Imaging device

Abstract

This reduces the total amount of current flowing through the flexible circuit board, thereby suppressing image quality degradation. [Solution] The system comprises a main board on which a power supply unit is located, an imaging sensor 102b having a pixel section on which pixels are located and a circuit section for reading signals from the pixels, an imaging board 101 on which the imaging sensor is mounted, a flexible board connected to the main board and the imaging board and supplying power from the power supply unit to the imaging board, and a step-down switching power supply 400 mounted on the imaging board on a side different from the side on which the imaging sensor is mounted and supplying power to the imaging sensor. The step-down switching power supply has a switching element, an integrated circuit 401, a first capacitor 403 connected to the power input side of the integrated circuit, an inductor 403 connected to the output terminal of the integrated circuit, and a second capacitor 404 connected to the inductor. The inductor and the second capacitor are located outside the area projected onto the imaging board from the imaging sensor.

Description

Technical Field

[0001] The present invention relates to a power supply technology for an imaging sensor in an imaging device.

Background Art

[0002] In conventional imaging devices such as single-lens reflex cameras and mirrorless cameras, the power supply for the imaging sensor is arranged on a separate substrate away from the imaging substrate on which the imaging sensor is mounted, due to concerns about image quality degradation caused by magnetic fields, and power is supplied from there to the imaging substrate via a flexible substrate.

[0003] In recent years, in order to realize an image blur correction function by moving the imaging sensor, it is common to be configured to physically move the imaging substrate. Therefore, it is desirable to provide a long extra length so that the flexible substrate does not interfere with the movement of the imaging substrate, and to make the wiring width as thin as possible and the thickness as thin as possible.

[0004] On the other hand, in recent years, with the increase in the readout speed and the increase in the number of pixels of the imaging sensor, the current consumption of the imaging sensor has increased, and accordingly, the current flowing through the flexible substrate tends to increase. An increase in the current flowing through the flexible substrate causes problems such as image quality degradation due to an increase in magnetic field strength. In addition, an increase in the current and an increase in the amount of heat generated due to wiring resistance and the like also lead to image quality degradation.

[0005] As a method for supplying power to the imaging sensor, Patent Document 1 describes a method of suppressing the current of the first power supply circuit unit by providing a second power supply circuit unit in addition to the first power supply circuit unit.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, the prior art disclosed in Patent Document 1 cannot reduce the total amount of current flowing through the flexible substrate.

[0008] Furthermore, in the prior art disclosed in Patent Document 1, if the second power supply circuit is placed near the imaging sensor, there is a concern that the image quality may deteriorate due to the magnetic field from the second power supply circuit.

[0009] The present invention has been made in view of the above-mentioned problems, and its objective is to provide an imaging device that can reduce the total amount of current flowing through a flexible substrate while also suppressing image quality degradation. [Means for solving the problem]

[0010] The imaging device according to the present invention comprises: a main board on which a power supply unit is arranged; an imaging sensor having a pixel section in which a plurality of pixels are arranged in two dimensions and a circuit section for reading signals from the pixels; an imaging board on which the imaging sensor is mounted; a flexible board connected to the main board and the imaging board and supplying power from the power supply unit to the imaging board; and a step-down switching power supply mounted on the imaging board on a side different from the side on which the imaging sensor is mounted, which steps down the voltage supplied via the flexible board and supplies power to the imaging sensor, wherein the step-down switching power supply comprises a switching element, an integrated circuit in which a control circuit is integrated, a first capacitor connected to the power input side of the integrated circuit, an inductor connected to the output terminal of the integrated circuit, and a second capacitor connected to a terminal of the inductor different from the terminal connected to the output terminal of the integrated circuit, wherein the inductor and the second capacitor are arranged on the imaging board outside the area in which the imaging sensor is projected onto the imaging board. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an imaging device that can reduce the total amount of current flowing through a flexible substrate while also suppressing image quality degradation. [Brief explanation of the drawing]

[0012] [Figure 1] A block diagram showing the configuration for supplying power to the imaging sensor in the imaging device of the first embodiment. [Figure 2] A diagram showing the schematic configuration of the imaging sensor installed in the imaging device. [Figure 3] A diagram illustrating the signal processing of an imaging sensor. [Figure 4] A diagram showing the configuration of a step-down switching power supply. [Figure 5] A conceptual diagram showing the relationship between the readout frequency of the image sensor and the switching frequency of the step-down switching power supply. [Figure 6] A diagram showing the arrangement of the step-down switching power supply for the imaging substrate in the first embodiment. [Figure 7] A diagram showing the arrangement of the step-down switching power supply for the imaging substrate in the second embodiment. [Figure 8] Cross-sectional view of the imaging unit in the third embodiment. [Figure 9] A first arrangement diagram of the conductors of the imaging substrate in the fourth embodiment. [Figure 10] A second arrangement diagram of the conductors of the imaging substrate in the fourth embodiment. [Figure 11] A diagram showing the arrangement of the step-down switching power supply for the imaging substrate in the fifth embodiment. [Figure 12] A diagram showing the arrangement of inductors on the imaging substrate in the sixth embodiment. [Figure 13] A diagram showing the schematic configuration of a stacked imaging sensor in the seventh embodiment. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

[0014] (First Embodiment) FIG. 1 is a block diagram showing a configuration for supplying power to an imaging sensor in an imaging device according to a first embodiment of the present invention.

[0015] In FIG. , an imaging device 300 includes an imaging unit 100, a main board unit 200, flexible boards 301 and 302 connecting these, and a battery 201.

[0016] The battery 201 corresponds to a power supply source of the imaging device 300 and is, for example, a removable lithium-ion battery.

[0017] The main board unit 200 includes a main board 202, a system control unit 203, a power supply 204, connectors 301a and 302a, and other resistors, capacitors, etc. not shown in the figure.

[0018] The main board 202 is a printed board on which a power supply circuit such as the system control unit 203 and the power supply 204 is mounted.

[0019] The system control unit 203 controls the entire imaging device including the imaging unit 100 and acquires an image signal from the imaging unit 100 via the flexible board 302.

[0020] The power supply (power unit) 204 is located on the main board 202 and includes one or more power supply circuits that convert the voltage supplied from the battery 201 into the voltages required by the system control unit 203 and the imaging unit 100, respectively, and output them. Power is supplied from the power supply 204 to the imaging unit 100 from the main board 202 via connector 301a and flexible board 301. Alternatively, power may be supplied directly from the battery 201 to the imaging unit 100. The flexible board 301 is connected to the imaging unit 100 via connector 301b.

[0021] The imaging unit 100 comprises an imaging substrate 101, an imaging sensor 102, a linear regulator 103, step-down switching power supplies 400a and 400b, connectors 301b and 302b, and other components such as resistors and capacitors (not shown).

[0022] The imaging substrate 101 is a printed circuit board having power wiring made of a metal such as copper. A rigid substrate is used for mounting the imaging sensor 102 on the imaging substrate 101, and is made of, for example, glass epoxy. However, it is not limited to these, and the imaging substrate 101 may be a flexible substrate made of a plastic material, or an LTCC (Low-Temperature Co-Fired Ceramics) substrate made of ceramics and copper wiring. In other words, any substrate that has a metal wiring pattern such as copper formed on a specific material and on which components can be mounted (assembled) is acceptable.

[0023] The imaging sensor 102 consists of a CMOS image sensor or the like that outputs an image signal in response to incident light. More specifically, the imaging sensor 102 is an XY address type CMOS image sensor, as will be described later with reference to Figures 2 and 3, and performs imaging operations and outputs an image signal according to control signals from the system control unit 203. The image signal is transmitted from the imaging unit 100 to the main board 202 via connector 302b, flexible board 302, and connector 302a, and input to the system control unit 203.

[0024] The step-down switching power supplies 400a and 400b are placed on the imaging substrate 101. Step-down switching power supply 400a is a power supply circuit that steps down the voltage supplied from the power supply 204 to the first power supply voltage required by the imaging sensor 102. Step-down switching power supply 400b is a power supply circuit that generates the voltage to be input to the linear regulator 103.

[0025] Although two examples of step-down switching power supplies have been shown, the imaging substrate 101 may have one or more step-down switching power supplies. Hereafter, when step-down switching power supplies 400a and 400b are referred to collectively, they will be written as step-down switching power supply 400.

[0026] The linear regulator 103 is a linear regulator that steps down the output voltage of the step-down switching power supply 400b to a second power supply voltage required by the imaging sensor 102.

[0027] As described above, by placing the step-down switching power supply 400 on the imaging substrate 101, the main substrate 202 can supply power to the imaging substrate 101 at a voltage higher than the voltage required by the imaging sensor 102. Therefore, the amount of current flowing through the flexible substrate 301 can be reduced, and the degradation of image quality due to the magnetic field radiated from the flexible substrate 301 can be mitigated. When the step-down switching power supply 400 is mounted on the imaging substrate 101, the step-down switching power supply 400 is placed close to the imaging sensor 102. A method for mitigating the degradation of image quality due to the magnetic field radiated from the step-down switching power supply 400 in this case will be explained below.

[0028] Figure 2 shows a schematic configuration of the imaging sensor 102 provided by the imaging device.

[0029] The image sensor 102 is a CMOS sensor having a pixel section 120a comprising a plurality of pixels 110, and a circuit section 170 comprising a signal processing section 171, a control section 172, and an output section 173. The pixel section 120a is composed of a plurality of pixels 110 arranged in a matrix (two-dimensional) in the mutually orthogonal horizontal (X direction) and vertical (Y direction) directions. In addition, the pixel section 120a has a 2x2 array of color filters, with odd-numbered rows consisting of repeating red (R) filters and green (G) filters, and even-numbered rows consisting of repeating green (G) filters and blue (B) filters, arranged to correspond to each pixel 110.

[0030] The signal processing unit 171 is a circuit that performs signal processing such as A / D conversion on row-by-row image signals sent via the vertical output line 130 (see Figure 3). The control unit 172 is a circuit that selects one row at a time from the pixel array of the pixel unit 120a and controls the reset and read operations of the selected pixel row. The output unit 173 is a circuit that outputs the digitized row-by-row image signals to the outside of the imaging sensor 102.

[0031] Figure 3 illustrates the signal processing of the imaging sensor 102.

[0032] The vertical output lines 130 are arranged in the direction of the pixel columns and are commonly connected to the pixels in each row for each pixel column. The image signals of the rows selected by the pixel control lines 320 are read out to the corresponding vertical output lines 130. The pixel control lines 320 also simultaneously control the pixels 110 in a horizontal row, enabling reset and signal readout. The load current source 330 drives the pixels 110 of the selected row via the vertical output lines 130.

[0033] One input terminal of comparator 340 receives the analog signal of pixel 110. The other input terminal of comparator 340 is connected to a reference signal line 350, through which a reference signal output from a reference signal generator (not shown) is received. The output terminal of comparator 340 is connected to a latch circuit 360. The latch circuit 360 holds the count value of a counter (not shown) input from signal line 370 when the relative magnitudes of the pixel analog signal and the reference signal are reversed, causing the output of comparator 340 to change. The held count value is stored in memory 380 and held as a digital value. The digital signal stored in memory 380 is transferred to the subsequent stage of signal processing unit 171 via horizontal transfer line 390, where various processing such as offset processing and gain processing is performed. The digital signal that has passed through signal processing unit 171 is output to the outside from output unit 173 via an interface (I / F). This I / F is, for example, SubLVDS, SLVS, or SLVS-EC.

[0034] Figure 4 shows the configuration of a step-down switching power supply 400. The step-down switching power supply 400 includes an integrated circuit 401 in which switching elements Q1, Q2 and a control circuit 410 are integrated, and a first capacitor 403 connected to the power input side of the integrated circuit 401. Furthermore, it includes an inductor 402 connected to the output terminal of the integrated circuit 401, and a second capacitor 404 connected to a terminal of the inductor 402 other than the terminal connected to the output terminal of the integrated circuit 401. Note that there may be multiple inductors 402, first capacitors 403, and second capacitors 404, rather than just one.

[0035] The control circuit 410 is a control circuit that controls the switching elements Q1 and Q2 so that the output voltage of the step-down switching power supply 400 becomes a desired value. The switching elements Q1 and Q2 are, for example, FETs and are switching elements that constitute the step-down switching power supply 400.

[0036] There are mainly two types of switching control for the step-down switching power supply 400: fixed PWM control and PFM control (pulse frequency modulation). Fixed PWM control operates at a fixed switching frequency, while PFM operation mode varies the switching frequency according to the load. In this embodiment, either switching control may be used.

[0037] The higher the frequency of the switching drive, the smaller the capacitors and inductors that can be selected, enabling miniaturization of the equipment. However, as the frequency increases, switching losses and dead time losses increase, reducing efficiency. Therefore, the switching frequency of a step-down switching power supply is selected to balance size and efficiency. The step-down switching power supply 400 switches at a frequency higher than the load fluctuation (readout frequency) of the image sensor 102 in order to supply a stable power supply. For example, the step-down switching power supply 400 is configured to switch at a frequency of 1 to 3 MHz (1 MHz or higher).

[0038] Figure 5 is a conceptual diagram showing the relationship between the readout frequency of the image sensor 102 and the switching frequency of the step-down switching power supply 400. The vertical axis represents current, and the horizontal axis represents time.

[0039] The graph above shows that the current flowing through the first capacitor 403 fluctuates at the switching frequency f1 due to the switching drive of the step-down switching power supply 400. In the step-down switching power supply 400, if T1 is the time it takes for switching element Q1 or Q2 to turn ON and then turn ON again, then the switching frequency f1 = 1 / T1.

[0040] The graph below shows that the current flowing through the inductor 402 and the second capacitor 404 fluctuates at the readout frequency f2 due to the readout operation of the image sensor 102 controlled by the control unit 172. If T2 is the time it takes for the image sensor 102 to read out one row of image signals via the vertical signal line 130 to the signal processing unit 171, perform A / D conversion, and output the digital signal externally, then the readout frequency f2 = 1 / T2. And frequency f1 is higher than frequency f2.

[0041] A first magnetic field is generated from the wiring between the first capacitor 403 and the integrated circuit 401 due to current fluctuations associated with the switching drive of the step-down switching power supply 400. Meanwhile, at the readout frequency of the imaging sensor 102, charging and discharging of current occurs in the wiring from the inductor 402 and the second capacitor 404 to the imaging sensor 102, generating a second magnetic field. The first magnetic field has a higher frequency than the second magnetic field.

[0042] The step-down switching power supply 400 is located on the back surface of the imaging substrate 101 where the imaging sensor 102 is positioned. Therefore, the magnetic field generated by the step-down switching power supply 400 has two paths to reach the imaging sensor 102: one that wraps around the edge of the imaging substrate 101 and another that penetrates the imaging substrate 101. The longer the path that wraps around the edge of the imaging substrate 101, the more the magnetic field reaching the imaging sensor 102 is attenuated. Thus, the further the step-down switching power supply 400 is from the edge of the imaging substrate 101, the more the magnetic field is attenuated. In the path that penetrates the imaging substrate 101, the magnetic field is attenuated by the skin effect due to the conductors within the imaging substrate 101, and this attenuation is particularly pronounced at higher frequencies.

[0043] Therefore, since the first magnetic field radiated by the first capacitor 403 has a higher frequency than the second magnetic field radiated by the inductor 402 and the second capacitor 404, the magnetic field penetrating the imaging substrate 101 is attenuated.

[0044] Figure 6 shows the arrangement of the step-down switching power supply 400 on the imaging substrate 101 in the first embodiment. The step-down switching power supply 400 is located on the back side of the surface of the imaging substrate 101 on which the imaging sensor 102 is located.

[0045] The pixel region 120b is the region where the pixel portion 120a of the imaging sensor 102 is located, projected onto the imaging substrate 101 (on the imaging substrate), and the imaging sensor region 102b is the region where the imaging sensor 102 is located, projected onto the imaging substrate 101 (on the imaging substrate). To prevent the magnetic field penetrating the imaging substrate 101 from reaching the pixel portion 120a, all elements that are magnetic field radiation sources of the step-down switching power supply 400 are placed outside the imaging sensor region 102b, as shown by the dashed rectangle 1400a in Figure 6. Alternatively, if there are constraints on the component placement area of ​​the imaging substrate 101 and it is difficult to place all magnetic field radiation sources outside the imaging sensor region 102b, they are placed outside the pixel region 120b.

[0046] Furthermore, considering the magnetic field attenuation due to the skin effect of the imaging substrate 101, the following may be done. That is, as shown by the dashed rectangle 1400b in Figure 6, the inductor 402 and the second capacitor 404, which are relatively low-frequency magnetic field sources of the step-down switching power supply 400, are placed outside the imaging sensor area 102b. The first capacitor 403, which is a relatively high-frequency magnetic field source, is placed inside the imaging sensor area 102b.

[0047] The arrangement of the step-down switching power supply 400 on the imaging substrate 101 described above is just one example and is not necessarily limited to this arrangement.

[0048] In the first embodiment, an example was described in which at least the inductor 402 and the second capacitor 404 of the step-down switching power supply 400 are arranged outside the pixel area 120b or the imaging sensor area 102b. By arranging the step-down switching power supply 400 on the imaging substrate 101 in this way, the amount of current flowing through the power supply path to the imaging substrate 101 can be reduced, and the degradation of image quality due to the magnetic field radiated from the flexible substrate 301 can be mitigated. Furthermore, by arranging the step-down switching power supply 400 on the imaging substrate 101 in the above arrangement, it is possible to further reduce the degradation of image quality due to the magnetic field radiated from the step-down switching power supply 400.

[0049] (Second embodiment) In the first embodiment, a configuration was described that reduces the influence of a magnetic field that penetrates the imaging substrate 101 and reaches the imaging sensor 102.

[0050] In a second embodiment of the present invention, a configuration is described that reduces the influence of the magnetic field emitted by the step-down switching power supply 400, which wraps around the edge of the imaging substrate 101 and reaches the imaging sensor 102.

[0051] Figure 7 shows the arrangement of the step-down switching power supply 400 on the imaging substrate 101 in the second embodiment. The magnetic field that wraps around from the switching power supply 400 is the magnetic field that wraps around the edge of the imaging substrate 101 and reaches the imaging sensor 102 on the back side. According to the Biot-Savart law, the magnetic field is inversely proportional to the square or cube of the distance, so the wrapping magnetic field can be suppressed as it is moved further away from the edge of the imaging substrate 101. In particular, the magnetic field suppression effect is high when it is 1 to 2 mm away from the edge of the substrate, so the wrapping magnetic field can be suppressed by placing the step-down switching power supply 400 in a region 701 that is 1 mm or more away from the edge of the imaging substrate 101.

[0052] In the second embodiment, an example was described in which the step-down switching power supply 400 is placed in a region 701 that is 1 mm or more away from the edge of the imaging substrate 101. With the configuration of the second embodiment, it is possible to reduce noise generated in the image signal due to the magnetic field that originates from the step-down switching power supply 400, wraps around the edge of the imaging substrate 101, and reaches the imaging sensor 102.

[0053] (Third embodiment) Figure 8 is a cross-sectional view showing the configuration of the imaging unit 100 in the third embodiment. The imaging substrate 101 is configured as a multilayer structure (multilayer substrate) and has a wiring layer 150, an insulating layer 900, and connecting conductors 800 that connect each wiring layer 150.

[0054] The wiring layer 150 is a layer for providing power lines and communication wiring, and is made of a conductor such as copper. An insulating layer 900 made of prepreg is provided between each wiring layer 150. The connecting conductor 800 is made of a conductor and serves to electrically connect each wiring layer 150. For example, it is made of drill vias.

[0055] Due to the skin effect of conductors, the magnetic field is attenuated. Therefore, the magnetic field radiated from the power lines wired in the wiring layer 150 is attenuated by each wiring layer 150 before reaching the image sensor 102. For this reason, power lines carrying large currents are placed in wiring layers far from the image sensor 102, while power lines carrying small currents and communication lines are placed in wiring layers closer to the image sensor 102.

[0056] In the third embodiment, an example was described in which a power supply line carrying a large current is routed away from the imaging sensor 102. With the configuration of the third embodiment, the magnetic field caused by the current flowing through the power supply wiring is attenuated by the skin effect, making it possible to suppress noise in the image signal.

[0057] (Fourth embodiment) In the fourth embodiment, a method for suppressing the surrounding magnetic field using a conductor will be described.

[0058] Figure 9 is a first arrangement diagram of the conductors on the imaging substrate 101 in the fourth embodiment. The suppression of the through-magnetic field due to the skin effect is performed by the conductors within the imaging substrate 101. Therefore, even if the conductor 501 is placed at the edge of the imaging substrate 101, the surrounding magnetic field can be suppressed by the skin effect. For this reason, the conductor 501 is placed in the substrate edge region 702 near the step-down switching power supply 400. Note that multiple conductors 501 may be placed in the substrate edge region 702.

[0059] Figure 10 is a second arrangement diagram of the conductors of the imaging substrate 101 in the fourth embodiment. By covering the step-down switching power supply 400 with the conductor 502 from the Z direction, the magnetic field in the Z direction is suppressed by the skin effect of the conductor 502. In electronic equipment equipped with an imaging device, the copper wires in the inductor are often wound clockwise or counterclockwise when viewed from the Z direction, and according to the right-hand rule, the magnetic field is radiated in the Z direction. Therefore, by suppressing the magnetic field in the Z direction with the conductor 502, the surrounding magnetic field can be suppressed.

[0060] In the fourth embodiment, an example was described in which conductors 501 and 502 are arranged on the imaging substrate 101. With the configuration of the fourth embodiment, it is possible to suppress the circulating magnetic field radiated by the step-down switching power supply 400.

[0061] (Fifth embodiment) In the fifth embodiment, the relationship between the direction of the magnetic field and the image sensor 102 will be described. As shown in Figure 3, the signals from multiple pixels 110 are read out in the Y direction by the vertical signal line 130. Noise in the image signal is mainly caused by the magnetic field in the X direction linking with the vertical signal line 130.

[0062] Figure 11 is a diagram showing the arrangement of the step-down switching power supply 400 on the imaging substrate 101 in the fifth embodiment. The surrounding magnetic field mainly occurs in the direction of the edge of the imaging substrate 101 closest to the step-down switching power supply 400. If the step-down switching power supply 400 is placed near the X-direction edge of the imaging substrate 101, the X-direction surrounding magnetic field radiated by the step-down switching power supply 400 links with the vertical signal line 130, causing noise in the image signal. If the step-down switching power supply 400 is placed in the region 703 near the Y-direction edge, the Y-direction surrounding magnetic field radiated by the step-down switching power supply 400 (indicated by the arrow in Figure 11) is parallel to the vertical signal line 130, suppressing noise in the image signal. Therefore, in the fifth embodiment, the step-down switching power supply 400 is placed in the region 703 near the Y-direction edge of the imaging substrate 101.

[0063] In the fifth embodiment, an example was described in which the step-down switching power supply 400 is placed in a vertical peripheral region 703 (near the edge in the direction intersecting the pixel column direction) on the imaging substrate 101. With the configuration of the fifth embodiment, it is possible to make it difficult for the circulating magnetic field to link with the vertical signal line 130, thereby suppressing noise in the image signal.

[0064] (Sixth embodiment) In the sixth embodiment, the direction of the radiated magnetic field of the inductor will be described.

[0065] Figure 12 is a diagram showing the arrangement of inductors 402a and 402b of the imaging substrate 101 in the sixth embodiment. Generally, an inductor is constructed by winding a wire in a spiral shape, and according to the right-hand rule, the direction in which the magnetic field is radiated is determined by the direction in which the current flows. In other words, the direction of the magnetic field is determined by the direction in which the wire is wound.

[0066] In Figure 12, inductor 402a has its wire wound counterclockwise (in the direction of the arrow), so an upward magnetic field is generated from the imaging substrate 101. However, inductor 402b has its wire wound clockwise, so a downward magnetic field is generated. Inductors 402a and 402b are close together, and current flows in the same direction, causing magnetic fields to be generated in opposite directions, and these opposing magnetic fields interfere with each other. When opposing magnetic fields interfere, they cancel each other out.

[0067] Therefore, when multiple inductors are arranged on the imaging substrate 101, such as when the step-down switching power supply 400 has multiple inductors, or when multiple step-down switching power supplies 400 are arranged on the imaging substrate 101, each inductor is arranged in a direction that cancels out each other's magnetic fields. This suppresses the magnetic field generated when multiple step-down switching power supplies 400 are arranged. The arrangement of inductors 402a and 402b in Figure 12 is just an example and is not necessarily limited to this arrangement. Alternatively, a coupled inductor (a type of inductor in which multiple inductors are enclosed in a single inductor package) may be selected.

[0068] In the sixth embodiment, an example was described in which a plurality of inductors on the imaging substrate 101 are arranged in a direction in which the magnetic fields cancel each other out. With the configuration of the sixth embodiment, it is possible to suppress the magnetic field radiated by the step-down switching power supply 400.

[0069] (Seventh Embodiment) In the seventh embodiment, a stacked type image sensor 102 will be described. Image sensors 102 exist in both non-stacked and stacked types, with the stacked type being less susceptible to magnetic field influences than the non-stacked type. The image sensor 102 (see Figure 2) has a pixel section 120a in which a plurality of pixels 110 are arranged in an array, and a circuit section 170 in which circuits responsible for control and signal processing are arranged.

[0070] Figure 13 shows a schematic configuration of the stacked image sensor 102b. The non-stacked image sensor 102 (see Figure 2) has a structure in which the pixel section 120a and the circuit section 170 are arranged on a plane (XY plane). In contrast, the stacked image sensor 102b has a structure in which the layer on which the pixel section 120a is mounted and the layer on which the circuit section 170 is mounted are stacked in the Z direction.

[0071] The mechanism by which noise is generated when the imaging device 300 is subjected to a magnetic field will now be explained. When a closed loop consisting of the vertical signal line 130 and power supply wiring and ground wiring (not shown) within the imaging device 300 is subjected to a magnetic field, an induced electromotive force is generated in the direction that cancels out the magnetic field. Next, an induced current flows according to Ohm's law due to the induced electromotive force and the resistance of the closed loop. Then, a voltage drop occurs due to the product of the induced current and the wiring resistance. Of this potential difference between the induced electromotive force and the voltage drop, the one generated within the pixel section 120a becomes the noise voltage that generates image noise.

[0072] Here, we focus on wiring that affects image noise, such as the vertical signal line 130 within the pixel section 120a, and power and ground wiring. As mentioned above, in the non-stacked type, the pixel section 120a and the circuit section 170 are mounted on a plane, so the area that can be used for wiring inside the pixel section 120a is small. On the other hand, in the stacked type, the pixel section 120a and the circuit section 170 are not on the same plane, so if the pixel area of ​​the non-stacked image sensor 102 and the stacked image sensor 102b are the same, the area that can be used for wiring inside the pixel section 120a is significantly larger in the stacked type than in the non-stacked type.

[0073] Generally, resistance is inversely proportional to surface area and proportional to length. Therefore, a stacked type, which allows for a larger wiring area within the pixel section 120a, reduces the wiring resistance of the image sensor. As a result, voltage drop is reduced, the potential difference with the induced electromotive force is reduced, and noise is reduced. In other words, by making the image sensor 102 a stacked type, it is possible to reduce noise in the image signal.

[0074] In the seventh embodiment, an example was described in which the circuit section and pixel section of the imaging sensor 102 are arranged in a stacked structure. The configuration of the seventh embodiment makes it possible to suppress noise in the image signal caused by the magnetic field.

[0075] (Other embodiments) Furthermore, the present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by a process in which one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0076] The disclosures herein include the following imaging devices:

[0077] (Item 1) The main board where the power supply unit is located, An imaging sensor having a pixel section in which multiple pixels are arranged in a two-dimensional manner, and a circuit section for reading signals from the pixels, An imaging substrate on which the aforementioned imaging sensor is mounted, A flexible board connected to the main board and the imaging board, which supplies power from the power supply unit to the imaging board, A step-down switching power supply is mounted on the imaging substrate on a side different from the side on which the imaging sensor is mounted, and it steps down the voltage supplied via the flexible substrate to supply power to the imaging sensor. Equipped with, The step-down switching power supply comprises a switching element, an integrated circuit with an integrated control circuit, a first capacitor connected to the power input side of the integrated circuit, an inductor connected to the output terminal of the integrated circuit, and a second capacitor connected to a terminal of the inductor different from the terminal connected to the output terminal of the integrated circuit. The imaging apparatus is characterized in that the inductor and the second capacitor are arranged on the imaging substrate outside the region in which the imaging sensor is projected onto the imaging substrate.

[0078] (Item 2) The imaging apparatus according to item 1, characterized in that the integrated circuit and the first capacitor are arranged on the imaging substrate inside the region in which the imaging sensor is projected onto the imaging substrate.

[0079] (Item 3) The imaging apparatus according to item 1 or 2, characterized in that the step-down switching power supply is located at a distance of 1 mm or more from the edge of the imaging substrate.

[0080] (Item 4) The imaging apparatus according to any one of items 1 to 3, characterized in that the switching frequency of the step-down switching power supply is higher than the readout frequency of the imaging sensor.

[0081] (Item 5) The imaging device according to any one of items 1 to 4, characterized in that the step-down switching power supply operates at a fixed switching frequency of 1 MHz or higher.

[0082] (Item 6) The imaging device according to any one of items 1 to 4, characterized in that the step-down switching power supply operates at a switching frequency that varies according to the load.

[0083] (Item 7) The imaging apparatus according to any one of items 1 to 6, characterized in that a conductor is placed at a position close to the step-down switching power supply at the edge of the imaging substrate.

[0084] (Item 8) The imaging apparatus according to any one of items 1 to 6, characterized in that the step-down switching power supply is covered with a conductor.

[0085] (Item 9) The imaging apparatus according to any one of items 1 to 8, characterized in that, when the imaging substrate comprises a plurality of inductors, each inductor is arranged in a direction that cancels out the magnetic fields of the others.

[0086] (Item 10) The imaging device according to any one of items 1 to 9, characterized in that the imaging sensor is a stacked type imaging sensor.

[0087] (Item 11) The imaging device according to any one of items 1 to 10, characterized in that the imaging sensor is arranged parallel to the column direction of a plurality of pixels arranged in two dimensions and includes signal lines for transferring signals from the pixels, and the step-down switching power supply is positioned near the edge of the side of the imaging substrate that intersects the column direction.

[0088] (Item 12) The imaging apparatus according to any one of items 1 to 11, characterized in that the imaging substrate is a multilayer substrate, and the power line from the step-down switching power supply is routed to a layer of the multilayer substrate that is away from the imaging sensor.

[0089] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of symbols]

[0090] 101: Imaging substrate, 102: Imaging sensor, 110: Pixel, 120a: Pixel section, 170: Circuit section, 400: Step-down switching power supply, 401: Integrated circuit, 402: Inductor, 403: First capacitor, 404: Second capacitor

Claims

1. The main board where the power supply unit is located, An imaging sensor having a pixel section in which multiple pixels are arranged in a two-dimensional manner, and a circuit section for reading signals from the pixels, An imaging substrate on which the aforementioned imaging sensor is mounted, A flexible board connected to the main board and the imaging board, which supplies power from the power supply unit to the imaging board, A step-down switching power supply is mounted on the imaging substrate on a side different from the side on which the imaging sensor is mounted, and it steps down the voltage supplied via the flexible substrate to supply power to the imaging sensor. Equipped with, The step-down switching power supply comprises a switching element, an integrated circuit with an integrated control circuit, a first capacitor connected to the power input side of the integrated circuit, an inductor connected to the output terminal of the integrated circuit, and a second capacitor connected to a terminal of the inductor different from the terminal connected to the output terminal of the integrated circuit. The imaging apparatus is characterized in that the inductor and the second capacitor are arranged on the imaging substrate outside the region in which the imaging sensor is projected onto the imaging substrate.

2. The imaging apparatus according to claim 1, characterized in that the integrated circuit and the first capacitor are arranged on the imaging substrate inside the region in which the imaging sensor is projected onto the imaging substrate.

3. The imaging apparatus according to claim 1, characterized in that the step-down switching power supply is located at a distance of 1 mm or more from the edge of the imaging substrate.

4. The imaging apparatus according to claim 1, characterized in that the switching frequency of the step-down switching power supply is higher than the readout frequency of the imaging sensor.

5. The imaging apparatus according to claim 1, characterized in that the step-down switching power supply operates at a fixed switching frequency of 1 MHz or higher.

6. The imaging apparatus according to claim 1, characterized in that the step-down switching power supply operates at a switching frequency that varies according to the load.

7. The imaging apparatus according to claim 1, characterized in that a conductor is placed at a position close to the step-down switching power supply at the edge of the imaging substrate.

8. The imaging apparatus according to claim 1, characterized in that the step-down switching power supply is covered with a conductor.

9. The imaging apparatus according to claim 1, characterized in that, when the imaging substrate is provided with a plurality of inductors, each inductor is arranged in a direction that cancels out the magnetic fields of the others.

10. The imaging apparatus according to claim 1, characterized in that the imaging sensor is a stacked type imaging sensor.

11. The imaging apparatus according to claim 1, wherein the imaging sensor is arranged parallel to the column direction of a plurality of pixels arranged in two dimensions and includes signal lines for transferring signals from the pixels, and the step-down switching power supply is positioned near the edge of the side of the imaging substrate that intersects the column direction.

12. The imaging apparatus according to claim 1, characterized in that the imaging substrate is a multilayer substrate, and the power line from the step-down switching power supply is routed to a layer of the multilayer substrate away from the imaging sensor.

Images