Intraoral imaging device

Abstract

To provide an oral cavity imaging device capable of suppressing increase in a temperature of an imaging part disposed in the oval cavity even when imaging is executed at a high frame rate, for example.SOLUTION: An oral cavity imaging device 1 includes an imaging part 2 for detecting a radioactive ray passing through an object in a state of being disposed in the oral cavity, and a control part 3 for controlling the imaging part 2 in a state of being disposed outside the oral cavity. The imaging part 2 includes an image sensor 22 having a plurality of pixels DA for acquiring an image of the object. In a state that power is supplied to the control part 3, the control part 3 executes supply of power to the image sensor 22 in an imaging period that the image sensor 22 executes imaging, and stops supply of power to the image sensor 22 in a stand-by period that the image sensor 22 stands by.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an intraoral imaging device. [Background technology]

[0002] An intraoral imaging device is known that includes an imaging unit that is placed inside the oral cavity and detects radiation that has passed through an object such as a tooth, and a control unit that is placed outside the oral cavity and controls the imaging unit (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5715960 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a growing demand for intraoral imaging devices such as those described above to capture images at a high frame rate (e.g., 3 fps or higher). However, there is a concern that capturing images at a high frame rate may increase the temperature of the imaging unit placed in the oral cavity.

[0005] The present invention aims to provide an intraoral imaging device that can prevent the temperature of the imaging unit placed in the oral cavity from increasing, even when imaging is performed at a high frame rate, for example. [Means for solving the problem]

[0006] The intraoral imaging device of the present invention comprises an imaging unit that detects radiation that has passed through an object when placed inside the oral cavity, and a control unit that controls the imaging unit when placed outside the oral cavity, wherein the imaging unit has an image sensor including a plurality of pixels for acquiring an image of the object, and the control unit supplies power to the image sensor during an imaging period when the image sensor is capturing an image while power is supplied to the control unit, and stops supplying power to the image sensor during a standby period when the image sensor is standby.

[0007] In this intraoral imaging device, power is supplied to the image sensor of the imaging unit during the imaging period, and power supply to the image sensor of the imaging unit is stopped during the standby period. As a result, even when imaging is performed at a high frame rate during the imaging period, heat generation in the image sensor is suppressed compared to when power is supplied to the image sensor throughout the imaging period and the standby period. Furthermore, because the control unit, which supplies power throughout the imaging period and the standby period, is located outside the oral cavity, the influence of heat generated by the control unit is less likely to affect the imaging unit. Therefore, with this intraoral imaging device, it is possible to suppress an increase in the temperature of the imaging unit located within the oral cavity, even when imaging is performed at a high frame rate, for example.

[0008] In the intraoral imaging device of the present invention, the control unit may output a drive signal to the image sensor during the imaging period and stop supplying the drive signal to the image sensor during the standby period, thereby more reliably suppressing heat generation in the image sensor and more reliably suppressing an increase in the temperature of the imaging unit.

[0009] In the intraoral imaging device of the present invention, the controller may start supplying power to the image sensor during the imaging period and then start outputting the drive signal to the image sensor, thereby suppressing an increase in load caused by simultaneously starting the supply of power to the image sensor and the output of the drive signal to the image sensor.

[0010] In the intraoral imaging device of the present invention, the control unit may output a clock signal to the image sensor during the imaging period and stop supplying the clock signal to the image sensor during the standby period, thereby more reliably suppressing heat generation in the image sensor and more reliably suppressing an increase in the temperature of the imaging unit.

[0011] In the intraoral imaging device of the present invention, the controller may start supplying power to the image sensor during the imaging period and then start outputting a clock signal to the image sensor, thereby suppressing an increase in load caused by simultaneously starting the supply of power to the image sensor and the output of the clock signal to the image sensor.

[0012] In the intraoral imaging device of the present invention, the control unit may terminate the supply of power to the image sensor when at least one of the conditions of the number of images to be taken and the image capturing time set for the imaging period is satisfied, thereby ensuring that the supply of power to the image sensor is terminated when the imaging period ends.

[0013] In the intraoral imaging device of the present invention, the image sensor may further include pixels for monitoring the radiation dose. If the pixels for monitoring the radiation are provided in a light-receiving element separate from the image sensor, for example, it would be necessary to separately control the supply of power to the light-receiving element. However, since the pixels for monitoring the radiation dose are included in the image sensor, such separate control is not necessary, and the configuration and operation of the control unit can be simplified.

[0014] In the intraoral imaging device of the present invention, the imaging unit may further include a light receiving element including pixels for monitoring the radiation dose. This can sufficiently suppress heat generation in the light receiving element, so that, for example, by constantly supplying power to the light receiving element to monitor the radiation dose and supplying power or a signal to the image sensor only when radiation is being irradiated, it is possible to reliably suppress heat generation in the image sensor. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide an intraoral imaging device that can prevent the temperature of the imaging unit placed in the oral cavity from becoming too high, even when imaging is performed at a high frame rate, for example. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a configuration diagram of an intraoral imaging system according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the imaging unit shown in FIG. [Figure 3] FIG. 2 is a block diagram of the intraoral imaging device shown in FIG. 1. [Figure 4] FIG. 4 is a circuit diagram of a pixel included in the image sensor shown in FIG. 3. [Figure 5] 4 is a flowchart of an imaging process according to the first embodiment. [Figure 6] 10 is a time chart of the first imaging process. [Figure 7] 10 is a time chart of the first imaging process. [Figure 8] 10 is a time chart of the first imaging process. [Figure 9] 10 is a flowchart of a second imaging process. [Figure 10] 10 is a time chart of the second imaging process. [Figure 11] 10 is a time chart of the second imaging process. [Figure 12] 10 is a flowchart of a third imaging process. [Figure 13] 10 is a time chart of the third imaging process. [Figure 14] 10 is a time chart of the third imaging process. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted. [Configuration of intraoral imaging system]

[0018] As shown in FIG. 1, the intraoral imaging system 100 includes an intraoral imaging device 1 and a control device 10. The intraoral imaging device 1 includes an imaging unit 2, a control unit 3, a cable 4, and a cable 5. The imaging unit 2 is disposed intraoral and detects radiation (e.g., X-rays) that has passed through an object such as a tooth. The control unit 3 is disposed extraoral and controls the imaging unit 2. The imaging unit 2 is electrically connected to the control unit 3 via the cable 4. The imaging unit 2 and the control unit 3 transmit and receive signals (i.e., communicate) via the cable 4. The control unit 3 is electrically connected to the control device 10 via the cable 5. The control unit 3 and the control device 10 transmit and receive signals (i.e., communicate) via the cable 5. The cables 4 and 5 are wired cables, such as USB (Universal Serial Bus) cables. The control device 10 is configured by a computer device such as a PC or a tablet terminal, and functions as a host controller for the control unit 3. In the intraoral imaging system 100, when radiation that has passed through the object is detected by the imaging unit 2, the electrical signal generated thereby is transmitted from the control unit 3 to the control device 10, and an image of the object (radiation transmission image) is generated by the control device 10 based on the electrical signal. [Image capture unit configuration]

[0019] As shown in FIG. 2, the imaging unit 2 has a wiring board 21, an image sensor 22, an FOP (Fiber Optical Plate) 23, a scintillator 24, and a case 25. The image sensor 22 is mounted on the wiring board 21. The image sensor 22 is, for example, a solid-state imaging element such as a CMOS image sensor. The FOP 23 is disposed on the image sensor 22. The scintillator 24 is disposed on the FOP 23. The case 25 houses the wiring board 21, the image sensor 22, the FOP 23, and the scintillator 24. Of the walls of the case 25, a wall portion 25a along the scintillator 24 is the wall portion onto which radiation is intended to be incident. An end of a cable 4 that penetrates a wall portion of the case 25 opposite to the wall portion 25a is electrically connected to the wiring board 21.

[0020] In the imaging unit 2 configured as described above, when the case 25 is placed in the oral cavity and radiation that has passed through the object passes through the wall 25a of the case 25 and enters the scintillator 24, fluorescence corresponding to the intensity of the incident radiation is emitted in the scintillator 24. When the fluorescence is guided by the FOP 23 and enters the image sensor 22, an electrical signal corresponding to the intensity of the incident fluorescence is generated in the image sensor 22 and transmitted to the control unit 3 via the cable 4. [Controller configuration]

[0021] 3, the control unit 3 includes a control circuit 31, a memory 32, a regulator 33, a drive signal generator 34, and a clock signal generator 35. The control unit 3 receives power from the control device 10 via, for example, a cable 5 (see FIG. 1). As a result, the control unit 3 drives the control circuit 31, the regulator 33, the drive signal generator 34, and the clock signal generator.

[0022] The control circuit 31 is configured by an integrated circuit such as an FPGA (field-programmable gate), a CPLD (Complex Programmable Logic Device), or a CPU (Central Processing Unit). The control circuit 31 receives various instructions (described later) from the control device 10. The control circuit 31 transmits responses to the various instructions to the control device 10. The control circuit 31 receives setting information (described later) related to imaging from the control device 10 and stores the received information in the memory 32.

[0023] The control circuit 31 transmits and receives information and the like to and from the imaging unit 2. The control circuit 31 receives an electrical signal from the imaging unit 2 and stores the received electrical signal in the memory 32. The control circuit 31 transmits the electrical signal stored in the memory 32 to the control device 10.

[0024] The control circuit 31 controls the drive signal generator 34 and each switch. Specifically, the control circuit 31 controls the generation of the drive signal S1 in the drive signal generator 34. The control circuit 31 controls the switches 33a, 34a, and 35a (described later).

[0025] The memory 32 stores information received from the control device 10 and electrical signals received from the imaging unit 2. The memory 32 stores setting information (described later) related to imaging received from the control device 10. The memory 32 stores electrical signals received from the imaging unit 2. The memory 32 may be included in the control circuit 31.

[0026] The regulator 33 converts the voltage of the supplied power (for example, 5 V) into a voltage at which the image sensor 22 can operate. The regulator 33 supplies the converted voltage to the image sensor 22. The regulator 33 has a switch 33a. The switch 33a switches the power supply from the regulator 33 to the image sensor 22 between ON and OFF. The regulator 33 may be included in the control circuit 31.

[0027] The drive signal generator 34 uses the supplied power to generate a drive signal S1. The drive signal generator 34 outputs the generated drive signal S1 to the image sensor 22. The drive signal S1 is made up of a high-level signal and a low-level signal. The drive signal generator 34 has a switch 34a. The switch 34a switches the signal supply from the drive signal generator 34 to the image sensor 22 between ON and OFF. The drive signal generator 34 may be included in the control circuit 31.

[0028] The clock signal generator 35 uses the supplied power to generate a clock signal S2. The clock signal generator 35 outputs the generated clock signal S2 to the image sensor 22. The clock signal S2 is a periodic pulse signal for driving the image sensor 22. The clock signal generator 35 has a switch 35a. The switch 35a switches ON and OFF the supply of a signal from the clock signal generator 35 to the image sensor 22. The clock signal generator 35 may be included in the control circuit 31.

[0029] The image sensor 22 of the imaging unit 2 has a plurality of imaging pixels 220A (a plurality of pixels for acquiring an image of an object) and a plurality of monitoring pixels 220B (pixels for monitoring the radiation dose). The plurality of imaging pixels 220A are arranged two-dimensionally to form a light detection region. The plurality of monitoring pixels 220B are arranged, for example, along the periphery of the plurality of imaging pixels 220A. Note that the number of monitoring pixels 220B needs to be at least one.

[0030] As shown in FIG. 4, when the imaging pixel 220A detects radiation, it converts the detected radiation into an electric charge. The imaging pixel 220A accumulates the detected electric charge. The imaging pixel 220A outputs an electric signal corresponding to the accumulated electric charge. The circuit of the imaging pixel 220A includes a readout transistor 221, a reset transistor 222, a charge accumulation control transistor 223, a charge retention transistor 224, a multiplication transistor 225, a photodiode (PD) 226, and a floating diffusion (FD) 227. The transistors used in FIG. 4 are, for example, MOS-FETs. The monitoring pixel 220B has the same configuration as the imaging pixel 220A, and therefore a description of the circuit of the imaging pixel 220A will be omitted.

[0031] In imaging pixel 220A, the anode of PD 226 is grounded. The cathode of PD 226 is connected to the source of transistor 223. The drain of transistor 223 is connected to the source of transistor 222 and the drain of transistor 224. The source of transistor 224 is connected to FD 227. The drain of transistor 222 is connected to the drain of transistor 225. FD 227 is connected to the gate of transistor 225. The source of transistor 225 is connected to the drain of transistor 221. The source of transistor 221 is connected to the output of imaging pixel 220A. Note that whether an input signal is present at the gates of transistors 221, 222, 223, and 224 is switched in response to drive signal S1 from drive signal generator 34. The state in which an input signal is present at the gate of transistor 221 corresponds to the state in which transistor 221, shown as a switch in FIG. 3, is ON. The absence of an input signal at the gate of transistor 221 corresponds to transistor 221 being OFF, shown as a switch in FIG.

[0032] The operation of the imaging pixel 220A will be described in detail. Hereinafter, a state in which an input signal is present at the gate of each transistor is defined as the transistor being in an ON state. When the imaging pixel 220A is initialized, the transistors 222, 223, and 224 are turned ON, and the transistor 221 is turned OFF. Then, the charge accumulated in the PD 226 and the FD 227 is discharged. When charge accumulation is performed in the imaging pixel 220A, the transistor 223 is turned OFF. Then, accumulation of the charge generated in the PD 226 begins. When charge accumulation in the imaging pixel 220A is completed, the transistor 222 is turned OFF, and the transistors 223 and 224 are turned ON. Then, the charge accumulated in the PD 226 is transferred to the FD 227. When the charge transfer in the imaging pixel 220A is completed, the transistor 221 is turned ON. When charge is accumulated in the FD227, the transistor 225 turns ON, and an electrical signal corresponding to the amount of charge accumulated in the FD227 is output from the imaging pixel 220A to the control circuit 31. When the output of the electrical signal in the imaging pixel 220A is completed, the transistors 222 and 224 turn ON and the transistor 223 turns OFF. The charge accumulated in the FD227 is then discharged. Note that in the imaging pixel 220A, the transistors 221 and 225 turn ON and the transistors 222, 223, and 224 turn OFF, allowing charge accumulation in the PD226 and output of the electrical signal to be performed simultaneously. Also, in the imaging pixel 220A, the transistors 222 and 224 turn ON and the transistors 221, 223, and 225 turn OFF, allowing charge accumulation in the PD226 and discharge of the charge accumulated in the FD227 to be performed simultaneously.

[0033] The functions of the control device 10 will be described. The control device 10 exchanges information with the control circuit 31. Specifically, the control device 10 supplies power to the control unit 3. The control device 10 transmits various instructions to the control circuit 31. The control device 10 receives responses to the various instructions from the control circuit 31. Here, the various instructions refer to instructions for causing the control circuit 31 to control the imaging unit 2, such as an instruction to start an imaging period T1 (described later), an instruction to wait for radiation irradiation, and an instruction to end the imaging period T1 (described later). The control device 10 also transmits setting information related to imaging to the control circuit 31. The setting information related to imaging includes, for example, the time for accumulating charge in the imaging pixels 220A (hereinafter referred to as the accumulation time), the time for reading out data from the imaging pixels 220A (hereinafter referred to as the readout time), the number of times imaging is performed in the imaging pixels 220A (hereinafter referred to as the number of imaging times), and the time for imaging in the imaging pixels 220A (hereinafter referred to as the imaging time) (details of which will be described later). The setting information regarding image capture may be set by the user or may be set by the control device 10. In this embodiment, the lengths of the accumulation time and readout time are always constant. [First imaging process]

[0034] The first imaging process will be described with reference to Figures 5 to 8. Figure 5 is a flowchart of the first imaging process. Figure 6 is a time chart at the start of the first imaging process. Figure 7 is a time chart during the first imaging process. Figure 8 is a time chart at the end of the first imaging process. Note that the radiation source in the first imaging process continuously irradiates X-rays of a constant intensity.

[0035] In the following description, the accumulation period of the imaging pixel 220A is a period during which the PD 226 of the imaging pixel 220A detects radiation, converts the detected radiation into electric charge, and accumulates the converted electric charge. The readout period of the imaging pixel 220A is a period during which electric charge is transferred from the PD 226 to the FD 227 of the imaging pixel 220A, an electrical signal is output, and the electric charge accumulated in the FD 227 is discharged. Note that the transfer of electric charge from the PD 226 to the FD 227 of the imaging pixel 220A is extremely short compared to the length of the readout period, and therefore is not shown in the following time chart. The readout period of the monitor pixel 220B is a period during which the monitor pixel 220B waits to detect radiation, and immediately outputs an electric signal to the control circuit 31 if radiation is detected.

[0036] The imaging period T1 is a period including a period during which imaging is performed a predetermined number of times at a predetermined frame rate. Imaging refers to an operation from the start of an accumulation period to the end of a readout period in a set of accumulation and readout periods.

[0037] Moreover, the waiting period T2 is the period between temporally adjacent imaging periods.

[0038] In the flowchart shown in FIG. 5, the control unit 3 is electrically connected to the control device 10 and the like, and is in a state where power is supplied from the control device 10 and the like. First, the control circuit 31 determines whether or not an instruction to start the imaging period T1 has been received from the control device 10 (step S101). If the answer is NO in step S101, the process returns to step S101. If the answer is YES in step S101, as shown in FIG. 6, the control circuit 31 starts supplying power to the image sensor 22, and the imaging period T1 starts (step S102). Specifically, first, the control circuit 31 turns on the switch 33a. Then, the regulator 33 supplies power to the image sensor 22. That is, with power being supplied to the control unit 3, the control unit 3 supplies power to the image sensor 22 during the imaging period T1 where the image sensor 22 captures an image.

[0039] 6, the control circuit 31 starts supplying the drive signal S1 to the image sensor 22 (step S103). Specifically, the control circuit 31 turns on the switch 34a. Then, the drive signal generator 34 supplies the drive signal S1 to the image sensor 22. The drive signal S1 supplied at this time is a High-level signal. That is, the control unit 3 supplies the drive signal S1 to the image sensor 22 during the imaging period T1. After starting the supply of power to the image sensor 22 during the imaging period T1, the control unit 3 starts supplying the drive signal S1 to the image sensor 22.

[0040] 6, the control circuit 31 starts supplying the clock signal S2 to the image sensor 22 (step S104). Specifically, the control circuit 31 turns on the switch 35a. Then, the clock signal generator 35 starts supplying the clock signal S2 to the image sensor 22. That is, the control unit 3 supplies the clock signal S2 to the image sensor 22 during the imaging period T1. After starting the supply of power to the image sensor 22 during the imaging period T1, the control unit 3 starts supplying the clock signal S2 to the image sensor 22.

[0041] Next, the control circuit 31 initializes the imaging pixels 220A and the monitor pixels 220B of the image sensor 22 (step S105). Specifically, the charges accumulated in the PDs 226 and FDs 227 of the imaging pixels 220A and the monitor pixels 220B are discharged. Then, as shown in FIG. 6, the control circuit 31 starts a readout period for the monitor pixels 220B. Next, the control circuit 31 determines whether the initialization of the imaging pixels 220A and the monitor pixels 220B of the image sensor 22 is completed (step S106). If the result in step S106 is NO, the process returns to step S106. If the result in step S106 is YES, the control circuit 31 transmits a notification to the control device 10 (step S107). Specifically, as shown in FIG. 6, the control circuit 31 transmits an acknowledgment to the instruction to start the imaging period T1 to the control device 10. The control device 10 transmits an instruction to wait for X-ray irradiation to the control circuit 31. When the control circuit 31 receives the standby instruction, it sends an acknowledgement to the control device 10 to acknowledge the standby instruction.

[0042] Next, the control circuit 31 determines whether a time-out has occurred (step S119). Specifically, if a predetermined time has elapsed since the control circuit 31 received the standby command, the control circuit 31 determines that a time-out has occurred. If the answer is NO in step S119, the control circuit 31 determines whether the monitor pixel 220B has detected radiation (step S108). If the answer is NO in step S108, the process returns to step S119. If the answer is YES in step S108, the control circuit 31 starts accumulation in the imaging pixel 220A (step S109), as shown in FIG. 7. Specifically, the control circuit 31 controls the drive signal generator 34 so that the waveform of the drive signal S1 is always a low-level signal. When the image sensor 22 receives the low-level signal, the control circuit 31 controls the imaging pixel 220A to perform accumulation. Next, control circuit 31 determines whether a predetermined time has elapsed since accumulation began in imaging pixel 220A (step S110). Specifically, control circuit 31 compares the accumulation time stored in memory 32 with the time elapsed since accumulation began in imaging pixel 220A. If the elapsed time reaches the accumulation time, control circuit 31 determines that the predetermined time has elapsed.

[0043] 7, the control circuit 31 ends the accumulation in the imaging pixel 220A (step S111). The control circuit 31 then ends the readout period for the monitoring pixel 220B and starts the readout period for the imaging pixel 220A (step S112). Specifically, the control circuit 31 controls the drive signal generator 34 so that the drive signal S1 becomes a High-level signal. When the image sensor 22 receives the High-level signal, the accumulation in the imaging pixel 220A ends and the readout period for the imaging pixel 220A starts. At this time, the control circuit 31 stores the electrical signal output from the imaging pixel 220A in the memory 32. Furthermore, the control circuit 31 transfers the stored electrical signal to the control device 10. The control circuit 31 then determines whether the readout period for the imaging pixel 220A has ended (step S113). If NO in step S113, the process returns to step S113.

[0044] If the answer is YES in step S113, the control circuit 31 determines whether the number of times imaging has been performed by the image sensor 22 has reached a preset number of times (step S114). If the answer is NO in step S114, the process returns to step S109. If the answer is YES in step S114 or step S119, the control circuit 31 stops outputting the drive signal S1 (step S115). Specifically, as shown in FIG. 8, when the control circuit 31 determines that the number of times imaging has been performed by the image sensor 22 has reached a preset number of times, the control circuit 31 transmits a notification to the control device 10 that imaging has been completed a predetermined number of times. Then, the control device 10 transmits an instruction to end the imaging period to the control circuit 31. Furthermore, the control circuit 31 turns off the switch 34a, and the supply of the drive signal S1 to the image sensor 22 is stopped.

[0045] Next, the control circuit 31 stops outputting the clock signal S2 (step S116). Specifically, the control circuit 31 turns off the switch 35a, stopping the output of the clock signal S2 to the image sensor 22. Next, the control circuit 31 stops the supply of power, ending the imaging period T1 (step S117). Specifically, the control circuit 31 turns off the switch 33a, stopping the supply of power to the image sensor 22. That is, the control unit 3 ends the supply of power to the image sensor 22 when a predetermined condition for the number of imaging attempts for the imaging period T1 is satisfied. Note that, since it is sufficient to ensure that the imaging period T1 ends without fail when no imaging is performed, the control unit 3 may end the supply of power to the image sensor 22 when at least one of the conditions for the number of imaging attempts and the imaging time is satisfied. In such a case, at least one of the conditions for the number of imaging attempts and the imaging time is set in the control device 10, transmitted to the control unit 3 by the control device 10, received by the control unit 3, and stored in the memory 32 by the control unit 3. Then, the control circuit 31 stops supplying power to the image sensor 22 when the number of times that imaging has been performed reaches the imaging number, or when the time that has elapsed since the start of imaging reaches the imaging time.

[0046] Finally, the control circuit 31 transmits an acknowledgment to the instruction to end the imaging period T1 to the control device 10 (step S118).

[0047] In controlling imaging in the first imaging process described above, the control circuit 31 stops the supply of power to the image sensor 22 during the standby period T2. That is, the control unit 3 stops the supply of power to the image sensor 22 during the standby period T2.

[0048] Furthermore, in controlling imaging in the first imaging process described above, the control circuit 31 stops supplying the drive signal S1 to the image sensor 22 during the standby period T2. That is, the control unit 3 stops supplying the drive signal S1 to the image sensor 22 during the standby period T2.

[0049] Furthermore, in controlling imaging in the first imaging process described above, the control circuit 31 stops supplying the clock signal S2 to the image sensor 22 during the standby period T2. That is, the control unit 3 stops supplying the clock signal S2 to the image sensor 22 during the standby period T2. [Second imaging process]

[0050] Fig. 9 is a flowchart of the second imaging process. In the intraoral imaging device 1 in the second imaging process, the processes shown in steps S120, S121, S122, and S123 shown in Fig. 9 are executed by replacing the processes in steps S113 and S114 shown in Fig. 5. Note that the radiation source in the second imaging process continuously irradiates X-rays of a constant intensity.

[0051] The second imaging process will be described with reference to FIGS. 9 to 11. The control circuit 31 determines whether a time-out has occurred (step S119). If the result in step S119 is NO, the control circuit 31 determines whether the monitor pixel 220B has detected radiation (step S108). If the result in step S108 is NO, the process returns to step S119. If the result in step S108 is YES, as shown in FIG. 10, the control circuit 31 starts accumulation in the image capturing pixel 220A (step S109). Next, the control circuit 31 determines whether a predetermined time has elapsed since the start of accumulation in the image capturing pixel 220A (step S110). The control circuit 31 ends the accumulation in the image capturing pixel 220A (step S111). Next, the control circuit 31 ends the readout period for the monitor pixel 220B and starts the readout period for the image capturing pixel 220A (step S112).

[0052] Next, the control circuit 31 determines whether the imaging time performed by the image sensor 22 has reached a preset imaging time (step S121). Specifically, the control circuit 31 derives the elapsed time from the start of the imaging period T1 to the current time. The control circuit 31 then compares the elapsed time with the imaging time. Finally, the control circuit 31 determines whether the elapsed time has reached the imaging time.

[0053] If the answer is NO in step S121, it is determined whether it is time to start the next accumulation (step S122). Specifically, first, the control circuit 31 derives the readout end time based on the time when readout started and the readout time. Next, the control circuit 31 adds the accumulation time to the current time to estimate the accumulation end time. Then, the control circuit 31 compares the readout end time with the accumulation end time. Finally, if the accumulation end time is a time after the readout time, the control circuit 31 determines that the current time is the time to start the next accumulation. If the answer is NO in step S122, the process returns to step S122. If the answer is YES in step S122, the process returns to step S109.

[0054] If the result of step S121 or step S119 is YES, as shown in FIG. 11, the control circuit 31 confirms the completion of the final readout from the imaging pixel 220A (step S123). Next, the control circuit 31 stops outputting the drive signal S1 (step S115). Specifically, the control circuit 31 sends a notification to the control device 10 that a predetermined time has been reached. Then, the control device 10 sends an instruction to end the imaging period to the control circuit 31. Furthermore, the control circuit 31 turns off the switch 34a, thereby stopping the supply of the drive signal S1 to the image sensor 22. Next, the control circuit 31 stops outputting the clock signal S2 (step S116). Next, the control circuit 31 stops the supply of power, thereby ending the imaging period (step S117). Finally, the control circuit 31 sends an acknowledgment to the instruction to end the imaging period T1 to the control device 10 (step S118). That is, when the imaging time condition is satisfied, the control unit 3 ends the supply of power to the image sensor 22. Note that, since it is only necessary to ensure that the imaging period T1 ends when no imaging is performed, the control unit 3 may end the supply of power to the image sensor 22 when at least one of the conditions of the number of imaging times and the imaging time is satisfied.

[0055] In controlling imaging in the second imaging process described above, the control circuit 31 stops the supply of power to the image sensor 22 during the standby period T2. That is, the control unit 3 stops the supply of power to the image sensor 22 during the standby period T2.

[0056] Furthermore, in controlling imaging in the second imaging process described above, the control circuit 31 stops supplying the drive signal S1 to the image sensor 22 during the standby period T2. That is, the control unit 3 stops supplying the drive signal S1 to the image sensor 22 during the standby period T2.

[0057] Furthermore, in controlling imaging in the second imaging process described above, the control circuit 31 stops supplying the clock signal S2 to the image sensor 22 during the standby period T2. That is, the control unit 3 stops supplying the clock signal S2 to the image sensor 22 during the standby period T2. [Third imaging process]

[0058] In the third imaging process, the radiation source irradiates pulse waves at a constant cycle when capturing a transmission image. The cycle of irradiating pulse waves is preset by the control device 10 or a user so as to be longer than the sum of the accumulation time and readout time.

[0059] 12 is a flowchart showing control of imaging in the third imaging process. In the intraoral imaging device 1 in the third imaging process, the process shown in step S201 shown in FIG. 12 is executed by replacing the process of step S114 shown in FIG.

[0060] The third imaging process will be described with reference to FIGS. 12 to 14. The control circuit 31 determines whether a time-out has occurred (step S119). If the answer is NO in step S119, the control circuit 31 determines whether the monitor pixel 220B has detected radiation (step S108). If the answer is NO in step S108, the process returns to step S119. If the answer is YES in step S108, the control circuit 31 starts accumulation in the image capturing pixel 220A (step S109), as shown in FIG. 13. Then, the control circuit 31 determines whether a predetermined time has elapsed since the start of accumulation in the image capturing pixel 220A (step S110). The control circuit 31 ends accumulation in the image capturing pixel 220A (step S111). Then, the control circuit 31 ends the readout period for the monitor pixel 220B and starts the readout period for the image capturing pixel 220A (step S112). Next, the control circuit 31 determines whether readout from the imaging pixels 220A has been completed (step S113). If NO in step S113, the process returns to step S113. If YES in step S113, the control circuit 31 determines whether the number of imaging operations performed by the image sensor 22 has reached a preset number of imaging operations (step S201). If NO in step S201, the process returns to step S119. Note that when returning from step S201 to step S119, in step S119, if a predetermined time has elapsed since the last X-ray detection by the monitoring pixels 220B, the control circuit 31 determines that a time-out has occurred.

[0061] If the answer is YES in step S201 or step S119, as shown in FIG. 14, the control circuit 31 stops outputting the drive signal S1 (step S115). Then, the control circuit 31 stops outputting the clock signal S2 (step S116). Then, the control circuit 31 stops the supply of power, and the imaging period T1 ends (step S117). In other words, the control unit 3 ends the supply of power to the image sensor 22 when the condition for the number of images taken set for the imaging period T1 is satisfied. Note that, since it is only necessary to ensure that the imaging period T1 ends when no imaging is performed, the control unit 3 may end the supply of power to the image sensor 22 when at least one of the conditions for the number of images taken and the imaging time is satisfied.

[0062] Finally, the control circuit 31 transmits an acknowledgment to the instruction to end the imaging period T1 to the control device 10 (step S118).

[0063] In controlling imaging in the third imaging process described above, the control circuit 31 stops the supply of power to the image sensor 22 during the standby period T2. That is, the control unit 3 stops the supply of power to the image sensor 22 during the standby period T2.

[0064] Furthermore, in controlling imaging in the third imaging process described above, the control circuit 31 stops supplying the drive signal S1 to the image sensor 22 during the standby period T2. That is, the control unit 3 stops supplying the drive signal S1 to the image sensor 22 during the standby period T2.

[0065] Furthermore, in controlling imaging in the third imaging process described above, the control circuit 31 stops supplying the clock signal S2 to the image sensor 22 during the standby period T2. That is, the control unit 3 stops supplying the clock signal S2 to the image sensor 22 during the standby period T2. [Action and effect]

[0066] As described above, in the intraoral imaging device 1, power is supplied to the image sensor 22 of the imaging unit 2 during the imaging period T1, and power supply to the image sensor 22 of the imaging unit 2 is stopped during the standby period T2. This reduces the time during which power is supplied to the image sensor 22 of the imaging unit 2 compared to when power is supplied to the image sensor 22 throughout the imaging period T1 and the standby period T2. Therefore, even when imaging is performed at a high frame rate during the imaging period T1, heat generation in the image sensor 22 is suppressed compared to when power is supplied to the image sensor 22 throughout the imaging period T1 and the standby period T2. Furthermore, because the control unit 3, which supplies power throughout the imaging period T1 and the standby period T2, is located outside the oral cavity, the influence of heat generated by the control unit 3 is less likely to affect the imaging unit 2. Therefore, according to the intraoral imaging device 1, it is possible to suppress an increase in the temperature of the imaging unit 2 located within the oral cavity, even when imaging is performed at a high frame rate, for example.

[0067] In the intraoral imaging device 1, the control unit 3 outputs the drive signal S1 to the image sensor 22 during the imaging period T1, and stops supplying the drive signal S1 to the image sensor 22 during the standby period T2. This reduces the time during which the drive signal S1 is supplied to the image sensor 22 of the imaging unit 2, compared to when the drive signal S1 is supplied to the image sensor 22 over both the imaging period T1 and the standby period T2. This more reliably suppresses heat generation in the image sensor 22, and more reliably prevents the temperature of the imaging unit 2 from increasing.

[0068] In the intraoral imaging device 1, during the imaging period T1, the controller 3 starts supplying power to the image sensor 22, and then starts outputting the drive signal S1 to the image sensor 22. This makes it possible to suppress an increase in load caused by simultaneously starting the supply of power to the image sensor and the output of the drive signal S1 to the image sensor.

[0069] In the intraoral imaging device 1, the control unit 3 outputs the clock signal S2 to the image sensor 22 during the imaging period T1, and stops supplying the clock signal S2 to the image sensor 22 during the standby period T2. This reduces the time during which the clock signal S2 is supplied to the image sensor 22 of the imaging unit 2, compared to when the clock signal S2 is supplied to the image sensor throughout the imaging period T1 and the standby period T2. This more reliably suppresses heat generation in the image sensor 22, and more reliably prevents the temperature of the imaging unit 2 from increasing.

[0070] In the intraoral imaging device 1, the controller 3 starts supplying power to the image sensor 22 during the imaging period T1, and then starts outputting the clock signal S2 to the image sensor 22. This makes it possible to suppress an increase in load caused by simultaneously starting the supply of power to the image sensor and the output of the drive signal S1 to the image sensor.

[0071] During the standby period T2, the intraoral imaging device 1 stops the supply of power, the supply of the drive signal S1, and the supply of the clock signal S2 to the image sensor 22. As a result, no electrical input is made to the image sensor 22 during the standby period T2, completely suppressing heat generation from the image sensor 22 during the standby period T2. This more reliably suppresses heat generation from the image sensor 22 and more reliably suppresses an increase in the temperature of the imaging unit 2.

[0072] In the intraoral imaging device 1, power, drive signal S1, and clock signal S2 are not supplied to the image sensor 22 until the control unit 3 receives an instruction to start the imaging period T1. As a result, compared to when the clock signal S2 is supplied to the image sensor throughout the imaging period T1 and the standby period T2, even if the user connects the control device 10 and the control unit 3 but does not start imaging, it is possible to suppress heat generation in the image sensor 22 and prevent the temperature of the imaging unit 2 from rising.

[0073] In the intraoral imaging device 1, the control unit 3 terminates the supply of power to the image sensor 22 when at least one of the conditions of the number of images to be taken and the imaging time set in advance for the imaging period T1 is satisfied. This ensures that the supply of power to the image sensor 22 is terminated reliably when the imaging period T1 ends, even without any operation or control by the user or the control device 10. Therefore, even if the user forgets to stop the supply of power to the intraoral imaging device 1, for example, it is possible to suppress heat generation in the image sensor 22 and prevent the temperature of the imaging unit 2 from rising.

[0074] In the intraoral imaging device 1, the image sensor 22 further includes a monitor pixel 220B for monitoring the radiation dose. If the monitor pixel 220B is provided in, for example, a light receiving element separate from the image sensor 22, the control unit 3 needs to have a function of separately supplying power to not only the image sensor 22 but also the light receiving element, and a function of separately controlling the supply of power to the light receiving element. Because the monitor pixel 220B for monitoring the radiation dose is included in the image sensor 22, such a separate function is not necessary, and the configuration and operation of the control unit 3 can be simplified.

[0075] In the intraoral imaging device 1 of the second imaging process, when the control circuit 31 performs readout in the imaging pixel 220A, it starts the next accumulation without waiting for the end of the readout. This reduces the time difference between the end time of the accumulation and the start time of the next accumulation. Therefore, imaging can be performed at a higher frame rate.

[0076] In the intraoral imaging device 1 of the third imaging process, an X-ray source that periodically emits pulsed waves irradiates X-rays. This minimizes the amount of radiation exposure to patients and users. Furthermore, by reducing the time the image sensor 22 is exposed to X-rays, the deterioration rate of the imaging unit 2 can be slowed. [Variations]

[0077] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. For example, since it is only necessary for power to be supplied from the control unit 3 to the imaging unit 2, the control circuit 31 may include a regulator 33. In such a case, the control circuit 31 converts the voltage of the power from the control device 10 into a voltage that can drive the image sensor 22, and the converted voltage is supplied to the image sensor 22.

[0078] Furthermore, in the embodiment of the present invention, since it is sufficient that the control unit 3 supplies the drive signal S1 to the imaging unit 2, the control circuit 31 may include a drive signal generator 34. In such a case, the control circuit 31 generates the drive signal S1, and the drive signal S1 is output to the image sensor 22. This allows the configuration of the control unit 3 to be simplified.

[0079] Furthermore, in the embodiment of the present invention, since it is sufficient that the clock signal S2 is supplied from the control unit 3 to the imaging unit 2, the control circuit 31 may include a clock signal generator 35. In such a case, the clock signal S2 is generated by the control circuit 31 and output to the image sensor 22. This allows the configuration of the control unit 3 to be simplified.

[0080] Furthermore, in an embodiment of the present invention, it is sufficient that information can be sent and received between the control device 10 and the control unit 3, so the control device 10 and the control unit 3 may communicate wirelessly (for example, via LAN, Bluetooth (registered trademark), or Wifi).

[0081] Furthermore, in the embodiment of the present invention, it is sufficient that information can be transmitted and received between the imaging unit 2 and the control unit 3, and therefore the imaging unit 2 and the control unit 3 may communicate wirelessly (for example, via LAN, Bluetooth (registered trademark), or Wi-Fi). However, when communicating wirelessly, the imaging unit 2 and the control unit 3 further include a transmitting / receiving device for wireless communication, and this device must be constantly supplied with power. Therefore, it is better for the imaging unit 2 and the control unit 3 to communicate via a wired connection. With this configuration, the configurations of the imaging unit 2 and the control unit 3 can be simplified compared to when communication is wireless, while minimizing the power supply to the imaging unit 2.

[0082] In the embodiment of the present invention, it is sufficient that the control unit 3 is supplied with power, and therefore the control unit 3 may be supplied with power from, for example, an outlet or the like, or may be supplied with power wirelessly.

[0083] In addition, in the embodiment of the present invention, the instruction to start the imaging period T1 and the instruction to wait for X-ray irradiation may be issued simultaneously. In such a case, the control unit 3 may transmit a response to the instruction to start the imaging period T1 and the instruction to wait for X-ray irradiation to the control device 10 only once. This simplifies the operation of the control unit 3.

[0084] Furthermore, the control circuit 31 according to the embodiment of the present invention may stop the supply of power to the image sensor 22 based on the readout from the monitor pixels 220B. In this way, the control circuit 31 can stop the supply of power to the image sensor 22, for example, when it determines that the X-ray irradiation has ended because there is no more readout from the monitor pixels 220B. Furthermore, the supply of power to the image sensor 22 can be reliably stopped without any operation or control by, for example, the user or the control device 10. As a result, heat generation in the image sensor 22 can be suppressed, and an increase in the temperature of the imaging unit 2 can be suppressed.

[0085] Furthermore, the imaging unit 2 according to an embodiment of the present invention may have a light receiving element including a monitor pixel 220B, which is a pixel for monitoring the radiation dose. This can sufficiently suppress heat generation in the light receiving element, so that, for example, by constantly supplying power to the light receiving element to monitor the radiation dose and supplying power or a signal to the image sensor 22 only when radiation is being irradiated, it is possible to reliably suppress heat generation in the image sensor 22. In such a case, the control unit 3 has a function of controlling the supply of power to the light receiving element.

[0086] Furthermore, the start time of the imaging period T1 in this embodiment may be earlier or later than the start of power supply to the image sensor 22, the start time of supplying the drive signal S1 to the image sensor 22, the start time of supplying the clock signal S2 to the image sensor 22, the start time of reading out the sensor pixels, the instruction to start the imaging period from the control device 10, the instruction to wait for X-ray irradiation from the control device 10, the confirmation response to the start instruction, the confirmation response to the wait instruction, and the start time of X-ray irradiation.

[0087] The end time of the imaging period T1 may be earlier or later than the end of the power supply to the image sensor 22, the end time of the supply of the drive signal S1 to the image sensor 22, the end time of the supply of the clock signal S2 to the image sensor 22, the instruction to end the imaging period from the control device 10, the confirmation response to the end instruction, the response to the control device 10 that the predetermined number of imaging sessions have been completed, and the end time of the X-ray irradiation.

[0088] In addition, the start time of the waiting period T2 in this embodiment may be earlier or later than the end time of supplying the drive signal S1 to the image sensor 22, the end time of supplying the clock signal S2 to the image sensor 22, the confirmation response to the end instruction, and the end time of X-ray irradiation.

[0089] Furthermore, in this embodiment, by synchronizing the driving of the X-ray source and the image sensor 22, it is not necessary to detect whether or not X-rays are being irradiated. Therefore, the monitor pixel 220B is not an essential component. This allows the configuration of the imaging unit 2 to be simplified.

[0090] In this embodiment, the electrical signal output from the image sensor 22 is only required to be ultimately transmitted to the control device 10, where a transmission image is generated. Therefore, the control unit 3 does not need to have the memory 32. In such a case, the control circuit 31 immediately transfers the electrical signal output from the image sensor 22 to the control device 10.

[0091] Furthermore, in this embodiment, when counting the number of imaging operations, if a combination of one accumulation period and one readout period in the imaging pixel 220A is considered to be one set, it is sufficient to know how many such combinations there are from the start of the imaging period T1 to the current time. Therefore, when counting the number of imaging operations, the number of accumulation periods or the number of readout periods may be counted.

[0092] Furthermore, in this embodiment, if the control circuit 31 does not perform imaging, imaging may be terminated. Therefore, the imaging time may be the criterion for determining whether or not the control circuit 31 terminates imaging. Specifically, the control device 10 may set the imaging time in advance, and the control circuit 31 may compare the imaging time with the elapsed time since the control circuit 31 determined that a predetermined number of imaging operations have been completed in each imaging process. If the elapsed time reaches the imaging time, steps S115 to S118 may be executed to terminate imaging. This allows the control circuit 31 to stop the supply of power to the image sensor 22 without any operation by the user or the control device 10. This more reliably suppresses heat generation in the image sensor 22 and more reliably suppresses an increase in the temperature of the imaging unit 2.

[0093] The elapsed time may be the time elapsed since the last readout from the imaging pixels 220A was completed. This allows the control circuit 31 to stop the supply of power to the image sensor 22 even if the imaging process is delayed due to an error or the like. This more reliably prevents the image sensor 22 from generating heat and more reliably prevents the temperature of the imaging unit 2 from rising.

[0094] The accumulation time in this embodiment may be derived by the control device 10. Specifically, the control device 10 analyzes the electrical signals output from the monitor pixels 220B in advance and sets the time (accumulation time) for charge accumulation in the imaging pixels 220A based on the analysis results. As an example, the control device 10 stores in advance a correlation between the X-ray dose per unit time (hereinafter referred to as the dose rate) and the output from the monitor pixels 220B. First, when X-rays are irradiated, the control device 10 receives the output from the monitor pixels 220B as an electrical signal. Then, the control device 10 derives the dose rate at the monitor pixels 220B by applying the above correlation to the received output from the monitor pixels 220B. Next, the control device 10 estimates the dose rate received by the imaging pixels 220A from the derived dose rate. Here, the control device 10 sets in advance a dose threshold at which the imaging pixels 220A do not saturate. Furthermore, the control device 10 sets the accumulation time from the estimated dose rate based on the set dose threshold so that the imaging pixels 220A do not become saturated. The control device 10 transmits information about the set accumulation time to the control unit 3.

[0095] Furthermore, the readout time in this embodiment may be set according to the accumulation time derived by the control device 10. Specifically, the control device 10 derives the radiation dose received by the imaging pixel 220A when the accumulation time for the imaging pixel 220A ends. The control device 10 derives the amount of charge accumulated from the radiation dose received by the imaging pixel 220A. The control device 10 derives the total time required for outputting an electrical signal from the imaging pixel 220A and discharging the charge accumulated in the FD 227 from the derived amount of charge. The control device 10 sets the derived total time as the readout time. The control device 10 transmits information about the set readout time to the control unit 3. [Explanation of symbols]

[0096] 1...intraoral imaging device, 2...imaging unit, 3...control unit, 22...image sensor, S1...drive signal, S2...clock signal, 220A...imaging pixels (multiple pixels for acquiring an image of an object), 220B...monitoring pixels (pixels for monitoring the radiation dose), T1...imaging period, T2...standby period.

Claims

1. an imaging unit that detects radiation that has passed through an object while being placed in the oral cavity; a control unit that controls the imaging unit in a state where the imaging unit is placed outside the oral cavity, the imaging unit has an image sensor including a plurality of imaging pixels for acquiring an image of the object and a monitor pixel for monitoring the dose of the radiation, or has an image sensor including a plurality of imaging pixels for acquiring an image of the object and a light receiving element including a monitor pixel for monitoring the dose of the radiation, When the imaging unit has the image sensor including the plurality of imaging pixels and the monitor pixels, the control unit, while power is being supplied to the control unit, supplies power to the image sensor and reads out data from the monitor pixels during an imaging period in which the image sensor captures an image, and stops supplying power to the image sensor and stops reading out data from the monitor pixels during a standby period in which the image sensor is on standby; An intraoral imaging device in which, when the imaging unit has an image sensor including the plurality of imaging pixels and a light receiving element including the monitor pixel, the control unit, when power is supplied to the control unit, supplies power to the image sensor and the light receiving element and reads out data from the monitor pixel during an imaging period in which the image sensor is imaging, and stops supplying power to the image sensor and stops reading out data from the monitor pixel during a standby period in which the image sensor is standby.

2. The intraoral imaging device of claim 1 , wherein the control unit outputs a drive signal to the image sensor during the imaging period and stops supplying the drive signal to the image sensor during the standby period.

3. The intraoral imaging device of claim 2 , wherein the control unit starts supplying the power to the image sensor during the imaging period, and then starts outputting the drive signal to the image sensor.

4. An intraoral imaging device as described in any one of claims 1 to 3, wherein the control unit outputs a clock signal to the image sensor during the imaging period and stops supplying the clock signal to the image sensor during the standby period.

5. The intraoral imaging device of claim 4 , wherein the control unit starts supplying the power to the image sensor during the imaging period and then starts outputting the clock signal to the image sensor.

6. An intraoral imaging device as described in any one of claims 1 to 5, wherein the control unit terminates the supply of power to the image sensor when at least one of the conditions of the number of images taken and the imaging time set for the imaging period is met.

Images