JP2009162491A - Radiographic image detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove an influence of a charge noise on a detection image, in a radiographic image detection device having an electric double layer capacitor. <P>SOLUTION: This radiographic image detection device has: a power receiving part for receiving power supplied from the outside; the first circuit for receiving the power from the power receiving part, and transmitting the power to a load; the second circuit for receiving the power from the power receiving part, and charging the electric double layer capacitor; the third circuit for transmitting the power charged into the electric double layer capacitor to the load; an on/off circuit for switching on/off the third circuit; and a control part for controlling the on/off circuit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radiation image detection apparatus having an 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.

  The electric double layer capacitor having such characteristics is often used in a portable device.

  A portable device having an electric double layer capacitor is connected to a charger to receive power from the charger, and sends power to the electric double layer capacitor to charge (a second circuit of the present invention). And a circuit (corresponding to the third circuit of the present invention) that sends electric power charged in the electric double layer capacitor to a load.

  Since it is desirable that the charging time is as short as possible, it takes time to charge at a constant voltage equal to the charging voltage up to a predetermined charging voltage, which is a working voltage, so charging with a constant current is often performed.

  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 risk of overcharging or insufficient charging depending on the electric double layer capacitor. To avoid this, setting corresponding to the variation It is necessary to obtain and set the voltage in advance. There is a demand for a charging method and a charging device that are not affected by variations in the characteristics of the electric double layer capacitor even when there is a characteristic change due to the above-described component variations or temperature characteristics.

On the other hand, in the radiographic image detection device having portability, not only when performing radiographic image detection by supplying power from the electric double layer capacitor in a state of being removed from the charger, but also in a state of being connected to the charger during emergency imaging A case where radiation image detection is performed while receiving power supply from a charger is assumed.
In this case, charging of the electric double layer capacitor by the second circuit and power supply from the charger to the load via the second circuit and the third circuit are performed in parallel.

For this reason, as a further problem relating to the charging of the electric double layer capacitor in the radiation imaging apparatus, when the electric double layer capacitor is charged when the radiographic image detection apparatus is in the detection state, it occurs in the second circuit. There is a problem that the charging noise is propagated to the load via the third circuit and appears as noise in the image.
Japanese Patent No. 3413527

  The present invention has been made in view of the above-described situation, and an object thereof is to eliminate the influence of charging noise on a captured image of a radiation image detection apparatus having an electric double layer capacitor.

The above-mentioned subject is achieved by realizing the following invention.
1. A power receiving unit that receives power supplied from outside;
A first circuit that receives power from the power receiving unit and sends power to a load;
A second circuit that receives power from the power receiving unit and charges the electric double layer capacitor;
A third circuit for sending power charged in the electric double layer capacitor to the load;
An ON / OFF circuit for turning ON / OFF the third circuit, and a control unit for controlling the ON / OFF circuit;
A radiation image detection apparatus comprising:
2. 2. The radiological image detection apparatus according to claim 1, wherein the control unit turns off the ON / OFF circuit when the electric double layer capacitor is charged by the second circuit.
3. The control unit turns off the ON / OFF circuit when determining that the power supply to the power receiving unit is started, and turns on the ON / OFF circuit when it determines that the power supply to the power receiving unit is stopped. 2. The radiological image detection apparatus according to item 1, wherein:
4). The second circuit includes:
The charging of the electric double layer capacitor is prohibited until the voltage between the terminals of the electric double layer capacitor is equal to or lower than a preset value after the charging of the electric double layer capacitor is completed. The radiographic image detection apparatus of any one.
5. The second circuit includes:
Start charging with a preset constant current,
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 lapse of the predetermined time, a second charging voltage is calculated,
The radiographic image detection apparatus according to any one of claims 1 to 4, wherein charging is performed with a preset constant current until a voltage at both ends of the electric double layer capacitor reaches the second charging voltage.

  According to the present invention, in a radiological image detection apparatus having an electric double layer capacitor, it is possible to suppress degradation of image quality due to noise during charging even if radiographic image detection is performed during charging.

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

  FIG. 1 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 at one corner of the upper exterior member 5, and a power receiving unit MC that is a connector for receiving power supply from the outside is provided on one side surface.

  FIG. 2 is a diagram illustrating the internal configuration of the radiation image detection apparatus D.

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

  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.

  As will be described later, the power supply unit B is a circuit (first circuit) that sends the power received by the power receiving unit MC to the control board 3 as a load, and charges the electric double layer capacitor with the power received by the power receiving unit MC. A circuit (second circuit), a circuit (third circuit) for sending electric power charged in the electric double layer capacitor to a load, an electric double layer capacitor, and the like.

  The power supply unit B is housed in a power supply unit accommodation unit 72 joined to the lower exterior member 6, and is covered and fixed by the power supply unit exterior member 70.

  Note that the power supply unit B housed in the power supply housing unit 72 is electrically connected to the control board 3 through a contact unit (not shown).

  FIG. 3 is a diagram for explaining a general charging method of an electric double layer capacitor by a constant current power source.

  FIG. 3A is a conceptual diagram of a charging circuit of the electric double layer capacitor CC using the constant current power source PS, and FIG. 3B 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. 3A 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. 3B, the length of the relaxation charge time (TV-T1) required after the charging with the constant current is finished becomes a practical problem.

  FIG. 4 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. 3, 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. 5 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. 6 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. 4, overcharge or insufficient charge occurs when there is a component variation or the like, but in the middle of charging, the target charging voltage specific to the electric double layer capacitor being used is set. Therefore, overcharging and insufficient charging due to variations in the characteristics of the electric double layer capacitor can be suppressed.

  As already described, the radiation image detection apparatus D has the power supply unit B including an electric double layer capacitor.

  The power supply unit B receives power supplied from the outside such as a charger at the power receiving unit MC and receives the power supplied from the outside to the load such as the control board 3. The second circuit that receives the power at the part MC and supplies the electric power for charging the electric double layer capacitor CC, and the electric double layer capacitor CC when driving the load without receiving power from the outside. A third circuit for supplying the power to the load.

  In the power supply unit B configured as described above, when the detection by the radiation image detection device D and the charging of the electric double layer capacitor CC are performed in parallel, the change in the charging current to the electric double layer capacitor CC becomes a load as noise. May propagate.

  Since such noise causes an image defect in the detected image, the electric double layer capacitor CC is not charged during detection, or the electric double layer capacitor CC is not detected during charging. It is desirable to do so.

  However, the interruption of charging causes a problem that the charging time of the electric double layer capacitor CC is extended, or photographing cannot be performed during charging.

  The present invention has been made to solve the above-described problems, and its purpose is to influence the detected image even if the electric double layer capacitor CC provided therein is charged during the detection of the radiation image detection apparatus D. An object of the present invention is to realize a power supply unit B that can prevent the propagation of noise.

  In particular, in the electric double layer capacitor charging method proposed in the present embodiment, when the voltage across the electric double layer capacitor reaches the first charging voltage set in advance, the charging is stopped for a certain period of time. When charging is resumed toward the second charging voltage, the image quality is particularly noticeably deteriorated.

  FIG. 7 is a block diagram of the power supply unit B of the present invention.

  The first circuit 100 converts the power supplied from the power receiving unit MC into a constant voltage by the power source PS10 and supplies the power to the control board 3 that is a load.

  The constant voltage is realized by a known technique, and is designed and manufactured based on the specifications of the supplied power and the specifications of the load.

  The second circuit 200 is a circuit in which the power supplied from the power receiving unit MC is converted to a constant voltage by the power source PS20 and supplied to the charging device A, and the electric double layer capacitor CC is charged by the charging device A with a constant current. It is the charging circuit demonstrated based on FIG.5 and FIG.6.

  The third circuit 300 is a circuit that supplies electric power stored in the electric double layer capacitor CC to a predetermined constant voltage by the power supply PS30 and then supplies the electric power to the control board 3 that is a load via an ON / OFF circuit. .

  The third circuit is provided with switches SW2 and SW3 which are ON / OFF circuits, and the contact of each switch moves in the direction of the arrow in accordance with the switching signal of the control unit 310 to switch the circuit. Do.

  For example, when the control unit 310 determines that the power supply to the power receiving unit MC is started, the control unit 310 switches the switches SW2 and SW3 from the state of the contact c-b to the state of the contact c-a. Conversely, when the control unit 310 determines that the power supply to the power receiving unit MC has been stopped, the control unit 310 switches the switches SW2 and SW3 from the state of the contact ca to the state of the contact cb.

  When the movable contacts of the switches SW2 and SW3 are in the c-a state, a predetermined constant voltage is supplied from the power source PS10 to the control board 3.

  For example, at this time, since the third circuit connected from the electric double layer capacitor CC to the control board 3 which is a load is in an off state, the second circuit generated when the electric double layer capacitor CC is charged. Is prevented from propagating to the load.

  On the other hand, the switch SW1 that controls the charging of the electric double layer capacitor CC is controlled by the control unit CT of the second circuit independently of the switches SW2 and SW3.

  That is, the switch SW1 is controlled to the state of the contact ba until the voltage at both ends of the electric double layer capacitor reaches the first charging voltage set in advance, and when the charging is stopped for a certain time thereafter, the contact bc When the charging is resumed toward the second charging voltage, the state of the contact ba is again controlled.

  When the radiation image detection device D is removed from the charger and the electric power stored in the electric double layer capacitor CC is supplied to the load, the movable contacts of the switches SW2 and SW3 are moved so as to be connected to b and c. To do.

  The electric power output from the electric double layer capacitor CC is converted to a constant voltage by the power conversion device PS30 and supplied to the control board 3 as a load.

  As described above, by controlling the third circuit of the power supply unit B, the captured image is affected even if the electric double layer capacitor CC provided inside is detected during the detection of the radiation image detection device D. Such noise propagation can be prevented.

  It is more preferable that the electric double layer capacitor CC is not charged during the detection of the radiation image detection device D. Therefore, the second circuit of the power supply unit B of the present invention is connected to both ends of the electric double layer capacitor CC. The charging frequency may be reduced by controlling the charging so as not to be performed unless the voltage becomes equal to or lower than a preset voltage.

  The above control is performed by the control unit CT of the second circuit.

  In the present embodiment, the power source PS30 is arranged on the upstream side of the ON / OFF circuit (on the side opposite to the control board 3 which is a load), but is not limited to this, and on the downstream side of the ON / OFF circuit. It is also possible to arrange.

  In this case, the power supply PS10 of the first circuit can be omitted, and the power supply PS30 can be a common power supply for the first circuit and the third circuit.

  SW2 and SW3 are switches for switching the contacts ca and cb. However, the present invention is not limited to this, and the contacts c and b are ON / OFF switches. The contacts ca are always connected. A configuration may be adopted.

It is an external view of a radiography apparatus. It is a figure explaining the internal structure of a radiography apparatus. 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 explaining the charge method which aimed at shortening of charge time. It is a figure which shows the relationship between the charging voltage V and charging time T by this invention. It is a block diagram of the charging device A by this invention. It is a power supply circuit block diagram of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Control board 100 1st circuit 200 2nd circuit 300 3rd circuit 310 Control part B Power supply part CC Electric double layer capacitor D Radiation image detection apparatus MC Power receiving part

Claims (5)

A power receiving unit that receives power supplied from outside;
A first circuit that receives power from the power receiving unit and sends power to a load;
A second circuit that receives power from the power receiving unit and charges the electric double layer capacitor;
A third circuit for sending power charged in the electric double layer capacitor to the load;
An ON / OFF circuit for turning ON / OFF the third circuit and a control unit for controlling the ON / OFF circuit;
A radiation image detection apparatus comprising: The radiographic image detection apparatus according to claim 1, wherein the control unit turns off the ON / OFF circuit when the electric double layer capacitor is charged by the second circuit. The control unit turns off the ON / OFF circuit when determining that power supply to the power receiving unit is started, and turns on the ON / OFF circuit when determining that power supply to the power receiving unit is stopped. The radiological image detection apparatus according to claim 1. The second circuit includes:
The charging of the electric double layer capacitor is prohibited until the voltage between the terminals of the electric double layer capacitor becomes equal to or lower than a preset value after the charging of the electric double layer capacitor is completed. The radiographic image detection apparatus of any one of these. The second circuit includes:
Start charging with a preset constant current,
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 lapse of the predetermined time, a second charging voltage is calculated,
The radiographic image detection apparatus according to claim 1, wherein charging is performed with a preset constant current until a voltage at both ends of the electric double layer capacitor reaches the second charging voltage.

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