JP2001028712A - Solid-state image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state image pickup device that a linear conversion or a logarithmic conversion for an electric signal with respect to an incident light to an area sensor can automatically be selected in response to a photographed range. SOLUTION: In the case of converting a light that is made incident via a zoom lens optical system 2 to an electrical signal by an area sensor 10, a CPU 19 decides logarithmic conversion that an object over a wide luminance range can be photographed or linear conversion that the object can be photographed with rich gradation depending on a zoom position detected by a position detector 14 and a switching signal generating circuit 11 transmits a switching signal to the area sensor 10. The logarithmic conversion or the linear conversion is switched for the area sensor by changing a bias voltage of a MOS transistor(TR) to which an optical current is supplied from photo diodes of each pixel provided in the area sensor 10 by this switching signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device having a solid-state imaging device capable of performing linear conversion and logarithmic conversion of an electric signal with respect to incident light.

[0002]

2. Description of the Related Art Conventionally, a solid-state imaging device such as an area sensor in which photosensitive elements such as photodiodes are arranged in a matrix form a signal obtained by linearly converting the luminance of light incident on the photosensitive element. Output. An area sensor that performs linear conversion in this manner (hereinafter, referred to as a “linear sensor”) is, for example, a photosensitive element that captures the brightest portion (highlight portion) of a subject by adjusting the aperture of a lens. It is adjusted so that it can be output as an electric signal at a level of about 90% of the maximum level.
By using such a linear sensor, the minimum value in the luminance distribution of the subject is represented by Lmin [cd / m ² ],
Assuming that the maximum value is Lmax [cd / m ² ], if the luminance range Lmax / Lmin of the subject is a narrow range of two digits or less, the subject information can be captured with rich gradation.

On the other hand, the present applicant has proposed a photosensitive element for generating a current corresponding to the amount of incident light, a MOS transistor for inputting the current, and a bias for biasing the MOS transistor to a state where a subthreshold current can flow. And an area sensor (hereinafter, referred to as a “LOG sensor”) that converts the current from the photosensitive element into a logarithm (see Japanese Patent Application Laid-Open No. 3-192664). When such a LOG sensor is adjusted so that a photosensitive element that captures an image of the brightest part (highlight part) of a subject can output an electric signal having a level of about 90% of the maximum level, the luminance range Lmax /
It is possible to capture information of a subject whose Lmin is in a wide range of 5 to 6 digits.

[0004]

In the above-described linear sensor, since the brightness range in which an image can be captured is as narrow as two digits, the brightness of the subject becomes bright due to factors such as direct sunlight.
When the bright portion exceeds the level that can be handled by the photosensitive element and overflows, information on the bright portion exceeding this level cannot be captured, and a phenomenon called overexposure occurs. In order to avoid this overexposure, if the luminance range that can be captured is shifted to the bright part side so that the information of the bright part can be captured, the information of the dark part cannot be captured. Occur.

On the other hand, the output characteristic of the LOG sensor shows a logarithmic function as shown in FIG. Therefore, when this LOG sensor is used, gradation in a high-luminance part tends to be poor. For example, for a bright subject, it is possible to capture both information of a dark part and a bright part. For a subject, there is a problem that the gradation of a bright part is poor.

Since the characteristics of the linear sensor and the LOG sensor are as described above, when the linear sensor captures an image of a subject having a narrow luminance range, and when the LOG sensor captures an image of a subject having a wide luminance range, each of It turns out to be effective. Therefore, when capturing an image of a subject by zooming up or capturing a subject at a close distance, the imaging range is narrowed and the luminance range is generally narrowed, so that the linear sensor is effective. On the other hand, when an image of a distant subject is taken without zooming up, especially when taking an image outdoors in fine weather, the LOG sensor is effective because the imaging range is widened and the luminance range is widened.

[0007] In view of such problems, an object of the present invention is to provide a solid-state imaging device capable of performing good imaging of various subjects. Another object of the present invention is to provide a solid-state imaging device capable of automatically switching between a linear conversion operation and a logarithmic conversion operation of an electric signal with respect to incident light of a solid-state imaging device. It is another object of the present invention to provide a solid-state imaging device in which one solid-state imaging device performs the linear conversion operation and the logarithmic conversion operation.

[0008]

According to a first aspect of the present invention, there is provided a solid-state imaging device having a solid-state imaging device for generating an electric signal according to an amount of incident light. The operation state of the element can be switched between a first state in which the electric signal is linearly converted with respect to the amount of incident light and output, and a second state in which the natural signal is converted and output as natural logarithm, The operation state of the solid-state imaging device is switched based on at least one imaging condition selected from a group consisting of a distance to a subject and an imaging magnification.

According to the solid-state imaging device having such a configuration,
The output state of the solid-state imaging device can be changed so as to be suitable for the size and image of the subject on the imaging screen where the image is actually taken, and good imaging can be performed for various subjects.

According to a second aspect of the present invention, there is provided a solid-state imaging device having a solid-state imaging device that generates an electric signal corresponding to an amount of incident light and an optical system with a variable focal length. Can be switched between a first state in which the electric signal is linearly converted with respect to the amount of incident light and output, and a second state in which the natural signal is converted and output logarithmically, and the optical system The operation state of the solid-state imaging device is switched based on a focal length.

According to a third aspect of the present invention, there is provided a solid-state imaging device comprising: a solid-state imaging device for generating an electric signal corresponding to the amount of incident light; and an optical system capable of forming an image by switching a subject between a wide-angle side and a telephoto side. In the solid-state imaging device, the operating state of the solid-state imaging device is changed between a first state in which the electric signal is linearly converted with respect to an incident light amount and output, and a second state in which the natural signal is converted into natural logarithm and output. And an operation state of the solid-state imaging device is switched according to whether the optical system forms an image on the telephoto side or forms an image on the wide-angle side.

According to the solid-state imaging device having such a configuration,
Depending on the focal length of the optical system, or whether the optical system is on the wide-angle side or on the telephoto side, the output state of the solid-state image sensor automatically changes, and good imaging of various subjects is achieved. It can be carried out. Then, for example, as described in claim 4, when the luminance range of a range in which the object to be imaged by the optical system is imaged on the telephoto side is narrowed,
In the first state with good gradation, and when the brightness range of the range to be imaged by forming an image of the subject captured by the optical system on the wide-angle side is wide, a subject with a wide brightness range can be captured. Each can be switched to the second state.

According to a fifth aspect of the present invention, there is provided a switching signal generating circuit for generating a switching signal for switching an operation state of the solid-state imaging device in response to an imaging state of a subject in the optical system. May be. Further, as described in claim 6, by changing the switching signal into a binary voltage signal, a value of a bias voltage applied to an element in the solid-state imaging device is changed to operate the solid-state imaging device. Can be switched to the first state or the second state.

According to a seventh aspect of the present invention, in the solid-state imaging device according to any one of the third to sixth aspects, the optical system continuously changes a wide-angle side and a telephoto side. It is characterized by being a system.

According to an eighth aspect of the present invention, in the solid-state imaging device according to any one of the third to sixth aspects, the optical system can switch between a plurality of optical systems having different focal points. Is a multifocal optical system.

According to a ninth aspect of the present invention, there is provided a solid-state imaging device having a solid-state imaging device for generating an electric signal corresponding to an amount of incident light and an optical system capable of forming an image by switching a subject between a wide-angle side and a telephoto side. In the imaging device, the operation state of the solid-state imaging device includes a first state in which the electric signal is linearly converted with respect to an incident light amount and output, and a second state in which the natural signal is converted into natural logarithm and output. Can be switched to
The operation state of the solid-state imaging device is switched according to a range in which the solid-state imaging device captures an image.

According to the solid-state imaging device having such a configuration,
The output state of the solid-state imaging device automatically changes in accordance with the range in which the solid-state imaging device captures an image, and good imaging of various subjects can be performed. And, for example, claim 1
As described in 0, when the imaging range is narrow and its luminance range is narrow, the first state with good gradation is
Further, when the range of image pickup is wide and its luminance range is wide, it is possible to switch to the second state in which a subject having a wide luminance range can be imaged.

According to another aspect of the present invention, there is provided a switching signal generating circuit for generating a switching signal for switching an operation state of the solid-state imaging device in response to a range in which the solid-state imaging device captures an image. good. Further, as described in claim 12, by setting the switching signal as a binary voltage signal, the value of a bias voltage applied to an element in the solid-state imaging device is changed to operate the solid-state imaging device. The first
The state or the second state can be switched.

According to a thirteenth aspect of the present invention, there is provided the solid-state imaging device according to any one of the ninth to twelfth aspects, wherein the optical system continuously changes the wide-angle side and the telephoto side. It is characterized by being a system.

According to a fourteenth aspect of the present invention, in the solid-state imaging device according to any one of the ninth to twelfth aspects, the optical system can switch between a plurality of optical systems having different focal points. It is a multifocal optical system.

According to a fifteenth aspect of the present invention, there is provided the solid-state imaging device according to any one of the ninth to fourteenth aspects, further comprising means for measuring a distance to a subject.
The imaging range is calculated based on the distance to the subject measured by the means and the magnification of the optical system.

According to a sixteenth aspect of the present invention, in the solid-state imaging device according to any one of the first to fifteenth aspects, the solid-state imaging device is a photosensitive element in which a DC voltage is applied to a first electrode. And a transistor including a first electrode, a second electrode, and a control electrode, wherein the first electrode and the control electrode are connected to a second electrode of the photosensitive element, and an output current from the photosensitive element flows into the transistor. The operation of the solid-state imaging device is switched between a first state and a second state by changing a potential difference between a first electrode and a second electrode of the transistor.

A solid-state imaging device according to a seventeenth aspect is the solid-state imaging device according to any one of the first to fifteenth aspects, wherein the solid-state imaging device is a photosensitive device in which a DC voltage is applied to a first electrode. And a first electrode, a second electrode, and a control electrode, wherein the first electrode is connected to a second electrode of the photosensitive element,
While the output current from the photosensitive element flows in, the second
A transistor having an electrode and a control electrode connected thereto, and by changing a potential difference between a first electrode and a second electrode of the transistor, the operation of the solid-state imaging device is
It is characterized by switching between the first state and the second state.

According to a twenty-eighth aspect of the present invention, in the solid-state imaging device according to any one of the first to fifteenth aspects, the solid-state imaging element is a photosensitive element in which a DC voltage is applied to a first electrode. A first electrode, a second electrode, and a control electrode, a DC voltage is applied to the control electrode, the first electrode is connected to the second electrode of the photosensitive element, and an output current from the photosensitive element is And a transistor that flows in, and the operation of the solid-state imaging device is switched between a first state and a second state by changing a potential difference between a first electrode and a second electrode of the transistor. .

According to a nineteenth aspect of the present invention, in the solid-state imaging device according to any one of the first to eighteenth aspects, the first mode automatically switches an operation state of the solid-state imaging device; A second mode for prohibiting automatic switching of the operation state of the solid-state imaging device.

According to a twentieth aspect of the present invention, in the solid-state imaging device according to the nineteenth aspect, switch means for manually switching an operation state of the solid-state imaging element is provided,
When the solid-state imaging device is in the second mode, the operating state of the solid-state imaging device is switched by the switch means.

Further, in such a solid-state imaging device,
As described in claim 21, the switch means may be a switch means capable of forcibly switching the operation state of the solid-state imaging device even in the first mode.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> A first embodiment of the present invention
An embodiment will be described with reference to the drawings. FIG.
1 is an external perspective view of a solid-state imaging device embodying the present invention. FIG. 2 is a block diagram showing the internal structure of the solid-state imaging device of the present invention. FIGS. 3 and 5 are block diagrams illustrating an example of the structure of an area sensor that is a solid-state imaging device provided in the solid-state imaging device illustrated in FIG. FIG. 4 is a circuit diagram showing an example of a configuration of a pixel in the area sensor shown in FIG. FIG. 7 is a circuit diagram showing an example of a configuration of a pixel in the area sensor shown in FIG.

The solid-state imaging device 1 shown in FIG. 1 has a zoom lens optical system 2, a distance measuring unit 3 for measuring the distance to the subject and focusing the lens, a shutter button 4, and an area sensor 10 (FIG. 2). ), A mode switch 5 for switching between an automatic mode for automatically switching between a logarithmic conversion operation and a linear conversion operation and a manual mode for inhibiting the automatic switching, a zoom key 6 for changing the imaging magnification, and a current state of the area sensor 10. Output switching key 7 for forcibly switching the conversion operation to the other conversion operation, a display screen 8 for outputting an image of a subject to be imaged, and a power switch for turning on / off the power of the solid-state imaging device 1. 22. The solid-state imaging device 1 may be a digital movie that captures a moving image or a digital camera that captures a still image.

This solid-state imaging device 1 has
A zoom lens optical system 2, an area sensor 10 that outputs an electrical signal that has been subjected to logarithmic or linear conversion according to light incident through the zoom lens optical system 2, a logarithmic conversion operation and a linear conversion operation of the area sensor 10 A switching signal generating circuit 11 for sending a switching signal for switching between the two to the area sensor 10, an optical system driving unit 12 for driving the zoom lens optical system 2 to continuously change the imaging magnification and focus, and Position detector 14 for detecting position
And an image processing unit 15 that performs image processing such as edge enhancement and color conversion processing of a subject using an electric signal transmitted from the area sensor 10, and an image for temporarily storing the signal processed by the image processing unit 15. Memory 16 and image processing unit 1
5, a screen control unit 17 for controlling the display screen 8 based on the signal processed in 5, a recording unit 18 for recording the signal processed in the image processing unit 15 on a recording medium (not shown), and the like.
A central processing unit (CP) that controls each unit in the solid-state imaging device 1
U: Central Processing Unit) 19, a ROM (Read Only Memory) 20 in which software for operating each unit in the solid-state imaging device 1 is stored, and a RAM (Random Access Memor) for temporarily storing data.
y) 21.

An example of the configuration of the area sensor 10 provided in the solid-state imaging device having such a configuration will be described with reference to FIG. In the figure, G11 to Gmn indicate pixels arranged in a matrix (matrix arrangement). Reference numeral 50 denotes a vertical scanning circuit, and rows (lines) 52-1, 52-2,
.., 52-n are sequentially scanned. Reference numeral 51 denotes a horizontal scanning circuit which outputs output signal lines 53-1, 53-2,
.., And the photoelectric conversion signals derived to 53-m are sequentially read in the horizontal direction for each pixel. Reference numeral 54 denotes a power supply line.
For each pixel, the lines 52-1, 52-2,.
, 52-n and output signal lines 53-1, 53-2,.
, 53-m and the power supply line 54 as well as other lines (for example, a clock line and a bias supply line) are connected, but these are omitted in FIG.

The output signal lines 53-1, 53-2,...
Every 53-m, an N-channel MOS transistor Q1,
, Qm are provided one by one as shown in the figure. The drains of the transistors Q1, Q2,..., Qm are output signal lines 53-1, 53-2,.
53-m, the source is connected to the final signal line 55, and the gate is connected to the horizontal scanning circuit 51.
As described later, an N-channel fourth MOS transistor T4 for switching is also provided in each pixel. Here, the transistor T4 selects a row,
The transistors Q1 to Qm perform column selection.

Further, the structure of the pixels G11 to Gmn in the area sensor 10 will be described with reference to FIG. In FIG. 4, a pn photodiode PD forms a photosensitive section (photoelectric conversion section). The anode of the photodiode PD is connected to the drain and gate of the first MOS transistor T1, the gate of the second MOS transistor T2, and the drain of the third MOS transistor T3. The source of the transistor T2 is the fourth MO for row selection.
It is connected to the drain of S transistor T4. The source of the transistor T4 is an output signal line 53 (this output signal line 53 is connected to 53-1, 53-2,..., 53-m in FIG. 3).
Corresponding to). The transistor T
1, T2, T3 and T4 are all N-channel MOS
The back gate of the transistor is grounded.

The DC voltage VPD is applied to the cathode of the photodiode PD. On the other hand, the signal φVPS is applied to the source of the transistor T1, and one end of the capacitor C is connected to the source of the transistor T2. The other end of capacitor C is supplied with signal φVPS. A DC voltage V RB is applied to the source of the transistor T3, and a signal φVRS is input to its gate. Signal φD is input to the drain of transistor T2. The signal φV is input to the gate of the transistor T4. In this embodiment, the signal φVPS is 2
The voltage for operating the transistors T1 and T2 in the subthreshold region is set to a low level, and a voltage substantially equal to the DC voltage VPD is set to a high level.

In the pixel having such a configuration, the signal φV
By switching the voltage value of PS to change the bias of the transistor T1, an electric signal output from the photodiode PD in accordance with the incident light (hereinafter, referred to as "photocurrent") is output to the output signal line 53. Can be realized by natural logarithm conversion and by linear conversion. Hereinafter, each of these cases will be briefly described.

(1) A case where a photocurrent is converted into a natural logarithm and output. First, the signal φVPS is set to low level, and the transistor T
The operation when 1, 1 and T2 are biased to operate in the sub-threshold region will be described. At this time, signal φVRS applied to the gate of transistor T3
Is at low level, the transistor T3 is
FF, which is equivalent to the fact that it does not substantially exist.
The signal φD applied to the transistor T2 is at a high level (a potential equal to or close to the DC voltage VPD).
And

In the circuit shown in FIG.
When light enters D, a photocurrent is generated, and a voltage having a value obtained by natural logarithmically converting the photocurrent is generated at the gates of the transistors T1 and T2 due to the subthreshold characteristic of the transistor. Due to this voltage, a current flows through the transistor T2, and a charge equivalent to a value obtained by natural logarithmically converting the integrated value of the photocurrent is accumulated in the capacitor C. That is,
At the connection node a between the capacitor C and the source of the transistor T2, a voltage proportional to the natural logarithmically converted value of the photocurrent is generated. However, at this time, it is assumed that the transistor T4 is in an OFF state.

Next, a pulse signal φV is applied to the gate of the transistor T4 to turn on the transistor T4.
The charge stored in the capacitor C is led out to the output signal line 53 as an output current. The current led out to the output signal line 53 is a value obtained by natural logarithmically converting the integrated value of the photocurrent. In this manner, a signal (output current) proportional to the logarithmic value of the incident light amount can be read. After reading the signal, the transistor T4 is turned off and the signal φD is set to a low level (potential lower than the signal φVPS) to discharge the electric charge accumulated in the capacitor C to the line of the signal φD through the transistor T2. The potentials of C and the connection node a are initialized. By repeating such an operation at predetermined time intervals, a subject image that changes every moment can be continuously captured in a wide dynamic range. When the incident light amount is converted into a natural logarithm, the signal φVRS is always kept at the low level, and the transistor T3 is in the OFF state.

(2) A case where a photocurrent is linearly converted and output. Next, an operation when the signal φVPS is set to the high level will be described. At this time, the potential on the source side of the transistor T1 increases. Therefore, the transistor T1 is substantially turned off, and no current flows between the source and the drain of the transistor T1. Also, the transistor T3
The signal φVRS applied to the gate of the transistor T1 is kept at a low level, and the transistor T3 is turned off.

Then, first, the transistor T4 is turned off.
At the same time, when the signal φD is set to a low level (a potential lower than the signal φVPS), the charge of the capacitor C is discharged to the line of the signal φD through the transistor T2, thereby resetting the capacitor C and setting the potential of the connection node a to, for example, DC. Initialize to a potential lower than the voltage VPD. This potential is held by the capacitor C. Thereafter, φD is returned to a high level (a potential equal to or close to the DC voltage VPD). In such a state, when light enters the photodiode PD, a photocurrent is generated. At this time, since a capacitor is formed between the back gate and the gate of the transistor T1, the junction capacitance of the photodiode PD, and the like, the charge due to the photocurrent is mainly stored in the gates of the transistors T1 and T2. Therefore, the gate voltage of the transistors T1 and T2 becomes a value proportional to the value obtained by integrating the photocurrent.

Now, since the potential of the connection node a is lower than the DC voltage VPD due to the initialization, the transistor T2 is turned ON, and a drain current corresponding to the gate voltage of the transistor T2 flows through the transistor T2, and the potential of the transistor T2 is reduced. An amount of charge proportional to the gate voltage is stored in the capacitor C. Therefore, the potential of the connection node a becomes a value proportional to the value obtained by integrating the photocurrent. Next, when the pulse signal φV is applied to the gate of the transistor T4 to turn on the transistor T4, the electric charge accumulated in the capacitor C is led out to the output signal line 53 as an output current. This output current is a value obtained by linearly converting the integrated value of the photocurrent.

Thus, a signal (output current) proportional to the amount of incident light can be read. Thereafter, the transistor T4 is turned off and the signal φD is set to low level to discharge the signal φD to the line of the signal φD through the transistor T2, thereby initializing the potential of the capacitor C and the connection node a. Thereafter, the transistor T3
A high-level signal φVRS is applied to the gate of the transistor PD3 to turn on the transistor T3, thereby turning the photodiode PD
The drain voltage of the transistor T1 and the transistor T
1, the gate voltage of T2 is initialized. By repeating such an operation at predetermined time intervals, a subject image that changes every moment can be continuously captured with a good S / N ratio.

As described above, the pixel shown in FIG. 4 can switch the photoelectric conversion output characteristic of the same pixel by a simple potential operation. When switching from a state in which the signal is logarithmically converted and output to a state in which the signal is linearly converted and output, the output is first switched by adjusting the potential of φVPS, and then the transistor T3 is reset by the transistor T3. Is preferred. On the other hand, when switching from a state in which the signal is linearly converted and output to a state in which the signal is logarithmically converted and output, resetting of the transistor T1 by the transistor T3 is not particularly necessary. This is because the carriers accumulated in the transistor T1 due to the fact that the transistor T1 is not in the complete OFF state are erased by carriers of the opposite polarity.

Another example of the configuration of the area sensor 10 will be described with reference to FIG. In FIG.
Gmn indicates pixels arranged in a matrix (matrix arrangement). Reference numeral 50 denotes a vertical scanning circuit, and a row (line) 52 is provided.
-1, 52-2,..., 52-n are sequentially scanned. Reference numeral 51 denotes a horizontal scanning circuit, which connects the pixel to the output signal line 5.
, 53-2,..., 53-m are sequentially read in the horizontal direction for each pixel. Reference numeral 54 denotes a power supply line. For each pixel, the line 52-
1, 52-2,..., 52-n and the output signal line 53-
1, 53-2,..., 53-m, the power supply line 54, and other lines (for example, a clock line and a bias supply line) are also connected, but these are omitted in FIG.

The output signal lines 53-1, 53-2,...
Every 53-m, an N-channel MOS transistor Q1,
, Qm and N-channel MOS transistors Qa1, Qa2,..., Qam are provided as a set as shown. The transistors Qa1, Qa2,.
, Qam are connected to a DC voltage line 56, and drains are output signal lines 53-1 and 53-2, respectively.
, 53-m, and the source is connected to the line 57 of the DC voltage VPS '. On the other hand, transistor Q1,
The drains of Q2,..., Qm are output signal lines 5 respectively.
, 53-2,..., 53-m, the source is connected to the final signal line 55, and the gate is connected to the horizontal scanning circuit 51.

As described later, the pixels G11 to Gmn have
An N-channel fifth MOS transistor T5 for outputting a signal based on the photocharge generated in those pixels is provided. The connection relationship between the transistor T5 and the transistor Qa (this transistor Qa corresponds to the transistors Qa1 to Qam in FIG. 5) is as shown in FIG.
Here, the relationship between the DC voltage VPS 'connected to the source of the transistor Qa and the DC voltage VPD' connected to the drain of the transistor T5 is VPD '>VPS', and the DC voltage VPS 'is, for example, a ground voltage ( Ground). In this circuit configuration, a signal is input to the gate of the upper transistor T5, and the DC voltage DC is constantly applied to the gate of the lower transistor Qa. Therefore, the lower transistor Q
“a” is equivalent to a resistor or a constant current source, and the circuit of FIG. 6A is a source follower-type amplifier circuit. In this case, what is amplified and output from the transistor T5 may be a current.

Transistor Q (this transistor Q is
This corresponds to the transistors Q1 to Qm in FIG. Is controlled by the horizontal scanning circuit 51 and operates as a switch element. As described later, an N-channel fourth MOS transistor T4 for switching is also provided in the pixel of FIG. When this transistor T4 is also included, FIG.
The circuit of FIG. 6A is exactly as shown in FIG. That is, the transistor T4 is inserted between the transistor Qa and the transistor T5. Here, the transistor T4 is for selecting a row, and the transistor Q is for selecting a column.

With the configuration as shown in FIG. 6, a large signal gain can be output. Therefore, when the pixel converts the photocurrent generated from the photosensitive element in a natural logarithmic manner to expand the dynamic range, the output signal is small as it is, but is amplified to a sufficiently large signal by the present amplifier circuit. Therefore, processing in a subsequent signal processing circuit (not shown) becomes easy. Also, the transistor Qa constituting the load resistance portion of the amplifier circuit is not provided in the pixel, and the output signal line 5 to which a plurality of pixels arranged in the column direction are connected is connected.
, 53-2,..., 53-m, the number of load resistors or the number of constant current sources can be reduced, and the area occupied by the amplifier circuit on the semiconductor chip can be reduced.

An example of each pixel of the area sensor 10 having the configuration shown in FIG. 5 will be described with reference to FIG. Elements and signal lines used for the same purpose as the pixel shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The pixel shown in FIG. 7 is the same as the pixel shown in FIG. 4 except that the fifth MOS transistor T5 has a gate connected to the connection node a and performs current amplification according to the voltage applied to the connection node a.
A fourth MOS transistor T4 for row selection in which the drain is connected to the source of the transistor T5, and a sixth MOS transistor T6 in which the drain is connected to the connection node a and initializes the potential of the capacitor C and the connection node a.
Are added. The source of the transistor T4 is an output signal line 53 (this output signal line 53 is
, 53-2,..., 53-m). Note that, similarly to the transistors T1 to T3, the transistors T4 to T6 are N-channel MOS transistors and have a back gate grounded.

The DC voltage VPD is applied to the drains of the transistors T2 and T5, and the signal φV is input to the gate of the transistor T4. The DC voltage V RB2 is applied to the source of the transistor T6, and the signal φVRS2 is input to the gate of the transistor T6. Note that, in the present embodiment, the transistors T1 to T3 and the capacitor C
The same operation as each element in the pixel shown in FIG.
Changing the bias value of the transistor T1 by switching the voltage value of VPS to convert the output signal led to the output signal line 53 into a natural logarithm with respect to the photocurrent;
And a case of linear conversion. The operation in each of these cases will be described below.

(1) A case where a photocurrent is converted into a natural logarithm and output. First, the signal φVPS is set to low level, and the transistor T
The operation when 1, 1 and T2 are biased to operate in the sub-threshold region will be described. At this time, since a low-level signal φVRS is applied to the gate of the transistor T3 as in the pixel shown in FIG. 4, the transistor T3 is turned off, which is equivalent to the fact that the transistor T3 does not substantially exist.

When light enters the photodiode PD, a photocurrent is generated, and a voltage having a value obtained by natural logarithmically converting the photocurrent is generated at the gates of the transistors T1 and T2 due to the subthreshold characteristic of the transistor. Due to this voltage, a current flows through the transistor T2 and the capacitor C
Accumulates a charge equivalent to a value obtained by natural logarithmically converting the integrated value of the photocurrent. That is, a voltage proportional to a value obtained by natural logarithmically converting the integrated value of the photocurrent is generated at the connection node a between the capacitor C and the source of the transistor T2. However, at this time, the transistors T4,
T6 is in the OFF state.

Next, when a pulse signal is applied to the gate of the transistor T4 to turn on the transistor T4, a current proportional to the voltage applied to the gate of the transistor T5 is led out to the output signal line 53 through the transistors T4 and T5. You. Now, the voltage applied to the gate of the transistor T5 is
Since the voltage is applied to the connection node a, the output signal line 53
Is a value obtained by natural logarithmically converting the integrated value of the photocurrent.

In this manner, a signal (output current) proportional to the logarithmic value of the amount of incident light can be read. After the signal is read, the transistor T4 is turned off, and the transistor T6 is turned on by applying a high-level signal φVRS2 to the gate of the transistor T6, whereby the potentials of the capacitor C and the connection node a can be initialized. When the output current is naturally logarithmically converted with respect to the amount of incident light, the signal φVRS always remains at the low level.

(2) A case where a photocurrent is linearly converted and output. Next, an operation when the signal φVPS is set to the high level will be described. At this time, a low-level signal φVRS is applied to the gate of the transistor T3, and
FF. Then, first, a high-level signal φVRS2 is applied to the gate of the transistor T6 to apply the transistor T6.
By turning ON 6, the capacitor C is reset, and the potential of the connection node a is initialized to a potential V RB2 lower than the DC voltage V PD. This potential is held by the capacitor C. Thereafter, the signal φVRS2 is set to low level, and the transistor T6 is turned off. In such a state, when light enters the photodiode PD, a photocurrent is generated. At this time, since a capacitor is formed between the back gate and the gate of the transistor T1 and the junction capacitance of the photodiode PD, a charge due to photocurrent is accumulated in the gate and the drain of the transistor T1. Therefore, the gate voltage of the transistors T1 and T2 becomes a value proportional to the value obtained by integrating the photocurrent.

Since the potential of the connection node a is lower than the DC voltage VPD, the transistor T2 is turned on, and a drain current corresponding to the gate voltage of the transistor T2 flows through the transistor T2. Electric charges are stored in the capacitor C. Therefore, the potential of the connection node a becomes a value proportional to the value obtained by integrating the photocurrent. Next, when a pulse signal is applied to the gate of the transistor T4 to turn on the transistor T4, a current proportional to the voltage applied to the gate of the transistor T5 is led out to the output signal line 53 through the transistors T4 and T5.
Since the voltage applied to the gate of the transistor T5 is the voltage of the connection node a, the current led out to the output signal line 53 is a value obtained by linearly converting the integrated value of the photocurrent.

In this way, a signal (output current) proportional to the amount of incident light can be read. After reading the signal, first, the transistor T4 is turned off,
By applying a high-level signal φVRS to the gate of the transistor T3, the transistor T3 is turned on, and the photodiode PD, the drain voltage of the transistor T1, and the gate voltages of the transistors T1 and T2 are initialized. Next, a high-level signal φVRS2 is applied to the gate of the transistor T6 to turn on the transistor T6 and initialize the potentials of the capacitor C and the connection node a.

The signal reading from each pixel may be performed using a charge-coupled device (CCD).
In this case, the charge can be read out to the CCD by providing a potential barrier having a variable potential level corresponding to the transistor T4 in FIG. 4 or FIG.

By the way, the area sensor having the configuration as shown in FIG. 3 provided with the pixels as shown in FIG. 4 or the area sensor having the configuration as shown in FIG. The operation of the solid-state imaging device 1 at the time of the occurrence will be described below with reference to FIGS. 1, 2, 8, and 9. FIGS. 8 and 9 are flowcharts showing the flow of processing performed by the CPU 19 of the solid-state imaging device 1. First, when the power switch 22 is operated by the photographer and the power of the solid-state imaging device 1 is turned on, the CPU 19 is activated and the internal R
Initialize AM. Further, the data in the image memory 16 and the RAM 21 in the solid-state imaging device 1 are initialized, and the image processing unit 15 and the like are set to the initial state (step 1). At this time, the area sensor 10 is set to perform a logarithmic conversion operation. Then, an internal timer (not shown) provided in the CPU 19 starts counting (step 2).

While the internal timer is operating as described above, first, it is determined whether or not the shutter button 4, the mode changeover switch 5, the zoom key 6, and the output changeover key 7, which are operation units, are operated by the photographer. The detection is performed by the CPU 19 (step 3). When the zoom key 6 of these operation units is operated, the zoom lens optical system 2 is continuously driven by the optical system driving unit 12 in accordance with the operation of the photographer, and the magnification of the zoom lens optical system 2 is increased. The zoom up or zoom down is performed by changing (step 4). At this time, based on the distance information to the subject measured by the distance measuring unit 3, the optical system driving unit 1
2 automatically focuses the optical system.

When the magnification of the zoom lens optical system 2 is changed as described above, the switching process between the logarithmic conversion operation and the linear conversion operation of the area sensor 10 is performed as in step S5. This switching process will be described with reference to the flowchart of FIG.
First, in step 20, it is determined whether or not the output switching key 7 has been operated. When it is detected in step 3 (FIG. 8) that the output switching key 7 has been operated (YES), the process proceeds to step 26, and when not detected, NO) Go to step 21. In step 21, it is determined whether or not the zoom key 6 has been operated, and when it is detected in step 3 (FIG. 8) that the zoom key 6 has been operated (YES), the process proceeds to step 22.

In step 22, the position detector 14 detects the zoom position of the zoom lens optical system 2. If the zoom position is on the telephoto side, the zoom position is wider than a predetermined position (threshold). It is determined whether the camera has moved to the telephoto side from the position (threshold). At this time, when it is determined that each of the zoom positions has moved beyond the predetermined threshold value (YES), the process proceeds to step S23. The determination of the zoom position can be performed by detecting the focal length of the zoom lens from the lens position, the number of rotations of the lens barrel, and the like when performing optical zooming. Further, the magnification intended by the operator indicated by the zoom key 6 may be electrically detected to determine the zoom position. In the latter case, it is also useful when electrically changing the magnification.

In step 23, the mode switch 5
It is determined whether or not the auto mode has been selected, and if the mode is the auto mode (YES), the process proceeds to step S24. When the process proceeds to step 24 in this manner,
When the output switch key 7 is operated, the area sensor 10
It is detected whether or not the operation has already been changed to the conversion operation to be changed, and it is determined whether or not a switching operation is necessary. At this time, if the operation of switching the operation state of the area sensor 10 is necessary (YES), the process proceeds to step 25, where a switching command is given to the switching signal generation circuit 11 to switch the conversion operation of the area sensor 10. CPU 19 instructs to generate a switching signal.

When the process proceeds from step 20 to step 26, the CPU 19 instructs the switching signal generation circuit 11 to forcibly issue a switching command to generate a switching signal for switching the conversion operation of the area sensor 10. I do.
It should be noted that if NO in steps 21 to 25, the process directly proceeds to step 6 in FIG. Step 25,
When the switching command is issued in step 26 and the conversion operation of the area sensor 10 is switched, the process also proceeds to step 6 in FIG.

In step 6, the converted electric signal is processed by the image processing device 15 by the conversion operation of the area sensor 10 determined through the switching process in step 5, and then, based on the processed electric signal. The screen controller 17 performs a process of displaying an image on the display screen 8.
Then, in step 7, when the operation of the shutter button 4 is detected in step 3, the image data is recorded on the recording medium by the recording unit 18 and the imaging process is performed. Finally, it is determined in step 8 whether or not the internal timer has expired. If it is confirmed that the internal timer has expired, the process shifts to step 3 and the same processing as described above is repeated. This process described above is repeated until the power switch 22 is turned off.

The operation of the solid-state imaging device 1 that performs the operation as shown in the flowcharts of FIGS. 8 and 9 will be described below. Now, when the power switch 22 is operated by the photographer to turn on the solid-state imaging device 1, the components are initialized as described above, and the area sensor 10 is set to perform a logarithmic conversion operation. Therefore, on the display screen 8, an image based on the electrical signal logarithmically converted by the area sensor 10 is displayed. Thereafter, the process shown in FIG. 8 is repeated at predetermined time intervals.

When the photographer operates the zoom key 6 to zoom up the object, the position detector 14 determines whether or not the zoom position has moved from the predetermined position to the telephoto side.
When the mode switch 5 has been moved to the telephoto side from the predetermined position and the mode switch 5 is set to the auto mode, the switching signal generation circuit 11 switches the area sensor 10 to perform a linear conversion operation. A signal is sent to the area sensor 10. Incidentally, when the mode changeover switch 5 is selected in the manual mode, this is detected in step 23 (FIG. 9), and the conversion operation of the area sensor 10 remains the logarithmic conversion operation.

As described above, when the area sensor 10 is switched to perform the linear operation, an image based on the electric signal linearly converted by the area sensor 10 is displayed on the display screen 8. Thereafter, when the shutter button 4 is operated by the photographer, the fact is detected in step 3 (FIG. 8), and then the imaging process is performed in step 7 (FIG. 8).

After the image is projected by the electric signal that has been linearly converted by zooming up, when the photographer operates the output switching key 7 to check the image based on the electric signal that has been logarithmically converted by the area sensor 10, After the fact is detected in step 3, the area sensor 10 is switched to perform a logarithmic conversion operation in steps 20 (FIG. 9) and 26 (FIG. 9). After the photographer confirms the image based on the electric signal that is logarithmically converted by the area sensor 10 as described above, when the shutter button 4 is operated, the fact is detected in step 3, and the imaging process is performed in step 7. Is performed.

Further, after the output switch key 7 is operated to force the area sensor 10 to perform a logarithmic conversion operation, when the photographer operates the zoom key 6 again to zoom down,
Whether or not the zoom position has moved to the wide angle side from the predetermined position is determined from information from the position detector 14. Here, if the zoom position moves to the wide angle side from the predetermined position,
It is determined that the conversion operation of the area sensor 10 is a logarithmic conversion operation. However, since the area switch 10 is still being switched to the logarithmic conversion operation by the output switch key 7, it is determined in step 24 (FIG. 9) that switching is not necessary. Therefore, the switching signal is not sent from the switching signal generation circuit 11 to the area sensor 10.

After zooming up and causing the area sensor 10 to perform a linear conversion operation, zooming down and moving the zoom position from the predetermined position to the wide angle side, step 2
2, the conversion operation of the area sensor 10 is switched to a logarithmic conversion operation. However, if the mode changeover switch 5 has been selected in the manual mode, this is detected in step 23, and the linear conversion operation remains. After the conversion operation of the area sensor 10 is converted into a logarithmic conversion operation, when the output switching key 7 is operated, the conversion operation of the area sensor 10 is forcibly switched to a linear conversion operation. At this time, when the zoom-up is performed again and the zoom position is moved to the telephoto side from the predetermined position, it is determined that switching is not necessary in step 24, so that the conversion operation of the area sensor 10 is not switched.

As described above, when the mode changeover switch 5 is set to the auto mode, when the zoom-up operation is performed and the zoom position moves to the telephoto side from the predetermined position, the conversion operation of the area sensor 10 is changed to a linear conversion operation. When the zoom position is shifted to the wide angle side from the predetermined position by zooming down, the conversion operation of the area sensor 10 is changed to a logarithmic conversion operation. When the mode changeover switch 5 is set to the manual mode, the conversion operation of the area sensor 10 is switched by operating the output changeover key 7. Further, even when the mode changeover switch 5 is set to the auto mode, the conversion operation of the area sensor 10 is forcibly switched by operating the output changeover key 7.

<Second Embodiment> FIG. 10 is a block diagram showing the internal configuration of a solid-state imaging device used in a second embodiment of the present invention. Parts used for the same purpose as in the solid-state imaging device 1 shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The solid-state imaging device 1 'shown in FIG.
A switching judgment circuit for judging whether to switch the conversion operation of the area sensor based on a signal sent from the switching circuit, and a switching signal for switching the conversion operation of the area sensor based on the judgment signal sent from the switching judgment circuit. It is generated from the switching signal generation circuit 11.

The operation of such a solid-state imaging device 1 'is basically the same as the operation of the solid-state imaging device 1 in the first embodiment. However, in the present embodiment, the determination in step 22 in FIG. 9 is based on the zoom position in the first embodiment.
And ). That is, the imaging range is calculated by the CPU 19 using the focus signal indicating the distance to the subject detected by the distance measuring unit 3 and the zoom signal indicating the magnification of the image transmitted from the operated zoom key 6. Then, the switching determination circuit 23 determines that the imaging range is wider than this reference value (threshold) as compared with a reference for switching the conversion operation of the area sensor 10 (for example, an imaging range of 3 m in length × 4 m in width). In this case, the area sensor 10 is caused to perform a logarithmic conversion operation, and when the switching determination circuit 23 determines that the width is smaller than the reference value (threshold), the area sensor 10 is caused to perform a linear conversion operation. Other processing operations are the same as the processing operations shown in the flowcharts of FIGS. Note that the switching process in step 5 (FIG. 8) is performed by the switching determination circuit 23.

When the solid-state imaging device 1 'performing such an operation is used in the auto mode by the mode changeover switch 5, when the magnification is increased by zooming in on a distant subject, for example, FIG. When the imaging range is 2 m × 1.5 m and becomes smaller than the reference value 4 m × 3 m, the conversion operation of the area sensor 10 is changed to a linear conversion operation. Similarly, when a subject at a short distance is imaged, the imaging range may be narrower than the reference value of 4 m × 3 m as shown in FIG. 11B, for example, even if the magnification is low. When the imaging range becomes narrow, the area sensor 1
The conversion operation of 0 is changed to a linear conversion operation. Further, when the magnification is reduced by zooming down toward a distant subject, for example, as shown in FIG.
When it is 25 m and becomes wider than the reference value 4 m × 3 m, the conversion operation of the area sensor 10 is changed to a logarithmic conversion operation.

As described above, in the auto mode, even if the magnification and the distance to the subject are different, the area sensor 10 can perform the linear conversion operation if the imaging range becomes narrower than the reference value. When the distance to the subject is long and the magnification is low, the area sensor 10 can perform the logarithmic conversion operation if the imaging range is wider than the reference value. Furthermore,
As in the first embodiment, when the manual mode is selected by the mode changeover switch 5, the conversion operation of the area sensor 10 is switched by the output changeover key 7. Even in the auto mode, the conversion operation of the area sensor 10 can be forcibly switched by operating the output switching key 7.

In the first and second embodiments, a solid-state imaging device having a zoom lens optical system whose imaging magnification changes continuously has been described. However, the present invention is not limited to this. It may have a multifocal optical system in which a plurality of optical systems having different focal points can be switched. In this case, there are advantages that the configuration is simplified as compared with the zoom lens optical system, and that a desired imaging magnification can be easily selected.

In the first and second embodiments, the area sensor having the configuration shown in FIG. 3 has been described using the pixels having the circuit configuration shown in FIG. Alternatively, for example, a pixel having a circuit configuration as shown in FIG. 12 or FIG. 13 may be used. Here, the configuration of the pixel in FIG. 12 is described below. Note that elements and signal lines used for the same purpose as the pixel shown in FIG.
The same reference numerals are given and the detailed description is omitted.

In the pixel shown in FIG. 12, unlike the pixel shown in FIG. 4, the source and the gate of the transistor T1 are connected without connecting the drain and the gate. First,
The operation of the pixel when the photocurrent is logarithmically converted and output will be described. By increasing the voltage difference between the source and the drain of the transistor T1, the voltage generated between the gate and the source is made smaller than the threshold voltage. In this manner, the same state as when the transistor T1 is biased to operate in the sub-threshold region is obtained. Therefore, the photocurrent generated from the photodiode PD can be logarithmically converted and output.

Next, the operation of the pixel when the photocurrent is linearly converted and output will be described. At this time, the signal φVPS applied to the source of the transistor T1 is changed to the DC voltage VPD
By making the potential slightly lower, the transistor T
1 is substantially in a cutoff state. Therefore, no current flows between the source and the drain of the transistor T1. The subsequent operation is the same as that of the pixel shown in FIG.

Next, the configuration of the pixel shown in FIG. 13 will be described below. Elements and signal lines used for the same purpose as the pixel shown in FIG. 12 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the pixel shown in FIG. 13, the transistor T1
Is applied with the DC voltage VRG. The other circuit configuration is the same as the circuit configuration in the pixel shown in FIG. When a pixel having such a configuration is used, its operation is essentially the same as that of the pixel shown in FIG. However, unlike the pixel of FIG. 12, the gate voltage of the transistor T1 can be set to an appropriate voltage. Therefore, when performing the logarithmic conversion operation, it is not necessary to set φVPS to a sufficiently low voltage as in the pixel of FIG. By setting the voltage to a certain low level, the same state as when the transistor T1 is biased in the sub-threshold region can be obtained. When the linear conversion operation is performed, the operation is the same as that of the pixel in FIG.

In the present embodiment, the area sensor having the configuration shown in FIG. 5 has been described using the pixels having the circuit configuration shown in FIG. 7. However, in addition to the pixels having the circuit configuration shown in FIG.
For example, a pixel having a circuit configuration as shown in FIG. 14 or FIG. 15 may be used. Here, the configuration of the pixel in FIG. 14 is described below. Elements and signal lines used for the same purpose as the pixel shown in FIG. 7 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the pixel shown in FIG. 14, unlike the pixel shown in FIG. 7, the source and the gate of the transistor T1 are connected without connecting the drain and the gate. First,
The operation of the pixel when the photocurrent is logarithmically converted and output will be described. By increasing the voltage difference between the source and the drain of the transistor T1, the voltage generated between the gate and the source is made smaller than the threshold voltage. In this manner, the same state as when the transistor T1 is biased to operate in the sub-threshold region is obtained. Therefore, the photocurrent generated from the photodiode PD can be logarithmically converted and output.

Next, the operation of the pixel when the photocurrent is linearly converted and output will be described. At this time, the signal φVPS applied to the source of the transistor T1 is changed to the DC voltage VPD
By making the potential slightly lower, the transistor T
1 is substantially in a cutoff state. Therefore, no current flows between the source and the drain of the transistor T1. The subsequent operation is the same as that of the pixel shown in FIG.

Next, the configuration of the pixel shown in FIG. 15 will be described below. Elements and signal lines used for the same purpose as the pixel shown in FIG. 14 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the pixel shown in FIG. 15, the transistor T1
Is applied with the DC voltage VRG. Other circuit configurations are the same as those in the pixel shown in FIG. When a pixel having such a configuration is used, its operation is essentially the same as that of the pixel shown in FIG. However, unlike the pixel of FIG. 14, the gate voltage of the transistor T1 can be set to an appropriate voltage. Therefore, when performing the logarithmic conversion operation, it is not necessary to set φVPS to a sufficiently low voltage as in the pixel of FIG. By setting the voltage to a certain low level, the same state as when the transistor T1 is biased in the sub-threshold region can be obtained. When the linear conversion operation is performed, the operation is the same as that of the pixel in FIG.

Further, the pixels used in the present invention need only be capable of performing a logarithmic conversion operation and a linear conversion operation with one pixel. For example, FIG. 4, FIG. 7, FIG. 12, FIG. Alternatively, a pixel having a circuit configuration in which the capacitor of the pixel in FIG. 15 is omitted may be used. Further, as long as the pixel can switch between the logarithmic conversion operation and the linear conversion operation, the circuit configuration is not limited to these circuit configurations.

Although the area sensor has been described using the area sensor having the structure as shown in FIG. 3 or FIG. 5, it is not limited to the area sensor having such a structure.
For example, an area sensor having another configuration in which the MOS transistor provided in the area sensor is a P-channel MOS transistor may be used.

[0092]

As described above, according to the present invention,
The operation state of the solid-state imaging device is switched according to imaging conditions such as a distance to a subject, an imaging magnification, a focal length of an optical system, and an imaging range. Therefore, good imaging can be performed for various subjects. For example, the operation state of the solid-state imaging device is switched according to whether the optical system forms an image on the telephoto side or forms an image on the wide-angle side. Thus, when the optical system is on the wide-angle side, the solid-state image sensor performs a logarithmic conversion operation so that an image in a wide luminance range can be captured, and when the optical system is on the telephoto side, it can capture images with good gradation. The solid-state imaging device can perform a linear conversion operation. In addition, by switching the operation state of the solid-state imaging device according to the imaging range, the imaging range is such that the distance of the imaging target is long and the optical system is on the telephoto side or when the distance of the imaging target is short. Is small, the solid-state imaging device performs a linear conversion operation so that the image can be captured with good gradation, and when the distance of the object to be imaged is long and the imaging range is wide such as when the optical system is on the wide angle side, In addition, the solid-state imaging device can perform a logarithmic conversion operation so that an image in a wide luminance range can be captured.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a solid-state imaging device according to a first embodiment.

FIG. 2 is a block diagram showing the internal structure of the solid-state imaging device according to the first embodiment.

FIG. 3 is an example of an internal structure of an area sensor used in the solid-state imaging device of the present invention.

FIG. 4 is an example of a circuit configuration of a pixel provided in the area sensor shown in FIG. 3;

FIG. 5 is an example of an internal structure of an area sensor used in the solid-state imaging device of the present invention.

FIG. 6 is a partial circuit diagram of FIG. 5;

FIG. 7 illustrates an example of a circuit configuration of a pixel provided in the area sensor illustrated in FIG.

FIG. 8 is a flowchart showing the operation of the solid-state imaging device of the present invention.

FIG. 9 is a flowchart showing a switching process of the flowchart of FIG. 8;

FIG. 10 is a block diagram showing the internal structure of the solid-state imaging device according to the second embodiment.

FIG. 11 is a diagram illustrating a range imaged by the solid-state imaging device in FIG. 10;

12 illustrates an example of a circuit configuration of a pixel provided in the area sensor illustrated in FIG.

13 illustrates an example of a circuit configuration of a pixel provided in the area sensor illustrated in FIG.

14 illustrates an example of a circuit configuration of a pixel provided in the area sensor illustrated in FIG.

15 illustrates an example of a circuit configuration of a pixel provided in the area sensor illustrated in FIG.

FIG. 16 shows output characteristics of a LOG sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solid-state imaging device 2 Zoom lens optical system 3 Distance measuring unit 4 Shutter button 5 Mode switching switch 6 Zoom key 7 Output switching key 8 Display screen 10 Area sensor (solid-state imaging device) 11 Switching signal generation circuit 12 Optical system driving unit 14 Position detection Device 15 image processing unit 16 image memory 17 screen control unit 18 recording unit 19 central processing unit (CPU) 20 ROM 21 RAM 22 switching signal determination circuit 50 vertical scanning circuit 51 horizontal scanning circuit 52-1 to 52-n line 53-1 -53-m Output signal line 54 Power supply line 55 Signal line G11-Gmn Pixel T1-T6 N-channel MOS transistor PD Photodiode C Capacitor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4M118 AA02 AA10 AB01 BA14 CA02 DD09 FA06 5C024 AA01 CA15 CA21 EA04 FA01 GA01 GA31 HA10 JA04

Claims (21)

[Claims] 1. A solid-state imaging device having a solid-state imaging device that generates an electric signal in accordance with an incident light amount, wherein an operation state of the solid-state imaging device is output by converting the electric signal linearly with respect to the incident light amount. A first state to be performed;
An operation state of the solid-state imaging device based on at least one imaging condition selected from a group consisting of a distance to an object and an imaging magnification, while being switchable to a second state in which the logarithmic conversion is performed and output. A solid-state imaging device characterized by switching. 2. A solid-state imaging device comprising: a solid-state imaging device that generates an electric signal according to an incident light amount; and an optical system with a variable focal length. A first state that is linearly transformed and output for the first state;
A solid-state imaging device capable of switching to a second state in which the logarithmic conversion is performed and output, and switching an operation state of the solid-state imaging element based on a focal length of the optical system. 3. A solid-state imaging device comprising: a solid-state imaging device that generates an electric signal according to an amount of incident light; and an optical system that can switch an object between a wide-angle side and a telephoto side to form an image. An operating state, a first state in which the electric signal is linearly converted with respect to an incident light amount and output;
The state can be switched to a second state in which the logarithmically converted and output is performed, and the operation of the solid-state imaging device is performed according to whether the optical system forms an image on a telephoto side or a wide-angle side. A solid-state imaging device characterized by switching states. 4. When the optical system forms an image of a subject on the telephoto side, the operation state of the solid-state imaging device is set to a first state. When the optical system forms an image of the subject on a wide-angle side, the solid-state imaging device is used. 4. The solid-state imaging device according to claim 3, wherein the operation state is set to a second state. 5. A switching signal generation circuit for generating a switching signal for switching an operation state of the solid-state imaging device in response to an imaging state of a subject in the optical system. The solid-state imaging device according to claim 4. 6. The solid-state imaging device according to claim 5, wherein the switching signal is a binary voltage signal. 7. The optical system according to claim 3, wherein the optical system continuously changes between a wide-angle side and a telephoto side.
The solid-state imaging device according to claim 6. 8. The solid-state imaging device according to claim 3, wherein said optical system is a multifocal optical system capable of switching a plurality of optical systems having different focal points from each other. . 9. A solid-state imaging device comprising: a solid-state imaging device that generates an electric signal according to the amount of incident light; and an optical system that can switch an object between a wide-angle side and a telephoto side to form an image. An operating state, a first state in which the electric signal is linearly converted with respect to an incident light amount and output;
A solid-state imaging device capable of switching to a second state in which the logarithmic conversion is performed and output, and switching an operation state of the solid-state imaging element according to a range in which the solid-state imaging element captures an image. 10. The operating state of the solid-state imaging device is set to a first state when the range in which the solid-state imaging device captures an image is narrow, and the operating state of the solid-state imaging device is changed when the range in which the solid-state imaging device captures an image is wide. The solid-state imaging device according to claim 9, wherein the solid-state imaging device is in a second state. 11. A switching signal generating circuit for generating a switching signal for switching an operation state of the solid-state imaging device in accordance with a range in which the solid-state imaging device captures an image. 3. The solid-state imaging device according to item 1. 12. The solid-state imaging device according to claim 11, wherein the switching signal is a binary voltage signal. 13. The solid-state imaging device according to claim 9, wherein said optical system is an optical system that continuously changes between a wide-angle side and a telephoto side. 14. The solid-state imaging device according to claim 9, wherein said optical system is a multifocal optical system capable of switching a plurality of optical systems having different focal points. . 15. A device for measuring a distance to a subject, wherein the range to be imaged is calculated based on the distance to the subject measured by the means and a magnification of the optical system. The solid-state imaging device according to claim 9. 16. The solid-state imaging device, comprising: a photosensitive element having a first electrode to which a DC voltage is applied; a first electrode, a second electrode, and a control electrode, wherein the first electrode and the control electrode are the photosensitive element. A transistor connected to a second electrode, into which an output current from the photosensitive element flows, and by changing a potential difference between a first electrode and a second electrode of the transistor, the operation of the solid-state imaging device is First
The solid-state imaging device according to claim 1, wherein the state is switched between a state and a second state. 17. The solid-state imaging device includes: a photosensitive element having a first electrode to which a DC voltage is applied; a first electrode, a second electrode, and a control electrode, wherein the first electrode is a second electrode of the photosensitive element. And a transistor to which an output current from the photosensitive element flows and to which a second electrode and a control electrode are connected, and changes a potential difference between a first electrode and a second electrode of the transistor. Thus, the operation of the solid-state imaging device
The solid-state imaging device according to claim 1, wherein the state is switched between a state and a second state. 18. The solid-state imaging device comprises: a photosensitive element having a first electrode to which a DC voltage is applied; a first electrode, a second electrode, and a control electrode, wherein the DC voltage is applied to the control electrode; A first electrode connected to a second electrode of the photosensitive element, and a transistor into which an output current from the photosensitive element flows, by changing a potential difference between the first electrode and the second electrode of the transistor. The operation of the solid-state imaging device
The solid-state imaging device according to claim 1, wherein the state is switched between a state and a second state. 19. A semiconductor device comprising: a first mode for automatically switching the operation state of the solid-state imaging device; and a second mode for inhibiting automatic switching of the operation state of the solid-state imaging device. The solid-state imaging device according to claim 1. 20. A switch device for manually switching an operation state of the solid-state imaging device, wherein the operation state of the solid-state imaging device is switched by the switch device when the solid-state imaging device is in a second mode. The solid-state imaging device according to claim 19, wherein 21. The solid-state imaging device according to claim 20, wherein said switch means is a switch means capable of forcibly switching an operation state of said solid-state imaging device even in a first mode.