JPH0449312B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid-state imaging device that includes a light receiving section made up of a plurality of photoelectric conversion elements and a shift register coupled to each of these photoelectric conversion elements.

A general solid-state imaging device consists of a sister register coupled to a light receiving part, and a one-dimensional imaging device is a dual-channel type in which multiple photoelectric conversion elements arranged in a line are distributed and coupled to two shift registers. There is something.

FIG. 1 schematically shows such a dual channel type conventional solid-state imaging device. In the figure, reference numeral 1 denotes a light receiving section that senses incident light and generates a charge according to the amount of light, and has, for example, 2048 photoelectric conversion elements arranged in a line. Reference numeral 2 designates a first shift register in which odd-numbered elements of the light receiving section 1 are coupled to each bit, and has 1k bits (1024), and electrode pair a to which two-phase clock pulses φa and φb are respectively applied for each bit. , b is a CCD (charge coupled device) type shift register. 3 is a CCD type shift register similar to the first shift register 2, but the even numbered elements of the light receiving section 1 are coupled to each bit. Reference numerals 4 and 4 designate transfer gate sections provided between the first row of light receiving sections and both shift registers 2 and 3, and the charges generated in the light receiving section 1 according to the amount of irradiation light are transferred to the first shift register 2. Alternatively, it has a gate electrode to which a gate signal Vg to be introduced into the second shift register 3 is applied.

The solid-state imaging device having such a configuration performs photoelectric conversion using 2048 photoelectric conversion elements arranged in a row in the light receiving section 1, and applies a gate signal Vg to the transfer gate sections 4, 4 to convert odd numbers. Charges, such as electrons, generated in the photoelectric conversion element of the photoelectric conversion element 3 are guided to the electrode a position of each bit of the first shift register 2, while electrons generated in the even numbered elements are guided to the position of the electrode a of each bit of the second shift register 3. is guided to the electrode b position.

In each of the shift registers 2 and 3 to which the charges from the light receiving section 1 are guided in this manner, a clock pulse φa is applied to the electrode a, and a clock pulse φb is applied to the electrode b, thereby sequentially transferring these charges. One-dimensional analog image signals are alternately output from the terminal ends of each shift register 2, 3 as an output signal Vout.

In such a solid-state imaging device, in order to accurately obtain an analog image signal Vout corresponding to the amount of light incident on each photoelectric conversion element of the light receiving section 1, the relationship between the amount of incident light and the voltage value of the image signal Vout must be determined. It is necessary that the relationship be linear, and it is necessary to set an optimal range of incident light amount in which this relationship is linear. For this reason, conventionally it was necessary to change the light intensity of the incident light and read the voltage value of the image signal Vout many times at that time.
This reduced the efficiency of this work.

The present invention has been made in view of these points,
An object of the present invention is to provide a solid-state imaging device with an added function that allows easy determination of the range of the optimum amount of incident light to a light receiving section.

FIG. 2 schematically shows an embodiment of the solid-state imaging device of the present invention. In the figure, A is an imaging section having the same configuration as the conventional device shown in FIG.
It is made up of. 1' is an attached light receiving section extending from the terminal end of the light receiving section 1, and for example, its opening area is 0%, 20%, 40% from the terminal end of the light receiving section 1.
Each attached photoelectric conversion element 11, 12, 13, 14, 15, 1 arranged in the order of %, 60%, 80%, 100%
It consists of 6. Incidentally, these photoelectric conversion elements 1
1, . . . , 16 are constructed in the same shape as the photoelectric conversion elements constituting the light receiving section 1 of the imaging section A, and these light receiving surfaces are partially coated with aluminum by vapor deposition. A portion of the opening is shielded from light, and the opening area is formed at a predetermined ratio. 2' is a first attached shift register of 3 bits extending from the last bit of the first shift register 2, and 3' is a second attached shift register of 3 bits extending from the last bit of the second shift register 3. It is an attached shift register. Each bit of these first and second attached shift registers 2' and 3' is connected to an electrode pair a to which two-phase clock pulses φa and φb are applied, respectively, similarly to the first and second shift registers 2 and 3. , b. Reference numerals 4' and 4' denote attached transfer gate sections having gate electrodes extending from the transfer gate sections 4 and 4 of the imaging section A, and the attached light receiving section 1' and both the first and second attached shift registers 2'. , 3'.

In the solid-state imaging device of the present invention having such a configuration, when determining the optimum amount of incident light, an attachment consisting of six photoelectric conversion elements 11, . Light whose amount is measured is incident on the light receiving section 1'. Then, immediately apply the gate signal Vg to the gate electrodes of the transfer gates 4, 4 and the attached transfer gate parts 4', 4',
driving the first and second shift registers 1, 2 as well as the first and second attached shift registers 1', 2' by the clock pulses φa, φb; ′ is obtained from the last bit of . The output signal Vout becomes the optimum incident light amount detection signal.

This detection signal is divided into three cases and shown in Figure 3.
They are shown in Vout1, Vout2, and Vout3, respectively. In these detection signals Vout, 1, 2, and 3, () is the output voltage obtained by the photoelectric conversion element 16 with an aperture area of 100%, that is, the photoelectric conversion element equivalent to that of the imaging section A, and () is a photoelectric conversion element 15 with an aperture area of 80%
Similarly, (), (), (),
() is the output voltage obtained by each photoelectric conversion element 14, 13, 12, 11 with an aperture area of 60%, 40%, 20%, and 0%, respectively.

Then, the output voltage in the time domain after this depends on the photoelectric conversion element of the imaging section A, and shows the same constant value as the above output voltage ( ).

Now, if a detection signal such as Vout1 is obtained, the output voltages () and () are equal, that is, the amount of light that is 20% of the amount of incident light at this time is at the dark current signal level. It can be seen that 20% or more of the incident light amount at this time is the lower limit of the optimal light amount.

Also, if a detection signal such as Vout2 is obtained, each output voltage (), ..., () increases proportionally in this order, so 20 of the amount of incident light at this time
It can be seen that the amount of light falls within the optimum light amount range from % to 100%. Furthermore, if a detection signal such as Vout3 is obtained, since the output voltages () and () are almost similar, that is, 80% of the amount of incident light at this time is at the saturation level, so the input voltage at this time It can be seen that 80% of the light amount is the upper limit of the optimal light amount.

In the above explanation, six attached photoelectric conversion elements 11, . A detection signal as shown is obtained, and its dark current level V _L and its saturation level V _H are obtained at the same time, and its linear region, that is, the range of the optimum amount of incident light can be detected in more detail.

In the embodiment of the device of the present invention as described above, when performing imaging, the time domain of the output signal due to the attached photoelectric conversion elements 11, . . . 16 is ignored among the pulse-like output voltage of the output signal. This allows it to perform the same imaging function as conventional devices. Further, even when detecting the range of the optimum amount of incident light, no new external terminal, output terminal, etc. are required for this purpose.

Furthermore, even if the first and second attached shift registers 2' and 3' in the embodiment of the apparatus of the present invention described above are configured separately from the image pickup section A together with the attached light receiving section 1',
As in the above-described embodiment, the range of the optimum amount of incident light can be detected. However, in this case, it is necessary to provide new external terminals and output terminals to drive the attached shift registers 2', 3' and attached gate sections 4, 4, but when performing imaging, only the imaging section A is required. is driven, so that an output signal Vout consisting only of an image signal can be obtained, similar to the conventional device.

Note that the solid-state imaging device of the present invention is not limited to the one-dimensional device described above, but can also be easily applied to a two-dimensional device.

As is clear from the above description, the solid-state imaging device of the present invention has a light-receiving section having a plurality of photoelectric conversion elements each having a constant light-receiving area;
Since an appropriate number of attached photoelectric conversion elements each having a different aperture area are added, by simply inputting a constant amount of light into the entire device, each output voltage due to the appropriate number of attached photoelectric conversion elements can be changed once. The dark current level and the saturation level can be measured depending on the relative changes in these output voltage values. Therefore, the range of the optimum amount of incident light can be easily derived, and the work for detecting the optimum amount of incident light can be greatly simplified.

Further, since the attached shift register associated with the attached photoelectric conversion element is integrally connected to the shift register associated with the photoelectric conversion element, the attached shift register can be driven together with the shift register, The solid-state imaging device according to the present invention can be configured without adding new external terminals or the like.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of a conventional solid-state imaging device, FIG. 2 is a schematic plan view of a solid-state imaging device of the present invention, and FIG.
4 and 4 respectively show output signal waveform diagrams obtained from the apparatus of the present invention. 1... Light receiving section, 1'... Attached light receiving section, 2, 3...
...Shift register, 2', 3'... Attached shift register, 4... Transfer gate section, 4'... Attached transfer gate section, 11, 12, 13, 14, 15, 16...
...attached photoelectric conversion element.

Claims (1)

[Scope of Claims] 1. A solid-state imaging device comprising a light receiving section in which a plurality of photoelectric conversion elements having a constant light receiving area are arranged, and a multi-bit shift register to which each of the photoelectric conversion elements of the light receiving section is respectively associated. In the device, an attached light receiving section is provided separately from the light receiving section and has an array of an appropriate number of photoelectric conversion elements having the same light receiving area as the photoelectric conversion elements of the light receiving section, and a photoelectric conversion element of the attached light receiving section. attached shift registers each associated with the
The photoelectric conversion element of the attached light receiving section is a first element that is completely shielded from light and obtains an output at a lower limit level;
Consisting of a second element that is fully apertured to obtain an output at an upper limit level, and a third element that is shaded stepwise at different ratios and whose output is compared with that of the first or second element, the lower limit level of the optimum amount of incident light is achieved. and an upper limit level. 2. Claim 1, wherein the attached light-receiving section is provided continuously to a photoelectric conversion element of the light-receiving section, and the attached shift register associated with the photoelectric conversion element and the shift register are integrally connected. The solid-state imaging device described.