JP4551301B2 - Solid-state imaging device - Google Patents

Description

  The present invention relates to a solid-state imaging device, and more particularly to a solid-state imaging device capable of preventing image degradation caused by the passage of usage time and suppressing power consumption.

  The solid-state imaging device includes a solid-state imaging element in which a plurality of light receiving elements that generate signal charges from incident light from an object field are arranged in a matrix, and an electric circuit formed by reading out signal charges from the light receiving elements. The signal is processed to form an image signal. At this time, the signal charge generated in the light receiving element needs to be completely read out by one pulse, that is, one read signal. This is because an image signal that can display only pixels having a certain brightness or more is formed because a sufficient signal charge cannot be obtained unless the signal charge is completely read out by one read signal, that is, in a fully depleted state. As a result, a blackish portion is present in the image, resulting in deterioration such as a scratch.

  Therefore, it is necessary to set the voltage of the readout signal to a voltage at which the signal charge can be completely read out by one readout signal, that is, a depletion voltage. The voltage of the read signal was set higher than the fully depleted voltage. This is because the light-receiving element deteriorates as the process of reading the signal charge from the light-receiving element is performed many times, that is, as the usage time of the solid-state imaging device elapses, and the signal charge can be completely read unless a high voltage is applied. This is because it has been known that reading is impossible, that is, reading failure occurs. In consideration of such a variation in the depletion voltage, the voltage of the read signal is set high. However, when the voltage is set to be high in this way, there is a problem that power consumption increases.

  Further, since the solid-state imaging device may be driven in a recording mode in which an image signal is recorded in a recording unit, and may be driven in a preliminary mode used for displaying or controlling the formed image signal, according to the conventional technology, The number of times of performing the reading process was different. As a result, even if the voltage of the readout signal is set to a high value, in the light receiving element where the number of times of readout processing is performed, readout failure occurs at an early stage, and the usage time has not passed so much. As a result, there has been a problem that the image is deteriorated.

More specifically, the recording mode is a mode in which an image signal is recorded in the recording unit in accordance with an operation signal from the operation means. The preliminary mode is a mode in which an image signal is displayed on the display unit before or after driving in the recording mode, or the solid-state imaging device is controlled using the image signal. For example, the image signal is displayed on the display unit. Moving image display mode, automatic focus adjustment mode for automatically focusing, automatic exposure adjustment mode for automatic exposure, and the like. When driving in the recording mode, signal charges are read from all the light receiving elements, whereas when driving in the preliminary mode, the light receiving elements are thinned out, and signal charges are read out from the thinned light receiving elements. Done. Therefore, the light receiving element from which the signal charge is read out in both the recording mode and the preliminary mode is deteriorated earlier because the number of times of reading processing is performed more than the light receiving element from which the signal charge is read only in the recording mode. Become. As a result, even if the readout signal voltage is set high, the light receiving element from which the signal charge is read out in both modes deteriorates quickly and the image deteriorates even though the usage time has not passed so much. It was. Therefore, there has been a demand for a solid-state imaging device that can prevent image degradation even after the usage time has elapsed and that can reduce power consumption.
JP-A-4-2877581

  It is an object of the present invention to provide a solid-state imaging device that can eliminate such drawbacks of the prior art, prevent image deterioration that occurs as the usage time elapses, and reduce power consumption. And

  In order to solve the above-described problems, the present invention focuses on the fact that depletion voltage fluctuations and read failures occur in a light-receiving element that has been read many times, and the signal charge when driving in the preliminary mode. The light receiving elements that perform reading are switched, and the time during which the reading process is performed, that is, the number of times the reading process is performed, is made substantially uniform for each light receiving element. By doing so, it is possible to make the deterioration state of each light receiving element substantially the same, and therefore it becomes possible to prevent the depletion voltage from fluctuating only with a specific light receiving element. Even if it is used for a long time, it becomes possible to prevent a reading failure and to prevent image deterioration. As for the switching timing, for example, every time the solid-state imaging device is started up, every time an image is taken, or when a reading process is performed, the time is measured and switched according to this time.

  Further, according to the present invention, the usage time using the solid-state imaging device is measured, and the voltage of the readout signal is gradually increased according to the usage time. Therefore, it is possible to suppress power consumption compared to the case where a high voltage is set from the beginning. Furthermore, in the present invention, when the solid-state imaging device is driven in the recording mode, the image signal is generated by reading the signal charge from the light receiving element that is unlikely to cause a reading failure. Therefore, reading failure can be prevented and image deterioration can be prevented.

  According to the solid-state imaging device of the present invention, it is possible to prevent the occurrence of reading failure even after the usage time has elapsed, and it is possible to suppress power consumption.

Next, an embodiment of a solid-state imaging device according to the present invention will be described in detail with reference to the accompanying drawings. Figure 1 is a block diagram showing the configuration of an embodiment of a solid-state image sensor of the present invention. In FIG. 1, a solid-state imaging device 1 includes an operation unit 3, a control unit 5, a time measurement unit 7, a timing generation unit 9, an imaging drive unit 11, a solid-state imaging device 13, an optical system drive unit 15, an optical system 17, and a preprocessing. The apparatus includes a unit 19, a signal processing unit 21, a display unit 23, and a recording media unit 25, and forms a digital image signal based on incident light from an object scene. More specifically, the solid-state imaging device 13 includes a plurality of light receiving elements 27 as shown in FIG. 2, and the light receiving elements 27 capture incident light from the object field via the optical system 17. Generate signal charge. The solid-state imaging device 1 is operated by the operation unit 3 to control the control unit 3, the timing generation unit 9, and the imaging drive unit 11 to read out the signal charge generated by the light receiving element 27 and take it out as an analog electric signal . Thereafter, the analog electrical signal is processed by the preprocessing unit 19 and the signal processing unit 21 to form a digital image signal. The formed digital image signal is displayed on the display unit 23 or recorded on the recording medium unit 25. Note that portions not directly related to understanding the present invention are not shown and redundant description is avoided. In the following description, each signal is specified by the reference number of the connecting line in which it appears.

  The operation unit 3 is a manual operation device to which an operator's instruction is input, and is a part that supplies an operation signal 31 to the control unit 5 according to an operator's manual operation state, for example, a stroke operation of a shutter button (not shown). is there. The control unit 5 is a part that controls and controls the overall operation of the individual imaging device 1 in response to the operation signal 31 supplied from the operation unit 3, and in this embodiment, the time measurement unit 7, the optical system drive unit 15. Connected to the timing generation unit 9, the signal processing unit 21, and the recording media unit 25, and supplies control signals 33, 35, 37, 39, and 41 for performing necessary processing. For example, the control unit 5 designates the light receiving element 27 that reads the signal charge out of the light receiving elements 27 included in the solid-state imaging element 13 according to the operation signal 31 from the operation unit 3, and the designated light receiving element 27 is solid-state imaged. A control signal 37 is transmitted to the timing generator 9 so as to form a timing signal 43 for specifying in the element 13.

  The time measuring unit 7 is a part that measures time, such as a timer, and is controlled by the control unit 5. In this embodiment, the time measurement unit 7 is provided separately from the control unit 5, but the present invention is not limited to this, and for example, the time measurement unit 7 can be provided in the control unit 5. .

  The optical system drive unit 15 is a part that forms a drive signal 47 that is controlled by the control unit 5 and drives the optical system 17 in the subsequent stage. In the present embodiment, the control unit 5 forms a control signal 35 for controlling the optical system drive unit 15 by the operation signal 31 from the operation unit 3, and thereby the optical system drive unit 15 drives the optical system 17. 47 is formed. The optical system 17 includes a lens, an aperture adjustment mechanism, a shutter mechanism, a zoom mechanism, an automatic focus (AF) adjustment mechanism, and an automatic exposure (AE) adjustment mechanism, although a specific configuration is not illustrated. It is out. An infrared ray (Infrared Rays: IR) cut filter and an optical low pass filter (Low Pass Filter: LPF) can also be included. The optical system 17 is controlled by a drive signal 47 from the optical system drive unit 15. For example, in this embodiment, the optical system 17 is driven by a drive signal 47 from the optical drive unit 15 to drive a lens, an automatic focus adjustment mechanism, and an automatic exposure adjustment mechanism, and captures a desired object scene image to obtain a solid-state image sensor. Incident on 13.

  The timing generator 9 is a part that is controlled by the controller 5 and forms timing signals 43, 49, 51 in response to a control signal 37 from the controller 5. The formed timing signals 43, 49, and 51 are supplied to the imaging drive unit 11, the preprocessing unit 19, and the signal processing unit 21, respectively. Note that what timing signal is generated and where it is supplied is determined by the control signal 37 of the control unit 5. For example, to the imaging drive unit 11, the timing signal 43 for specifying the light receiving element 27 specified by the control unit 5 in the solid-state imaging element 13, that is, the position of the light receiving element 27 specified by the control unit 5 in the solid-state imaging element 13. A timing signal 43 is supplied.

  The imaging drive unit 11 is a part that forms a read signal 53 for reading the signal charge from the light receiving element 27 at the position indicated by the timing signal 43 in response to the timing signal 43 from the timing generation unit 9. The formed readout signal 53 is supplied to the solid-state image sensor 13. The solid-state imaging device 13 photoelectrically converts a signal charge generated in the light receiving element 27 by incident light incident through the optical system 17 into an analog electric signal 55 in accordance with a read signal 53 from the imaging driving unit 11. That is, it is the part to be imaged. In this embodiment, a photoelectric coupling device (Charge Coupled Device: CCD) is adopted as the solid-state imaging device 13. The analog electrical signal 55 is supplied to the preprocessing unit 19.

  The preprocessing unit 19 is a part that reduces the noise in the analog electrical signal 55 in response to the timing signal 49 of the timing generation unit 9, adjusts the gain of the analog electrical signal 55, and performs analog-digital conversion. This is the part that processes the analog electrical signal 55 to form the digital image signal 57. The digital image signal 57 processed by the preprocessing unit 19 is supplied to the signal processing unit 21. The signal processing unit 21 responds to the control signal 39 of the control unit 5 and the timing signal 51 of the timing generation unit 9, and displays a signal 59 for displaying the digital image signal 57 on the subsequent display unit 23, This is the part that processes the signal 61 to be recorded by the recording medium unit 25. The display unit 23 includes a display device such as a display, for example, and displays the signal 59 supplied from the signal processing unit 21. The recording media unit 25 includes, for example, a memory and stores the signal 61 supplied from the signal processing unit 21 in the memory.

  The solid-state imaging device 1 having the above-described configuration corresponds to a device that includes the solid-state imaging element 13 and can capture an object scene image. For example, an electronic still camera, an image input device, a movie camera, and a camera are included. Examples include a mobile phone provided, or a device that images a subject and prints it on a sticker, but the present invention is not limited to these. In the present invention, the configuration of each unit is not limited to the present embodiment, and an arbitrary configuration can be adopted according to the solid-state imaging device 1.

  The solid-state imaging device 1 has at least a recording mode and a preliminary mode. The recording mode is a mode in which the digital image signal 57 is recorded on the recording medium unit 25 by the operation signal 31 from the operation unit 3. The preliminary mode is a mode used for displaying the digital image signal 57 on the display unit 23 without controlling the digital image signal 57 on the recording medium unit 25 or for controlling the optical system 17. For example, a moving image display mode in which the object scene image is displayed as a moving image on the display unit 23, an automatic focus adjustment mode for automatically focusing, an automatic exposure adjustment mode for automatic exposure, and the like can be given.

  When driving in such a preliminary mode, it is often the case when the solid-state imaging device 1 is turned on, before driving in the recording mode, etc., and in this embodiment the solid state provided in the operation unit 3 Pressing a button (not shown) that turns on the imaging device 1 activates the moving image display mode, and pressing the shutter button provided on the operation unit 3 halfway causes an automatic focus adjustment mode or an automatic exposure adjustment mode. It is driven by. Note that the present invention is not limited to this embodiment, and driving in each mode can be started by adopting an arbitrary method. In the solid-state imaging device 1, when it is driven in either the imaging mode or the preliminary imaging mode, a process of reading signal charges from the light receiving element 27 is performed as shown in FIG.

  FIG. 2 is a conceptual diagram showing the front, that is, the imaging surface of the solid-state imaging device 13 in FIG. In FIG. 2, the same reference numerals as those in FIG. As shown in FIG. 2, the solid-state imaging device 13 includes a light receiving element 27 arranged in a two-dimensional matrix, a transfer gate (not shown) that controls reading of signal charges generated by the light receiving element 27, and the light receiving element 27. The vertical transfer CCD 67 is connected to each vertical direction, i.e., the column and transfers the charge generated in the light receiving element 27 in the vertical direction, and the horizontal direction of the light receiving element 27, i.e., parallel to the row. The horizontal transfer CCD 69 for transferring charges from the vertical transfer CCD 67 in the horizontal direction and the output circuit 71 provided at the left end of the horizontal transfer CCD 69 are included. The light receiving element 27, the vertical transfer CCD 67, and the horizontal transfer CCD 69 constitute an imaging surface that forms one screen of the imaging screen.

  Incident light from the object scene enters the light receiving element 27 via the optical system 17 shown in FIG. 1, and signal charges are generated by the light receiving element 27 by this incident light. The generated signal charge is transferred to the vertical transfer CCD 67 when the transfer gate is turned on in response to the read signal 53 from the imaging drive unit 11. The transferred charge is transferred in the vertical direction by the vertical transfer CCD 67, transferred to the horizontal transfer CCD 69, transferred in the horizontal direction by the horizontal transfer CCD 69, and sent to the output circuit 71. Output as an electrical signal 55. In the present invention, the solid-state imaging device 13 is not limited to the present embodiment, and any solid-state imaging device 13 can be adopted according to the solid-state imaging device 1.

  The difference between when the solid-state imaging device 1 is driven in the recording mode and when the solid-state imaging device 1 is driven in the preliminary mode is that signal charges are normally received from all the light receiving elements 27 in the solid-state imaging device 13 when driven in the recording mode. On the other hand, when driving in the preliminary mode, signal charges are read from some of the light receiving elements 27 in the solid-state imaging device 13. Specifically, when driving in the recording mode, the control unit 5 controls the timing generation unit 9 to read the signal charges from all the light receiving elements 27, and the timing for identifying all the light receiving elements 27 in the timing generation unit 9 Create a signal. On the other hand, when driving in the preliminary mode, the timing generator 9 is set so that the horizontal direction of the matrix, that is, the vertical direction of the matrix is thinned out for each row, and the signal charge is read from the light receiving elements 27 located in the thinned rows. And a timing signal for specifying the thinned-out row is formed in the timing generator.

  For example, in the case of driving in the preliminary mode in the example shown in FIG. 2, the control unit 5 moves the light receiving element 27 in the horizontal direction of the matrix composed of the light receiving element 27 and the vertical transfer CCD, that is, for each row. The timing generator 9 is controlled so that the signal charges are read from the light receiving elements 27 located in the vertical direction, i.e., the columns are thinned out at equal intervals and located in the thinned rows. Specifically, the control unit 9 thins out the matrix in the vertical direction four by four from the first row, that is, thins out 1/4 in the vertical direction, the first row, the fifth row, the ninth row (not shown), .. Are supplied, and a control signal 37 is supplied to the timing generator 9 so as to form a timing signal for specifying the light receiving elements 27 located in these rows in the matrix. In FIG. 2, n is a positive integer. Note that the thinning interval is not limited to this embodiment, and thinning can be performed at an arbitrary interval. Further, when thinning out, it is preferable to thin out at a constant interval because an image displayed on the display unit is easy to see when the preliminary imaging mode is driven.

  The timing generation unit 9 forms a timing signal 43 that identifies the first row, the fifth row, the ninth row (not shown), that is, the readout row, in accordance with the control signal 37 from the control unit 5, and performs imaging. In response to the timing signal 43, the drive unit 53 forms a read signal 53 for reading signal charges from the light receiving elements 27 located in these rows. When driving in the preliminary mode, thinning the light receiving element 27 in this way is sufficient if a rough image of the object scene image can be obtained when driving in the preliminary mode. This is because the signal read out from the element 27 must be processed quickly.

  In the present embodiment, the light receiving elements 27 are thinned out for each row, but the present invention is not limited to this. For example, thinning can be performed for each light receiving element 27, and thinning can be performed for each column. Is possible. In FIG. 2, the thinning unit is one line, but the present invention is not limited to this, and the thinning unit can be arbitrarily determined according to the solid-state imaging device 13. For example, in the case where the solid-state imaging device 13 includes a color filter, it is necessary to make one row including all the color filters R, G, and B. For example, in the case of the solid-state imaging device 13 in which the light receiving elements 27 are shifted in the vertical direction for each column of the matrix, since the rows including all the color filters R, G, B are every two rows, the thinning unit is Every two lines. However, the present invention is not limited to this.

  When driving the solid-state imaging device 1 in such a preliminary mode, if the signal charge is always read from the light receiving element 27 located in the same readout row, the light receiving element 27 located in that row is quickly deteriorated, Even if the depletion voltage is set high, as the number of times of reading increases, that is, as the time of use elapses, reading failure tends to occur early and the image deteriorates. Therefore, in the present invention, when driving in the preliminary mode, the row designated by the control unit 5 is switched. By doing so, the number of times the reading process is performed, that is, the time when the reading process is performed is substantially uniform in each row, and the deterioration state of each light receiving element 27 can be substantially uniform. Therefore, it is possible to lengthen the period until a scratch or the like is formed on the image. As a result, it is possible to suppress the occurrence of read failure even when the read process is performed many times. Hereinafter, switching of a row from which signal charges are read will be described in detail with reference to FIGS.

  FIG. 3 is a flowchart illustrating an example of a processing procedure for switching a row from which signal charges are read in the control unit 5 of the solid-state imaging device 1 illustrated in FIG. 1. FIG. 4 is a conceptual diagram schematically showing the imaging surface of the solid-state imaging device 1 shown in FIG. In FIG. 1 and FIG. 3, when the button for starting up the solid-state imaging device 1 provided in the operation unit 3 is turned on, a moving image that displays an object scene image as one of the preliminary imaging modes on the display unit 23 as a moving image. The display mode is selected, and an operation signal 31 for driving in the moving image display mode is input to the control unit 5 (step S1).

  When the operation signal 31 for driving in the preliminary mode is input to the operation unit 3, the control unit 5 designates the light receiving element 27 for reading the signal charge by thinning out the vertical direction in the matrix for each row. At this time, it is confirmed from the time measured by the time measuring unit 7 how long the read process is performed in the designated row (step S2). In the present embodiment, the control unit 5 reads out for how long the row designated for thinning out the light receiving elements immediately before driving in the preliminary mode, that is, immediately before driving in the preliminary mode or the recording mode. Check if processing has been performed. Note that the time measuring unit 7 measures the time when the process of reading this row is performed. The time measured by the time measuring unit 7 is an accumulated time, and is not reset even when the power of the solid-state imaging device 1 is turned off.

  For example, when driving in the preliminary mode or the recording mode before driving in the preliminary mode of this time, four rows are designated from the first row as shown in FIG. In the case of the first row, the fifth row, the ninth row,..., That is, the first readout row 73 that has been thinned out, the time of the process for reading out in the first readout row 73 is set as the time measuring unit 7. Confirm with. As a result, when the time is less than a predetermined time, it is determined that the row to be read is not switched, and the signal charge is directly received from the light receiving element 27 located in the first read row 73 even in the driving in the preliminary mode. The timing generator is controlled to read (step S3), and the switching process is terminated.

  On the other hand, in the case where the reading process is performed for a time equal to or longer than a predetermined time in the first reading row 73 or substantially the same as the predetermined time, the control unit 5 performs the processing as shown in FIG. , The second row, the sixth row, the tenth row,..., That is, the second readout row 75 is designated, and the light receiving element 27 positioned in the second readout row 75 is specified. The timing generator 9 is controlled so as to read the signal charge from (step S4). In other words, the row from which charges are read is switched from the first readout row 73 to the second readout row 75, and the signal charges are read out from the light receiving elements 27 located in the second readout row 75 in the current drive in the preliminary mode. To.

  When switching, the lines located at the same position in the thinned interval as in this embodiment, i.e., the line designated first for the thinning is shifted, and then the thinned at the same interval as the previous thinned interval. It is possible to make it easier to see the image displayed on the display unit 23 when driving in the preliminary imaging mode, and to easily specify the next line to be specified when switching the line. However, the present invention is not limited to this.

  When the control unit 5 switches the row from which charges are read from the first readout row 73 to the second readout row 75, the control unit 5 causes the time measurement unit 7 to reset the measurement time (step S5) and causes the time measurement unit 7 to perform the second measurement. The measurement of the time when the reading process is performed in the reading line 75 is started. Note that the present invention is not limited to this embodiment. For example, a plurality of timers may be provided in the time measuring unit 7, and the time in each readout row may be measured by each timer. In this case, the control unit 5 does not cause the time measurement unit 7 to reset the measurement time, but temporarily stops the measurement timer for the first readout row 73 and sets the measurement timer for the second readout row 75 to Drive. However, the present invention is not limited to this. When the reset is finished, the control unit 5 finishes the process of switching the rows.

  The timing generation unit 9 that receives an instruction from the control unit 5 forms a timing signal 43 for specifying the first read row 73 when not switching, and a timing for specifying the second read row 75 when switching. Signal 43 is formed. The formed timing signal 43 is supplied to the image pickup drive unit 11, and the image pickup drive unit 11 responds to the supplied timing signal 43 and outputs a signal from the light receiving element 27 located in the first readout row 73 when switching is not performed. A drive signal 53 for reading out charges is formed, and when switching, a drive signal 53 for reading out signal charges from the light receiving elements 27 located in the second readout row 75 is formed, and the drive signal 53 is sent to the solid-state imaging device 13. Supply. In the solid-state imaging device 13, in response to the supplied drive signal 53, if the switching is not performed, the signal charge is read from the light receiving element 27 located in the first readout row 73 and output as an analog electric signal 55. When switching, the signal charge is read from the light receiving element 27 located in the second readout row 75 and output as an analog electric signal 55. The output analog electric signal 55 is converted into a digital image signal 57 by the preprocessing unit 19 and displayed on the display unit 23 through the signal processing unit 21. Note that the digital image signal 57 is not recorded in the recording medium unit 25 because it is driven in the preliminary mode.

  As described above, in the solid-state imaging device 1, when driving in the preliminary imaging mode, the row from which signal charges are read is switched. Therefore, all the rows are read out at substantially the same time.For example, when driving in the preliminary mode, the light receiving element 27 is read out by thinning out 1/4 in the vertical direction for each row. In this embodiment, the time until a read failure occurs can be substantially increased by four times, and as a result, the image deteriorates even after the usage time elapses. It becomes possible to prevent. In addition, since it becomes possible to make the deterioration state of each light receiving element 27 in the solid-state imaging device 13 substantially uniform, it is possible to prevent occurrence of reading failure for a long time without increasing the voltage of the reading signal. This makes it possible to reduce power consumption.

  Although not shown in the figure, when the solid-state imaging device 1 is started up again and the readout process is performed for a predetermined time in the second readout row 75, the control unit 5 performs the third, seventh, and eleventh rows. .., That is, a third readout row is designated, and a row from which signal charges are read out is switched to the third readout row. Further, when the solid-state imaging device 1 is started up again, if the readout process is performed for a predetermined time in the third readout row, the control unit 5 performs the fourth row, the eighth row, the twelfth row,. That is, the fourth readout row is designated, and the row from which signal charges are read is switched to the fourth readout row. Eventually, the first readout row 73, the second readout row 75, the third readout row, and the fourth readout row are switched in this order, and the next to the fourth readout row is switched to the first readout row again. The order of switching is not limited to the present embodiment, and can be arbitrarily set.

  FIG. 5 is a flowchart showing an example of another processing procedure for switching the row from which charges are read in the control unit 5 of the solid-state imaging device 1 shown in FIG. In FIG. 5, steps S2 to S5 are the same as steps S2 to S5 in FIG. In the example shown in FIG. 5, the line is switched every time the recording mode ends. By doing so, in order to determine whether or not to switch at a short interval in time compared to the case of switching each time the solid-state imaging device 1 starts up, the time when the readout process is performed in each row, It becomes possible to make uniform with high accuracy.

  Describing in detail with reference to FIG. 5, the solid-state imaging device 1 is turned off from the operation unit 3 when driving in the recording mode is completed, that is, when shooting of one still image is completed. As long as the operation signal 31 is not input, driving is performed in the moving image mode, which is one of the preliminary imaging modes, in order to perform the next shooting. Therefore, when the operation signal 31 for turning off the power of the solid-state imaging device 1 is not input after the end of driving in the recording mode, the control unit 5 starts driving in the preliminary mode (step S1), In the case of driving in the preliminary mode, it is confirmed how long the designated row has been read (step S2). As a result, when the time is less than the predetermined time, it is determined that the row to be read is not switched, the row is not switched (step S3), and the switching process is terminated. On the other hand, if the specified line is read for a time longer than the predetermined time or substantially the same as the predetermined time, the specified line is switched and positioned on the switched line. A control signal 37 for reading the signal charge from the light receiving element 27 is transmitted to the timing generator 9 (step S4). Thereafter, the time measured by the time measuring unit 7 is reset (step S5), and the switching process is terminated.

  In this embodiment, the row to be read is switched every time driving in the recording mode is finished once. However, the present invention is not limited to this, and how many times the driving is finished is arbitrarily set. It is possible. As described above, by determining whether or not to switch the row every time driving in the recording mode is completed, the interval until the determination is shorter than when determining each time the solid-state imaging device 1 is started up, It is possible to make the time for performing the reading process in each row uniform with high accuracy.

  Note that how to perform the switching process is not limited to the example illustrated in FIGS. 3 and 5. For example, the time for performing the reading process is not measured, and each time the solid-state imaging device starts up, or It is also possible to switch rows every time driving in the recording mode is completed. Further, for example, it is possible to combine the examples shown in FIG. 3 and FIG. 5 so as to switch each time the solid-state imaging device starts up and every time driving in the recording mode is completed. Therefore, since it is determined whether or not to switch at a shorter interval, it is possible to make the time for performing the reading process in each row more uniform. In addition, it is not limited to setting one switching method in the solid-state imaging device 1, for example, every time the solid-state imaging device 1 starts up, every time driving in the recording mode is finished, and every time it starts up and the recording mode It is also possible to set three switching methods each time driving is completed and select the switching method by operating the operation unit 3, and any method can be adopted. . The present invention is not limited to this.

  FIG. 6 is a block diagram showing the configuration of another embodiment of the individual imaging apparatus of the present invention. In FIG. 6, the same reference numerals as those in FIG. In FIG. 6, the solid-state imaging device 101 includes a voltage adjustment unit 103. The voltage adjustment unit 103 is a part that adjusts the voltage of the readout signal 53 formed by the imaging drive unit 11, and is a part that supplies the voltage 107 to the imaging drive unit 11 under the control of the control signal 105 of the control unit 5. More specifically, in the solid-state imaging device 101 shown in FIG. 6, the voltage of the read signal for reading the signal charge from the light receiving element 27 is not set high from the beginning, but is set to a low voltage. Yes. This voltage is a voltage at which signal electrification can be read out with a single readout signal in the initial use of the solid-state imaging device 101, and is set when the solid-state imaging device 101 is manufactured.

  However, in the case where the voltage of the read signal 53 is kept low, if the depletion voltage fluctuates as a result of deterioration of the light receiving element 27 after the usage time has elapsed, it is impossible to read completely. Therefore, in the solid-state imaging device 101, the time measuring unit 7 measures the time when the process of reading each row is performed, and also measures the time using the solid-state imaging time 101. The time when the solid-state imaging device 101 to be measured, that is, the usage time is an accumulated time, and the time measuring unit 7 does not reset the measured usage time even when the power of the solid-state imaging device 101 is turned off. Further, the control unit 5 supplies the control signal 105 to the voltage adjustment unit 101 so as to increase the voltage of the read signal in accordance with the time during which the solid-state imaging device 101 measured by the time measurement unit 7 is used. In response to this control signal, the voltage adjusting unit 103 forms a voltage 107 and supplies it to the imaging drive unit 11. In the imaging drive unit 11, a high-voltage readout signal 53 is formed by the supplied voltage 107 and is supplied to the solid-state imaging device 13. In the example shown in FIG. 6, the time measuring unit 7 measures both the time for performing the process of reading the charge from the light receiving element 27 and the time for using the solid-state imaging device 101. For example, there are provided two measuring units, for example, a time measuring unit that measures the time for performing the process of reading out charges from the light receiving element, and a time measuring unit that measures the time using the solid-state imaging device 101, It is also possible to measure each time in each time measurement unit.

  FIG. 7 is a flowchart illustrating an example of a processing procedure for adjusting the voltage in the solid-state imaging device 101 illustrated in FIG. 6. 6 and 7, the time measuring unit 7 measures the time during which the solid-state imaging device 101 is on, that is, the time during which the solid-state imaging device 101 is used. When the predetermined time is reached, the control unit 5 is notified that the predetermined time has been reached (step S1). In this embodiment, since the 2V voltage is set to increase substantially in 1000 hours, the time measurement unit 7 controls every time when the solid-state imaging device 101 has been used for substantially 250 hours. Inform Part 5 of that. Note that the present invention is not limited to this embodiment, and it is possible to arbitrarily set how much it is increased according to how much usage time. For example, when the 2V voltage is increased in 1000 hours as in this embodiment, each unit can be set so that the 1V voltage increases every 1000 hours. The present invention is not limited to this.

  When notified from the time measuring unit 7, the control unit 5 supplies the control signal 105 to the voltage adjusting unit 103 in order to increase the voltage of the read signal 53 (step S2). Specifically, a control signal 105 is supplied to make the voltage of the read signal 53 0.5 V higher than the voltage of the current read signal 53. In response to the control signal 105 from the control unit 5, the voltage adjustment unit 103 forms a voltage 107 that is 0.5V higher, and supplies the formed voltage 107 to the imaging drive unit 13 (step S3). In the present embodiment, a voltage 107 increased by 0.5 V is supplied to the imaging drive unit 11 in response to a control signal 105 from the control unit 5. In response to this, the imaging drive unit 11 forms a readout signal 53 that is 0.5 V higher than the voltage thus far. The read signal 53 is supplied to the solid-state image sensor 13, and in the solid-state image sensor 13, the signal charge is read by the read signal 53 whose voltage is 0.5V higher, so that it is possible to prevent the occurrence of read failure.

  When the control unit 5 supplies the voltage adjustment unit 103 with a control signal 105 to increase the voltage, the control unit 5 determines whether or not the cumulative total of the voltages that have been raised by the voltage adjustment unit 103 reaches a preset limit value. (Step S4). The limit value is the maximum voltage that can be raised. This value varies depending on the solid-state imaging device 101, but is generally substantially 2V to 3V. As a result of the determination in step S4, if the cumulative total of the voltages raised so far is substantially the same as or greater than the limit value, the control unit 5 causes the time measurement unit to stop measuring time (step S5), the process of adjusting the voltage is terminated. On the other hand, if the time is small, the time of use of the individual imaging device 103 measured by the time measuring unit 7 is reset, and when the time of use reaches 250 hours again, the processing of steps S1 to S4 is performed, and the cumulative total of the increased voltage is limited When the value is reached, the process of increasing the voltage is terminated.

  As described above, in the solid-state imaging device 101, the voltage of the readout signal 53 is gradually increased according to the usage time. Therefore, compared with the case where a high voltage is set from the beginning, it is possible to reduce the consumption voltage. Since the timing for increasing the voltage is specified by measuring the usage time of the solid-state imaging device 101 by the time measuring unit 7, no reading failure occurs even if a high voltage is not set from the beginning. Note that the present invention is not limited to the present embodiment. For example, when a scratch or the like is formed on the image without measuring the usage time, the operator operates the operation unit to set the voltage of the read signal. It is also possible to raise it. However, the present invention is not limited to this.

  FIG. 8 is a flowchart showing an example of a processing procedure in the control unit 5 when the solid-state imaging devices 1 and 101 shown in FIGS. 1 and 6 are driven in the recording mode. FIG. 9 is a conceptual diagram schematically showing the imaging surface of the solid-state imaging device 13 shown in FIG. In FIG. 9, the same reference numerals as those in FIG. In FIG. 8, when the operation signal 31 indicating that the recording unit is driven in the recording mode is input to the operation unit 3, the control unit 5 thins out the light receiving elements when driving in the preliminary mode immediately before driving in the current recording mode. The line designated for the purpose is grasped (step S1). For example, as shown in FIG. 9, when the signal charge is read from the second readout row 75 when the row designated when driving in the immediately preceding preliminary mode is read as the second readout row 75. .

  Next, when driving in the recording mode, the control unit 5 designates a readout row other than the second readout row 75, and reads out the signal charges from the light receiving elements 27 located in the designated readout row. Is controlled (step S2). In the present embodiment, as shown in FIG. 9, the control unit 5 designates the third row, the seventh row, the eleventh row,..., That is, the third readout row 111, and is positioned at the third readout row 111. A control signal 37 is supplied to the timing generator 9 so as to read the signal charge from the light receiving element. In the present embodiment, the control unit 5 designates the third readout line 111 in the solid-state imaging devices 1 and 101 in the present embodiment when the light receiving element 27 is thinned out, the first readout line 73 and the second readout line. 75, since the third readout row 111 and the fourth readout row are switched and thinned in this order, the readout time of the third readout row 111 is shorter than that of the first readout row 73, and a readout failure occurs. This is because the possibility is low. Thus, when switching in the recording mode and switching in the preliminary mode, if the switching order is the same, the signal charge from the light receiving element 27 is less likely to cause a read failure when driving in the recording mode. However, the present invention is not limited to this, and an arbitrary line can be designated.

  For example, regardless of the order in which the control unit 5 has switched in the preliminary mode, any read row is designated as long as it is a read row different from the read row from which the signal charge was read immediately before driving in the recording mode. You may do it. Further, for example, when the time measurement unit 7 measures the time when the reading process is performed in each reading row and is driven in the recording mode, the time when the control unit 5 performs the reading process of each reading row is compared. The timing generation unit 9 may be controlled so that the readout row having the shortest readout time is designated and the signal charge is read out from the light receiving element located in the readout row. However, the present invention is not limited to these.

  When the control unit 5 switches from the second readout row 75 to the third readout row 111, the control unit 5 resets the time for performing the readout process in the second readout row measured by the time measuring unit 7, and reads out the third readout row. Measurement of the processing time is started (step S3). This is because, in this embodiment, when the recording mode ends, it is determined whether or not to switch the row to be read according to the time measured by the time measuring unit 7. For example, when the recording mode is switched regardless of the measured time, the time measured by the time measuring unit 7 does not need to be reset. The control unit 5 ends the switching process when the reset is performed.

  In this embodiment, the control unit 5 designates one line at the thinned-out interval, but the present invention is not limited to this, and the control unit 5 is a preliminary mode immediately before driving in the recording mode. Any row other than the row from which the signal charge has been read at the time of driving can be designated. For example, in the present embodiment, it is possible to designate a read line other than the second read line 75, that is, the first, third, and fourth read lines. Among the rows other than the row from which the signal charge has been read out during the driving in the preliminary mode, the row having a short reading time, that is, the third and fourth readout rows are designated in this embodiment. It is also possible to do.

  Upon receiving the control signal 37 from the control unit 5, the timing generation unit 9 forms a timing signal 43 for specifying the third readout row 111 and supplies the timing signal 43 to the imaging drive unit 13. In response to the supplied timing signal 43, the imaging drive unit 13 forms a drive signal 53 for reading the signal charge from the light receiving element 27 located in the third readout row 111 and supplies it to the solid-state image sensor 13. In the solid-state imaging device 13, in response to the supplied drive signal 53, the signal charge is read from the light receiving element 37 located in the third readout row 111 and output as an analog electric signal 55. The output analog electric signal 55 is converted into a digital image signal 57 by the preprocessing unit 19, displayed on the display unit 23 through the signal processing unit 21, and recorded on the recording medium unit 25. When the drive in the recording mode is completed, the control unit 5 determines whether or not to switch the row for reading the signal charge when driving in the preliminary mode as shown in FIG. If not, do not switch.

  As described above, in the example shown in FIG. 8, when driving in the recording mode, the row from which the signal charge is read is switched. By switching in this way, it is possible to read out signal charges from the light receiving element 27, which reduces the size of the image but has a low possibility of occurrence of read failure, so it is possible to suppress the occurrence of read failure. It is possible to prevent image degradation.

  In all cases of driving in the recording mode, it is not necessary to limit to driving in the recording mode shown in FIG. 8. For example, in the normal recording mode, signal charges are read from all the light receiving elements 27 and high sensitivity is achieved. It is also possible to employ the recording mode shown in FIG. 8 when driving in the recording mode. The high-sensitivity recording mode is a case where imaging is performed with a higher imaging sensitivity compared to the imaging sensitivity that is normally used.For example, even when the signal charge formed on the light receiving element is small, it can be obtained. This corresponds to an imaging mode or the like that can correct the gain of the image signal and form a beautiful digital image signal. By driving in the recording mode shown in FIG. 8 in the case of high sensitivity, it becomes possible to suppress the occurrence of reading failure even if the signal charge formed in the light receiving element is small, so that sufficient signal charge is obtained. And a digital image with little deterioration can be obtained. Note that the present invention is not limited to this, and driving in the recording mode shown in FIG. 8 can be performed in any environment.

It is a block diagram showing the structure of the Example of the solid-state imaging device of this invention. It is the conceptual diagram which showed the front of the solid-state image sensor in FIG. 2 is a flowchart illustrating an example of a processing procedure for switching a row from which charges are read in the control unit of the solid-state imaging device illustrated in FIG. 1. It is the conceptual diagram which showed the front of the solid-state image sensor shown in FIG. 2 simply. 5 is a flowchart illustrating an example of another processing procedure for switching a row from which charges are read in the control unit of the solid-state imaging device illustrated in FIG. 1. It is a block diagram showing the structure of another Example of the solid-state imaging device of this invention. 7 is a flowchart illustrating an example of a processing procedure for adjusting a voltage in the solid-state imaging device illustrated in FIG. 6. It is a flowchart which shows an example of the process sequence in the control part at the time of driving the solid-state imaging device shown in FIG. 1 and FIG. 6 in a recording mode. It is the conceptual diagram which showed the front of the solid-state image sensor shown in FIG. 2 simply.

Explanation of symbols

1 Solid-state imaging device
3 Operation unit
5 Control unit
7 Time measurement part

Claims (5)

A plurality of light-receiving elements that generate signal charges from incident light from the object scene, arranged in a matrix, and a solid-state imaging element that forms an electrical signal by reading the signal charges from the light-receiving elements;
Processing means for processing the electrical signal to form an image signal;
An operation means for inputting an operator's instruction;
In a solid-state imaging device including a recording unit that records the image signal in response to an operation instruction input to the operation unit, the device includes:
The light receiving element is designated for each row in the matrix depending on when the image signal is driven in a recording mode for recording in the recording means and when the image signal is driven in a preliminary mode used for display or control. Control means for controlling to read out the signal charge from the designated light receiving element,
When driving in the preliminary mode, the control means designates the row by thinning out the vertical direction of the matrix for each row, and switches the designated row every time the recording mode is finished. A solid-state imaging device.   2. The solid-state imaging device according to claim 1, wherein the control unit switches the row each time the solid-state imaging device starts up. 3. 3. The apparatus according to claim 1, further comprising drive time measuring means for measuring a time when the signal charge is read in the row.
The solid-state imaging device, wherein the control means is switched according to the time. 4. The device according to any one of claims 1 to 3 , further comprising:
Usage time measuring means for measuring the time when the solid-state imaging device is used;
A solid-state imaging device comprising: voltage adjusting means for adjusting the voltage of the readout signal in accordance with the time. In the solid-state imaging device according to any one of claims 1 to 4, wherein, when driving in the recording mode, to specify a different row from the row that is specified in the drive in the preliminary mode A solid-state imaging device.