG. B. T. It is needless to say that a circuit of a type that outputs the ON voltage may be adopted.

However, when a drive control circuit of the type described above is employed, the SCR 18 or the transistor 15
At the time of transition to the ON state. G. FIG. B. T. Is sufficiently turned on, it is said that I. G. FIG. B. T. From the viewpoint of preventing the destruction of I.I.
G. FIG. B. T. The output timing of the ON voltage of the SCR
It is preferable to precede the output timing of the ON voltage such as 18.

[0063]

The flash device according to the present invention has a doubler capacitor capable of charging the flash discharge tube at the same time as the ionization of the flash discharge tube. G. FIG. B.
T. When the flash is turned on, the charging voltage of the doubler capacitor can be applied between the main electrodes of the flash discharge tube while being superimposed on the charging voltage of the main capacitor.
The above-described high-speed repetitive light-emitting operation can be realized without occurrence of light-emission, in other words, I.I. G. FIG. B. T. Has the effect that the flash discharge tube can emit light reliably following the high-period on / off operation.

Further, since a high voltage can be stably applied between the main electrodes of the flash discharge tube, light can be emitted reliably and stably even when the flash start voltage of the flash discharge tube is high. This has the effect of adopting a flash discharge tube whose impedance has been reduced, and consequently has the effect of realizing a reduction in the size of the device and an increase in the amount of emitted light.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of a strobe device according to the present invention.

FIG. 2 is an electric circuit diagram showing another embodiment of the strobe device according to the present invention.

FIG. 3 is an electric circuit diagram showing an example of an apparatus disclosed in Japanese Patent Application Laid-Open No. Sho 64-17033.

[Explanation of symbols]

 Reference Signs List 1 DC high-voltage power supply 2 Main capacitor 5 Flash discharge tube 10 First series connected body 11 Series body 12 First diode 13 Drive control circuit 14 Second series connected body 15 Transistor 16 Second diode 17 Doubler capacitor 18 SCR 19 Third diode REFERENCE SIGNS LIST 20 operation control circuit 21 discharge circuit 22 resistance 23 resistance 24 charging means 25 charging resistance 26 trigger circuit 27 trigger capacitor 28 trigger transformer 29 gate means 30 transistor 31 transistor 32 resistance 33 resistance 34 resistance 35 resistance 36 resistance 37 resistance

Claims (3)

(57) [Claims] 1. A DC high-voltage power supply, a main capacitor connected to both ends of the DC high-voltage power supply, a flash discharge tube, a first diode, and an insulated gate bipolar transistor are sequentially arranged.
A first series connection body connected in series and connected to both ends of the main capacitor, a first control switch element having a control pole and a second diode are connected in series , and the first diode and the insulation A second series-connected body connected to both ends of the series body with the gate bipolar transistor;
A voltage-doubler capacitor having one end connected to the anode of the second diode and the other end connected to the collector of the insulated gate bipolar transistor via a second control switch element having a control pole ;
A third diode connected to the cathode, the cathode connected to the other end of the voltage doubler capacitor , charging means for charging the voltage doubler capacitor via the second diode, and a light emitting start signal Operate the first control
Switch control means for turning on the control switch element and the second control switch element, and controlling the supply of an on-voltage to the control electrode of the insulated gate bipolar transistor to turn on and off the insulated gate bipolar transistor
And a trigger circuit which operates to excite the flash discharge tube. Wherein the switch control means, an operation control circuit for supplying the on-voltage to the control electrode of the second controlled switch element operates by light emission start signal is supplied, the second control switch element and the insulated gate A discharge loop of the voltage doubler capacitor is formed via the bipolar transistor, and a voltage drop generated in the discharge loop during the discharging operation of the voltage doubler capacitor via the discharge loop is applied to the control electrode of the first control switch element. 2. The strobe device according to claim 1, further comprising a discharge circuit for supplying an ON signal. 3. An operation control circuit which operates when a light emission start signal is supplied and supplies an on-voltage to a control pole of a second control switch element, and a switch for operation.
And an input terminal of the light emission start signal with a reference power supply terminal to which the reference power is supplied is supplied, a first control switch the reference power operates in response to the supply of the light emission start signal to the input terminal 2. A flash device according to claim 1, further comprising a gate means including a switch circuit for supplying a control electrode of the element.