JPH06233173A - Automatic focusing device of video tape recorder with camera and its method - Google Patents

Abstract

PURPOSE: To adjust the focus of a camcorder at a high speed correspondingly to the inclination of video detecting data, without providing special microprocessors for driving a lens by controlling the moving speed of the lens according to the inclination of the data. CONSTITUTION: In the camcorder being a VTR provided with camera, the detected data corresponding to the video data of the present frame and the last frame are latched to the latch circuits 203 and 202 of an object movement diagnosis section 200. The inclination of the video detection data are found by processing the latched contents by means of a subtractor 205 and an absolute value generator 206 and dividing the difference between the latched contents by the moving speed of a lens 100. A comparator 207 discriminates whether or not the lens 100 has reached the vortex by comparing the inclination with a reference value, and a microprocessor 210 changes the moving speed of the lens 100 to a low speed from a high speed, as the inclination becomes closer to the reference value. Therefore, the focusing adjustment of the lens 100 corresponding to the inclination of the video detected data can be performed quickly, without providing special microprocessors for driving the lens 100.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video tape recorder with a camera (hereinafter referred to as a camcorder), and more specifically, the inclination of image detection data is calculated, and the rotational speed of a lens is changed by the inclination. The present invention relates to an automatic focus adjusting device for a camcorder and a method thereof for stopping a lens to prevent overshoot and adjusting a focus at high speed.

[0002]

2. Description of the Related Art Conventionally, in an automatic focus adjusting device for a camcorder, as shown in FIG. 5, a lens 1 and an aperture 2 for adjusting the shooting and focus of a subject, and the amount of light input from the lens 1 and the aperture 2, respectively. To electrical signals,
A solid-state image sensor 3 that outputs a video signal, an amplifier 4 that amplifies the video signal output from the solid-state image sensor 3, and a video that processes the video signal output from the amplifier 4 into a signal for displaying on a screen. The signal processing unit 5, the band-pass filter units 6 and 7 for filtering the video signals output from the amplification unit 4 into different frequency bands, and the focus of the video signals filtered by the band-pass filter units 6 and 7. The video signal in the frame is divided into blocks in order to match with each other, the divided video signals are converted into digital signals, and then integrated to output video detection data. A screen division section 8, an A / D conversion section 9 and an integration section. And a main microprocessor 11 that outputs a control signal for adjusting the focus according to the level of the image detection data output from the integration unit 10. It was equipped with a motor driven microprocessor 12 outputs a control signal for driving the lens motor drive unit 13 by a control signal outputted from the microprocessor 11.

The operation of the conventional automatic focus adjusting device for a camcorder thus constructed will be described below.
As shown in FIGS. 5 and 6, first, when the light is input from the optical lens 1 of the subject, the light is adjusted by the diaphragm 2, converted into an electric signal by the solid-state image sensor 3, output as a video signal, and amplified. After being amplified by the section 4, it is processed by the video signal processing section 5 so that it can be displayed on the screen, and at the same time, it is filtered by the band pass filter 6.
That is, in the initial stage of adjusting the focus, the image signal is filtered by the frequency band pass filter 6, and the filtered image signal is divided into the image signal for searching the subject to be focused through the screen dividing unit 8. The divided video signal is converted into a digital signal by the A / D converter 9 and the integrator 10, and then integrated and output as video detection data for adjusting the focus.

Next, after the image detection data is analyzed by the main microprocessor 11, the movement of the subject to be focused is checked, and if the subject is moving, the lens 1 is moved to the moved position. To output a control signal for moving and focusing. Thereafter, the control signal of the main microprocessor 11 is applied to the motor-driven microprocessor 12 to detect the level of the image detection data, and the control signal to move the lens 1 to the position where the level of the image detection data is increased. Is output.

In this case, as shown in FIG. 6, it is checked whether the image detection data input to the motor drive microprocessor 12 is stable data, and if it is determined that the data is stable, A control signal for moving the lens 1 to the lens motor drive unit 13 at a predetermined interval is output from the motor drive microprocessor 12, and the lens 1 is moved by the control signal. Next, after the lens 1 is moved, when the image detection data detected from the image signal input through the lens 1 is input to the motor-driven microprocessor 12, the image detection data currently input and the previously input image detection data are input. The size of the image detection data is compared with that of the motor-driven microprocessor 12.

Next, when the currently input image detection data is larger than the previously input image detection data, the lens 1 is moved in the same direction as the moving lens 1 so that the currently input image detection data is The moving lens 1 when it is smaller than the previously input video detection data
The motor drive microprocessor 12 outputs a control signal for moving the lens 1 in the opposite direction. After that, the above process is repeated to reach a vertex (a point for focusing) at which the level of the image detection data becomes the highest, and when the vertex is passed, the image detection data input to the motor-driven microprocessor 12 is the same as before. It is smaller than the input video detection data.

That is, the input image detection data is compared with a preset critical value, and when the image detection data is smaller than the critical value, the control signal is moved so that the lens 1 is moved in the direction opposite to the moving direction. When the image detection data output from the driving microprocessor 12 is larger than the critical value, the control signal is moved to the same direction as the moving direction of the lens 1 until the currently input image detection data becomes smaller than the critical value. Outputs from the motor-driven microprocessor 12 to move the lens 1. in this case,
The step of moving the lens 1 is counted until the image detection data passes the highest peak and reaches a critical value, and the lens 1 is moved by the count value to focus. After that, the moving state of the subject to be focused is sensed by the motor-driven microprocessor 12, and when the subject moves, the lens 1 moves to the moving position of the subject by the above process to focus the subject.

[0008]

However, in the conventional automatic focus adjusting device for the camcorder constructed as above,
It takes a considerable amount of time to control the lens driving motor, and a separate motor driving microprocessor is required, which makes the circuit configuration complicated. Moreover, since the lens is moved again to the apex after passing the apex for accurate focusing, it is difficult to realize high image quality due to the overshoot of the apex, and the moving speed of the lens is always constant. Therefore, there is an inconvenience that it takes a considerably long time to adjust the focus.

An object of the present invention is to obtain an inclination of image detection data, vary the moving speed of the lens based on the inclination, adjust the focus at high speed, and eliminate an additional lens driving microprocessor. Is to provide. Another object of the present invention is to detect the image detection data by the image signal filtered in the frequency band before passing the apex, adjust the focus according to the level of the detected data, and cause the overshoot of the apex. It is an object of the present invention to provide a camcorder automatic focus adjusting device and a method thereof which can realize a high image quality by preventing a change of a video signal.

Still another object of the present invention is to provide an automatic camcorder capable of detecting a horizontal movement of an object to be focused and stopping the movement of a lens while the object is moving so that the object can be accurately focused. A focus adjustment device and method thereof are provided.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lens and an aperture for adjusting the photographing of a subject and the amount of light respectively, and the amount of light input from the aperture to an electric signal to convert a video signal. A solid-state imaging device that is generated, an amplification unit that amplifies a video signal generated from the solid-state imaging device, a video signal processing unit that processes the video signal amplified by the amplification unit into a signal for displaying on a screen, A high-pass filter that filters the video signal amplified by the amplification unit into different frequency bands, a screen division unit that divides the video signal in the frame filtered by the high-pass filter into blocks, and the screen A low-pass filter for filtering the video signal divided by the dividing unit to reduce the video signal, and a video signal filtered by the low-pass filter. An A / D conversion unit and an integration unit that output the image detection data for integrating the converted image signal and adjusting the focus after the conversion to the digital signal; and the current image detection data output from the integration unit. The level is compared with the level of the previous image detection data, a control signal for moving the lens to the apex at which the image detection data is highest is output and applied to the drive unit of the lens motor, and the inclination of the image detection data is calculated. Then, the present invention is achieved by providing an automatic focusing device for a camcorder, which is provided with a microprocessor that changes the moving speed of the lens according to the tilt.

[0012]

According to the first aspect of the present invention, the inclination of the image detection data is calculated by moving the lens at a predetermined interval and the image detection data input at present and the image detection data input before, and the moving speed of the lens is changed according to the calculated inclination. In the step, comparing the image detection data detected by the image signal input while the lens is moving in the first step with a preset value, and when the level of the image input data currently input decreases below a set value, A video signal filtered in a predetermined frequency band is selected, and a lens is moved at a predetermined interval to determine whether the level of video detection data detected from the video signal filtered in the predetermined frequency band reaches a peak. The second step of checking, and when the level of the image detection data detected in the second step reaches the apex, the lens is moved to the front / rear side of the apex, After There confirming whether the vertex, it is checked whether or not the vertex is moved by moving the object in the shooting, when moving, the third to adjust the focus of the lens
The steps and are sequentially performed to perform automatic focus adjustment of the camcorder.

[0013]

Embodiments of the present invention will be described in detail below with reference to screens. As shown in FIG. 1, an automatic focus adjusting device for a camcorder according to the present invention includes a lens 100 and a diaphragm 110 for respectively adjusting the photographing and light amount of a subject, and the diaphragm 11
A solid-state imaging device 120 that converts the amount of light input from 0 into an electrical signal to generate a video signal, an amplification unit 130 that amplifies the video signal generated from the solid-state imaging device 120, and an image amplified by the amplification unit 130. A video signal processing unit 140 that processes the signal into a signal for displaying on a screen, and the amplification unit 1
High-pass filter units 151 and 15 for filtering the video signals amplified by 30 into different frequency bands.
2, a screen division unit 160 that divides the video signal in the frame filtered by the high-pass filter units 151 and 152 into blocks, and the screen division unit 1
A low-pass filter unit 170 for filtering the video signal divided by 60 into a low-pass band, a video signal filtered by the low-pass filter unit 170 is converted into a digital signal, and then the converted video image is converted. An A / D conversion unit 180 and an integration unit 190 that integrate the signals and output image detection data for adjusting the focus, and an image signal for each block of the frame that is output from each of the high-pass filter units 151 and 152. A subject movement diagnosis unit 200 that counts only video signals that are equal to or greater than a preset reference value, determines that the subject has moved horizontally when the count value is equal to or greater than a set value, and outputs a high potential signal to the microprocessor 210. When the subject movement diagnosis unit 200 determines that the subject has moved, the integration unit 19
Check the level of video detection data output from 0,
A microprocessor 210 for outputting a control signal for moving the lens 100 to the apex where the image detection data is maximum and applying the control signal to the lens motor driving unit 220;
Is equipped with.

In the subject movement diagnosis unit 200, the video signal for each block of the frame output from each of the high pass filter units 151 and 152 is compared with a preset reference value (Vref). A comparator 201 that outputs a high potential signal when the video signal is larger than the value and a low potential signal when the video signal is smaller than the value, a counter 202 that counts the high potential signal output from the comparator 201, and a count by the counter 202. A first latch 203 and a second latch 204 for sequentially delaying the calculated values, a subtractor 205 for calculating a difference between count values output from the first latch 203 and the second latch 204, and the subtractor 20.
Absolute value generator 20 for generating the absolute value of the value output from 5
6 and the absolute value generated from the absolute value generator 206 are compared with a set value, and when the absolute value is larger than the set value, it is determined that the movement of the subject has occurred, and a high potential signal is sent to the microprocessor 210. And a comparator 207 for applying the voltage. The microprocessor 210 is controlled by a high potential signal output from the subject movement diagnosis unit 200, and stops the movement of the lens 100.

The operation and the adjusting method of the automatic focus adjusting device for the camcorder according to the present invention having the above-described structure will be described below. As shown in FIG. 1, first, the light of the subject input from the lens 100 is adjusted by the diaphragm 110, and the amount of light adjusted by the diaphragm 110 is converted into an electric signal by the solid-state imaging device 120, and then by the amplification unit 130. After being amplified, it is processed by the video signal processing unit 140 into a signal to be displayed on the screen. Next, as shown in FIG. 2, the video signal amplified by the amplification unit 130 is filtered by a high-pass filter unit 151 having a frequency characteristic, and the filtered video signal is a low-pass filter. After being filtered by 170, the screen division unit 160 divides the video signal in the frame into blocks.

Thereafter, the divided video signal is converted into a digital signal by the A / D conversion unit 180, and the converted digital video signal is integrated by the integration unit 190 and the video corresponding to the level of the divided video signal. It is output to the detection data, and the video detection data is output to the microprocessor 21.
Applied to zero. Then, the microprocessor 21
As shown in FIGS. 2 to 4, 0 indicates whether the image detection data to be applied is stable data capable of focus adjustment. Output a control signal, and as shown in FIG.
The light input from the moved lens 100 is applied to the microprocessor 210 through the above process.

In this case, when the currently input image detection data is larger than the previously input image detection data,
When the lens 100 is continuously moved in the same direction as the moving direction of the lens 100 and the currently input image detection data is smaller than the previously input image detection data, the lens 100
The microprocessor 210 outputs a control signal to move the lens 100 in a direction opposite to the moving direction of the lens. Then, the above process is repeated to set a vertex plug for checking whether the currently input video detection data reaches the highest vertex (the position of the subject to be focused on in the frame screen). If the apex plug is not set, the size of the image detection data filtered by the high-pass filter unit 151 is compared with that of the image detection data previously input, and the image currently input is compared. When the detection data is larger than the previously input image detection data, the lens 100 is moved in the direction of the current movement, and when the currently input image detection data is smaller than the previous input image detection data, the current movement is performed. The lens 100 is moved in the direction opposite to that of the lens 100, and at the same time, the inclination of the image detection data is calculated.

The inclination of the image detection data is obtained by dividing the difference between the image detection data currently input and the image detection data previously input by the moving speed of the lens 100, and the obtained inclination is calculated by the lens 100. It is compared with a preset reference value to determine whether it has reached the apex, and as the inclination is closer to the reference value, the moving speed of the lens 100 is changed from high speed to low speed. If the slope is smaller than or equal to the reference value, the video signal amplified by the amplification unit 130 is filtered by the high-pass filter 152 having a frequency band characteristic as shown in FIG. Then, the lens 100 is reversely rotated in a predetermined step to set the apex plug. After that, the above process is repeated, and when the image detection data input from the lens 100 reaches the apex and then passes the apex, the inclination of the image detection data gradually decreases. The reference value (THv) of is calculated. In this case, since the apex plug is set, the lens 100 is moved at a predetermined interval after the image detection data reaches the apex and reaches the lower limit reference value, and the count value of the counter is incremented by +1. , The currently input video detection data is compared with the previously input video detection data.

Next, as a result of the comparison, when the currently input video detection data is smaller than the previously input video detection data, as shown in FIG. 3, it is because the inclination of the video detection data has passed the apex. , The difference between the image detection data is calculated and compared with the reference value (THv). When the image detection data is smaller than the reference value (THv), the lens 100 is at the apex, so the driving of the lens 100 is stopped. When the image detection data is larger than the reference value (THv), the lens 100 is reached. Is rotated by the value counted by the counter in the opposite direction of rotation and moved to the top. On the other hand, the video signal filtered by the high pass filter 151 is compared with the reference value Vref set by the comparator 201 of the subject movement diagnosis unit 200, and is high when the filtered video signal is larger than the reference value. The potential signal is output from the comparator 201, and when the potential signal is smaller than the reference value, the low potential signal is output from the comparator 201.
And the high potential signal is counted by the counter 202.

Next, the value counted by the counter 202 is latched by the first latch 203 and the second latch 204 for a predetermined time and then subtracted by the subtractor 205, and the absolute value of the difference between them is calculated by the absolute value generator 206. Is output. Then, the absolute value is compared with a critical value by a comparator 207, and when the absolute value is larger than the critical value, it is determined that the object to be focused has moved, and a high potential signal is output, and the high potential signal is output by a micrometer. The processor 210 outputs a control signal for stopping the movement of the lens 100, and the lens 100 is stopped by the control signal to prevent rubbing of the focal point.

[0021]

As described above, according to the automatic focus adjusting device for a camcorder and the method therefor according to the present invention,
Since the moving speed of the lens is made variable according to the inclination of the image detection data, there is an effect that the time for adjusting the auto focus is shortened and the lens driving microprocessor can be omitted to simplify the circuit configuration. In addition, since the image detection data is detected by the image signal filtered in the frequency band before passing the apex and the focus is adjusted according to the level of the detected data, the image generated by the overshoot of the apex is detected. Prevents signal changes,
It has the effect of realizing high image quality. Furthermore, since the horizontal movement of the subject to be focused is detected and the movement of the lens is stopped while the subject moves, there is an effect that accurate focusing can be achieved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an automatic focus adjustment device for a camcorder according to the present invention.

FIG. 2 is a flowchart showing an operation process of a camcorder automatic focus adjustment method according to the present invention.

FIG. 3 is a graph showing a process of adjusting a focus by an automatic focus adjusting method for a camcorder according to the present invention.

FIG. 4 is a detailed flowchart showing an operation process of the automatic focus adjustment method for a camcorder according to the present invention.

FIG. 5 is a block diagram showing a conventional automatic focus adjustment device for a camcorder.

FIG. 6 is a flowchart showing an operation process of a conventional automatic focus adjustment method for a camcorder.

FIG. 7 is a graph showing a process of adjusting a focus by a conventional automatic focus adjustment method for a camcorder.

[Explanation of symbols]

 100 ... Lens 110 ... Aperture 120 ... Solid-state image sensor 130 ... Amplification section 140 ... Video signal processing section 151, 152 ... High-pass filter 160 ... Screen division section 170 ... Low-pass filter 180 ... A / D conversion section 190 ... Integration section Reference numeral 200 ... Subject movement diagnosis unit 201, 207 ... Comparator 202 ... Counter 203 ... First latch 204 ... Second latch 205 ... Subtractor 206 ... Absolute value generator 210 ... Microprocessor 220 ... Lens motor drive unit

Claims (8)

[Claims] 1. An automatic focus adjusting device for a video tape recorder with a camera, comprising: a lens and a diaphragm for respectively adjusting the photographing of a subject and the light amount; and converting the light amount input from the diaphragm into an electric signal to convert a video signal. A solid-state imaging device that is generated, an amplification unit that amplifies a video signal generated from the solid-state imaging device, a video signal processing unit that processes the video signal amplified by the amplification unit into a signal for displaying on a screen, A high-pass filter unit that filters the video signals amplified by the amplification unit into different frequency bands, and a screen division unit that divides the video signal in the frame filtered by the high-pass filter unit into blocks. A low-pass filter unit that filters the video signals divided by the screen division unit in the low-pass range, and a filter by the low-pass filter unit. After the converted video signal is converted into a digital signal, the converted video signal is integrated, and an A / D conversion unit and an integration unit for outputting image detection data for adjusting the focus, and an output from the integration unit With a camera that checks the level of the image detection data to be output, outputs a control signal for moving the lens to the apex where the level of the image detection data is maximum, and applies the signal to the lens motor drive unit. Automatic focus adjustment device for video tape recorders. 2. The microprocessor for detecting movement of an object to be focused by the image signal filtered by the high-pass filter unit and stopping the movement of the lens while the object moves. The subject movement diagnosis unit for supplying information to the subject.
An automatic focus adjusting device for a video tape recorder with a camera according to. 3. The subject movement diagnosis unit compares the video signal filtered by the high-pass filter unit with a preset setting value, and outputs a high potential signal when the video signal is larger than the preset value. A comparator that outputs a low potential signal when the value is smaller than a set value, a counter that counts a high potential signal that is output by the comparator, and a first latch and a second latch that sequentially latch the values counted by the counter. A subtractor for subtracting the values sequentially latched by the first latch and the second latch, an absolute value generator for generating an absolute value of a value output by the subtractor, and an absolute value output from the absolute value generator. Compare the value to the critical value,
The comparator according to claim 2, further comprising a comparator for applying a high potential signal to the microprocessor to output a control signal for stopping the movement of the lens when the absolute value is larger than a critical value. Automatic focus adjustment device for video tape recorders. 4. An inclination is calculated based on image detection data detected from an image signal input by a lens moving at a predetermined gap and input image signal, and a moving speed of the lens based on the calculated inclination. In the first step, and in the first step, the image detection data detected from the image signal input while the lens is moving is compared with the set value, and the currently input image detection data is set. When the value is decreased below the value, the image detection data detected from the image signal filtered in the predetermined frequency band by moving the lens at a predetermined interval while selecting the image signal filtered in the predetermined frequency band A second step of checking whether or not the apex is reached, and when the level of the image detection data detected in the second step reaches the apex By moving the lens,
After confirming that the point is the apex, check whether the subject has moved and the apex has moved, and adjust the focus of the lens when moving. Automatic focus adjustment method for tape recorder. 5. The first step compares the currently input image detection data with the previously input image detection data, and when the currently input image detection data is larger than the previously input image detection data, the present process is performed. The lens is moved in the same direction as the moving lens, and at the same time, the first step of calculating the tilt from the image detection data, and whether the tilt calculated in the first step reaches the vicinity of the apex before passing the apex In order to detect whether or not there is a second step of comparing with a preset value, and when the inclination calculated by comparison in the second step is larger than the preset value, the moving speed of the lens is increased until reaching the preset value. The automatic focus adjusting method for a video tape recorder with a camera according to claim 4, wherein the third step of changing the position is performed. 6. The second process comprises detecting image data from a video signal filtered by a high-pass filter having a predetermined filter characteristic when the slope calculated in the first process is less than a set value. Is detected and the lens is moved at a predetermined interval, and then the fourth step of calculating a reference value, which is the lower limit value of the image detection data, is checked in order to check whether or not the image detection data currently input has reached the apex. The difference between the input image detection data and the previously input image detection data is compared, the above steps are repeated until the difference becomes equal to or more than the reference value, and the step in which the lens moves to the predetermined gap until the apex is counted. The automatic focus adjusting method for a video tape recorder with a camera according to claim 4, wherein the fifth step of: 7. The third step compares the image detection data input around the apex with the apex in the second step and a reference value, and drives the lens when the difference is equal to or larger than the reference value. The automatic focus adjusting method for a video tape recorder with a camera according to claim 4, wherein after moving in the direction opposite to the direction by the value counted in the fifth step of the second step, the seventh step of resetting the apex plug is performed. 8. The automatic focus of a video tape recorder with a camera according to claim 5, wherein the tilt is calculated by dividing a difference between the image detection data input at present and the image detection data input previously by the moving speed of the lens. Adjustment method.