KR19980065892A - Digital Camera Auto Iris Control Circuit - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control circuit of a digital camera. The present invention relates to a circuit for controlling an auto iris so that an image by window marking set to an arbitrary size and position set by a user in a imaging area can be obtained clearly. To provide.

The automatic iris control circuit of the digital camera lens may include a digital image signal generator for converting an image received through an aperture of the lens into an electrical signal and converting the image into a digital image signal, and a window parameter input from the outside of the digital image signal. A window averaging unit which detects an average value of the digital image of the area of the image, compares the average value with a predetermined reference brightness value, detects the difference value, and controls the control data for opening and closing the aperture according to the detected comparison difference value. And a driving unit configured to control rotation of a motor for driving the opening / closing of the aperture by converting the generated aperture control unit into an analog signal. The user may arbitrarily set a window area within the image capturing area to obtain an average value in the area so that the backlight or the position of the subject. A clear image can be obtained regardless of the distance.

Description

Digital Camera Auto Iris Control Circuit

The present invention relates to a circuit for automatically controlling the opening and closing of the aperture of a digital camera lens, in particular, so as to obtain a clear image of the window area set to an arbitrary size and position set by the user in the imaging area. It relates to a circuit for controlling the auto iris.

In general, digital cameras using imaging devices such as high-resolution CCDs (charge coupled depths) are widely used in precision image recognition, image information transmission, machine tools such as robots, and engineering and medical image processing sensors.

Digital cameras used in the industrial fields as described above have an automatic iris control circuit for obtaining a more accurate image of only an image of a subject placed in an image capturing area.

The automatic iris control circuit as described above has a function of controlling the opening and closing amount of the iris (opening and closing amount of the iris) by detecting the brightness in the imaging area. That is, the auto iris circuit closes the iris when the brightness of the screen in the imaging area is too bright to prevent the image from being saturated, and when it is too dark, generates a control signal to obtain more light by opening the iris to obtain a good quality screen. It is. The adjustment circuit of the auto iris of the digital camera lens is shown in FIG. 1.

1 is an automatic aperture control circuit diagram of a digital camera according to the prior art. This configuration includes a CCD (Charge Coupled Device) 12 for converting an image of a subject into an electrical signal, a lens 10 for imaging a focus of an image of a subject in an imaging area on the light receiving surface of the CCd 12, and the CCD. A brightness information detector 14 for sampling and holding the electric image signal outputted from 12, accumulating sample and hold information in an area designated by the window pulse, and accumulating and outputting brightness information of a selected screen; A window selector for converting sample and hold information into a digital video signal, dividing one screen into a plurality of screens, and generating window pulses corresponding to one of the divided screens in response to input of window selection information. And a motor controller 18 for controlling opening and closing of the iris in response to the detected screen brightness information.

In the above configuration, the brightness information detector 14 is composed of a sample and hold (S / H) section 16, a GC 18, a signal selector 20, a waveform shaper 22 and an integrator 24. The window selector 16 digitally converts an image processor circuit 26 which processes and outputs the sampled and held image signal, and an analog image signal processed from the IPC 26. An analog digital converter 28 (hereinafter referred to as an ADC) to output, a screen divider (SDC) to divide and output a digital video signal output from the ADC 28, and in response to a user's selection A window pulse generator for supplying a switching switch 32 for selectively switching one of the divided screens and outputting a window pulse corresponding to the divided screen selected by the switching switch 32 to the signal processing unit 20 in the brightness information detector 14; (Hereinafter referred to as WPG) 34.

2A, 2B and 2C show setting state diagrams of windows of a digital camera lens according to the prior art, which show examples of some windows set by a digital camera manufacturer (producer). 2A, 2B, and 2C, the horizontal axis represents a horizontal pulse of one screen, and the vertical axis represents a vertical pulse.

First, before describing the operation of the automatic aperture circuit according to the related art with reference to FIGS. 1 and 2, it is assumed that the CCD 12 outputs an electric image signal corresponding to the subject image received through the lens 10. .

Now, when the circuit of Fig. 1 is operated, S / H 16 samples and holds the analog signal output from the CCD 12 and outputs it to GC 18 and IPC 26. The IPC 26 processes an image signal of the sample-and-held analog signal and outputs the image signal, and the ADC 28 connected to the output converts the analog signal into a digital image signal. The SDC 30 connected to the output node of the ADC 28 divides the digital image signal input in one screen state into a plurality of screens and outputs the same to the switching switch 32. At this time, the number of screen divisions is divided into a fixed number in hardware. For example, as shown in FIGS. 2A, 2B, and 2C, 100, 102, and 104, one screen is divided into three modes.

When the user selects the window selection key (not shown) of the subject to generate the window selection signal, the changeover switch 32 is divided into SDC 30 in response to the window selection signal input. Select one and feed it to WPG 34. At this time, the WPG 34 supplies the horizontal and vertical window pulses corresponding to the selected split screen to the signal selector 20 in the brightness information detector 14. For example, when the window selection signal is a signal for selecting a screen such as 100 of FIGS. 2A, 2B, and 2C, horizontal and vertical window pulses are output as shown in FIG. 2A.

On the other hand, the GC 18 in the brightness information detector 14 amplifies and outputs the sampled and held analog signal with a predetermined gain. The signal selector 20 selects and outputs only the analog video signal input to the effective section of the horizontal and vertical window pulses (horizontal is high and vertical is low) among the amplified analog video signals. For example, a horizontal image value of a screen as shown in FIGS. 2A, 2B, and 2C is selected and output from one screen according to the input state of the horizontal and vertical window pulses. The signal shaper 22 for inputting the analog image signal selected and output from the signal selector 20 forms an input signal according to the clamp signal CS and the blank signal BS input from the outside and outputs the input signal to the integrator 24. The integrator 24 integrates and outputs an image signal input in units of horizontal lines. Accordingly, the brightness information detector 14 operating as described above analogically accumulates the brightness values of the window image in which the horizontal and vertical window pulses set as shown in FIGS. 2A, 2B, and 2C are activated and compares the comparator in the motor controller 18 ( CP) It is supplied to the inverting terminal (-) of 36.

The reference voltage divided by the resistors R1 and R2 is input to the non-inverting terminal + of the comparator 36 in the motor controller 18. In this case, the reference voltage is a voltage set as the reference brightness. Accordingly, the comparator 36 outputs a negative voltage to the motor 38 when the brightness value of the window image is greater than the reference brightness value, and drives the aperture to be closed. When the brightness value of the window image is less than the reference brightness value, the comparator 36 outputs a motor to the positive voltage. Output 38 to drive the iris open.

However, the conventional automatic iris control circuit configured as shown in FIG. 1 does not allow the user to arbitrarily select a window area for adjusting the brightness of an image of a specific area of the captured image, and provides several windows provided by the producer (producer). By selecting one of the areas, a problem arises that limits the use of digital cameras. That is, there is a limit to accurately recognize a specific screen of a subject by installing a camera in surveillance, industrial, and medical applications, which brings a lot of limitations to the installation of the camera. In more detail, it is inconvenient to move the camera body when it is necessary to move the subject to a specific area of the screen so that the window cannot be moved or the size of the window is adjusted so that the subject to be photographed is located in the specific selection area of the screen. .

In addition, the conventional automatic diaphragm control circuit having the configuration as shown in FIG. 1 has a limitation in quantitative control by analogously processing driving control of a motor that controls the accumulation of the brightness signal of the window screen and the opening and closing degree of the aperture. Aperture could not be adjusted.

Accordingly, an object of the present invention is to provide an automatic iris control circuit that allows a user to freely mask an image placed at an arbitrary size and position in an area that can be photographed with one screen.

It is another object of the present invention to obtain a desired image of a desired subject clearly, regardless of the brightness of the background screen by a window area set by a user at an arbitrary size and position within an area that can be photographed by one screen. It is to provide a circuit for controlling the auto iris.

Still another object of the present invention is to provide an automatic aperture control circuit for digitally controlling a motor for opening and closing an automatic aperture of a digital camera lens.

Another object of the present invention is to freely window mask only an image of a specific subject among screens of an area captured by one screen, and to adjust the brightness of the window masking area so that the image of the window can be obtained well regardless of the brightness of the background. It is to provide a circuit for adjusting the automatic iris to average.

The present invention for achieving the above object, the automatic aperture of the digital camera lens having a digital image signal generating unit for converting an image received through the aperture (not shown) of the lens into an electrical signal to change into a digital image signal In the adjusting circuit, a window average for detecting an average value of a digital image of an area of an image corresponding to a window parameter input from the outside of the digital image signal is compared with the average value and an arbitrarily set reference brightness value to detect the difference value. And an aperture controller for generating control data for opening and closing of the aperture according to the detected comparison difference value, and a driving unit for controlling rotation of a motor for driving the opening / closing of the aperture by converting the control data into an analog signal. It is characterized by the configuration.

1 is an automatic iris adjustment circuit diagram of a digital camera according to the prior art.

2 is a state diagram of a window of a digital camera lens according to the related art.

3 is an automatic iris adjustment circuit diagram of a digital camera according to an embodiment of the present invention.

4 is a diagram illustrating a window setting state by an area of a user-programmable according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings of the embodiments of the present invention, those having substantially the same configuration and function as those in the above-described drawings will use the same reference numerals.

It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to obscure the subject matter of the present invention.

3 is an automatic iris adjustment circuit diagram of a digital camera according to an embodiment of the present invention. This configuration includes a CCD 12 for changing an image of a subject into an electrical signal, an ADC 40 for converting an image signal output from the CCD 12 into a digital image signal, window setting data for determining a window of a subject in an imaging area, and a reference. A local value of the brightness of the video signal located in the area of the window setting data from the local computer 44 is extracted from the local computer 44 generating brightness data and the digital image signal output from the ADC 40, and the average value and the reference brightness arbitrarily set. Aperture control unit 46 for comparing the values and generating control data for opening and closing of the aperture according to the difference value, and converting the control data output from the throttle control unit 46 into an analog signal to drive the opening / closing of the aperture motor. It consists of a drive unit 56 for.

In the above configuration, the aperture control unit 46 is a signal processing unit 54 for processing and outputting the digital video signal, and a window for calculating an average value of digital data located in an area of the window setting data output from the local computer 44 among the digital video signals. The output of the aperture controller 50 and the local computer 44 which compares the average value 48 with the window average value and the reference brightness value from the local computer 44 and generates control data such as aperture holding, opening and closing according to the comparison difference. And an interface 52 for interfacing with the window averager 48 and the aperture controller 50. The main drive unit 56 includes a digital to analog converter (DAC) 58 that converts the control data output from the aperture controller 50 into an analog signal to drive the aperture motor 60.

4 is a diagram illustrating a window setting state by an area of a user-programmable according to an embodiment of the present invention. In the drawing, reference numeral 62 denotes a window start width, which indicates the position of the start line in the horizontal direction of the image in the imaging area. 64 is a window size width, and means a pixel opening in the horizontal direction. Reference numerals 66 and 68 denote variable values representing a window start height and a window size height, and indicate the position of the vertical start line and the number of vertical lines, respectively. Therefore, the window shown in Fig. 4 can be marked by designating the four variable values 62, 64, 66, 68, etc. on the screen of the imaging area.

Hereinafter, a description will be given in detail of an operation exaggeration for obtaining an image in a window as a high quality screen regardless of the brightness of a background by extracting a window that is set programmable by a user and an average brightness within the set window.

Now, the user inputs the values of the window variables 62, 64, 66, 68 and reference brightness into the local computer 44 as shown in FIG. 4 in order to obtain an image of a subject positioned in the imaging area as shown in FIG. Then, the local computer 44 converts the window variables 62, 64, 66, 68 into serial data and transmits it to the interface 52. The interface 52 supplies window variables 62, 64, 66, and 68 transmitted from the local computer 44 to the averager 48, and supplies a reference brightness value to the aperture control 50.

In this state, when the image signal in the imaging area is output from the CCD 12, it is converted into a digital image signal by the ADC 40. The output of the ADC 40 is input to the signal processor 54 and the window averager 48 of the aperture control unit 46LH. The signal processor 54 processes and outputs the digital video signal. For example, the processed digital video signal is supplied to an NTSC encoder (not shown) or the like for display on a monitor (not shown).

On the other hand, the window averager 48 calculates an average value of the digital data located in the area of the window variable output from the local computer 44 among the digital image signals. For example, in the digital image data of the image capturing area as shown in FIG. 4, the horizontal average of the pixels in the window area set by the window variables 62, 64, 66, and 68 is calculated (the pixel brightness value of one horizontal line in the window area). The average value of the horizontal direction is calculated again in the vertical direction (vertical line in the window region). This method results in a value of one horizontal line average block and one field average block. By this operation, the signal size (brightness) of the pixels in the window is accumulated, and the sum is divided by the size of the window to extract the average value. The average value of the pixel brightness in the window region extracted by this operation is supplied to the aperture controller 50.

The aperture control unit 50 compares the reference brightness value through the interface 52 with the extracted window average value, detects the difference value, and generates control data for closing, opening, or maintaining (stopping) the aperture motor accordingly. For example, if the current brightness, that is, the window average value, is greater than the reference brightness value, the aperture is closed by subtracting the preset interval (the rotation length of the preset motor), and the current brightness value (window average value) is greater than the reference brightness value. If it is small, control data is generated to add the aperture by a certain interval.

If the current brightness value (window average value) is the same as the reference brightness value, the control data is output to hold the aperture motor.

The DAC 58 connected to the output of the aperture controller 50 converts the input control data into an analog signal to drive the aperture motor 60 for opening and closing the aperture.

Therefore, when the backlight of the digital camera automatic iris control circuit as shown in FIG. 3 is input to the entire background and the subject to be photographed, a good image quality can be obtained by setting a window for a specific screen to the user's discretion and controlling the aperture therefor. There is an advantage to this.

As described above, the user can set the window area size and position setting for the aperture control arbitrarily, thereby removing the limitation of the camera installation. In addition, by controlling the driving of the motor for opening and closing the aperture as a digital value, the opening and closing degree of the aperture can be more precisely obtained, so that an image of the window area can be satisfactorily obtained regardless of the background.

Claims (5)

In the automatic iris control circuit of a digital camera lens having a digital video signal generator for converting an image received through the aperture of the lens into an electrical signal to convert to a digital video signal, A window averaging unit for detecting an average value of a digital image of an area corresponding to a window parameter input from outside of the digital image signal system; An aperture controller for comparing the average value with a reference brightness value set arbitrarily and detecting a difference value, and generating control data for opening and closing the aperture according to the detected difference value; And a drive unit for converting the control data into an analog signal to control rotation of a motor for driving the opening / closing of the aperture. The method of claim 1, The window averager calculates an average value in a horizontal direction of the digital image of the window parameter among the digital image signals in the input image capturing region, and averages the average value in the horizontal direction again in the vertical direction to calculate an average value of pixel brightness in the window region. Automatic aperture control circuit of the digital camera, characterized in that. The method of claim 2, The aperture controller generates control data to close the aperture by subtracting the average value in the window area and the reference brightness value by a predetermined interval. When the average value is smaller than the reference brightness value, the aperture controller adds the aperture by a specific interval to open the aperture. Automatic aperture control circuit of a digital camera, characterized by generating control data. Automatic aperture control circuit of a digital camera lens having a charge coupled device for converting an image of a subject into an electrical signal and an analog digital converter for converting an image signal output from the charged coupled device into a digital video signal. To A local computer for issuing window setting data and reference brightness data for determining a window of a subject in the imaging area; Among the digital image signals outputted from the analog digital converter, an average value of brightness of a video signal located in an area of window setting data from the local computer is extracted, and the average value is compared with an arbitrarily set reference brightness value. An aperture control unit for generating control data for opening and closing of the, And an opening / closing of the diaphragm motor as a driving unit for driving the control data output from the diaphragm control unit into an analog signal. The method of claim 3, The local computer has a window starting width for setting the position of the horizontal pixel of the image in the image capturing region, the number of pixels in the horizontal direction, a variable of the size width, and a vertical start line in the image capturing region. A digital camera, comprising: inputting a window start height and a window size height variable for setting the position and the number of lines in the vertical direction from the outside to the window averaging device, and transmitting a reference brightness value from the outside to the iris controller; Automatic aperture control circuit in the lens.