WO2013069422A1

WO2013069422A1 - Power supply circuit, imaging module, and imaging device

Info

Publication number: WO2013069422A1
Application number: PCT/JP2012/076807
Authority: WO
Inventors: 野瀬　修司
Original assignee: 富士フイルム株式会社
Priority date: 2011-11-10
Filing date: 2012-10-17
Publication date: 2013-05-16
Also published as: JP2015018000A

Abstract

Provided is a power supply circuit capable of avoiding the effects of electromagnetic noise caused by an inductor, and of capturing high-quality images. The power supply circuit (10), which provides a power supply voltage (Vo) to an imaging element (20): has a transistor (11a) connected to a battery (Ba), an inductor (11b) connected to the transistor (11a), and a control circuit (11c) that performs switching control for the transistor (11a); and comprises a switching regulator (11) that, by turning the transistor (11a) on and off, converts the magnetic energy stored in the inductor (11b) into electric energy, and generates the power supply voltage (Vo). The control circuit (11c) turns off the transistor (11a) at the timing that a signal is read from a pixel cell in the imaging element (20), in accordance with a drive clock (ck1) synchronized with a read clock (ck) that determines the read timing for the signal from the pixel cell; and turns on the transistor (11a) at the timing that the signal is not being read from the pixel cell.

Description

Power supply circuit, imaging module, and imaging apparatus

The present invention relates to a power supply circuit, an imaging module, and an imaging apparatus.

Electronic devices (for example, mobile phones) equipped with an imaging module have been improved in functionality and performance, and the number of mounted components has been increased and the display panel has been increased in size. For this reason, the imaging module itself must be further reduced in size, and the power supply circuit needs to be provided close to the imaging element (image sensor) (see, for example, Patent Document 1).

FIG. 8 is a cross-sectional view showing an example of a recent imaging module. The imaging module 100 includes an imaging element 102 and a photographing lens group 103 arranged on the light incident side of the imaging element 102. Around the photographing lens group 103, an actuator 104 for focus position adjustment and zoom adjustment is provided in the vicinity. A power supply circuit 105 that receives power from a battery power source on the electronic device (device main body) side and generates a voltage for driving the image sensor 102 and the like is provided in the vicinity of the image sensor 102.

A switching regulator or the like is used for a power supply circuit that receives power supply from a battery power source and converts the voltage to generate a predetermined DC constant voltage (for example, 3.3 V). In order to efficiently perform this voltage conversion, an inductor (coil) is used as shown in the circuit diagrams of Patent Documents 2 to 4, for example.

That is, as shown in FIG. 8, the inductor 106 of the power supply circuit 105 is disposed close to the image sensor 102.

JP 2010-154591 A JP 2005-168230 A JP 2005-198484 A JP 2009-177325 A Japanese Patent Laid-Open No. 2003-116045 JP 2007-142738 A

When a current flows through the inductor 106 of the power supply circuit 105, electromagnetic energy is accumulated in the inductor 106, and electromagnetic noise 107 is generated as shown in FIG. When the inductor 106 is disposed close to the image sensor 102, electromagnetic noise 107 enters the image sensor 102.

In recent years, the image sensor 102 has been miniaturized because of the increase in the number of pixels, and the amount of signal charge detected by each pixel cell in accordance with the amount of incident light has been reduced. For this reason, even weak electromagnetic noise 107 deteriorates the image quality of the captured image.

Conventionally, since the distance between the image sensor 102 and the inductor 106 can be set to some extent and the size of the pixel cell is not so small, the weak electromagnetic noise has not been a problem. However, since the imaging module has been miniaturized, it has become necessary to avoid image quality degradation caused by this electromagnetic noise.

Although it suffices to use a power supply circuit (for example, a linear regulator) that does not generate electromagnetic noise, that is, does not use the inductor 106, the voltage conversion efficiency is lowered, and the battery life on the apparatus main body side is shortened.

In Patent Document 5, in an imaging apparatus having an imaging device and a signal processing circuit, the reference voltage of a regulator circuit that supplies a voltage to the signal processing circuit is changed according to the operating state of the imaging device, thereby reducing power consumption. It is described that the reduction of the above is attempted. Further, Patent Document 6 describes that power consumption is reduced by setting the current flowing through the load transistor connected to each vertical signal line of the MOS sensor to zero when the signal is not read from the image sensor. Yes.

However, all of the techniques described in Patent Documents 5 and 6 are intended to reduce power consumption, and do not consider the influence of electromagnetic noise due to the inductor of the power supply circuit.

The present invention has been made in view of the above circumstances, and provides a power supply circuit capable of capturing a high-quality image while avoiding the influence of electromagnetic noise caused by an inductor, an imaging module including the power supply circuit, and an imaging apparatus including the power supply circuit. The purpose is to do.

A power supply circuit of the present invention is a power supply circuit that supplies a power supply voltage to an image sensor, and includes a switching transistor connected to an external power supply, an inductor connected to the transistor, and a control circuit that performs switching control of the transistor. And a switching power supply circuit unit that generates a power supply voltage by converting magnetic energy stored in the inductor into electrical energy by turning on and off the transistor by the control circuit, and the control circuit receives a signal from the pixel cell of the image sensor. At least a first switching control for turning on and off the transistor in accordance with a first driving clock synchronized with a reading clock for determining a timing for reading out the pixel cell. Read signal from To turn off the transistor when a control for the transistor on when no signal is read out from the pixel cell.

The imaging module of the present invention includes the power supply circuit of the present invention and an imaging device to which a power supply voltage is supplied by the power supply circuit.

The imaging apparatus of the present invention includes the imaging module of the present invention.

According to the present invention, it is possible to provide a power supply circuit that can capture a high-quality image while avoiding the influence of electromagnetic noise due to an inductor, an imaging module including the power supply circuit, and an imaging apparatus including the power supply circuit.

The figure which shows schematic structure of the electronic device with an imaging function for describing one Embodiment of this invention The figure which shows the internal structure of the imaging module 1 in the electronic device shown in FIG. The figure which shows an example of clock ck1 which the frequency dividing circuit 40 of the imaging module 1 shown in FIG. 2 produces | generates. FIG. 6 is a diagram showing a modification of the imaging module 1 in the electronic apparatus shown in FIG. FIG. 6 is a diagram showing a modification of the imaging module 1 in the electronic apparatus shown in FIG. The figure which shows the modification of the imaging module 1 shown in FIG. The figure which shows the modification of the imaging module 1 shown in FIG. Sectional drawing which shows an example of a recent imaging module

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an electronic apparatus having an imaging function for explaining an embodiment of the present invention. This electronic apparatus is, for example, a portable terminal such as a digital camera or a camera-equipped mobile phone, an electronic endoscope apparatus, or the like.

The imaging system of the electronic apparatus of FIG. 1 includes an imaging module 1, an analog signal processing unit 4 that performs analog processing on a captured image signal output from the imaging module 1, and a captured image signal that is output from the analog signal processing unit 4. An A / D converter 5 for conversion. The imaging module 1, the analog signal processing unit 4, and the A / D conversion unit 5 are controlled by a system control unit 2 that performs overall control of the entire electronic device. An instruction signal from a user is input to the system control unit 2 through the operation unit 3.

The electric control system of the electronic apparatus in FIG. 1 includes an interpolation calculation for the system control unit 2, the main memory 7, the memory control unit 6 connected to the main memory 7, and the captured image signal output from the imaging module 1. The digital signal processing unit 8 that generates captured image data by performing gamma correction calculation, RGB / YC conversion processing, and the like, and the captured image data generated by the digital signal processing unit 8 is compressed into JPEG format or compressed image data A compression / expansion processing unit 9 that performs expansion, an external memory control unit 16 to which a detachable recording medium 17 is connected, and a display control unit 18 to which a display unit 19 such as a liquid crystal display device is connected. The memory control unit 6, the digital signal processing unit 8, the compression / decompression processing unit 9, the external memory control unit 16, and the display control unit 18 are connected to each other by a control bus 21 and a data bus 22 and controlled by the system control unit 2. The

FIG. 2 is a diagram showing an internal configuration of the imaging module 1 in the electronic device shown in FIG.

The imaging module 1 includes an imaging element 20, such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor, an imaging element driving circuit 30 that drives the imaging element 20, and an external device mounted on an electronic device. And a power supply circuit 10 that generates a power supply voltage Vo from a voltage supplied from a power supply (battery Ba) and supplies the power supply voltage Vo to the image sensor 20. Note that, as illustrated in FIG. 8, the imaging element 20 and the power supply circuit 10 are arranged close to each other at a distance that allows electromagnetic noise generated from an inductor included in the power supply circuit 10 to enter the imaging element 20.

The power supply circuit 10 includes a switching (SW) regulator 11 that is a switching power supply circuit section, a capacitor 12 connected between the output terminal of the power supply circuit 10 and the ground, and a frequency dividing circuit 40.

The switching regulator 11 controls the on / off of the transistor 11a in accordance with the switching transistor 11a connected to the battery Ba of the electronic device, the inductor 11b connected to the transistor 11a, and the drive clock supplied from the frequency divider circuit 40. And a control circuit 11c that performs control. The output voltage of the inductor 11b is fed back to the control circuit 11c via a feedback resistor (not shown).

The switching regulator 11 performs on / off control of the transistor 11a to store the magnetic energy stored in the inductor 11b in the capacitor 12 as electric energy, so that the power supply voltage Vo required for the operation of the image sensor 20 (the image sensor 20 is In the case of a CMOS image sensor, for example, a voltage of about 3.3 V is generated and output.

The image sensor driving circuit 30 includes a timing generator that generates a clock necessary for driving the image sensor 20, and a drive unit that drives the image sensor 20 according to the clock.

The clock generated by the timing generator includes a read clock ck that determines the timing for reading a signal from each pixel cell (including a photoelectric conversion element) included in the image sensor 20. The image sensor driving circuit 30 inputs this read clock ck not only to the driving unit but also to the frequency dividing circuit 40.

The frequency dividing circuit 40 divides the read clock ck input from the image sensor driving circuit 30, generates a clock ck1 synchronized with the read clock ck, and inputs the clock ck1 to the control circuit 11c.

The clock ck1 is at a low level when the read clock ck1 is at a high level (timing for reading a signal from the pixel cell of the image sensor 20), and no signal is read from the pixel cell at the image sensor 20 when the read clock ck1 is at a low level. The clock becomes a high level at (timing).

For example, as shown in FIG. 3, the frequency dividing circuit 40 generates the clock ck1 with the frequency of the read clock ck halved and the phase shifted.

The control circuit 11c of the power supply circuit 10 performs on / off control of the transistor 11a according to the clock ck1 generated by the frequency dividing circuit 40. For example, the control circuit 11c turns on the transistor 11a when the clock ck1 is at a high level, and turns off the transistor 11a when the clock ck1 is at a low level.

Since the magnetic energy is stored in the inductor 11b while the transistor 11a is on, electromagnetic noise is generated from the inductor 11b. On the other hand, when the transistor 11a is turned off, the magnetic energy of the inductor 11b disappears, so that no electromagnetic noise is generated from the inductor 11b. In this way, by matching the signal readout timing from the pixel cell of the image sensor 20 (timing when the clock ck becomes high level) with the timing when the transistor 11a is turned off (timing when the clock ck2 becomes low level). In addition, it is possible to prevent the electromagnetic noise from the inductor 11b from riding on the signal read from the pixel cell of the image sensor 20.

In the electronic apparatus configured as described above, when the power is turned on, the imaging module 1 is activated and the imaging module 1 enters a standby state. When the shooting mode is set by the user, the system control unit 2 controls the image sensor driving circuit 30 to start moving image shooting by the image sensor 20.

The captured image signal obtained from the image sensor 20 in each frame of the moving image shooting is sequentially processed by the digital signal processing unit 8 to become captured image data. Then, the system control unit 2 causes the display unit 19 to sequentially display images based on the captured image data sequentially generated by the digital signal processing unit 8. Thereby, the subject image being photographed by the image sensor 20 is displayed on the display unit 19 in real time as a live view image.

Subsequently, when a shutter button included in the operation unit 3 is pressed, the subject is imaged, and an instruction to record captured image data obtained by processing a captured image signal obtained by the imaging on the recording medium 17 is given. A photographing / recording instruction signal is input to the system control unit 2. Then, the system control unit 2 causes the image sensor 20 to take a still image in accordance with the shooting / recording instruction signal, and records the captured image data obtained by the still image shooting in the storage medium 11.

While imaging is performed by the imaging device 20, the switching regulator 11 performs control to turn on the transistor 11 a during a period in which no signal is read from the pixel cell of the imaging device 20, and from the pixel cell of the imaging device 20. Control is performed to turn off the transistor 11a during a period in which the signal is read.

As described above, according to the electronic device shown in FIG. 1, since the transistor 11a is turned on and magnetic energy is stored in the inductor 11b during a period in which no signal is read from the pixel cell of the imaging device 20, imaging is performed. The picked-up image signal output from the element 20 can be prevented from being subjected to electromagnetic noise generated from the inductor 11b, and high-quality shooting can be performed.

In addition, by using the switching regulator 11 that can reduce the influence of electromagnetic noise in this way, the degree of freedom of arrangement of the inductor 11b is improved, and it is not necessary to consider measures for countermeasures against electromagnetic noise. For this reason, the design of the imaging module 1 becomes easy and the cost can be reduced.

Note that the frequency dividing circuit 40 mounted on the imaging module 1 may, for example, invert the read clock ck without frequency division. In this case, the transistor 11a is switching-controlled with a clock having the same frequency as the read clock ck. However, in the switching regulator 11, the higher the switching frequency of the transistor 11a, the lower the voltage conversion efficiency and the higher the power consumption. Therefore, as described above, the power consumption of the imaging module 1 can be reduced by generating the clock ck1 with the frequency reduced by dividing the read clock ck.

FIG. 4 is a diagram showing a modification of the imaging module 1 in the electronic device shown in FIG. The imaging module 1 shown in FIG. 4 has the same configuration as the imaging module 1 shown in FIG. 2 except that a selector 41 is added to the power supply circuit 10. In FIG. 4, the same components as those in FIG.

The selector 41 receives a clock ck1 generated by the frequency dividing circuit 40 and a clock ck2 having a frequency lower than the clock ck1 generated by, for example, a clock generator (not shown) in the imaging module 1. The clock ck2 may be any clock as long as the switching regulator 11 can generate the power supply voltage Vo.

The selector 41 selects one of the two input clocks under the control of the system control unit 2, and inputs the selected clock to the control circuit 11c. The control circuit 11c of the imaging module 1 illustrated in FIG. 4 performs on / off control of the transistor 11a in accordance with the clock input from the selector 41.

When the photographing / recording instruction signal is input from the operation unit 3, the system control unit 2 transmits a command signal indicating that the photographing / recording instruction has been made to the selector 41. When the selector 41 receives this command signal, the selector 41 receives a predetermined time (for example, until a still image is picked up by the image pickup device 20 and a picked-up image signal is output from the image pickup device 20 by the still image pickup). The clock ck1 is input to the control circuit 11c only for the time required for the time), and the clock ck2 is input to the control circuit 11c when the time has elapsed.

In the electronic apparatus configured as described above, the clock ck2 is selected by the selector 41 during the period in which the imaging device 20 performs moving image capturing for displaying a live view image (live view mode), and the clock ck2 Accordingly, the on / off control of the transistor 11a is performed. Since the frequency of the clock ck2 is lower than that of the clock ck1, the power consumption in the switching regulator 11 is relatively low.

On the other hand, when the shutter button included in the operation unit 3 is pressed, the clock ck1 is selected for a certain period by the selector 41, and on / off control of the transistor 11a is performed according to the clock ck1 during this certain period. Since the frequency of the clock ck1 is higher than that of the clock ck2, the power consumption in the switching regulator 11 is relatively high. However, as described above, the quality of the captured image data recorded on the recording medium 17 in accordance with the imaging recording instruction Will improve.

As described above, the imaging module 1 shown in FIG. 4 performs the on / off control of the transistor 11a according to the clock ck2 in the live view mode, and performs the on / off control of the transistor 11a according to the clock ck1 only when a shooting / recording instruction is given. I am doing so. For this reason, the image quality of the captured image data recorded on the recording medium 17 can be improved while minimizing the deterioration of the voltage conversion efficiency in the switching regulator 11.

In the imaging module 1 shown in FIG. 2, the power consumption of the switching regulator 11 can be reduced while the imaging module 1 is activated if the frequency dividing number in the frequency dividing circuit 40 is considerably increased. . However, this increases the area of the frequency dividing circuit 40 and is not suitable for downsizing the imaging module 1. Therefore, by adopting the configuration as shown in FIG. 4, it is possible to realize downsizing, low power consumption, and high quality of image quality of the imaging module 1.

Note that the system control unit 2 shown in FIG. 4 causes the selector 41 to select the clock ck1 for a certain period when a shooting / recording instruction is given, and causes the selector 41 to select the clock ck2 during other periods. The selector 41 may be controlled as follows.

For example, the system control unit 2 causes the selector 41 to select the clock ck1 when the set photographing ISO sensitivity (the magnitude of the gain multiplied by the captured image signal output from the image sensor 20) exceeds the threshold value, When the photographing ISO sensitivity is equal to or lower than the threshold value, the selector 41 is caused to select the clock ck2. When the photographing ISO sensitivity is high, noise in the captured image data becomes conspicuous. Therefore, only when the photographing ISO sensitivity is high, the on / off control of the transistor 11a is performed according to the clock ck1, so that the captured image data to be recorded on the recording medium 17 is suppressed while suppressing the deterioration of the voltage conversion efficiency in the switching regulator 11. Image quality can be improved.

Alternatively, the system control unit 2 causes the selector 41 to select the clock ck1 when the brightness of the subject known from the captured image signal or the like in the live view mode is equal to or less than the threshold, and when the brightness of the subject exceeds the threshold The selector 41 is made to select the clock ck2. When the brightness of the subject is dark, noise in the captured image data becomes conspicuous. For this reason, the on-off control of the transistor 11a is performed according to the clock ck1 only when the subject is dark, so that the captured image to be recorded on the recording medium 17 while suppressing the deterioration of the voltage conversion efficiency in the switching regulator 11. The image quality of data can be improved.

FIG. 5 is a view showing a modified example of the imaging module 1 in the electronic apparatus shown in FIG. The imaging module 1 illustrated in FIG. 5 has the same configuration as the imaging module 1 illustrated in FIG. 2 except that a linear regulator 13, a switching unit 14, and a timer 15 are added to the power supply circuit 10. In FIG. 5, the same components as those in FIG.

The linear regulator 13 includes a transistor 13b as a variable resistor having one end connected to the battery Ba and the other end connected to the output terminal of the power supply circuit 10, and a control circuit 13a that controls the gate voltage of the transistor 13b.

The control circuit 13a compares the voltage obtained by dividing the output voltage at the other end of the transistor 13b with a resistor (not shown) with a reference voltage, and controls the on-resistance of the transistor 13b with the output of the amplifier circuit. Thus, the linear regulator 13 generates the power supply voltage Vo by continuously controlling the current flowing through the transistor 13b.

The switching unit 14 controls which of the switching regulator 11 and the linear regulator 13 is operated.

The timer 15 starts measuring time when the electronic device in which the imaging module 1 shown in FIG. 5 is mounted and the power supply circuit 10 is activated, and notifies the switching unit 14 when a certain time has elapsed. To do. The switching unit 14 operates the control circuit 13a without operating the control circuit 11c until the notification is received, and causes the linear regulator 13 to generate the power supply voltage Vo. In addition, after the notification, the switching unit 14 stops the control circuit 13a, operates the control circuit 11c, and causes the switching regulator 11 to generate the power supply voltage Vo.

It takes some time until the power supply circuit 10 is activated when the power of the electronic device is turned on and the relationship between the clock ck1 and the clock ck generated by the frequency dividing circuit 40 becomes as shown in FIG. For this reason, if the power supply voltage Vo is generated by the switching regulator 11 immediately after the power supply of the electronic device is turned on and the power supply circuit 10 is activated, the signal readout timing from the pixel cell and the on timing of the transistor 11a overlap. A period occurs, and noise is added to the captured image signal. Therefore, in the electronic device equipped with the imaging module 1 shown in FIG. 5, the power supply voltage Vo is generated by the linear regulator 13 for a certain period from the start of the power supply circuit 10, and the power supply voltage Vo is generated by the switching regulator 11 after the certain period has elapsed. Like to do.

Since the linear regulator 13 does not include an inductor, noise entering the captured image signal is reduced. On the other hand, since the linear regulator 13 has high power consumption, it is difficult to always operate the imaging module 1 while the imaging module 1 is activated. According to the electronic device equipped with the imaging module 1 shown in FIG. 5, the linear regulator 13 operates only for a certain period from the startup of the power supply circuit 10, so that the power consumption is improved while improving the image quality at the startup of the power supply circuit 10. Can be minimized.

Note that the embodiment of FIG. 5 and the embodiment of FIG. 4 can be implemented in combination. That is, the power supply voltage Vo is generated by the linear regulator 13 for a certain period from the start of the power supply circuit 10, and then the power supply voltage Vo is generated by the switching regulator 11. Then, after the operation of the linear regulator 13 is stopped, the control circuit 11c of the switching regulator 11 performs switching control according to a clock selected from either the clock ck1 or the clock ck2.

FIG. 6 is a diagram showing a modification of the imaging module 1 shown in FIG. The imaging module 1 shown in FIG. 6 does not perform the switching control according to the notification from the timer 15, but the switching module 14 performs the switching control under the control of the system control unit 2. The configuration is the same as that shown in FIG.

The switching unit 14 of the imaging module 1 shown in FIG. 6 operates the switching regulator 11 and does not operate the linear regulator 13 when the imaging module 1 is activated. When the switching unit 14 receives a command signal indicating that an imaging / recording instruction has been received from the system control unit 2, the switching unit 14 operates the linear regulator 13 for a certain period of time after receiving the command signal, and switches the switching regulator 11. Stop. Then, after a predetermined time has elapsed, the switching unit 14 stops the linear regulator 13 and operates the switching regulator 11.

According to the imaging module 1 shown in FIG. 6, the power supply voltage Vo is generated by the switching regulator 11 during a period when the shooting / recording instruction is not given (in the live view mode). For this reason, the quality of the image displayed on the display part 19 can be improved. In addition, power consumption in this period can be reduced.

On the other hand, the power supply voltage Vo is generated by the linear regulator 13 for a certain period after the shooting / recording instruction is given. For this reason, noise in the captured image data recorded on the recording medium 17 can be reduced. The power consumption of the linear regulator 13 is larger than that of the switching regulator 11. However, since the linear regulator 13 operates only for a certain period after the shooting / recording instruction is given, the power consumption of the entire imaging module 1 can be suppressed.

Note that the switching unit 14 of the imaging module 1 illustrated in FIG. 6 operates only the linear regulator 13 when the imaging ISO sensitivity that has been set exceeds the threshold during the startup of the imaging module 1, and the imaging ISO sensitivity is the threshold. In the following cases, only the switching regulator 11 may be operated. As described above, the image quality of the captured image data recorded on the recording medium 17 can be improved by operating the linear regulator 13 with less noise only when the photographing ISO sensitivity is high. Further, since the power supply voltage Vo is generated by the switching regulator 11 when the photographing ISO sensitivity is equal to or lower than the threshold value, the power consumption of the entire imaging module 1 can be suppressed.

Alternatively, the switching unit 14 of the imaging module 1 illustrated in FIG. 6 operates only the linear regulator 13 when the brightness of the subject is equal to or less than the threshold, and operates only the switching regulator 11 when the brightness exceeds the threshold. You may do it. In this way, the image quality of the captured image data recorded on the recording medium 17 can be improved by operating the linear regulator 13 with less noise only when shooting a dark subject in which noise is conspicuous. Further, when the brightness exceeds the threshold value, the power supply voltage Vo is generated by the switching regulator 11, so that the power consumption of the entire imaging module 1 can be suppressed.

In FIG. 6, the control circuit 11 c of the switching regulator 11 may perform on / off control of the transistor 11 a according to, for example, the clock ck 2 described in FIG. 4 instead of the clock ck 1 synchronized with the read clock ck. .

FIG. 7 is a view showing a modification of the imaging module 1 shown in FIG. The imaging module 1 shown in FIG. 7 has the same configuration as that of the imaging module 1 shown in FIG. 6 except that the control circuit 11c controls on / off of the transistor 11a according to the clock ck2.

That is, in the imaging module 1 shown in FIG. 7, the switching regulator 11 in FIG. 6 has the conventional general configuration, and the switching regulator 11 is operated by the low-frequency clock ck2, thereby reducing the power consumption when the switching regulator 11 operates. is doing.

Since the operation clock of the switching regulator 11 in the imaging module 1 shown in FIG. 7 is the clock ck2, electromagnetic noise of the inductor 11b is mixed in the captured image signal output from the imaging element 20 during the operation of the switching regulator 11. there is a possibility. However, in the imaging other than the imaging according to the imaging / recording instruction, the captured image data obtained by the imaging is not recorded in the recording medium 17, and therefore the influence of the electromagnetic noise at the time of imaging does not matter so much.

The configurations of the switching regulator 11 and the linear regulator 13 described so far are merely examples, and various modifications can be made without departing from the scope of the present invention.

As described above, the following items are disclosed in this specification.

A disclosed power supply circuit is a power supply circuit that supplies a power supply voltage to an image sensor, and includes a switching transistor connected to an external power supply, an inductor connected to the transistor, and a control circuit that performs switching control of the transistor. And a switching power supply circuit unit that generates a power supply voltage by converting magnetic energy stored in the inductor into electrical energy by turning on and off the transistor by the control circuit, and the control circuit receives a signal from the pixel cell of the image sensor. At least a first switching control for turning on and off the transistor in accordance with a first driving clock synchronized with a reading clock for determining a timing for reading out the pixel cell. The signal is read from To turn off the transistor when it is a control of the transistor to turn on if no signal is read out from the pixel cell.

The disclosed power supply circuit includes a frequency dividing circuit that divides a read clock to generate a first drive clock.

The disclosed power supply circuit includes a selector that selects and inputs one of a first drive clock and a second drive clock having a frequency lower than the first drive clock to the control circuit. First switching control is performed when the first driving clock is input, and second switching control is performed to turn on and off the transistor according to the second driving clock when the second driving clock is input. Is.

In the disclosed power supply circuit, the selector sets the first drive clock to the control circuit for a certain period when an imaging / recording instruction for recording captured image data obtained by imaging a subject with an imaging device is recorded on a recording medium. The second drive clock is input to the control circuit when an image capturing / recording instruction for recording the captured image data obtained by capturing the captured image of the subject on the recording medium is not made.

In the disclosed power supply circuit, the selector inputs the first drive clock to the control circuit when the brightness of the subject imaged by the imaging device is equal to or less than the threshold value, and the second when the brightness of the subject exceeds the threshold value. The drive clock is input to the control circuit.

In the disclosed power supply circuit, the selector inputs the first drive clock to the control circuit when the shooting ISO sensitivity set in the image sensor exceeds the threshold value, and the second drive when the shooting ISO sensitivity is equal to or lower than the threshold value. The clock is input to the control circuit.

The disclosed power supply circuit is provided in parallel with the switching power supply circuit unit, and includes a linear regulator circuit unit that continuously controls a current flowing through a load to generate a power supply voltage, and a switching power supply circuit unit and a linear regulator circuit unit. A switching unit that operates by switching, the switching unit operates the linear regulator circuit unit for a certain period from the start of the power supply circuit to generate a power supply voltage, and operates the switching power supply circuit unit after a certain period of time has elapsed. A power supply voltage is generated.

The disclosed power supply circuit is provided in parallel with the switching power supply circuit unit, and includes a linear regulator circuit unit that continuously controls a current flowing through a load to generate a power supply voltage, and a switching power supply circuit unit and a linear regulator circuit unit. A switching unit that operates by switching, and the switching unit includes a linear regulator circuit unit for a certain period of time when an imaging recording instruction for recording captured image data obtained by imaging a subject with an imaging device is recorded on a recording medium. The power supply voltage is generated by operating, and after a certain period of time, the power supply voltage is generated by operating the switching power supply circuit unit.

The disclosed power supply circuit is provided in parallel with the switching power supply circuit unit, and includes a linear regulator circuit unit that continuously controls a current flowing through a load to generate a power supply voltage, and a switching power supply circuit unit and a linear regulator circuit unit. A switching unit that operates by switching, and the switching unit operates the linear regulator circuit unit to generate a power supply voltage when the brightness of the subject imaged by the imaging device is equal to or lower than the threshold, and the brightness exceeds the threshold In this case, the switching power supply circuit unit is operated to generate a power supply voltage.

The disclosed power supply circuit is provided in parallel with the switching power supply circuit unit, and includes a linear regulator circuit unit that continuously controls a current flowing through a load to generate a power supply voltage, and a switching power supply circuit unit and a linear regulator circuit unit. A switching unit that operates by switching, and the switching unit operates the linear regulator circuit unit to generate a power supply voltage when the imaging ISO sensitivity set in the imaging element exceeds a threshold value, and the imaging ISO sensitivity is equal to or lower than the threshold value. In this case, the switching power supply circuit unit is operated to generate a power supply voltage.

The disclosed imaging module includes the power supply circuit and an imaging element to which a power supply voltage is supplied by the power supply circuit.

The disclosed imaging device includes the imaging module.

DESCRIPTION OF SYMBOLS 1 Imaging module 10 Power supply circuit 11 Switching regulator

11a Switching transistor 11b Inductor

11c Control circuit 12 Capacitor 20 Imaging element 30 Imaging element drive circuit ck Read clock ck1 Driving clock of switching regulator 11

Claims

A power supply circuit for supplying a power supply voltage to the image sensor,
A switching transistor connected to an external power source, an inductor connected to the transistor, and a control circuit that performs switching control of the transistor are stored in the inductor by turning on and off the transistor by the control circuit. A switching power supply circuit unit that converts the generated magnetic energy into electrical energy to generate the power supply voltage,
The control circuit performs at least a first switching control for turning on and off the transistor according to a first drive clock synchronized with a read clock that determines a timing for reading a signal from a pixel cell of the image sensor,
The first switching control by the first drive clock is configured such that when a signal is read from the pixel cell according to the read clock, the transistor is turned off, and when a signal is not read from the pixel cell, the transistor Power supply circuit that is the control to turn on.
The power supply circuit according to claim 1,
A power supply circuit comprising a frequency dividing circuit that divides the read clock to generate the first drive clock.
The power supply circuit according to claim 1 or 2,
A selector that selects and inputs one of the first drive clock and a second drive clock having a frequency lower than the first drive clock to the control circuit;
The control circuit performs the first switching control when the first drive clock is input, and the transistor according to the second drive clock when the second drive clock is input. A power supply circuit that performs second switching control to turn on and off.
The power supply circuit according to claim 3, wherein
The selector inputs the first drive clock to the control circuit for a certain period when an imaging recording instruction for recording captured image data obtained by imaging the subject with the imaging element on a recording medium is given, A power supply circuit for inputting the second drive clock to the control circuit when a shooting / recording instruction for recording captured image data obtained by imaging the subject with the imaging device on a recording medium is not given;
The power supply circuit according to claim 3, wherein
The selector inputs the first drive clock to the control circuit when the brightness of the subject imaged by the imaging device is equal to or lower than a threshold value, and the second drive clock when the brightness of the subject exceeds the threshold value. A power supply circuit that inputs a drive clock of the control circuit to the control circuit.
The power supply circuit according to claim 3, wherein
The selector inputs the first driving clock to the control circuit when the photographing ISO sensitivity set in the image sensor exceeds a threshold value, and the second driving when the photographing ISO sensitivity is equal to or less than the threshold value. A power supply circuit for inputting a clock to the control circuit.
The power supply circuit according to any one of claims 1 to 6,
A linear regulator circuit unit that is provided in parallel with the switching power supply circuit unit and that continuously controls a current flowing through a load to generate the power supply voltage;
A switching unit for switching and operating the switching power supply circuit unit and the linear regulator circuit unit,
The switching unit operates the linear regulator circuit unit to generate the power supply voltage for a predetermined period from the start of the power supply circuit, and operates the switching power supply circuit unit to operate the power supply voltage after the predetermined period has elapsed. Power supply circuit to be generated.
The power supply circuit according to claim 1 or 2,
A linear regulator circuit unit that is provided in parallel with the switching power supply circuit unit and that continuously controls a current flowing through a load to generate the power supply voltage;
A switching unit for switching and operating the switching power supply circuit unit and the linear regulator circuit unit,
The switching unit operates the linear regulator circuit unit for a certain period of time to set the power supply voltage when an imaging recording instruction for recording captured image data obtained by imaging a subject with the imaging element on a recording medium is made. A power supply circuit that generates the power supply voltage by operating the switching power supply circuit section after the predetermined period has elapsed;
The power supply circuit according to claim 1 or 2,
A linear regulator circuit unit that is provided in parallel with the switching power supply circuit unit and that continuously controls a current flowing through a load to generate the power supply voltage;
A switching unit for switching and operating the switching power supply circuit unit and the linear regulator circuit unit,
The switching unit operates the linear regulator circuit unit to generate the power supply voltage when the brightness of a subject imaged by the imaging device is equal to or lower than a threshold value, and generates the power supply voltage when the brightness exceeds the threshold value. A power supply circuit for operating the circuit unit to generate the power supply voltage.
The power supply circuit according to claim 1 or 2,
A linear regulator circuit unit that is provided in parallel with the switching power supply circuit unit and that continuously controls a current flowing through a load to generate the power supply voltage;
A switching unit for switching and operating the switching power supply circuit unit and the linear regulator circuit unit,
The switching unit operates the linear regulator circuit unit to generate the power supply voltage when the imaging ISO sensitivity set in the image sensor exceeds a threshold value, and generates the power supply voltage when the imaging ISO sensitivity is equal to or lower than the threshold value. A power supply circuit for operating the circuit unit to generate the power supply voltage.
A power supply circuit according to any one of claims 1 to 10,
An imaging module comprising: the imaging element to which a power supply voltage is supplied by the power supply circuit.
An imaging apparatus comprising the imaging module according to claim 11.