JP2018066746A - Electronic cassette and electronic cassette operation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic cassette and an electronic cassette operation method that can allow a short rise time after battery replacement.SOLUTION: An electronic cassette 10 comprises a main battery 19 removably attached to a battery attachment part 36, and a sub-battery 20 for supplying electric power to a bias power supply circuit 50 and the like in place of the main battery 19. A supply source controller 70 switches the supply source of the electric power from the main battery 19 to the sub-battery 20 when determining that a replacement work of the main battery 19 is started. Because the electric power is continuously supplied to the bias power supply circuit 50 and a bias voltage is seamlessly applied to a photo-electric converter 44, there is no need for stabilization of the photo-electric converter or detection of an offset-correcting image after the main power supply is turned on, thus substantially shortening a rise time TR2.SELECTED DRAWING: Figure 11

Description

  The present invention relates to an electronic cassette used for radiography and a method for operating the electronic cassette.

  Electronic cassettes are widely used in medical radiography, for example, X-ray imaging. The electronic cassette has a configuration in which an image detection unit (also referred to as a flat panel detector (FPD)) that detects an X-ray image of a subject such as a patient is accommodated in a portable housing.

  The image detection unit includes, for example, a scintillator that converts X-rays into visible light and emits it, and a light detection substrate that detects visible light emitted from the scintillator and converts it into an electrical signal. A plurality of pixels are arranged two-dimensionally on the light detection substrate. A pixel generates a charge in response to visible light, a photoelectric conversion unit that accumulates the charge, and a TFT (Thin Film Transistor) that is connected to the photoelectric conversion unit and reads out the charge accumulated in the photoelectric conversion unit. It is comprised with a switching element. A bias voltage is applied to the photoelectric conversion unit from a bias power supply circuit.

  As described in Patent Document 1, the electronic cassette includes a wireless communication unit that wirelessly communicates with an external device such as a control device that controls the operation of the electronic cassette, and a battery that supplies power for driving the electronic cassette. And can be used without a so-called cable. In Patent Document 1, power is supplied from a battery to each part of an electronic cassette such as a bias power supply circuit.

  As described in Patent Document 2, the battery is detachably attached to the housing. When the battery capacity is low, an operator such as a radiologist removes the battery from the housing and replaces it with a charged battery.

  Japanese Patent Application Laid-Open No. 2004-228561 describes that offset correction is performed to remove the influence of fixed pattern noise caused by the usage environment of the electronic cassette from the X-ray image. As is well known, the offset correction is performed by causing the image detection unit to detect an image in a state in which X-rays are not irradiated and using this as an offset correction image, and for offset correction from the X-ray image detected based on the X-ray transmitted through the subject This is correction processing for subtracting an image in units of pixels.

JP 2014-160046 A JP 2014-142355 A

  When the battery is removed from the housing for replacement, power is naturally not supplied to the bias power supply circuit and other components, and no bias voltage is applied to the photoelectric conversion unit. For this reason, it takes a very long start-up time after the battery is replaced and the main power supply of the electronic cassette is turned on until the radiographing ready state where X-ray imaging is possible. This is because once the application of the bias voltage is interrupted, it is necessary to re-detect the offset correction image when the application of the bias voltage is resumed. In order to accurately detect the offset correction image, This is because a considerable time is required to stabilize the operation of the photoelectric conversion unit.

  For example, if the battery is replaced during X-ray imaging, it takes a considerable amount of time to restart X-ray imaging if it takes a long time to start up, so that unnecessary stress is applied to the subject and the imaging efficiency is reduced. I was invited. Accordingly, there has been a demand for shortening the startup time when the battery is replaced.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electronic cassette and a method for operating the electronic cassette that can shorten the startup time when the battery is replaced.

  In order to achieve the above object, an electronic cassette according to the present invention includes an image detection unit having pixels for detecting a radiographic image of a subject based on radiation transmitted through the subject, and a portable housing that houses the image detection unit. A photoelectric conversion unit that constitutes pixels, generates charges in response to visible light converted from radiation, accumulates the generated charges, a bias power supply circuit that applies a bias voltage to the photoelectric conversion unit, and a housing Whether or not the replacement of the main battery has started, and a main battery for detachably mounting the main battery for supplying power to each part, a sub battery for supplying power to at least the bias power supply circuit instead of the main battery, and And a supply source control unit that switches the power supply source from the main battery to the sub-battery when the replacement work is determined to be started.

  A removal detection unit that detects whether or not the removal work for removing the main battery from the housing is started, and the supply source control unit determines that the replacement work has started when the removal detection unit detects the start of the removal work However, it is preferable to switch the supply source to the sub-battery.

  A main power switch for operating on / off of the main power supply and a first timer for measuring a first elapsed time after the main power switch is turned off, and the supply source control unit has the main power switch turned off Thereafter, the first elapsed time is maintained even when the supply of power from the main battery is continued until the first elapsed time reaches a predetermined first set time, and the removal detection unit does not detect the start of the removal operation. After the first set time is reached, it is preferable to stop the supply of power from the main battery.

  Alternatively, a main power switch for operating on / off of the main power supply is provided, and the supply source control unit determines that the replacement work has started when the main power switch is turned off, and switches the supply source to the sub battery. preferable.

  The supply source control unit includes a second timer for measuring a second elapsed time after the supply source is switched to the sub battery, and the supply source control unit until the second elapsed time reaches a predetermined second set time. It is preferable that the supply of power from the sub-battery is continued during the period, and the supply of power from the sub-battery is stopped when the second elapsed time reaches the second set time.

  The supply source control unit preferably switches the supply source to the main battery when the main power source is turned on while supplying power from the sub-battery.

  The pixel is composed of a photoelectric conversion unit, a switching element connected to the photoelectric conversion unit and for reading out electric charges, a driving circuit for driving the switching element, and a first power supply for supplying a driving voltage for the switching element to the driving circuit. And the first power supply circuit is preferably supplied with electric power from the sub-battery.

  A signal processing unit that converts charge into an image signal constituting a radiation image, and a second power supply circuit that supplies a drive voltage to the signal processing unit, and power is also supplied from the sub-battery to the second power supply circuit. preferable.

  An impact history acquisition unit having an impact detection sensor that detects an impact applied to the housing, a storage unit that stores an output of the impact detection sensor, and a storage control unit that controls storage of the output of the impact detection sensor to the storage unit; And a third power supply circuit for supplying a driving voltage to the impact history acquisition unit, and it is preferable that power is also supplied to the third power supply circuit from the sub battery.

  It is preferable to include a charging circuit that charges the sub battery with the power of the main battery.

  The operation method of the electronic cassette according to the present invention includes an image detection unit having pixels for detecting a radiographic image of a subject based on radiation transmitted through the subject, a portable housing that houses the image detection unit, and the pixels A photoelectric conversion unit that generates charges in response to visible light converted from radiation, stores the generated charges, a bias power supply circuit that applies a bias voltage to the photoelectric conversion unit, and a detachable attachment to the housing An electronic cassette operating method comprising: a main battery for supplying power to each unit; and a sub-battery for supplying power to at least the bias power supply circuit instead of the main battery, wherein the main battery is exchanged A determination step for determining whether or not it has been started, and when it is determined in the determination step that the replacement work has been started, And a supply source control step of switching the Tteri.

  According to the present invention, a sub battery for supplying power to at least a bias power supply circuit is provided in place of the main battery, separately from the main battery for detachably attaching to the housing and supplying power to each part, When it is determined that the replacement operation of the main battery is started, the power supply source is switched from the main battery to the sub battery, so that the bias voltage is applied to the photoelectric conversion unit even while the main battery is replaced. For this reason, when the main battery is replaced and the main power supply is turned on, it is not necessary to stabilize the operation of the photoelectric conversion unit and to detect the offset correction image again. Therefore, it is possible to provide an electronic cassette and a method for operating the electronic cassette that can shorten the startup time when the battery is replaced.

It is an external appearance perspective view of the electronic cassette seen from the front side. It is an external appearance perspective view of the electronic cassette seen from the back side. It is a block diagram which shows the electric constitution of an electronic cassette. It is a figure which shows the correction | amendment part which performs various correction processes, such as offset correction, with respect to an X-ray image. It is a figure which shows the outline | summary of imaging | photography preparation processing. It is a block diagram which shows an electric power feeding part. It is a figure which shows the case where electric power is supplied from a main battery. It is a figure which shows the case where electric power is supplied from a sub battery. It is a flowchart which shows operation | movement of an electronic cassette. It is a timing chart which shows operation | movement of an electronic cassette when a main battery is removed with intentions other than replacement | exchange of a main battery. It is a timing chart which shows operation | movement of an electronic cassette when a main battery is removed with the intention of replacement | exchange of a main battery. It is a figure which shows the electric power feeding part of 2nd Embodiment provided with the main power switch. It is a flowchart which shows operation | movement of the electronic cassette of 2nd Embodiment. It is a timing chart which shows operation | movement of an electronic cassette when a main power switch is turned off by intention other than replacement | exchange of the main battery of 2nd Embodiment. It is a timing chart which shows operation | movement of an electronic cassette when the main power switch is turned off with the intention of replacing the main battery of the second embodiment. It is a figure which shows the electric power feeding part of 3rd Embodiment provided with the main power switch. It is a block diagram which shows the electric constitution of the electronic cassette of 4th Embodiment provided with the impact log | history acquisition part. It is a block diagram which shows an impact log | history acquisition part. It is a figure which shows the case where electric power is supplied from the sub battery of 4th Embodiment.

[First Embodiment]
1 and 2, an electronic cassette 10 is used for medical X-ray imaging, for example, and includes an image detection unit 15, a circuit board 16, a wireless communication unit 17, a female connector 18, and a main battery. 19, a sub-battery 20, and a portable casing 21 having a rectangular parallelepiped shape for storing them.

  The housing 21 has a rectangular parallelepiped shape including a front surface 22 on which X-rays are incident, a rear surface 23 facing the front surface 22, and four side surfaces 24, 25, 26 and 27. The casing 21 is formed of, for example, a conductive resin, and also functions as an electromagnetic shield that prevents electromagnetic noise from entering the electronic cassette 10 and radiating electromagnetic noise from the electronic cassette 10 to the outside. The casing 21 has a size conforming to an international standard ISO (International Organization for Standardization) 4090: 2001, which is substantially the same as, for example, a film cassette, an IP (Imaging Plate) cassette, or a CR (Computed Radiography) cassette.

  The electronic cassette 10 is detachably set on the holder of the standing position photographing stand or the standing position photographing stand so that the X-ray source for irradiating X-rays and the front face 22 are held in a posture facing each other. Further, the electronic cassette 10 is used alone for a subject lying on the bed or a subject who cannot move by himself such as an elderly person or a sudden illness, in addition to being set on the holder of the standing photographing table or the standing photographing table. Sometimes. Further, when the casing 21 is approximately the same size as the film cassette, the IP cassette, and the CR cassette, the electronic cassette 10 can be attached to an existing photographing table for these cassettes.

  A rectangular opening is formed in the front surface 22, and a transmission plate 28 is attached to the opening. The transmission plate 28 is made of a carbon material that is lightweight, has high rigidity, and has high X-ray permeability. In addition, the casing 21 has other indicators such as an LED (Light Emitting Diode) for reporting the operation state of the electronic cassette 10 such as on / off of the main power supply, the capacity of the main battery 19, and the imaging preparation completion state. (Not shown) is provided.

The image detection unit 15 includes a scintillator 30 and a light detection substrate 31. The scintillator 30 and the light detection substrate 31 are laminated in the order of the scintillator 30 and the light detection substrate 31 when viewed from the front surface 22 side on which the X-rays enter. The scintillator 30 has a phosphor such as CsI: Tl (thallium-activated cesium iodide) or GOS (Gd ₂ O ₂ S: Tb, terbium-activated gadolinium oxysulfide), and is incident through the transmission plate 28. Is converted into visible light and emitted.

  The light detection substrate 31 detects visible light emitted from the scintillator 30 and converts it into an electrical signal. The circuit board 16 controls driving of the light detection board 31 and generates an X-ray image based on the electric signal output from the light detection board 31.

  Two wireless communication units 17 are provided, one for each of the corner where the side surface 25 and the side surface 26 intersect, and the corner where the opposite side surface 24 and side surface 27 intersect. The wireless communication unit 17 is covered with a cover 32 formed of a nonconductive material such as a resin having radio wave permeability. The wireless communication unit 17 wirelessly communicates various information such as an X-ray image with a control device (not shown) that controls the operation of the electronic cassette 10. When the wireless communication unit 17 is used, the electronic cassette 10 is driven by the power from the main battery 19 and can be used without a so-called cable.

  The female connector 18 is provided on the side surface 27. The female connector 18 is a function for wired communication with the control device. A male connector 33 is connected to the female connector 18. One end of a cable 34 for wired connection between the electronic cassette 10 and the control device is connected to the male connector 33. The other end of the cable 34 is connected to a connector (not shown) connected to the control device. The female connector 18 is covered and protected by the lid 35 when the male connector 33 is not connected, such as during use of the wireless communication function.

  The electronic cassette 10 receives not only various information but also power supply from the control device via the female connector 18. When the female connector 18 and the male connector 33 are connected, the electronic cassette 10 is driven by electric power from the control device.

  The main battery 19 is composed of a rechargeable secondary battery. The main battery 19 supplies power to each part of the electronic cassette 12 through the power feeding unit 59 (see FIG. 3). A battery mounting portion 36 to which the main battery 19 is detachably mounted is provided at the central portion of the back surface 23. FIG. 2 shows a state where the main battery 19 is attached to the battery attachment portion 36. Although not shown, the battery mounting portion 36 has a lock mechanism described in Patent Document 2 that fixes the main battery 19 to the battery mounting portion 36 to prevent the main battery 19 from falling off and release the main battery 19. A well-known dropout prevention / release mechanism such as a lock release mechanism is also provided.

  The on / off of the main power supply of the electronic cassette 10 is linked with the attachment / detachment of the main battery 19 to / from the battery mounting portion 36. Specifically, the main power supply is turned off when the main battery 19 is removed from the battery mounting portion 36, and the main power supply is turned on when the main battery 19 is mounted on the battery mounting portion 36.

  The sub battery 20 is built in the housing 21. The sub battery 20 supplies power to the bias power supply circuit 50 (see FIG. 3) and the like through the power supply unit 59 instead of the main battery 19 when the replacement work of the main battery 19 is started. The sub-battery 20 is configured by a rechargeable secondary battery as with the main battery 19. The sub-battery 20 may be composed of a rechargeable power storage element such as an electric double layer capacitor or a lithium ion capacitor in addition to the secondary battery.

  In FIG. 3, a light detection substrate 31 includes pixels 40 arranged in a two-dimensional matrix of N rows × M columns on a glass substrate (not shown), N scanning lines 41, and M signals. Line 42 is provided. The scanning lines 41 extend in the X direction along the row direction of the pixels 40 and are arranged at a predetermined pitch in the Y direction along the column direction of the pixels 40. The signal lines 42 extend in the Y direction and are arranged at a predetermined pitch in the X direction. The scanning lines 41 and the signal lines 42 are orthogonal to each other, and the pixels 40 are provided corresponding to the intersections of the scanning lines 41 and the signal lines 42. N and M are integers of 2 or more, for example, N and M≈2000. Further, the arrangement of the pixels 40 may not be a square arrangement as in this example, but may be a honeycomb arrangement.

  As is well known, each pixel 40 includes a photoelectric conversion unit 44 that generates charges (electron-hole pairs) by the incidence of visible light and accumulates them, and a TFT 45 that is a switching element. The photoelectric conversion unit 44 has a structure in which a semiconductor layer that generates electric charges and an upper electrode and a lower electrode are arranged above and below the semiconductor layer. The semiconductor layer is, for example, a PIN (p-intrinsic-n) type, and an N-type layer is formed on the upper electrode side and a P-type layer is formed on the lower electrode side. The TFT 45 has a gate electrode connected to the scanning line 41, a source electrode connected to the signal line 42, and a drain electrode connected to the lower electrode of the photoelectric conversion unit 44.

  A bias line 46 is connected to the upper electrode of the photoelectric conversion unit 44. The bias lines 46 are provided for the number of columns of the pixels 40 (for M columns) and are connected to one bus 47. The bus 47 is connected to the bias power supply circuit 50. A positive bias voltage is applied from the bias power supply circuit 50 to the upper electrode of the photoelectric conversion unit 44 through the bus line 47 and its bias line 46. Application of a positive bias voltage generates an electric field in the semiconductor layer. The photoelectric conversion unit 44 is used in a reverse bias state. Electrons of the electron-hole pairs generated in the semiconductor layer by photoelectric conversion move to the upper electrode and are absorbed by the bias line 46, and the holes move to the lower electrode and are collected as electric charges.

  The circuit board 16 is provided with the bias power supply circuit 50, the scanning circuit 55, the signal processing unit 56, the memory 57, the power supply circuit 58, the power feeding unit 59, and the control unit 60 for controlling them. ing.

  The scanning circuit 55 is connected to the end of each scanning line 41 and emits a gate pulse G (K) (K = 1 to N) for driving the TFT 45. The scanning circuit 55 corresponds to a driving circuit, and the gate pulse G (K) corresponds to a driving voltage. The control unit 60 drives the TFT 45 through the scanning circuit 55 to read out and reset (discard) the dark charge from the pixel 40 and to store the charge corresponding to the X-ray arrival dose in the pixel 40. The image detection unit 15 is caused to perform the operation and the image reading operation for reading out charges from the pixels 40.

  In the pixel reset operation and the image reading operation, the scanning circuit 55 sequentially applies the gate pulse G (K) to each scanning line 41, and the TFTs 45 connected to each scanning line 41 are sequentially turned on line by line. In the accumulation operation, the gate pulse G (K) is not applied from the scanning circuit 55, and the TFT 45 is turned off.

  The signal processing unit 56 is connected to the end of each signal line 42. The signal processing unit 56 includes an integration amplifier, a gain amplifier, a CDS (Correlated Double Sampling) circuit, a multiplexer, and an A / D (Analog-to-Digital) converter (all not shown).

  The integrating amplifier accumulates and accumulates charges inputted from the signal line 42, and outputs an analog voltage value (image signal) corresponding to the accumulated charges. The integrating amplifier has an amplifier reset switch. By turning on the amplifier reset switch, the charge accumulated in the integrating amplifier is reset (discarded). In the pixel reset operation, the charge is reset without outputting an image signal from the integrating amplifier. In the image reading operation, after an image signal corresponding to the electric charge is output from the integrating amplifier, the amplifier reset switch is turned on to reset the electric charge.

  The gain amplifier amplifies the image signal output from the integration amplifier with a predetermined gain value. The CDS circuit performs a well-known correlated double sampling process on the image signal amplified by the gain amplifier, and removes the reset noise component of the integration amplifier from the image signal. An integrating amplifier, a gain amplifier, and a CDS circuit are provided for each of the M signal lines 42.

  The multiplexer sequentially selects the CDS circuits in the first column to the M column one by one, and serially inputs the image signal output from each CDS circuit to the A / D converter. The A / D converter performs A / D conversion processing on the input image signal and outputs a digital image signal. The digital image signal output from the A / D converter is stored in the memory 57 as an X-ray image.

  The power supply circuit 58 supplies a gate pulse G (K) to the scanning circuit 55. Further, the power supply circuit 58 supplies a drive voltage to the signal processing unit 56. That is, the power supply circuit 58 corresponds to a first power supply circuit and a second power supply circuit. Although not shown, the power supply circuit 58 also supplies a drive voltage to peripheral electric circuits other than the scanning circuit 55 and the signal processing unit 56 such as the wireless communication unit 17, the memory 57, and the control unit 60.

  The batteries 19 and 20 and the removal detection unit 61 are connected to the power supply unit 59. The power supply unit 59 supplies power from the main battery 19 or the sub battery 20 to each part of the electronic cassette 10 including the bias power supply circuit 50 and the power supply circuit 58. The power supply unit 59 is a DC (Direct Current) -DC converter that converts a DC voltage from each of the batteries 19 and 20 into a voltage having a value according to a supply destination, and a voltage stabilization circuit that stabilizes the converted voltage value. Etc. Although not shown in the figure, the female connector 18 is also connected to the power supply unit 59. When the female connector 18 and the male connector 33 are connected, the power supply unit 59 connects the female connector 18 to the power connector 59. The power from the control device is received via the control device, and the power from the control device is supplied to each unit.

  The removal detection unit 61 detects whether or not a removal operation for removing the main battery 19 from the battery mounting unit 36 has been started. The removal detection unit 61 includes, for example, a micro switch or a photo sensor that detects whether or not a release operation has been performed by the operator with respect to the drop prevention / release mechanism of the battery mounting unit 36. When a release operation is performed on the drop-off prevention / release mechanism, the removal detection unit 61 outputs a detection signal indicating that the removal work has been started to the power supply unit 59.

  The control unit 60 outputs the X-ray image stored in the memory 57 to the wireless communication unit 17 or the female connector 18. The control unit 60 also receives various information from the control device that is input via the wireless communication unit 17 or the female connector 18 and performs control according to the various information. For example, the control unit 60 receives X-ray imaging conditions as various information, changes the gain value of the gain amplifier of the signal processing unit 56 according to the imaging conditions, or sets the X-ray irradiation time included in the imaging conditions. Accordingly, the start timing of the image reading operation is controlled.

  In FIG. 4, the control unit 60 includes correction units 65, 66, and 67 that perform various correction processes such as offset correction, sensitivity correction, and defective pixel correction on the X-ray image stored in the memory 57. Yes. Each of the correction units 65 to 67 reads the X-ray image by accessing the memory 57, performs various correction processes on the X-ray image, and then writes the processed X-ray image back to the memory 57.

  The offset correction unit 65 performs signal processing by subtracting the image for offset correction detected by the control unit 60 by causing the image detection unit 15 to perform an image reading operation in a state where X-rays are not irradiated, from the X-ray image in units of pixels. The fixed pattern noise caused by the individual difference of the unit 56 and the use environment of the electronic cassette 10 is removed from the X-ray image.

  The sensitivity correction unit 66 corrects variations in sensitivity of the photoelectric conversion unit 44 of each pixel 40 and variations in output characteristics of the signal processing unit 56 based on the sensitivity correction data. The defective pixel correction unit 67 linearly interpolates the pixel value of the defective pixel with the pixel value of the surrounding normal pixel 40 based on defective pixel information having an abnormal pixel value among the pixels 40 generated at the time of shipment or periodic inspection. To do. The X-ray image subjected to such correction processing is transmitted to the control device via the wireless communication unit 17 and the female connector 18. Note that the offset correction image, sensitivity correction data, and defective pixel information are stored in an internal memory (not shown) of the control unit 60 and are appropriately read out by the correction units 65 to 67 during various correction processes.

  In FIG. 5, the control unit 60 applies the bias power supply circuit 50 to the photoelectric conversion unit 44 when the main battery 19 is mounted on the battery mounting unit 36 and the main power supply of the electronic cassette 10 is turned on at the start of the medical facility. When the application of the bias voltage is interrupted, the image detection unit 15 is caused to perform shooting preparation processing. The imaging preparation process is a process for setting the electronic cassette 10 to an imaging preparation complete state in which X-ray imaging is possible, and mainly includes an operation stabilization process (photoelectric conversion unit stabilization process) of the photoelectric conversion unit 44 and an image detection unit 15. And processing for detecting an offset correction image (offset correction image detection processing).

  The photoelectric conversion unit stabilization process is for offset correction before the operation of the photoelectric conversion unit 44 is stabilized after the application of the bias voltage to the photoelectric conversion unit 44 by the bias power supply circuit 50 is restarted. If an image is detected, an offset correction image that accurately reflects the usage environment of the electronic cassette 10 is not necessarily obtained. Therefore, this is performed for the purpose of detecting an accurate offset correction image. Specifically, the photoelectric conversion unit stabilization process is a process for prohibiting the image detection process for offset correction without operating the image detection unit 15 until the operation of the photoelectric conversion unit 44 is stabilized. The photoelectric conversion unit stabilization process takes, for example, more than half the time required for the entire imaging preparation process.

  The offset correction image detection process is performed after the photoelectric conversion unit stabilization process. When the main power supply is turned on at the start of the medical facility, the offset correction image detection processing is performed because the use environment of the electronic cassette 10 may have changed since the previous offset correction image was detected. . In the offset correction image detection processing, in order to prevent dark charge components from being superimposed on the offset correction image, the image reading operation is performed after the dark charge is reset by the pixel reset operation.

  Note that the imaging preparation processing includes processing for starting the wireless communication unit 17 to establish wireless communication with the control device, initialization processing for the scanning circuit 55, the signal processing unit 56, and the memory 57, and the like. Such a process is performed in parallel with the photoelectric conversion unit stabilization process.

  In FIG. 6, the power feeding unit 59 includes a supply source control unit 70, a timer 71, and a charging circuit 72. A detection signal from the removal detection unit 61 is input to the supply source control unit 70. The supply source control unit 70 selectively switches the supply source of power to the bias power supply circuit 50, the power supply circuit 58, and the like to one of the batteries 19 and 20 in accordance with the detection signal.

  The timer 71 measures the second elapsed time TP2 (see FIGS. 10 and 11) after the supply source control unit 70 switches the power supply source to the sub battery 20. That is, the timer 71 corresponds to a second timer. When the second elapsed time TP2 reaches a predetermined second set time TS2 (see FIGS. 10 and 11), the timer 71 outputs a notification signal indicating that to the supply source control unit 70. In the second set time TS2, a sufficient time (for example, 5 minutes) from the start to the end of the replacement work of the main battery 19 is set.

  The charging circuit 72 receives power from the main battery 19 and charges the sub battery 20 with this power. The charging circuit 72 operates while the main battery 19 is mounted on the battery mounting portion 36. The charging circuit 72 stops charging the sub battery 20 when the sub battery 20 is fully charged. Although not shown, the charging circuit 72 also has a function of charging the main battery 19 with power from the control device received via the female connector 18.

  As shown in FIG. 7, when the main battery 19 is attached to the battery attachment unit 36 and the main power supply is turned on, the supply source control unit 70 sets the power supply source to the main battery 19, and the bias power supply from the main battery 19. Power is supplied to the circuit 50, the power supply circuit 58, and the like.

  Further, the supply source control unit 70 determines whether or not the replacement work of the main battery 19 has been started. When it is determined that the main battery 19 is removed and the replacement work is started, the supply source control unit 70 switches the power supply source from the main battery 19 to the sub battery 20 as shown in FIG. Power is supplied from the battery 20 to the bias power supply circuit 50, the power supply circuit 58, and the like.

  Here, when the capacity of the main battery 19 is reduced and the main battery 19 is replaced, a release operation is performed on the drop-off prevention / release mechanism of the battery mounting portion 36, and the main battery 19 is removed from the battery mounting portion 36. It is. The removed main battery 19 is charged by a dedicated charger (not shown), and another charged main battery 19 is mounted on the battery mounting portion 36. That is, the replacement work of the main battery 19 is started from a release operation to the drop-off prevention / release mechanism of the battery mounting portion 36.

  Therefore, in this embodiment, the supply source control unit 70 determines that the replacement operation of the main battery 19 is started when the release operation to the drop-off prevention / release mechanism of the battery mounting unit 36 is performed, as shown in FIG. The power supply source is switched to the sub battery 20. For this reason, for example, when the electronic cassette 10 is not used for a long time (at least longer than the second set time TS2), such as at the end of a medical facility, for example, when the main battery 19 is removed from the battery mounting portion 36, that is, the main Even when the main battery 19 is removed for the purpose other than the replacement of the battery 19, the supply source control unit 70 switches the power supply source to the sub battery 20 as shown in FIG. 8.

  The supply source control unit 70 continues to supply power from the sub-battery 20 until the second elapsed time TP2 reaches the second set time TS2 (TP2 <TS2) as shown in FIG. When the second elapsed time TP2 reaches the second set time TS2 (TP2 = TS2) and a notification signal indicating that is input from the timer 71, the supply of power from the sub-battery 20 is stopped. Further, the supply source control unit 70 supplies the main battery 19 to the battery mounting unit 36 while supplying power from the sub-battery 20, that is, until the second elapsed time TP2 reaches the second set time TS2. Is attached and the main power supply is turned on, the supply source is switched to the main battery 19 as shown in FIG.

  Next, the effect | action by the said structure is demonstrated with reference to the flowchart of FIG. 9, and the timing chart of FIG. 10, FIG. 10 shows a case where the main battery 19 is removed with an intention other than the replacement of the main battery 19, and FIG. 11 shows a case where the main battery 19 is removed with the intention of replacing the main battery 19, respectively. In the following description, the description starts from a state in which the main battery 19 is already mounted and the main power source is turned on, and each unit is operated by the power supplied from the main battery 19.

  9 to 11, the supply source control unit 70 monitors the detection signal from the removal detection unit 61 and determines whether or not the replacement operation (removal operation) of the main battery 19 has been started. . While the replacement work is not started, the power supply from the main battery 19 to each unit is continued (NO in step S100).

  When the operator performs a release operation on the drop-off prevention / release mechanism of the battery mounting unit 36, a detection signal is input from the removal detection unit 61 to the supply source control unit 70. Supply source control unit 70 receives the detection signal and determines that the replacement operation of main battery 19 has started (YES in step S100). Then, the supply source control unit 70 switches the power supply source from the main battery 19 to the sub battery 20. At the same time, the timer 71 starts measuring the second elapsed time TP2 (step S110). As a result, power is supplied from the sub-battery 20 to the bias power supply circuit 50, the power supply circuit 58, and the like (step S120).

  The power supply from the sub-battery 20 is performed when the main battery 19 is attached to the battery attachment portion 36 and the main power supply is not turned on before the second elapsed time TP2 reaches the second set time TS2 (step S130, step NO in S140 is continued until the second elapsed time TP2 reaches the second set time TS2. When electric power is supplied from the sub battery 20 and the capacity of the sub battery 20 is reduced, the sub battery 20 is charged by the electric power of the main battery 19 by the charging circuit 72.

  When the second elapsed time TP2 reaches the second set time TS2 (YES in step S130), a notification signal indicating that is output from the timer 71 to the supply source control unit 70. Then, the supply source control unit 70 stops the supply of power from the sub battery 20 (step S150). For this reason, when the main battery 19 is removed for the purpose other than the replacement of the main battery 19, the main battery 19 is mounted and the main power supply is turned on until the second elapsed time TP2 reaches the second set time TS2. If it is not turned on, no power is supplied to the bias power supply circuit 50 from either of the batteries 19 and 20, and the application of the bias voltage to the photoelectric conversion unit 44 is interrupted.

  When the main battery 19 is mounted and the main power supply is turned on with the bias voltage applied to the photoelectric conversion unit 44 being interrupted (YES in step S160), the supply source control unit 70 causes the power supply source to Is switched from the sub battery 20 to the main battery 19 (step S170), and power is supplied from the main battery 19 to the bias power supply circuit 50, the power supply circuit 58, and the like (step S180). In this case, since the application of the bias voltage to the photoelectric conversion unit 44 is interrupted, the control unit 60 performs photoelectric conversion unit stabilization processing and offset correction image detection processing (steps S190 and S200).

  If the main battery 19 is mounted and the main power supply is turned on before the second elapsed time TP2 reaches the second set time TS2, the main power supply is turned on (NO in step S130, YES in step S140), step S170 and step S180. Similarly, the supply source control unit 70 switches the power supply source from the sub battery 20 to the main battery 19 (step S210), and power is supplied from the main battery 19 to the bias power supply circuit 50, the power supply circuit 58, and the like ( Step S220).

  In this case as well, when the second elapsed time TP2 reaches the second set time TS2 (YES in step S130) and the main battery 19 is attached and the main power supply is turned on (YES in S160), power supply is performed. Originally, the sub-battery 20 is removed from the main battery 19 before the main battery 19 is removed, and after the main battery 19 is installed, the sub-battery 20 is sequentially switched to the main battery 19 again, but power is supplied to the bias power supply circuit 50. Is continued by the batteries 19 and 20, and the bias voltage is continuously applied to the photoelectric conversion unit 44 without interruption. Therefore, in this case, the photoelectric conversion unit stabilization process and the offset correction image detection process are not performed. Therefore, the start-up time TR2 shown in FIG. 11 in this case is significantly shortened compared to the start-up time TR1 shown in FIG. 10 in which the photoelectric conversion unit stabilization process and the offset correction image detection process are performed.

  Since the startup time TR2 is greatly shortened, when the main battery 19 is replaced during X-ray imaging, X-ray imaging can be resumed in a relatively short time without waiting for a long time. Therefore, unnecessary stress is not applied to the subject, and the photographing efficiency can be improved.

  Even when the main battery 19 is removed for the purpose other than the replacement of the main battery 19, the main battery 19 is mounted and the main power is turned on until the second elapsed time TP2 reaches the second set time TS2. In this case, since the photoelectric conversion unit stabilization process and the offset correction image detection process are not performed, the start-up time TR2 is greatly shortened, so that the main battery 19 is frequently removed / attached for power saving. Even in this case, there is a secondary effect that X-ray imaging can be resumed in a short time.

  Since the sub-battery 20 is used alternatively for power supply during the replacement work of the main battery 19, power supply for at least the time from the start of the replacement work of the main battery 19 to the end thereof is provided. It is enough if there is a capacity available. For this reason, compared with the main battery 19, the sub battery 20 can be made extremely small capacity and small.

  When the main battery 19 is replaced, it is a matter of course that the main battery 19 is surely removed. Therefore, if the start of the main battery 19 removal operation is detected and it is determined that the replacement operation of the main battery 19 is started, the main battery 19 is removed. Never miss the start timing of the 19 replacement work.

  After the main battery 19 is removed from the battery mounting portion 36 and the supply of power from the main battery 19 is completely interrupted, even if the power supply source is switched to the sub-battery 20 at that moment, the power supply is instantaneously interrupted. Since this occurs, the switching timing may be late. In the present embodiment, in order to prevent such a momentary interruption of power supply, the start of the removal work of the main battery 19 is detected, and the power supply source is changed to the sub battery 20 before the power supply from the main battery 19 is completely interrupted. It has been switched to.

  The second elapsed time TP2 after switching the power supply source to the sub-battery 20 is measured by the timer 71, and when the second elapsed time TP2 reaches the second set time TS2, the supply of power from the sub-battery 20 is performed. Since it is stopped, waste of electric power can be suppressed.

The timer 71 may not be provided. When the timer 71 is not provided, the time until the sub battery 20 is charged by the charging circuit 72 only when the capacity of the sub battery 20 becomes zero and the capacity becomes zero from the fully charged state is the second set time. The sub battery 20 having a capacity that matches that of the TS 2 is used, and the sub battery 20 may serve as the timer 71.
[Second Embodiment]
In the first embodiment, the on / off of the main power supply of the electronic cassette 10 and the attachment / detachment of the main battery 19 to / from the battery mounting portion 36 are interlocked. A main power switch may be provided.

  In this case, as shown in FIG. 12, in this embodiment, in addition to the detection signal of the removal detection unit 61, an operation signal of the main power switch 80 is input to the supply source control unit 81. When the main battery 19 is replaced, first, the main power switch 80 is turned off, and then the main battery 19 is removed from the battery mounting portion 36.

  In the present embodiment, the timer 82 has a first elapsed time TP1 (see FIGS. 14 and 15) from when the main power switch 80 is turned off, in addition to the second elapsed time TP2 of the first embodiment. Keep time. That is, the timer 82 corresponds to a first timer and a second timer. When the first elapsed time TP1 reaches a predetermined first set time TS1 (see FIGS. 14 and 15), the timer 82 outputs a notification signal indicating that to the supply source control unit 81. The first set time TS1 is set to the same time as the second set time TS2 of the first embodiment or shorter than the second set time TS2.

  When the main power switch 80 is turned on, the supply source control unit 81 sets the power supply source to the main battery 19 and supplies power from the main battery 19 to the bias power supply circuit 50, the power supply circuit 58, and the like. The supply source control unit 81 continues the supply of power from the main battery 19 until the first elapsed time TP1 reaches the first set time TS1 after the main power switch 80 is turned off. Further, even when the detection signal is not input from the removal detection unit 61, the supply source control unit 81 stops the supply of power from the main battery 19 after the first elapsed time TP1 reaches the first set time TS1. .

  Furthermore, when a detection signal is input from the removal detection unit 61 before the first elapsed time TP1 reaches the first set time TS1, the supply source control unit 81 has started the replacement operation of the main battery 19 The power supply source is switched from the main battery 19 to the sub battery 20.

  Next, the operation of the present embodiment will be described with reference to the flowchart of FIG. 13 and the timing charts of FIGS. 14 shows a case where the main power switch 80 is turned off for the purpose other than the replacement of the main battery 19 as in FIG. 10. FIG. 15 shows a case where the main power switch 80 is intended for the replacement of the main battery 19 as in FIG. Each of the cases is turned off. As in the case of the description of FIGS. 9 to 11, the description starts from a state in which the main power switch 80 is already turned on and each unit is operated by the power supplied from the main battery 19.

  13 to 15, the supply source control unit 81 determines whether the main power switch 80 is turned off. In the first embodiment, when the removal operation of the main battery 19 is started, the supply source control unit 70 switches the power supply source from the main battery 19 to the sub battery 20. Even when the switch 80 is turned off (YES in step S300), the supply control unit 81 continues to supply power from the main battery 19. At the same time, the timer 81 starts measuring the first elapsed time TP1. As a result, power is continuously supplied from the main battery 19 to the bias power supply circuit 50, the power supply circuit 58, and the like (step S310).

  The supply of power from the main battery 19 is performed when the detection signal is not input from the removal detection unit 61 before the first elapsed time TP1 reaches the first set time TS1, that is, when the removal work of the main battery 19 is not started. (NO in Step S320 and Step S330) is continued until the first elapsed time TP1 reaches the first set time TS1.

  When the first elapsed time TP1 reaches the first set time TS1 (YES in step S320), a notification signal indicating that is output from the timer 82 to the supply source control unit 81. Then, the supply control unit 81 stops the supply of power from the main battery 19 (step S340). For this reason, when the main power switch 80 is turned off for the purpose other than the replacement of the main battery 19, the detection signal is input from the removal detection unit 61 until the first elapsed time TP1 reaches the first set time TS1. If not, no power is supplied to the bias power supply circuit 50 from either of the batteries 19 and 20, and the application of the bias voltage to the photoelectric conversion unit 44 is interrupted. The subsequent processing is the same as that after step S160 in the first embodiment, except that the main power-on trigger is changed from the installation of the main battery 19 to the main power switch 80 being turned on.

  When the detection signal is input from the removal detection unit 61 until the first elapsed time TP1 reaches the first set time TS1, that is, when the removal operation of the main battery 19 is started (NO in step S320, step If YES in S330, the process proceeds to step S110 of the first embodiment. That is, the supply source control unit 81 switches the power supply source from the main battery 19 to the sub battery 20, and power is supplied from the sub battery 20 to the bias power supply circuit 50, the power supply circuit 58, and the like. The subsequent processing is the same as that after step S110 of the first embodiment, except that the main power-on trigger is changed from the installation of the main battery 19 to the main power switch 80 being turned on.

  Also in the present embodiment, during the replacement work of the main battery 19, the power supply to the bias power supply circuit 50 is continued by the batteries 19 and 20, and the bias voltage to the photoelectric conversion unit 44 is continuously applied to the main power supply. Since the photoelectric conversion unit stabilization process and the offset correction image detection process after being turned on are not necessary, the startup time TR2 shown in FIG. 15 is significantly shortened compared to the startup time TR1 shown in FIG.

Further, when the main power switch 80 is turned off for the purpose other than the replacement of the main battery 19 shown in FIG. 14, the sub battery 20 does not operate. Also in this case, the use frequency of the sub-battery 20 can be reduced and deterioration of the sub-battery 20 can be suppressed as compared with the first embodiment in which the sub-battery 20 operates. Compared with the main battery 19 that can be immediately replaced with a new battery when it deteriorates, the sub battery 20 is provided in the housing 21 and cannot be easily replaced or repaired. If it is possible, troublesome maintenance such as replacement and repair of the sub-battery 20 is not required.
[Third Embodiment]
In each of the above embodiments, when it is detected that the removal work of the main battery 19 is started, it is determined that the replacement work of the main battery 19 is started. However, as in the second embodiment, the main power switch When 80 is provided, it may be determined that the replacement work of the main battery 19 has started when the main power switch 80 is turned off.

  In this case, as shown in FIG. 16, in this embodiment, only the operation signal of the main power switch 80 is input to the supply source control unit 90. The removal detection unit 61 is not provided. The timer 71 is used as in the first embodiment. The supply source control unit 90 determines that the replacement operation of the main battery 19 has been started when the main power switch 80 is turned off, and switches the power supply source to the sub battery 20. Since it is not necessary to provide the removal detection unit 61, the manufacturing cost can be reduced.

  The operation of the present embodiment is that the trigger for starting the replacement work of the main battery 19 is changed from the detection of the start of the removal work of the main battery 19 to turning on the main power switch 80, and the trigger for turning on the main power is Since only the main power switch 80 is turned on, the description is omitted because it is the same as the first embodiment.

  When the main power switch 80 is provided in the housing 21 as in the second and third embodiments, it is necessary to form an opening in the housing 21 for attaching the main power switch 80. Sex is reduced. Therefore, the main power switch 80 is not provided as in the second and third embodiments, but the main power on / off of the electronic cassette 10 and the main power to the battery mounting portion 36 are not provided as in the first embodiment. It is preferable to link the attachment and detachment of the battery 19.

  The main power switch may be an operation member provided in the casing 21 like the main power switch 80 of the second and third embodiments, or may not be provided with a dedicated operation member, and may be turned on / off from the control device. It may be software that operates by an off command.

  In each of the above embodiments, power is also supplied from the sub-battery 20 to the power supply circuit 58 that supplies the drive voltage to the peripheral electric circuits such as the scanning circuit 55, the signal processing unit 56, the memory 57, and the control unit 60. Even if the power is supplied from the sub battery 20 to the power supply circuit 50, it is not necessary to perform the photoelectric conversion unit stabilization processing and the offset correction image detection processing. Only the circuit 50 may be used.

If power is also supplied to the power supply circuit 58 from the sub-battery 20, the start-up time TR2 can be further shortened. However, the sub-battery 20 is increased in capacity and enlarged accordingly. If the supply destination is narrowed down to the bias power supply circuit 50, the sub battery 20 can be further reduced in size and reduced in size.
[Fourth Embodiment]
When the electronic cassette 10 is carried alone from the shooting room where the standing-up or stand-up shooting stand is installed to the patient room where the subject is located, the electronic cassette 10 is accidentally dropped on the floor or hit against the wall. Sometimes. For this reason, the electronic cassette 10 detects the impact applied to the housing 21 with a sensor, and if the detected impact is excessive, the history of sensor output, time, etc. at that time is stored in the storage unit. Or has a function of displaying a warning that the electronic cassette 10 may be broken.

  In many cases, the electronic cassette 10 is dropped or hit not only when the electronic cassette 10 is carried but also when the main battery 19 is replaced. However, since the main power supply is turned off in the replacement work of the main battery 19 as described above, the replacement work of the main battery 19 is performed unless power is supplied to the sensor for detecting the impact, the storage unit for storing the history, or the like. The impact generated inside will not remain in the history. Therefore, in the present embodiment, power is supplied from the sub-battery 20 to the power supply circuit that supplies the drive voltage to the function of acquiring the history of the impact given to the casing 21.

  In FIG. 17, an impact history acquisition unit 95 is provided in the electronic cassette of the present embodiment. Similarly to the power supply circuit 58 of the first embodiment, the power supply circuit 96 supplies a driving voltage to the peripheral electric circuits such as the scanning circuit 55, the signal processing unit 56, the memory 57, and the control unit 60, and an impact history acquisition unit. The drive voltage is also supplied to 95. That is, the power supply circuit 96 corresponds to a third power supply circuit.

  In FIG. 18, the impact history acquisition unit 95 includes an impact detection sensor 100, a storage control unit 101, and a storage unit 102. The impact detection sensor 100 detects an impact applied to the housing 21. The impact detection sensor 100 includes, for example, a triaxial direction of a thickness direction of the casing 21 orthogonal to the front face 22 and the rear face 23 of the casing 21, a direction parallel to the side faces 24 and 25, and a direction parallel to the side faces 26 and 27. It is a three-axis acceleration sensor that detects acceleration. From the output of the impact detection sensor 100, it is possible to know the direction of impact and the magnitude of the impact.

  The storage control unit 101 controls storage of the output of the impact detection sensor 100 to the storage unit 102. When the output of the impact detection sensor 100 is equal to or greater than a predetermined threshold, the storage control unit 101 causes the storage unit 102 to store the history of the output of the impact detection sensor 100 and the time at that time.

  The storage control unit 101 outputs the history stored in the storage unit 102 to the control unit 60. The control unit 60 displays a warning that the electronic cassette 10 may be broken through the indicator. The history may be transmitted to the control device via the wireless communication unit 17 or the female connector 18, and a warning that the electronic cassette 10 may be broken may be displayed on the display of the control device.

  In FIG. 19, when the supply source control unit 70 determines that the replacement operation of the main battery has been started, the supply source control unit 70 switches the power supply source from the main battery 19 to the sub battery 20, and from the sub battery 20 to the bias power supply circuit 50 and the power supply circuit. Electric power is supplied to 96 or the like. As a result, the impact history acquisition unit 95 also operates when the main battery 19 is replaced. Therefore, the impact generated during the replacement work of the main battery 19 can also be left as a history.

  Like the power supply circuit 58 of the first embodiment and the power supply circuit 96 of the fourth embodiment, a common power supply circuit is used for the scanning circuit 55, the signal processing unit 56, other peripheral electric circuits, the impact history acquisition unit 95, and the like. Alternatively, a power supply circuit may be individually provided for each unit, such as for a scanning circuit and a signal processing unit.

  In each of the above embodiments, the main power supply is turned off when the main battery 19 is removed from the battery mounting portion 36 or when the main power switch 80 is operated, but the main power supply is turned on. The main power supply may be automatically turned off when there is no operation for a predetermined time.

  The image detection unit 15 is not limited to the scintillator 30 arranged on the X-ray incident side of the light detection substrate 31 as in the first embodiment, but the scintillator 30 is connected to the X-ray incidence side of the light detection substrate 31. May be arranged on the opposite side. In this case, the scintillator 30 absorbs X-rays that have passed through the light detection substrate 31 to generate visible light, and the light detection substrate 31 detects this visible light. Further, although a TFT type image detection unit is illustrated, a CMOS (Complementary Metal Oxide Semiconductor) type image detection unit may be used. Furthermore, the present invention can be applied not only to X-rays but also to electronic cassettes that take images based on other radiation such as γ rays.

DESCRIPTION OF SYMBOLS 10 Electronic cassette 15 Image detection part 19 Main battery 20 Sub battery 21 Case 36 Battery mounting part 40 Pixel 44 Photoelectric conversion part 45 TFT (switching element)
50 Bias power supply circuit 55 Scanning circuit (driving circuit)
56 Signal Processing Unit 58 Power Supply Circuit (First and Second Power Supply Circuits)
61 Detachment detection unit 65 Offset correction unit 70, 81, 90 Supply source control unit 71 Timer (first timer)
72 charging circuit 82 timer (second timer)
95 Impact history acquisition unit 96 Power supply circuit (third power supply circuit)
100 Impact detection sensor 101 Storage control unit 102 Storage unit TP1, TP2 First and second elapsed times TS1, TS2 First and second set times TR1, TR2 Start-up time

Claims (17)

An image detector having pixels for detecting a radiographic image of the subject based on radiation transmitted through the subject;
A portable housing for housing the image detection unit;
A photoelectric conversion unit that constitutes the pixel, generates charges in response to visible light converted from the radiation, and accumulates the generated charges;
A bias power supply circuit for applying a bias voltage to the photoelectric conversion unit;
A main battery that is detachably attached to the housing and supplies power to each part;
A sub battery for supplying power to the bias power supply circuit instead of the main battery;
After the main battery removal operation is started, which is an operation started before the main battery is removed and the supply of power from the main battery is completely interrupted, the power supply source is connected to the main battery from the main battery. An electronic cassette comprising a supply source control unit for switching to a sub-battery. A removal detection unit for detecting whether or not the removal work is started,
The electronic cassette according to claim 1, wherein the supply source control unit switches the supply source to the sub-battery when the removal detection unit detects the start of the removal work. A drop-off prevention and release mechanism for fixing the main battery to the casing to prevent the main battery from falling off the casing and releasing the fixing of the main battery to the casing is provided,
The removal detection unit detects whether or not a release operation for releasing the fixation of the main battery to the housing has been performed on the drop-off prevention and release mechanism, and when the release operation is performed, The electronic cassette according to claim 2, wherein the electronic cassette detects that a removal operation has started. A main power switch that turns the main power on or off according to the operation;
A first timer for measuring a first elapsed time from when the main power switch is turned off,
The supply source control unit continues supplying power from the main battery until the first elapsed time reaches a predetermined first set time after the main power switch is turned off, 4. The power supply from the main battery is stopped after the first elapsed time reaches the first set time even when the removal detection unit does not detect the start of the removal work. 5. Electronic cassette. It has a main power switch that turns the main power on or off according to the operation,
2. The electronic cassette according to claim 1, wherein the supply source control unit determines that the removal work has been started when the main power switch is turned off, and switches the supply source to the sub battery. A second timer for measuring a second elapsed time after the supply source control unit switches the supply source to the sub-battery;
The supply source control unit continues supplying power from the sub-battery until the second elapsed time reaches a predetermined second set time, and the second elapsed time is the second set time. The electronic cassette according to any one of claims 1 to 5, wherein the supply of electric power from the sub-battery is stopped when reaching the value.   The supply source control unit switches the supply source to the main battery when a main power supply is turned on while supplying power from the sub-battery. Electronic cassette according to item. The pixel includes the photoelectric conversion unit and a switching element connected to the photoelectric conversion unit for reading out charges.
A drive circuit for driving the switching element;
A first power supply circuit for supplying a driving voltage for the switching element to the driving circuit;
The electronic cassette according to claim 1, wherein power is also supplied from the sub-battery to the first power supply circuit. A signal processing unit that converts charges into image signals constituting the radiation image;
A second power supply circuit for supplying a driving voltage to the signal processing unit,
The electronic cassette according to claim 1, wherein power is also supplied to the second power supply circuit from the sub-battery.   Impact having an impact detection sensor for detecting an impact applied to the housing, a storage unit for storing the output of the impact detection sensor, and a storage control unit for controlling storage of the output of the impact detection sensor to the storage unit The electronic cassette according to claim 1, further comprising a history acquisition unit.   The electronic cassette according to claim 10, wherein power is also supplied from the sub-battery to the storage unit and the storage control unit. A third power supply circuit that supplies driving power to the impact detection sensor, the storage unit, and the storage control unit that constitute the impact history acquisition unit;
The electronic cassette according to claim 10 or 11, wherein electric power is supplied from the sub-battery to the third power supply circuit.   The storage control unit causes the storage unit to store a history based on at least one of the output of the impact detection sensor or time when the output of the impact detection sensor is equal to or greater than a predetermined threshold. 13. The electronic cassette according to any one of 12 above.   The electronic cassette according to claim 13, further comprising an indicator that displays a warning based on the history stored in the storage unit.   The electronic cassette according to claim 13, further comprising a communication unit that transmits the history stored in the storage unit to an external device.   The electronic cassette according to claim 1, further comprising a charging circuit that charges the sub battery with electric power of the main battery. An image detector having pixels for detecting a radiographic image of the subject based on radiation transmitted through the subject;
A portable housing for housing the image detection unit;
A photoelectric conversion unit that constitutes the pixel, generates charges in response to visible light converted from the radiation, and accumulates the generated charges;
A bias power supply circuit for applying a bias voltage to the photoelectric conversion unit;
A main battery that is detachably attached to the housing and supplies power to each part;
A method of operating an electronic cassette comprising a sub-battery for supplying power to the bias power supply circuit instead of the main battery,
After the main battery removal operation is started, which is an operation started before the main battery is removed and the supply of power from the main battery is completely interrupted, the power supply source is connected to the main battery from the main battery. A method of operating an electronic cassette, comprising: a supply source control step for switching to a sub-battery.

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