JPH04172780A - Image pickup device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an imaging device.

2. Description of the Related Art In recent years, efforts have been made to improve the image quality of imaging devices. An example of a conventional imaging device will be shown below with reference to FIG.

FIG. 3 schematically shows a conventional imaging device. In FIG. 3, 10 is a lens, 11 is an imaging unit that converts the optical information of the subject focused by the lens 10 into an electrical signal, and 12 is a unit that converts the subject signal converted into an electrical signal by the imaging unit 11 into a TV signal. A signal processing section, 13 is an imaging drive section that drives the imaging section 11, and 14 is a signal processing section 12. This is a synchronization generation section that generates a synchronization signal that serves as a reference for the operation of the imaging drive section 13.

The operation of the imaging device having the above configuration will be described in detail below.

FIG. 4 shows the structure of a CCD image sensor, which is a typical image sensor. 100A in Figure 4.

100B is a photoelectric conversion unit that converts optical information into an electrical signal and stores it by a photoelectric conversion action, and 101 is a photoelectric conversion unit 100A.
, 100B is a vertical transfer section that reads out the signal charge accumulated in 100B and transfers it in the vertical direction.
105 are vertical transfer pulses φV+106. φV
2107. This is a unit register driven by φV3108° and φV4109.

110 is a horizontal transfer unit that horizontally transfers the signal charge sent from the vertical transfer unit IC) 1;
are unit registers driven by horizontal transfer pulses 113 and 114. 115 is a floating diffusion amplifier which is an output section of the CCD image sensor, and 116 is a signal output terminal.

The operation of the above-mentioned CCD image sensor will be described below. C.C.
There are two types of operation of the D image sensor: a field readout method and a frame readout method. First, we will explain the field readout method using Figures 5 and 6, and then we will explain the field readout method using Figures 5 and 6.
The frame readout method will be explained using figures.

In the field reading method, different reading methods are performed alternately for each field.

5 and 6 show the field readout type imaging drive signal of the CCD imaging device and the signal flow within one horizontal period of the vertical transfer stage indicated by the arrow in FIG. 4A at that time.

First, FIG. 5 shows the imaging drive signal and signal flow in the first field. The shaded area is the signal charge. In Fig. 5, 120 are photoelectric conversion units 100A and 100B.
A readout signal 121 is a horizontal synchronization pulse synchronized with the horizontal scanning period, and these are sent from the synchronization generation section 14 to the imaging drive section 13. When the read signal 120 becomes H (1=1+)φV+106
゜φV3108 applies read pulses 122 and 123 to the registers 102 and 104, and the photoelectric conversion units 100A and 1
Take out all the signal charges accumulated in 00B at once.

Next, φV+106. Transfer applied voltage to φV3108 124
, 125 and register 10 by φV2107.
A transfer applied voltage 126 is applied to the register 3 (t=t2), and the signal charges accumulated in the registers 102 and 104 are added. Subsequently, the transfer applied voltage 124 of the register 102 is released (t=t3), and then the register 105 is released by φV4109.
A transfer applied voltage 127 is applied to (1=1+) and the signal is shifted by the register. If we perform the same operation, t=t+o
At the point in time, one horizontal scanning line can be transferred from the point in time t=t2, and if the operation is continued, the horizontal transfer unit 1 can be transferred.
Signal charges can be sent to the register 111 of the horizontal transfer unit 110 from the side closer to 10 every horizontal period. The sent signal charges are transferred through the horizontal transfer section 110 by horizontal transfer pulses 113 and 114, and are outputted from the output terminal 116 through the floating diffusion amplifier 115. In this way, all the charges of the first field accumulated in the photoelectric conversion section 100 are output.
Next, the transfer of the second field signal will be explained using FIG. 6.

While performing the above transfer, charging conversion units 100A, 10
In 0B, object information for the second field period is converted into an electrical signal and stored. The reading and transfer of this signal is basically the same as the transfer of the first field signal, but the difference is that in the transfer of the first field signal, at t=t2, the registers 102 and 104 are The accumulated signal charge is transferred to the register 10 by φV 107.
3, whereas in the transfer of the second field signal, an applied voltage is applied to the register 105 by φV4109 and addition is performed.

The flow after that is the same. As described above, the signal charge of the second field is output.

The above-mentioned first field and second field are read out alternately (this method is called a field read method).

Next, a frame reading method will be described. FIG. 7 shows how signals are transferred in the line indicated by A in the vertical transfer section of FIG. 4 using the frame read method.

In Figure 7, 130 and 131 are respectively photoelectric conversion H100A
, 100B. First, when reading the signal of the first field, the read signal 130 is set to H, and (t=ta+)φV+106
A read pulse 132 is applied to the register 102, and the signal charges accumulated in the photoelectric conversion section 100A are taken out.

Next, while applying the transfer applied voltage 133 to the register 102 by φV+106, the register 10 is applied by φV2107.
A transfer applied voltage 134 is applied to the register 102 (t=ta2), and the signal charge accumulated in the register 102 is expanded by the register.

Subsequently, the transfer applied voltage 133 of the register 102 is released and the transfer applied voltage 135 is applied to the register 104 (t=t
a3) Shift the signal by the number of registers. Similar operations are repeated to send signal charges from the vertical transfer section 101 to the register 111 of the horizontal transfer section 110 every horizontal period.

The sent signal charges are transferred by a horizontal transfer section 110, passed through a floating diffusion amplifier 115, and outputted from eight terminals 116. This sent out photoelectric conversion unit 10
The 0A signal is treated as a first field signal.

Next, when reading out the signal of the second field, the readout signal 131 is set to H, and the readout pulse 136 is applied to the register 104 with t=tb+)φV3108, and the photoelectric conversion unit 1
Take out the signal charge accumulated in 00B. Next φV3
At step 108, the transfer applied voltage 137 is applied to the register 104, and at φV4109, the transfer applied voltage is applied to the register 105 (t=tb2), and the signal charges accumulated in the register 104 are expanded by the register. Thereafter, all the signal charges accumulated in the photoelectric conversion section 100B are outputted in the same manner as the first field signal transfer. This sent signal is the second
Treated as a field signal.

The above signal readout method is called a frame readout method.

Regardless of the field or frame readout method, the readout signal charge is converted by the signal processing section 12 into a form suitable for a TV signal and output. Problems to be Solved by the Invention The differences between the aforementioned field readout and frame readout methods are summarized as shown in FIG. That is, regarding the signal readout format, in the field readout method, signals from two photoelectric conversion units are mixed and read out, whereas in the frame readout method, signals from each photoelectric conversion unit are read out separately. Therefore, the frame readout method has an adiabatic advantage in terms of resolution in the vertical direction. On the other hand, regarding the accumulation time of the subject signal, in the field readout method, the signals of all pixels are read out for each field, so the accumulation time is 1 field - 1/60 sec, whereas in the frame readout method, each photoelectric conversion unit is To read out the signal, the storage time is 1 frame - 1
/ 30 sec.

This is because the frame readout method takes twice as long to accumulate compared to the field readout method, so afterimages tend to remain (and for fast-moving subjects, the image looks like a tail, making it very difficult to see). It shows the frame like this.

Each field reading method has advantages and disadvantages, and the reading method is fixed to one.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides an imaging apparatus that includes an imaging means that can switch between field readout scanning and frame readout scanning, and a motion detection means that detects movement of an image. The imaging means selects field readout scanning when the motion detection means determines that there is "image movement," and selects frame readout scanning when the motion detection means determines that "there is no image movement." We propose an imaging device that

Effect: With the above means, the field readout method is selected for a motionless subject, and the frame readout method is selected for a moving subject.

Embodiment FIG. 1(a) shows an example of an imaging apparatus of the present invention. In FIG. 1(a), 200 is a lens, 201 is an imaging section, 202 is a signal processing section, and 203 is an imaging drive section, inside which a frame readout drive section 204 and a field readout drive section 205 are present. 206 is a synchronization generation unit, 207 is a motion detection unit that detects the movement of a subject, 208 is a frame readout drive unit 204, and a field readout drive unit 20.
This is a switch for selecting a drive signal from 5.

FIG. 1(b) shows an outline of the motion detection section 207. 211 is a signal input terminal and corresponds to the terminal a of 207. 212 is an A/D conversion circuit that converts an analog signal into a digital signal, 213 is a field memory that stores a signal for one field period, and 214 is a directly input signal and field memory 213 that delay the signal for one field period. 215 is an absolute value circuit (hereinafter referred to as ABS circuit) that takes the absolute value of the signal; 216 is a low-pass filter circuit (hereinafter referred to as P, F circuit) that cuts the high frequency of the signal; 217 A comparison circuit (hereinafter referred to as a DET circuit) compares the signal output from the low-pass filter circuit 217 with an internal reference voltage, and 218 is a synchronization signal input terminal, which corresponds to the b terminal of 207. 219 is the switch 2 in synchronization with the synchronization signal input to the synchronization signal input terminal.
220 is a signal output terminal and corresponds to C in 207.

The operation of the imaging apparatus having the above configuration will be explained using FIG. 2. 230 to 237 in FIG. 2 show waveforms at points A-H of the image pickup circuit in FIG. 1, respectively.

The object information imaged through the lens 200 is collected by the imaging unit 2.
01, it is converted into an electrical signal (231).

This signal is converted into a digital signal by an A/D converter 212 in the motion detector 207 (in FIG. 2, the analog waveform is shown for simplicity), and is stored in a field memory 213 and output. That is, it is delayed by one field period (232).

The directly sent signal and the delayed signal are transferred to a differential circuit 21.
4 (233>), this signal has movement information from the previous field.Next, the ABS
The absolute value of this signal is taken in the circuit 215 (234), and the LP
The F circuit 216 cuts high frequency components (235). Next, the DET circuit 217 compares the reference potential 2397 and extracts a signal larger than the reference (236).
. This extracted point is the point at which it is determined that "the image has moved." Next, in the switching signal generation circuit, the field period next to this extracted point is changed in accordance with the timing of the synchronization signal 230. This signal is output from the motion detection section 207 as a motion detection signal, and the switch 208 is switched. That is, when it is determined that there is no movement, the signal is sent from the frame readout drive unit 204 with a high vertical resolution, and when it is determined that there is movement, the signal is sent from the field readout drive unit 205 with less dynamic afterimage. Select the signal. 238 shows the flow of the signal. Note that the frame readout and field readout drive signals shown here are exactly the same as those shown in the conventional example.

Effects of the Invention As described above, with the imaging device of the present invention, it is possible to select field readout when there is movement and frame readout when there is no movement, and as a result, images with high vertical resolution and less dynamic afterimage can be obtained. obtained, and the effect is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an imaging device according to an embodiment of the present invention, FIG. 2 is a waveform diagram showing the signal flow of the imaging device, and FIG. 3 is a block diagram showing the configuration of a conventional imaging device. , FIG. 4 is a block diagram showing the configuration of the CCD image sensor, FIGS. 5 and 6 are schematic diagrams for explaining the field readout method, FIG. 7 is a schematic diagram for explaining the frame readout method, and FIG. FIG. 8 is a schematic diagram for explaining a comparison between field readout and frame readout. 200...Lens, 201...Imaging unit, 202...Signal processing unit, 203...
Imaging drive unit, 204...Frame readout drive unit, 205...Field readout drive unit, 2
06...Synchronization generation section, 207.210...
...Motion detection unit, 208...Switch, 212
...A/D, 213...Field memory, 214...Differential circuit, 215...
...Absolute value circuit, 216...L, P, F,
217... Comparison circuit, 219... Switching signal generation circuit. Name of agent: Patent attorney Haruaki Koba and 2 others Firewood 1 Figure Enemy 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] An imaging device comprising an imaging means capable of switching between field readout scanning and frame readout scanning, and a motion detection means for detecting movement of an image, the imaging means comprising:
An imaging apparatus characterized in that when the motion detecting means determines that there is "image movement", field readout scanning is selected, and when determining that there is "no image movement", frame readout scanning is selected.