JP4020872B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus suitable for mounting on a portable information terminal device such as a mobile phone or a portable information device (for example, a portable personal computer).

  In the conventional imaging device, an inductance is inserted between the input and output terminals of the horizontal transfer clock to improve the rising characteristic of the horizontal transfer clock and realize low power driving (for example, see Patent Document 1), horizontal transfer Some have realized a high-speed drive by inserting a capacitor for high-speed drive correction in parallel with a damping resistor provided between the input and output terminals of the clock (for example, see Patent Document 2).

JP-A-8-46879 (FIG. 1) Japanese Patent Laid-Open No. 11-220567 (FIG. 1)

  However, in the conventional imaging device having the configuration in which the inductance is inserted between the horizontal transfer clock terminals or the configuration in which the capacitor is inserted in parallel with the damping resistor, the rising characteristic of the horizontal transfer clock becomes steep, and the higher order of the horizontal transfer clock. The multiplied wave increases. As a result, unnecessary radiation (electromagnetic radiation) due to the horizontal transfer clock increases, and this unnecessary radiation causes EMI problems such as deterioration of transmission / reception sensitivity of the portable information terminal device having a communication function.

  The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide an imaging apparatus capable of reducing unnecessary radiation due to a drive clock without providing a complicated EMI filter. is there.

The imaging device of the present invention is
An image sensor that photoelectrically converts an incident light image of a subject in a light receiving unit, and transfers and outputs a charge train corresponding to the light image in a vertical direction and a horizontal direction;
The above two kinds of horizontal of the imaging device polar driven by the horizontal transfer portion, respectively equivalent drivability to generate two types of horizontal transfer clock backwards from the output terminal of the two horizontal transfer clock of the image pickup element A timing generator that supplies the input terminal of the transfer clock with the same drive capability ,
An imaging apparatus comprising the two types of horizontal transfer clock wirings that connect the output terminals of the two types of horizontal transfer clocks and the input terminals of the two types of horizontal transfer clocks, respectively.
The above-mentioned two types of horizontal transfer clock wirings are first and second wirings, respectively.
The output terminal and the input terminal connected by the first wiring are defined as a first output terminal and a first input terminal, respectively.
The output terminal and the input terminal connected by the second wiring as a second output terminal and a second input terminal, respectively.
In the imaging device, the horizontal transfer unit that transfers in the horizontal direction is a capacitive load, and the equivalent capacitance between the first input terminal and the ground and the equivalent capacitance between the second input terminal and the ground are different from each other. In case,
A first capacitor is provided between the first wiring and the ground, and a first low-pass filter is configured by the output impedance of the first output terminal and the first capacitor,
A second capacitor is provided between the second wiring and the ground, and a second low-pass filter is configured by the output impedance of the second output terminal and the second capacitor ;
The equivalent capacitance between the first input terminal and the ground in the image sensor and the parallel combined capacitance of the first capacitor, the equivalent capacitance between the second input terminal and the ground in the image sensor, and the The first capacitor and the parallel capacitor of the second capacitor are equal to each other so that load capacity conditions (each parallel composite capacitor) viewed from the output terminals of the two types of horizontal transfer clocks of the timing generator are equal to each other. The capacity of the second capacitor is set .

  According to the present invention, there is an effect that unnecessary radiation can be reduced without providing a complicated EMI filter.

Embodiment 1 FIG.
FIG. 1 is a block configuration diagram of an imaging apparatus according to Embodiment 1 of the present invention. The image pickup apparatus according to the first embodiment includes an image pickup element 1, a vertical CCD drive signal drive unit 2, an image pickup system control unit 3, and an image pickup signal processing unit 4.

  The imaging system control unit 3 includes a horizontal counter that counts pixel clocks, and a vertical counter that counts carry output when the horizontal counter reaches a predetermined count value.

  The imaging system control unit 3 generates vertical transfer control pulses φV1, φV2, φV3, φV4, readout control pulses φTG1, φTG3, and an electronic shutter control pulse φOFD, and supplies these pulses to the vertical CCD drive signal drive unit 2 To do.

  In addition, the imaging system control unit 3 generates horizontal transfer clocks H <b> 1 and H <b> 2 and a reset gate clock RS, and supplies these clocks to the imaging device 1.

  Further, the imaging system control unit 3 generates a CDS black level sample hold pulse SHP, a CDS signal level sample hold pulse SHD, an A / D clock ADCLK, a blanking signal PBLK, and an OB (optical black) level detection pulse CPOB. These are supplied to the imaging signal processing unit 4.

  The vertical CCD drive signal drive unit 2 drives the vertical transfer control pulses φV1, φV2, φV3, φV4, the read control pulses φTG1, φTG3, and the electronic shutter control pulse φOFD from the imaging system control unit 3 at high voltage, and the vertical transfer clock V1. , V2, V3, V4 and the electronic shutter pulse OFD are supplied to the image sensor 1.

  The image pickup device 1 is a vertical four-phase drive horizontal two-phase drive type inline (interline) CCD image pickup device, and includes a light receiving unit, a vertical transfer unit (VCCD), and a horizontal transfer unit (HCCD).

  The light receiving unit photoelectrically converts an incident light image of a subject using a plurality of photodiodes, and accumulates pixel charges.

  The VCCD reads out the pixel charges accumulated in the light receiving unit by the vertical transfer clocks V1, V2, V3, V4 from the vertical CCD drive signal drive unit 2 and transfers them in the vertical direction.

  The HCCD transfers the pixel charges transferred from the VCCD in the horizontal direction by horizontal transfer clocks H 1 and H 2 from the imaging system control unit 3. The pixel charge train transferred in the horizontal direction is output to the imaging signal processing unit 4 as a pixel charge signal OS.

  The imaging signal processing unit 4 samples the pixel charge signal OS from the imaging device 1 by the CDS black level sample hold pulse SHP and the CDS signal level sample hold pulse SHD from the imaging processing control unit 3 and performs CDS processing. This CDS-processed signal is gain-adjusted, A / D converted by the A / D clock ADCLK from the imaging processing control unit 3, and an imaging signal CCDOUT is output.

  Further, the imaging signal processing unit 4 corrects the black level of the imaging signal CCDOUT by the blanking signal PBLK and the optical black level detection pulse CPOB.

  FIG. 2 is a circuit diagram of a horizontal transfer clock drive circuit in the imaging apparatus of the first embodiment. The H1 output terminal of the timing generator 30 and the H1 input terminal of the CCD 31 are connected by an H1 wiring, and the H2 output terminal of the timing generator 30 and the H1 input terminal of the CCD 31 are connected by an H2 wiring.

  In the following description, a connection node of the H1 output terminal, the H1 input terminal, and the H1 wiring is referred to as an H1 node, and a connection node of the H2 output terminal, the H2 input terminal, and the H2 wiring is referred to as an H2 node.

  The timing generator 30 is an element having the function of the imaging system control unit 3 in FIG. 1, generates a horizontal transfer clock H1 and outputs it from the H1 output terminal, and a horizontal transfer clock H2 having a polarity opposite to that of the horizontal transfer clock H1. And output from the H2 output terminal.

  The CCD 31 is an element having the function of the image pickup element 1 in FIG. In the CCD 31, the internal HCCD is driven by the horizontal transfer clock H1 input to the H1 input terminal from the timing generator 30 and the horizontal transfer clock H2 input to the H2 input terminal, and the pixel charge train is horizontally transferred.

  The HCCD in the CCD 31 is a capacitive load, and the H1 and H2 input circuits (the circuit between the H1 input terminal and the H2 input terminal in the CCD 31) are connected between the H1 input terminal and the ground as shown in FIG. It can be shown as an equivalent circuit constituted by an equivalent capacitance CH1, an equivalent capacitance CH2 between the H2 input terminal and the ground, and an equivalent capacitance CH12 between both input terminals.

  The horizontal transfer clocks H1 and H2 that are high-speed drive pulses output from the timing generator 30 are designed to have a high linearity in transient characteristics at the rising and falling edges in order to improve the transfer efficiency of pixel charges in the HCCD. . As a result, the horizontal transfer clocks H1 and H2 have a spectrum extending to a high frequency, and higher-order multiplied waves increase, thereby increasing unnecessary radiation in the high frequency.

  Therefore, as shown in FIG. 2, in the first embodiment, a capacitor C1 is provided between the H1 node and the ground, and a primary LPF (low-pass filter) is formed by the output impedance of the H1 output terminal of the timing generator 30 and the capacitor C1. The capacitor C2 is provided between the H2 node and the ground, and the primary LPF is configured by the output impedance of the H2 output terminal of the timing generator 30 and the capacitor C2, thereby removing unnecessary high frequency components. Unnecessary radiation is reduced.

  3A and 3B are waveform diagrams of horizontal transfer clocks H1 and H2 in the image pickup apparatus. FIG. 3A shows an equivalent capacity (load capacity) CH1 and CH2 in the CCD 31, and FIG. When different from each other, (c) is a case of the image pickup apparatus of the first embodiment in which different load capacitances CH1 and CH2 are corrected by the capacitors C1 and C2.

  When the load capacitors CH1 and CH2 are equivalent, as shown in FIG. 3A, the cross point at timing CP1 at which the falling voltage of the horizontal transfer clock H1 and the rising voltage of the horizontal transfer clock H2 become equal. The voltage VCP1 and the cross-point voltage VCP2 at the timing CP2 at which the rising voltage of the horizontal transfer clock H1 and the falling voltage of the horizontal transfer clock H2 become equal have substantially the same value.

  On the other hand, when the load capacities CH1 and CH2 are different and the timing generator 30 has the same drive capability as that shown in FIG. 3A, the timings of the transient characteristics of the horizontal transfer clocks H1 and H2 are different. Therefore, as shown in FIG. 3B, the cross-point voltage VCP1A at the timing CP1A at which the falling voltage of the horizontal transfer clock H1 is equal to the rising voltage of the horizontal transfer clock H2, and the horizontal transfer clock The cross-point voltage VCP2A at the timing CP2A at which the rising voltage of H1 is equal to the falling voltage of the horizontal transfer clock H2 has different values. Further, the timings CP1A and CP2A are respectively delayed from the timings CP1 and CP2 in FIG. 3A, and the delay amount of the timing CP1A and the delay amount of CP2A are different from each other.

  As described above, in FIG. 3B, the cross-point voltages VCP1A and VCP1B have different values, and the delay amounts of the timings CP1A and CP2A are different from each other, so that the charge transfer efficiency of the HCCD decreases.

  In the case of FIG. 3B, the load capacity condition viewed from the timing generator 30 is that the period A in which the horizontal transfer clocks H1 and H2 are both in the transition period and only the horizontal transfer clock H2 is in the transition period. Since the horizontal transfer clock H1 is different from the period B in which the horizontal transfer clock H1 is at the GND or DC level, if the drive condition of the output buffer of the timing generator 30 in the period A is optimally designed, the push-pull circuit of the output buffer in the period B The discharge current and the pull-in current are different. For this reason, the drive current from the H1 output terminal of the timing generator 30 is different from the drive current from the H2 output terminal, and a wide spectrum of unwanted radiation increases due to the difference in the drive current.

  Further, when a driver having a driving capability equivalent to the horizontal transfer clocks H1 and H2 is used, since the load capacitors CH1 and CH2 are different, the driving current from the H1 output terminal and the H2 output terminal via the equivalent capacitor CH12 between the input terminals. As shown in FIG. 4, the load balance with the drive current from the output current is lost, and overshoot / undershoot occurs in the horizontal transfer clocks H1 and H2.

  In the case of a structure using a band-limited filter including an inductance as a measure against unnecessary radiation, this overshoot / undershoot is applied to the protection diode at the input / output terminal of the CCD 31 as a forward bias, and this protection diode may be destroyed. is there.

Therefore, in the first embodiment, different load capacitances CH1 and CH2 in the capacitors C1 and C2 and the CCD 31 are
CH1 + C1≈CH2 + C2 (C1, C2 ≧ 0 [pF]) (1)
The capacitances of the capacitors C1 and C2 are set so as to satisfy the above.

  As shown in FIG. 3C, the capacitors C1 and C2 that satisfy the condition of the above expression (1), at the timing CP1B at which the rising voltage of the horizontal transfer clock H1 becomes equal to the falling voltage of the horizontal transfer clock H2, as shown in FIG. And the cross-point voltage VCP2B at the timing CP2B at which the rising voltage of the horizontal transfer clock H2 is equal to the falling voltage of the horizontal transfer clock H1 can be corrected to substantially the same value, and the timing CP1B. And the delay amount of the timing CP2B can be corrected to substantially the same value, so that the charge transfer efficiency of the HCCD can be improved.

  In addition, the capacitors C1 and C2 that satisfy the condition of the above expression (1) can correct the load capacity condition viewed from the timing generator 30 almost equally in the period A and the period B. Spectral radiation can be reduced.

  In addition, the capacitors C1 and C2 that satisfy the condition of the above expression (1) can secure the load balance between the drive current from the H1 output terminal and the drive current from the H2 output terminal via the equivalent capacitance CH12 between the input terminals. The occurrence of overshoot / undershoot in the horizontal transfer clocks H1 and H2 can be prevented.

  Even when the load capacitors CH1 and CH2 are equivalent in capacity as shown in FIG. 3A, when the EMI is eliminated by dulling the high frequency characteristics of the output terminal of the timing generator 30, the equivalent capacitors are used. By providing C1 and C2 as shown in FIG. 2, it is possible to reduce unnecessary radiation while maintaining the cross-point voltages VCP1 and VCP2 at the same value and without deteriorating the charge transfer efficiency of the HCCD.

  Capacitors C1 and C2 are not limited to horizontal transfer clock nodes (H1 node and H2 node), but can be provided at other high-speed drive clock nodes.

  As described above, according to the first embodiment, the capacitors C1 and C2 are provided between the horizontal transfer clock nodes (H1 node and H2 node) and the ground, and the output terminals (H1 output terminal and H2 output terminal) of the timing generator 30 are provided. By configuring the LPF with the output impedance and the capacitors C1 and C2, unnecessary radiation due to the drive clock can be reduced without providing a complicated EMI filter.

  Furthermore, by setting the capacitances of the capacitors C1 and C2 so as to satisfy the above equation (1), the charge transfer efficiency of the HCCD can be improved, unnecessary wide-band radiation caused by the difference in drive current can be reduced, and horizontal transfer The occurrence of overshoot / undershoot in the clock can be prevented.

Embodiment 2. FIG.
FIG. 5 is a circuit diagram of a horizontal transfer clock drive circuit in the image pickup apparatus according to Embodiment 2 of the present invention. Components similar to those in FIG.

  In the second embodiment, as shown in FIG. 5, a resistor R1 is provided between the H1 output terminal and the H1 input terminal, a resistor R2 is provided between the H2 output terminal and the H2 input terminal, and between the H1 input terminal and the ground. A capacitor C3 is provided, a capacitor C4 is provided between the H2 input terminal and ground, a capacitor C5 is provided between the H1 output terminal and ground, and a capacitor C6 is provided between the H2 output terminal and ground.

  Thus, in the second embodiment, the primary LPF is configured by the output impedance of the H1 output terminal of the timing generator 30 and the capacitor C5, and the primary LPF is configured by the output impedance of the H2 output terminal of the timing generator 30 and the capacitor C6. In addition to the LPF, a primary LPF is formed by the resistor R1 and the capacitor C3 between the capacitor C5 and the H1 input terminal of the CCD 31, and the resistor R2 and the capacitor C4 are formed between the capacitor C6 and the H2 input terminal of the CCD 31. A primary LPF is constructed.

  The unnecessary radiation is more reliably reduced than in the first embodiment by the two-stage LPF provided between the H1 input / output terminals and between the H2 input / output terminals.

In the second embodiment, for example, when the horizontal transfer clocks H1 and H2 of the timing generator 30 have the same driving capability, the capacitors C3 and C4 and the equivalent capacitors CH1 and CH2 in the CCD 31 are different from each other.
CH1 + C3≈CH2 + C4 (C3, C4 ≧ 0 [pF]) (2)
Capacitors C3 and C4 are set so as to satisfy, and capacitors C5 and C6 and resistors R1 and R2 are set so that capacitors C5 and C6 are C5≈C6, and resistors R1 and R2 are R1≈R2.

  By setting the capacitors C3, C4 and the like in this way, the charge transfer efficiency of the HCCD can be improved, the unnecessary radiation of a wide spectrum due to the difference in the drive current can be reduced, and the horizontal transfer, as in the first embodiment. The occurrence of overshoot / undershoot in the clock can be prevented.

  It is also possible to provide inductances L1 and L2 instead of the resistors R1 and R2.

  As described above, according to the second embodiment, in addition to the LPF configured by the output impedance of the output terminal (H1 output terminal, H2 output terminal) of the timing generator 30 and the capacitors C5, C6, the resistors R1, R2 By providing an LPF composed of capacitors C3 and C4 and having a two-stage LPF, unnecessary radiation can be reduced more reliably than in the first embodiment.

Embodiment 3 FIG.
FIG. 6 is a circuit diagram of a horizontal transfer clock drive circuit in the image pickup apparatus according to Embodiment 3 of the present invention. Components similar to those in FIG.

  In the first embodiment, the capacitors C1 and C2 are arranged outside the timing generator 30 and the CCD 31, but in this third embodiment, the capacitors C1 and C2 are arranged inside the timing generator 30 as shown in FIG. is doing. Thus, even when the capacitors C1 and C2 are arranged inside the timing generator 30, the same effects as those of the first embodiment can be obtained.

  As described above, according to the third embodiment, by disposing the capacitors C1 and C2 inside the timing generator 30, the same effects as those of the first embodiment can be obtained, and the mounting area of external components can be reduced. can do.

Embodiment 4 FIG.
FIG. 7 is a circuit diagram of a horizontal transfer clock drive circuit in the image pickup apparatus according to Embodiment 4 of the present invention. Components similar to those in FIG.

  In the fourth embodiment, as shown in FIG. 7, an H1 capacity selector, an H2 capacity selector, capacitors C1a, C1b, C1c, and capacitors C2a, C2b, C2c are arranged inside the timing generator 30. .

  The capacitors C1a, C1b, and C1c are provided in parallel with each other between the H1 capacitance selector and the ground. Similarly, the capacitors C2a, C2b, and C2c are provided in parallel with each other between the H2 capacitance selector and the ground.

  The H1 capacity selector connects any one, two, or all of the capacitors C1a, C1b, and C1c to the H1 output terminal according to the H1 capacity control signal. Similarly, the H2 capacity selector connects any one, any two, or all of the capacitors C2a, C2b, and C2c to the H2 output terminal according to the H2 capacity control signal. The capacity control signal is input from the outside by, for example, serial communication. One capacity control signal may include data for controlling the H1 capacity selector and data for controlling the H2 capacity selector.

  As described above, in the fourth embodiment, the capacitances of the capacitor for the H1 node and the capacitor for the H2 node can be switched and controlled by the above-described capacitance control signal. Therefore, when the CCD 31 is different or changed, Even when the capacitance value is not optimally set, each of the capacitors can be individually adjusted to an optimum capacitance for reducing unnecessary radiation.

  It is also possible to provide an H1 capacity selector or / and capacitors C1a, C1b, C1c outside the timing generator 30. Similarly, an H2 capacity selector or / and capacitors C2a, C2b, C2c can be provided outside the timing generator 30.

  As described above, according to the fourth embodiment, the capacitor can be adjusted to an optimum capacity for reducing unnecessary radiation by switching and controlling the capacity of the capacitor.

Embodiment 5 FIG.
FIG. 8 is a block diagram of the imaging apparatus according to the fifth embodiment of the present invention. The imaging apparatus according to the fifth embodiment includes an imaging element 1, a vertical CCD drive signal drive unit 2, an imaging system control unit 3, and an imaging signal processing unit 4.

  The imaging system control unit 3 includes a horizontal counter that counts pixel clocks, and a vertical counter that counts carry output when the horizontal counter reaches a specified count value.

  This imaging system control unit 3 generates vertical transfer control pulses φV1A / B, φV2, φV3A / B, φV4, readout control pulses φTG1A, φTG1B, φTG3A, φTG3B, and an electronic shutter control pulse φOFD, and drives a vertical CCD drive signal Supply to part 2.

  In addition, the imaging system control unit 3 generates horizontal transfer clocks H1A, H1B, H1C, H1D, H2A, H2B, a reset gate clock RS, and a line memory control signal LM, and supplies them to the imaging device 1.

  Further, the imaging system control unit 3 outputs a CDS black level sample hold pulse SHP, a CDS signal level sample hold pulse SHD, an A / D clock ADCLK, a blanking signal PBLK, and an OB (optical black) level detection pulse CPOB. These are generated and supplied to the imaging signal processing unit 4.

  The vertical CCD drive signal drive unit 2 receives vertical transfer control pulses φV1A / B, φV2, φV3A / B, φV4, readout control pulses φTG1A, φTG1B, φTG3A, φTG3B, and an electronic shutter control pulse φOFD from the imaging system control unit 3. High-voltage driving is performed, and vertical transfer clocks V1A, V1B, V2, V3A, V3B, V4 and an electronic shutter pulse OFD are supplied to the image sensor 1.

  The imaging device 1 is a vertical 6-phase horizontal 6-phase drive type inline type (interline type) CCD imaging device, and includes a light receiving unit, a vertical transfer unit (VCCD), a horizontal transfer unit (HCCD), and a line memory unit. And have.

  The light receiving unit photoelectrically converts an incident light image of a subject using a plurality of photodiodes, and accumulates pixel charges.

  The VCCD reads out the pixel charges accumulated in the light receiving unit by the vertical transfer clocks V1A, V1B, V2, V3A, V3B, V4 from the vertical CCD drive signal drive unit 2 and transfers them in the vertical direction.

  The line memory unit is provided to perform horizontal pixel mixing (mixing of two pixels of the same color in the horizontal direction), temporarily holds the horizontal pixel charges transferred from the VCCD, and is Are transferred to the HCCD.

  The HCCD transfers pixel charges transferred from the VCCD or the line memory unit in the horizontal direction by horizontal transfer clocks H1A, H1B, H1C, H1D, H2A, and H2B from the imaging system control unit 3. The pixel charge train transferred in the horizontal direction is output to the imaging signal processing unit 4 as a pixel charge signal OS.

  Whether the pixel charge is transferred from the VCCD to the HCCD via the line memory unit (whether the pixel mixture is read out) or whether it is transferred from the VCCD to the HCCD without going through the line memory unit (whether all pixels are read out) ) Is controlled by a line memory control signal LM.

  In the imaging apparatus of the fifth embodiment, the horizontal transfer clock H1 is four H1A, H1B, H1C, and H1D, and the horizontal transfer clock H2 is two H2A and H2B.

  For this reason, the CCD element (corresponding to the CCD 31 in FIG. 2 and the like) is provided with a total of four input terminals for the horizontal transfer clock H1, H1A input terminal, H1B input terminal, H1C input terminal, and H1D input terminal. For the horizontal transfer clock H2, a total of two input terminals, an H2A input terminal and an H2B input terminal, are provided.

  Similarly, the timing generator elements (corresponding to the timing generator 30 in FIG. 2 and the like) have a total of four output terminals for the horizontal transfer clock H1, H1A output terminal, H1B output terminal, H1C output terminal, and H1D output terminal. A total of two output terminals, an H2A output terminal and an H2B output terminal, are provided for the horizontal transfer clock H2.

  Therefore, for example, for the H1A input terminal and the H2A input terminal, in either FIG. 2 or FIG. 5 to FIG. 7, the H1 input terminal is replaced with the H1A input terminal, the H2 input terminal is replaced with the H2A input terminal, and the equivalent capacitance CH1 is set. By replacing the equivalent capacitance CH1A between the H1A input terminal and the ground, replacing the equivalent capacitance CH2 with the capacitance CH2A between the H2A input terminal and the ground, and replacing the equivalent capacitance CH12 with an equivalent capacitance CH1A2A between the H1A input terminal and the H2A input terminal, A model similar to that of the CCD 31 shown in FIG. 2 can be used. The same applies to other H1B input terminals and H2B input terminals.

  At this time, since the combined equivalent capacitance between all H1 input terminals and the ground and the combined equivalent capacitance between all H2 input terminals and the ground are considered to be structurally identical, the equivalent capacitances CH1A and CH2A are the same. The capacity value is different.

  Under such a load condition, the horizontal transfer clock H1A and the horizontal transfer clock H2A have different timings of transient characteristics. Therefore, the horizontal transfer clocks H1A and H2A are the same as the horizontal transfer clocks H1 and H2 in FIG. It becomes like this.

  In this case, as in the case of FIG. 3B of the first embodiment, the charge transfer efficiency of the HCCD is reduced, the unnecessary wide spectrum radiation due to the difference in the drive current is increased, and the horizontal transfer clocks H1A, Overshoot / undershoot occurs in H2A. The same applies to other H1B output terminals and H2B output terminals.

  Therefore, also in the imaging apparatus of the fifth embodiment, the horizontal transfer clock drive circuit is the same as any of the horizontal transfer clock drive circuits of the first to fourth embodiments (FIGS. 2 or 5 to 7). In this configuration, capacitors C1A and C2A are provided so as to correct the difference between the load capacitances CH1A and CH2A. The same applies to the other horizontal transfer clocks H1B and H2B.

  In this way, the capacitors are provided at each of the horizontal transfer clock input terminals so as to correct the difference in load capacitance between the four H1 input terminals and the two H2 input terminals. As in the first to fourth embodiments, the charge transfer efficiency of the HCCD can be improved, unnecessary wide-band radiation due to the difference in drive current can be reduced, and the occurrence of overshoot / undershoot in the horizontal transfer clock can be prevented. .

  As described above, according to the fifth embodiment, the same effects as those of the first to fourth embodiments can be obtained in the horizontal six-phase drive type imaging apparatus.

Embodiment 6 FIG.
FIG. 9 is a block diagram of a portable information terminal device according to the sixth embodiment of the present invention. The portable terminal device according to the sixth embodiment is a cellular phone or a portable information device (for example, a portable personal computer) having a function of displaying imaging data, a function of recording, and a function of communication. A signal drive unit 2, an imaging system control unit 3, an imaging signal processing unit 4, a main system control unit 5, a main signal processing unit 6, a recording device 7, a display device 8, and a communication device 9 are provided. ing.

  In the portable information terminal device according to the sixth embodiment shown in FIG. 9, the imaging device 1, the CCD drive signal drive unit 2, the imaging system control unit 3, the imaging signal processing unit 4, the main system control unit 5, and the main signal The processing unit 6 constitutes the imaging device of the sixth embodiment.

  In the imaging apparatus of the sixth embodiment, the main system control unit 5 and the main signal processing unit 6 are provided in any one of the imaging apparatuses of the first to fourth embodiments. In other words, the portable information terminal device of the sixth embodiment is configured by mounting any of the imaging devices of the first to fourth embodiments. Note that the image pickup apparatus according to Embodiment 5 may be mounted.

  The main signal processing unit 6 is controlled by the main system control unit 5 and corrects the image pickup signal CCDOUT output from the image pickup signal processing unit 4 to white (white balance function), detects the signal level of the image pickup signal CCDOUT, and performs automatic exposure. It corrects (AE function) and corrects the signal level by detecting the leakage charge amount in the OB area of the imaging signal CCDOUT (smear / dark current correction function).

  In addition, the main signal processing unit 6 is controlled by the main system control unit 5 and is capable of displaying the imaging signal CCDOUT output from the imaging signal processing unit 4 or the imaging data recorded in the recording device 7 on the display device 8. The signal is converted into a signal and output to the display device 8. Further, the imaging signal CCDOUT is compressed and converted into imaging data that can be recorded in the recording device 7 and is output to the recording device 7.

  The recording device 7 is a device for recording imaging data in the recording format converted by the main signal processing unit 6, and records the imaging data on a recording medium such as a flash memory, FDD, HDD, DAT, DV, DVD, for example. Is possible. The recording device 7 can have a configuration built in the portable information terminal device or an external configuration.

  The display device 8 is a device that displays the RGB signals from the main signal processing unit 6, and can display a moving image, a still image, a preview display of image data recorded in a storage device, and the like.

  The communication device 9 is controlled by the main system control unit 5 and is connected to a portable information terminal device having other communication functions by wireless communication such as a mobile phone system or a wireless LAN system, or wired communication such as USB or IEEE1394, and image data. And voice data.

  The main system control unit 5 controls the imaging system control unit 3 in synchronization with the vertical synchronization signal VD and the horizontal synchronization signal HD from the imaging system control unit 3, thereby performing electronic shutter operation, AGC (Auto Gain Control) of the imaging device. ) Control the operation, long exposure operation, and the like, and when the imaging apparatus of the fifth embodiment is provided, the switching between the all-pixel readout operation and the pixel mixture readout operation is further controlled. As described above, the main system control unit 5 controls the imaging device in synchronization with the vertical synchronization signal VD and the horizontal synchronization signal HD (synchronization control).

  The main system control unit 5 controls the imaging system control unit 3 asynchronously to control a power-up sequence when the imaging apparatus is turned on, a power-down sequence when the power is turned off, a reset operation of the imaging apparatus, and the like. . As described above, the main system control unit 5 controls the imaging device asynchronously with the vertical synchronization signal VD and the horizontal synchronization signal HD (asynchronous control).

  Further, the main system control unit 5 detects an ON signal of a shutter button, a recording pixel number setting value set and input by a user, and the like.

  In the information portable terminal device, a driving clock of several [MHz] such as a horizontal transfer clock is used in the imaging device. In the case of having a wireless communication function, a frequency band of several hundreds [MHz] to several [GHz] is used as a transmission / reception band. For this reason, radiation of harmonic components of the drive clock may interrupt the transmission / reception band of the portable information terminal device, resulting in EMI problems such as deterioration in transmission / reception sensitivity (transmission / reception S / N) and inability to perform wireless communication. .

That is, the frequency of the horizontal transfer clock of the image sensor is from several [MHz] to several tens [MHz] in order to deal with high frame rate moving images and high-definition still images.
FIG. 10 shows a frequency band used for communication of the mobile phone terminal. As shown in the figure, a wide band from 800 [MHz] to several [GHz] is used for communication of mobile phone terminals. Note that the [GHz] level band is also used in wireless LANs defined by the IEEE 802.11a, IEEE 802.11b, and IEEE 802.11g standards. Therefore, unnecessary radiation of the tens to hundreds of horizontal transfer clocks may affect the transmission / reception sensitivity of the mobile phone terminal. In addition, when shooting with a camera, this unnecessary radiation may affect the standby sensitivity of communication.
Furthermore, mobile phone terminals are products that are extremely required to be small and thin. Therefore, the camera module and the RF receiving antenna are close to each other, and are easily affected by unnecessary radiation of the horizontal transfer clock, and it is often impossible to secure a space for providing a shield.

Therefore, if a capacitive load is used and an LPF having no inductor component or resonance point in the transmission / reception band of the mobile phone terminal is configured, it becomes an effective measure against unnecessary radiation even for a mobile phone terminal whose transmission / reception band changes with time. Further, since only a capacitive load is added to the circuit, effects such as cost reduction and reduction in mounting area are great. Furthermore, the LPF configured by the capacitive load does not need to change the countermeasure against unnecessary radiation for each mobile phone terminal, and has a great effect of suppressing the development cost of the mobile phone.
It is desirable that the capacitive load be arranged near the output terminal of the horizontal transfer clock. This is due to the following reasons. That is, the wiring between the capacitive load and the vicinity of the output terminal serves as an antenna, and unnecessary radiation is generated from the antenna, so that the reception sensitivity of the mobile phone terminal is deteriorated. Therefore, by disposing the capacitive load in the vicinity of the output terminal of the horizontal transfer clock, a portion that becomes an antenna that generates unnecessary radiation can be shortened, and reception sensitivity deterioration can be suppressed.

  By the way, when the wiring connecting the timing generator and the CCD is long, the path through which the return current from the connected capacitive load returns to the timing generator through the ground plane becomes complicated, and the possibility of generating unnecessary radiation increases. Therefore, the generation of unnecessary radiation can be suppressed by shortening the wiring connecting the timing generator and the CCD and connecting the ground plane to the timing generator side. In many cases, the ground plane is shared with other circuits, devices, and the like, and when unnecessary radiation flows into the ground plane, the EMI also occurs for other circuits.

  FIGS. 11A and 11B are diagrams schematically showing connections between the timing generator, the capacitive load, and the ground plane. In the figure, 30 is a timing generator, 35 is a capacitive load, 36 is wiring of horizontal transfer clocks H1 and H2, and 37 is a ground plane connected to a terminal on the ground side of the timing generator. In FIG. 11A, since the wiring between the ground plane 37 and the timing generator 30 is long, even if the ground plane 37 to which the capacitive load is connected is wide, this wiring becomes an antenna, and unnecessary radiation increases. . On the other hand, in FIG. 11B, the wiring between the timing generator 30 and the ground plane 37 is shortened to suppress generation of unnecessary radiation. Further, the current path from the timing generator 30 via the capacitive load 35 is arranged so as not to affect other ground lines.

  That is, in the information portable terminal device of the sixth embodiment, the harmonic component of the drive clock is provided by mounting any one of the imaging devices of the first to fourth embodiments or the imaging device of the fifth embodiment. Unnecessary radiation is reduced to prevent radiation of harmonic components of the drive clock from interrupting the transmission / reception band, thereby improving transmission / reception sensitivity.

  As described above, according to the sixth embodiment, by providing any one of the imaging devices of the first to fifth embodiments to an information portable terminal device having a communication function, a complicated EMI filter is not provided. Since unnecessary radiation due to the drive clock can be reduced, it is possible to prevent the unnecessary radiation from interrupting the transmission / reception band of the portable information terminal device and improve the transmission / reception sensitivity of the portable information terminal device.

It is a block block diagram of the imaging device of Embodiment 1 of this invention. FIG. 2 is a circuit diagram of a horizontal transfer clock drive circuit in the image pickup apparatus according to Embodiment 1 of the present invention. FIG. 6 is a waveform diagram of a horizontal transfer clock in the imaging apparatus, where (a) shows the case where the capacitances in the CCD (load capacitance of the timing generator) CH1 and CH2 are equivalent, and (b) shows the case where the load capacitances CH1 and CH2 differ from each other (C) is a case of the imaging apparatus according to the first embodiment of the present invention in which different load capacities CH1 and CH2 are corrected by the capacitors C1 and C2. It is a waveform diagram of overshoot / undershoot of the horizontal transfer clock of the imaging apparatus. It is a circuit diagram of the horizontal transfer clock drive circuit in the imaging device of Embodiment 2 of the present invention. It is a circuit diagram of the horizontal transfer clock drive circuit in the imaging device of Embodiment 3 of the present invention. It is a circuit diagram of the horizontal transfer clock drive circuit in the imaging device of Embodiment 4 of the present invention. It is a block block diagram of the imaging device of Embodiment 5 of this invention. It is a block block diagram of the imaging device of Embodiment 6 of this invention. It is a figure which shows the frequency band used for communication of a mobile telephone terminal. It is the figure which showed typically the connection in the imaging device of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Imaging element, 2 CCD drive signal drive part, 3 Imaging system control part, 4 Imaging signal processing part, 5 Main system control part, 6 Main signal processing part, 7 Recording apparatus, 8 Display apparatus, 9 Communication apparatus, 30 Timing generator 31 CCD, C1, C1a, C1b, C1c, C2, C2a, C2b, C2c, C3, C4, C5, C6 capacitors, R1, R2 resistors.

Claims (4)

An image sensor that photoelectrically converts an incident light image of a subject in a light receiving unit, and transfers and outputs a charge train corresponding to the light image in a vertical direction and a horizontal direction;
The above two kinds of horizontal of the imaging device polar driven by the horizontal transfer portion, respectively equivalent drivability to generate two types of horizontal transfer clock backwards from the output terminal of the two horizontal transfer clock of the image pickup element A timing generator to be supplied to each input terminal of the transfer clock ;
An imaging apparatus comprising the two types of horizontal transfer clock wirings that connect the output terminals of the two types of horizontal transfer clocks and the input terminals of the two types of horizontal transfer clocks, respectively.
The above-mentioned two types of horizontal transfer clock wirings are first and second wirings, respectively.
The output terminal and the input terminal connected by the first wiring are defined as a first output terminal and a first input terminal, respectively.
The output terminal and the input terminal connected by the second wiring as a second output terminal and a second input terminal, respectively.
In the imaging device, the horizontal transfer unit that transfers in the horizontal direction is a capacitive load, and the equivalent capacitance between the first input terminal and the ground and the equivalent capacitance between the second input terminal and the ground are different from each other. In case,
A first capacitor is provided between the first wiring and the ground, and a first low-pass filter is configured by the output impedance of the first output terminal and the first capacitor,
A second capacitor is provided between the second wiring and the ground, and a second low-pass filter is configured by the output impedance of the second output terminal and the second capacitor ;
The equivalent capacitance between the first input terminal and the ground in the image sensor and the parallel combined capacitance of the first capacitor, the equivalent capacitance between the second input terminal and the ground in the image sensor, and the The first capacitor and the parallel capacitor of the second capacitor are equal to each other so that the load capacitance condition (each parallel combined capacitor) seen from the output terminals of the two types of horizontal transfer clocks of the timing generator is equal to each other. An image pickup apparatus in which a capacity of a second capacitor is set . An image sensor that photoelectrically converts an incident light image of a subject in a light receiving unit, and transfers and outputs a charge train corresponding to the light image in a vertical direction and a horizontal direction;
Two types of horizontal transfer clocks having opposite polarities for driving the horizontal transfer units of the image pickup device with the same driving capability are generated, and the two types of horizontal transfer clocks of the image pickup device are generated from output terminals of the two types of horizontal transfer clocks. A timing generator that supplies the input terminal of the transfer clock;
Wiring of the two types of horizontal transfer clocks respectively connecting the output terminals of the two types of horizontal transfer clocks and the input terminals of the two types of horizontal transfer clocks;
In an imaging device comprising:
The above-mentioned two types of horizontal transfer clock wirings are first and second wirings, respectively.
The output terminal and the input terminal connected by the first wiring are defined as a first output terminal and a first input terminal, respectively.
The output terminal and the input terminal connected by the second wiring as a second output terminal and a second input terminal, respectively.
In the imaging device, the horizontal transfer unit that transfers in the horizontal direction is a capacitive load, and the equivalent capacitance between the first input terminal and the ground and the equivalent capacitance between the second input terminal and the ground are different from each other. In case,
A first capacitor is provided between the first wiring and the ground, and a first low-pass filter is configured by the output impedance of the first output terminal and the first capacitor,
A second capacitor is provided between the second wiring and the ground, and a second low-pass filter is configured by the output impedance of the second output terminal and the second capacitor;
A first selector is provided between the first wiring and the first capacitor, and the first capacitors are provided in parallel with each other, and the first selector selectively selects between the first wiring and the ground. A plurality of capacitors that can be connected to each other, and in accordance with the input first control signal, any one, any two, or all of the plurality of capacitors of the first capacitor are connected to the first selector . Select by switching control and connect to the first wiring ,
A second selector is provided between the second wiring and the second capacitor, and the second capacitor is provided in parallel with each other, and the first selector selectively selects between the first wiring and the ground. A plurality of capacitors that can be connected to each other, and in accordance with an input second control signal, any one, any two, or all of the plurality of capacitors of the second capacitor are connected to the second selector . Select by switching control and connect to the second wiring ,
The equivalent capacitance between the first input terminal and the ground in the image sensor and the parallel combined capacitance of the first capacitor, the equivalent capacitance between the second input terminal and the ground in the image sensor, and the The first capacitor and the parallel capacitor of the second capacitor are equal to each other so that the load capacitance condition (each parallel combined capacitor) seen from the output terminals of the two types of horizontal transfer clocks of the timing generator is equal to each other. An imaging apparatus , wherein a capacitance of a second capacitor is set by being selected by the first selector and the second selector by the first control signal and the second control signal . The image sensor is a CCD image sensor;
The imaging apparatus according to claim 1, wherein the first and second horizontal transfer clocks are horizontal transfer clocks having opposite polarities for driving a horizontal transfer unit of the CCD image pickup device. The imaging device according to claim 1 , wherein the imaging device is mounted on a portable information terminal device.

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