JP2009153313A - Method and device for charging electric double-layer capacitor, and radiographic image detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging method and a charger in which changes in charging time due to unevenness of the electric double-layer capacitor characteristics are suppressed, and a device using the same. <P>SOLUTION: In the method for charging an electric double-layer capacitor, charge is started with a preset constant current of a first current value, the charge is stopped for a certain time when the voltage at both ends of the electric double-layer capacitor reaches a first preset charging voltage, a second charging voltage is calculated based on the first charging voltage and the voltage at both ends of the electric double-layer capacitor after passage of the certain time, and the charge is carried out with the preset constant current of the second current value until the voltage at both ends of the electric double-layer capacitor reaches the second charging voltage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for charging an electric double layer capacitor, a charging device for an electric double layer capacitor, and a radiation image detecting and photographing apparatus having the electric double layer capacitor.

  An electric double layer capacitor has many advantages such as small size, large electrostatic capacity, resistance to deterioration of the capacitor performance even after repeated charge / discharge, rapid charge / discharge, and high safety. It is used as a component for accumulating electric power in the direction.

  In general, when charging an electric double layer capacitor to a predetermined charging voltage, which is a working voltage, it takes time to charge with a constant voltage equal to the charging voltage, and therefore it is charged with a constant current.

  However, in the case of charging with a constant current, when charging is started and the potential difference between both ends of the electric double layer capacitor approaches a predetermined charging voltage, it is necessary to take measures to prevent overcharging.

  For this reason, it is possible to take a measure to continue charging at a constant voltage up to a predetermined charging voltage while decreasing the current without maintaining a constant current.

  The charging time from reaching this full current range until reaching full charge is longer than the amount of electricity charged, but it is necessary to store a sufficient amount of electricity in the electric double layer capacitor. Is.

  As a method for shortening the charging time, there is known a method for shortening the charging time to the use voltage by providing a set voltage higher than the use voltage and maintaining a constant current until approaching the set voltage. (For example, refer to Patent Document 1).

However, since there are variations in capacitance and internal resistance in the electric double layer capacitor, there is a possibility that overcharging or insufficient charging may occur depending on the electric double layer capacitor.
Japanese Patent No. 3413527

  The present invention has been made in view of the above-described situation, and an object of the present invention is to provide a charging method, a charging device, and a device applying them, which suppress overcharging and insufficient charging due to variations in characteristics of the electric double layer capacitor. Is to provide.

The above-mentioned subject is achieved by realizing the following invention.
1. In the charging method of the electric double layer capacitor,
Start charging at a preset constant current of the first current value,
When the voltage across the electric double layer capacitor reaches a preset first charging voltage, charging is stopped for a certain period of time,
Based on the first charging voltage and the voltage across the electric double layer capacitor after the fixed time has elapsed, a second charging voltage is calculated,
The electric double layer capacitor is charged with a constant current having a preset second current value until the voltage across the electric double layer capacitor reaches the second charging voltage.
2. 2. The method for charging an electric double layer capacitor according to claim 1, wherein the first current value is equal to the second current value.
3. In the electric double layer capacitor charger,
A power source for charging the electric double layer capacitor;
When the voltage across the electric double layer capacitor reaches a preset first charging voltage by charging with a preset constant current of a first current value, charging is stopped for a certain period of time, A second charging voltage is calculated based on the charging voltage of 1 and the voltage across the electric double layer capacitor after the fixed time has elapsed, and the voltage across the electric double layer capacitor is calculated as the second voltage. A control unit that controls the power supply to charge with a constant current of a second current value set in advance until the charging voltage is reached;
A charging device for an electric double layer capacitor, comprising:
4). 4. The electric double layer capacitor charging device according to claim 3, wherein the first current value and the second current value are equal.
5. A radiological image detection apparatus comprising the electric double layer capacitor charging device according to item 5 or 4.
6). 6. The radiological image detection apparatus according to claim 5, wherein the control unit decreases the first current value and the second current value based on a detection operation start signal of the radiological image detection apparatus. .

  According to the present invention, during charging, it can be set to a target charging voltage specific to the electric double layer capacitor being used, so that it is possible to suppress the effects of overcharging and insufficient charging due to variations in the characteristics of the electric double layer capacitor, and for a short time Can complete charging.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram for explaining a general charging method of an electric double layer capacitor using a constant current power source.

  FIG. 1A is a conceptual diagram of a charging circuit of an electric double layer capacitor CC using a constant current power source PS, and FIG. 1B is a charge that is a voltage across the electric double layer capacitor CC to be charged. It is a figure which shows the relationship between the voltage V and the charging time T, and the relationship between the charging current I and the charging time T.

  The power supply PS shown in FIG. 1A applies a voltage across the electric double layer capacitor CC so that the charging current I maintains a preset constant current value I1.

  When charging of the electric double layer capacitor CC is started and the voltage V at both ends thereof reaches the use voltage VV, the power supply PS starts from maintaining the constant current value I1 to avoid overcharge exceeding the use voltage VV. It works as a constant voltage power source for applying VV.

  Charging is stopped when the voltage V across the electric double layer capacitor CC reaches a predetermined charging voltage VV and a charging time TV called a relaxed charging time elapses.

  As shown in FIG. 1B, the length of the relaxation charge time (TV-T1) required after the charging with the constant current is finished becomes a practical problem.

  FIG. 2 is a diagram showing the relationship between the charging voltage V and the charging time T and the relationship between the charging current I and the charging time T according to a known technique proposed for shortening the charging time.

  As in the general example described with reference to FIG. 1, a voltage is applied to both ends of the electric double layer capacitor CC so as to maintain a preset constant current value I1.

  However, unlike the general example, the electric double layer capacitor CC is not charged so that the voltage V at both ends rising due to charging reaches the use voltage VV provided in advance, but is set higher than the use voltage VV. Until the voltage V2 is reached, the battery is overcharged with a constant current that maintains a preset constant current value I1.

  As a matter of course, the voltage V2 is set to a high voltage that does not cause inconvenience to the electric double layer capacitor.

  When charging is stopped, the voltage across the electric double layer capacitor CC drops to the working voltage VV. That is, the voltage V2 is set so that the voltage across the electric double layer capacitor CC that has undergone a voltage drop after overcharging is just the working voltage VV.

  Thus, by providing an overcharge region in which the voltage across the electric double layer capacitor CC is increased to a voltage V2 that is higher than the use voltage VV, which is the voltage at the start of use, the charging time TV is the same as described in FIG. The charging time in the example is significantly shortened compared to TV.

  However, the electric double layer capacitor CC, which is an electric component, has variations in capacitance and internal resistance.

  Therefore, if the electric double layer capacitor CC is not charged as described in FIG. 2 after grasping in advance the voltage V2 specific to the electric double layer capacitor, it cannot be fully charged, and overcharge or charge A shortage occurs.

  The present invention realizes shortening of the charging time, and even if there is a component variation (characteristic variation) of the electric double layer capacitor, it is possible to suppress overcharging and insufficient charging and to fully charge in a short time. .

  FIG. 3 is a diagram showing the relationship between the charging voltage V and the charging time T and the relationship between the charging current I and the charging time T according to the present invention. As an example, an example in which the internal resistance of the electric double layer capacitor CC is different is shown. This is a case where the dotted line has a larger internal resistance than the solid line. FIG. 4 is a block diagram of the charging device A according to the present invention.

  First, charging of the electric double layer capacitor CC is started with a preset constant current I1.

  When the voltage measuring unit VM detects that the voltage across the electric double layer capacitor CC has reached the working voltage VV, the control unit CT switches the switch circuit SW to turn off charging by the power source PS1. Each of the time T10 and the time T11 is turned off.

  When a preset time (T20-T10 or T21-T11) elapses, the control unit CT takes in the voltage across the electric double layer capacitor CC from the voltage measurement unit VM.

  The voltage measured in this manner varies as shown by a solid line V30 and a dotted line V31 depending on the capacitance of the electric double layer capacitor CC and variations in internal resistance.

  Based on the measured voltage (for example, VV-V30 or VV-V31), the control unit CT calculates a charging voltage for stopping the second charging, for example, V20 or V21 in the figure.

  The calculation formula or the calculation table is derived from experiments.

  When the calculation is completed, charging of the electric double layer capacitor CC is started again at the constant current value I1, and the charging is stopped when the voltage at both ends of the electric double layer capacitor CC reaches the calculated voltage value V20, for example. The

  When charging is stopped, the voltage V across the electric double layer capacitor CC drops to the use voltage VV and maintains the voltage VV.

  By charging the electric double layer capacitor by the method described above, the charging time TV is shortened as compared with the general charging method as shown in FIG. In addition, in the charging method shown in FIG. 2, overcharge or insufficient charge occurs when there are component variations, etc., but the target charge voltage specific to the electric double layer capacitor used is set during the charge. Therefore, overcharging and insufficient charging due to variations in the characteristics of the electric double layer capacitor can be suppressed.

  FIG. 5 is an external view of the radiation image detection apparatus D.

  The radiographic image detection apparatus D shown in the figure is called a cassette type radiographic image detection apparatus, and is widely used for radiographic image capturing.

  As shown in the figure, the cassette K of this example is composed of two main exterior members, that is, an upper exterior member 5 and a lower exterior member 6.

  A display device H and an operation button E are provided in one corner of the upper exterior member 5, and a connector MC for receiving power supply and exchanging information with an external device is provided on one side surface. It has been.

  FIG. 6 is a diagram illustrating the internal configuration of the radiation imaging apparatus D.

  Inside the cassette K are housed a radiation detection panel 1, a panel support plate 2, a control board 3, a connection cable 4, a power supply B, and the like.

  Since the upper exterior member 5 of the cassette K should not be a shield when the radiation traveling from the direction of the arrow a in the figure reaches the radiation detection panel 1, the radiation transmittance is high. In addition, a material having excellent strength, for example, a resin containing carbon fiber is employed.

  The radiation detection panel 1 includes a phosphor 11 and a photoelectric conversion unit 12.

  The phosphor 11 receives radiation incident from the direction of the arrow a in the figure and emits light according to the intensity of the received radiation. The phosphor 11 is coated with a phosphor on a resin plate.

  The photoelectric conversion unit 12 includes photoelectric conversion elements arranged in a lattice pattern on a glass plate. The photoelectric conversion unit 12 receives light emitted from the phosphor 11 and converts it into an electrical signal.

  The electrical signal output from the photoelectric conversion unit 12 is sent to the control board 3 via the connection cable 4 which is a flexible circuit board. The control board 3 is based on the electrical signal sent from the photoelectric conversion unit 12. Captured image information is generated.

  The panel support plate 2 supports the radiation detection panel 1 and the control board 3, and has flatness and rigidity necessary for maintaining the flatness of the radiation detection panel 1.

  The power supply unit B including the electric double layer capacitor and the charging device is housed in the power supply unit accommodating unit 72 joined to the lower exterior member 6 and is fixed by being covered with the power supply unit exterior member 70.

  In addition, the power supply part B accommodated in the power supply accommodating part 72 is electrically connected with the said control board 3 via a contact part (not shown).

  FIG. 7 is a block diagram of the power supply unit B of the radiation image detection apparatus D provided with the charging apparatus A according to the present invention.

  The power supplied from the outside to the power supply unit B via the connector MC is converted into a predetermined (direct current) voltage by the power supply unit PS2, and is supplied to the constant voltage power supply ST via the changeover switch SW2 and the DC-DC converter DC. Supplied.

  The electric power output from the constant voltage power supply ST is supplied to the control board 3 of the radiation image detection apparatus D.

  On the other hand, the charging device A that receives power supply from the power supply unit PS2 charges the electric double layer capacitor CC by the charging method described with reference to FIG.

  The electric power stored in the electric double layer capacitor CC is supplied to the constant voltage power supply ST via the DC-DC converter DC by switching of the changeover switch SW2 whose switching is controlled by the control unit CT of the charging device A. .

  In this case, the circuit connected from the power supply unit PS2 to the constant voltage power supply ST is cut off by the changeover of the changeover switch SW2.

  A further feature of the charging device A of the present invention is that the control unit CT receives information h indicating whether or not the radiographic image detection device D enters the detection operation from the control board 3 or not. The current value I1 of the constant current I for charging the electric double layer capacitor shown in FIG.

  For example, when the start signal of the detection operation is received, the current value I1 of the constant current I is reduced by 50% or zero.

  Such control naturally increases the charging time of the electric double layer capacitor, but noise generated by ON / OFF (abrupt current change) of the current during charging of the electric double layer capacitor propagates to the control board 3. Therefore, the problem of deterioration of image quality (for example, linear density change) can be reduced.

  When the current value I1 of the constant current I that charges the electric double layer capacitor shown in FIG. 3 is changed in response to the information h, the changed current value is determined by experiment.

  As described above, the electric double layer capacitor charging method and the electric double layer capacitor charging device according to the present invention can reduce the charging time of the electric double layer capacitor, and also due to variations in parts and characteristics of the electric double layer capacitor. Overcharging and insufficient charging can be suppressed.

  In addition, since the noise caused by charging the electric double layer capacitor is reduced during reading of the radiation image detection device D, the quality of the read image of the radiation image detection device D is prevented from being deteriorated.

It is a figure explaining the general charging method of the electric double layer capacitor by a constant current power supply. It is a figure which shows the relationship between the charging voltage by a well-known technique, and charging time. It is a figure which shows the relationship between the charging voltage by this invention, and charging time. It is a block diagram of the charging device by this invention. It is an external view of a radiographic image detection apparatus. It is a figure explaining the internal structure of a radiographic image detection apparatus. It is a block diagram of the power supply part of the radiographic image detection apparatus provided with the charging device.

Explanation of symbols

A charging device CC electric double layer capacitor CT (charging device) control unit D radiation image detection device

Claims (6)

In the charging method of the electric double layer capacitor,
Start charging at a preset constant current of the first current value,
When the voltage across the electric double layer capacitor reaches a preset first charging voltage, charging is stopped for a certain period of time,
Based on the first charging voltage and the voltage across the electric double layer capacitor after the fixed time has elapsed, a second charging voltage is calculated,
The electric double layer capacitor is charged with a constant current having a preset second current value until the voltage across the electric double layer capacitor reaches the second charging voltage. 2. The method for charging an electric double layer capacitor according to claim 1, wherein the first current value and the second current value are equal. In the electric double layer capacitor charger,
A power source for charging the electric double layer capacitor;
When the voltage across the electric double layer capacitor reaches a preset first charging voltage by charging with a preset constant current of a first current value, charging is stopped for a certain period of time, A second charging voltage is calculated based on the charging voltage of 1 and the voltage across the electric double layer capacitor after the fixed time has elapsed, and the voltage across the electric double layer capacitor is calculated as the second voltage. A control unit that controls the power supply to charge with a constant current of a second current value set in advance until the charging voltage is reached;
A charging device for an electric double layer capacitor, comprising: 4. The electric double layer capacitor charging device according to claim 3, wherein the first current value and the second current value are equal. A radiographic image detection apparatus comprising the electric double layer capacitor charging apparatus according to claim 3. 6. The radiological image detection according to claim 5, wherein the control unit decreases the first current value and the second current value based on a detection operation start signal of the radiological image detection apparatus. apparatus.

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