KR100558522B1 - Apparatus and method for adjusting a camera clock - Google Patents

Abstract

A method for varying the camera driving clock, the method including a timing signal generator capable of oscillating camera driving clocks having different frequencies, which is executable in the apparatus.

A first step of separating the luminance signal and the color signal from the signal captured by the camera unit;

Extracting and integrating only the high frequency component among the separated luminance signal components;

A third step of comparing the integrated luminance signal level with at least one reference value previously stored;

And generating a clock variable control signal for generating camera driving clocks having different frequencies according to the comparison result and outputting the generated clock variable control signal to the timing signal generator.

Camera, driving clock, variable.

Description

Camera driving clock variable device and its method {APPARATUS AND METHOD FOR ADJUSTING A CAMERA CLOCK}

1 is a block diagram of a camera driving clock variable apparatus according to an embodiment of the present invention.

2 is an exemplary camera driving clock variable flow in accordance with an embodiment of the present invention.

The present invention relates to a camera phone, and more particularly, to an apparatus and method for varying a camera driving clock.

The camera phone is a mobile communication terminal that adds the function of a digital camera to a general mobile phone. The user can directly check the photographs taken with the digital camera through the LCD of the camera phone or upload it on a PC to edit and customize it according to his / her preferences. The prevalence is rapidly expanding in that it can be processed and provided to others by convenient means such as e-mail.

Such a camera phone also needs a camera driving clock for signal processing and transmitting a captured image as in a normal digital camera. The camera driving clock is a signal required to process a signal captured by a CCD into a displayable image signal and transmit the signal to a post processor. It can be said that the frame rate of the display image is determined by the camera driving clock.

For example, a typical camera phone uses either 27MHz or 16MHz as the camera driving clock. In such camera phones, images are displayed at a rate of 30 frames per second and 15 frames per second in a preview mode for taking a picture. In other words, the higher the camera driving clock, the higher the frame rate, and thus the more powerful the moving image photographing, but the higher the power consumption of the driving clock, the higher the power consumption.

Therefore, if the camera driving clock can be changed according to the degree of movement of the subject without affecting the quality of the captured image, in some cases, the power consumption of the camera phone can be significantly reduced. It is expected to prevent the deterioration of preview quality.

Accordingly, an object of the present invention is to provide a camera driving clock variable device and a method which can reduce power consumption during preview operation by varying the camera driving clock,

Furthermore, the present invention provides a camera driving clock variable device and a method for changing a frame rate of a display image according to the movement of a subject or the degree of movement of the terminal itself during the preview operation.

A method according to an embodiment of the present invention for achieving the above object is a method executable in an apparatus including a timing signal generator capable of oscillating a camera driving clock having a different frequency,

A first step of separating the luminance signal and the color signal from the signal captured by the camera unit;

Extracting and integrating only the high frequency component among the separated luminance signal components;

A third step of comparing the integrated luminance signal level with at least one reference value previously stored;

And generating a clock variable control signal for generating camera driving clocks having different frequencies according to the comparison result and outputting the generated clock variable control signal to the timing signal generator.

According to the feature of the present invention as described above, in the auto focusing (AF) state, the high frequency component of the luminance signal increases due to the edge component of the image. Therefore, comparing the high-frequency component integral value of the luminance signal with a preset reference value can predict the degree of movement of the subject or camera. Therefore, when the subject or the camera movement is small, the camera driving clock can be relatively lowered to reduce power consumption. Will be.

On the other hand, the camera driving clock variable apparatus according to another embodiment of the present invention is a CCD for converting and outputting an optical signal to an electrical imaging signal, and a signal for removing the noise included in the imaging signal and converting the signal into digital data A built-in camera phone including a correction unit and a luminance / color signal separation unit for separating the luminance signal and the color signal from the digital data,

A luminance signal level calculator for extracting only a high frequency component of the separated luminance signal components and integrating the same to output a luminance signal level;

A control unit for outputting a clock variable control signal for generating a camera driving clock having a different frequency by comparing the luminance signal level with one or more stored reference values;

And a timing signal generator for outputting camera driving clocks of different frequencies oscillated according to the clock variable control signal to the CCD, the signal corrector, and the luminance / color signal separator.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

First, FIG. 1 illustrates a configuration diagram of a camera driving clock variable apparatus according to an embodiment of the present invention. More specifically, FIG. 1 illustrates only a partial configuration diagram embedded in a camera phone, and FIG. A flowchart illustrating a variable camera driving clock according to the present invention is illustrated.

Referring to FIG. 1, the lens unit 10 includes a lens group including a zoom lens, a focus lens, and the like, an aperture mechanism, a driving circuit thereof, and the like. The lens unit 10 may be referred to as a camera unit together with a charge coupled device (CCD) 20 to be described later. Light incident through the lens unit 10 is picked up by the imaging surface of the CCD 20 and converted into an electrical imaging signal.

On the other hand, the signal correction unit 30 behind the CCD 20 removes the noise included in the captured image signal and converts the signal into digital data. To this end, the signal compensator 30 includes a sample & hold and AGC circuits as already known, and an A / D converter at a rear end thereof. The signal correction unit 30 may be referred to as a camera signal processing unit together with the luminance / color signal separation unit 40 to be described later.

The luminance / color signal separator 40 separately outputs a luminance signal and a color signal from the digital data output from the signal corrector 30. The luminance / color signal separator 40 may be implemented as a chroma signal separator and a luminance signal separator as already known. For reference, each signal processed by the luminance / color signal separation unit 40 is then processed into a signal that can be displayed on the display unit and transmitted to the display unit.

The luminance signal level calculator 50 extracts only the high frequency component among the luminance signal components of the luminance / color signal separator 40 and outputs the luminance signal level obtained by integrating the luminance signal component. The luminance signal level calculator 50 includes a high pass filter and an integrated circuit.

The controller 60 generates and outputs a clock variable control signal for generating a camera driving clock having a different frequency by comparing the luminance signal level input from the luminance signal level calculator 50 with one or more stored reference values. . The controller 60 also controls the lens unit 10 to perform auto focusing or zoom control.

Finally, the timing signal generator 70 oscillates and outputs a camera driving clock having different frequencies according to the clock variable control signal output from the controller 60. The oscillated camera driving clock is input to the CCD 20, the signal corrector 30, and the luminance / color signal separator 40, respectively, and is used as a clock for signal processing and signal transmission. In the embodiment of the present invention, it is assumed that the timing signal generator 70 oscillates camera driving clocks of three different frequencies, for example, 27 MHz, 24 MHz, and 16 MHz.

For reference, the timing signal generator 70 may generate and output various synchronization signals required by the camera unit and the camera signal processor in addition to the camera driving clock.

Hereinafter, the operation of the camera driving clock variable device having the above-described configuration will be described in more detail with reference to FIG. 2.

First, in the camera photographing mode, the controller 60 checks whether the auto focusing mode is set (step 60). If the auto focusing mode is not set, the control unit 60 performs a fixed control (step 70) of the timing signal generator 70 so that the camera driving clock is oscillated at a default frequency value as in a normal camera phone.

However, if the auto focusing mode is set, the controller 60 changes the frequency of the camera driving clock as described below. In order to change the camera driving clock frequency, the luminance signal level of the captured image must be read (step 80) through the luminance signal level calculator 50.

Summarizing the process of leading the luminance signal level for the captured image, first, the signal captured by the camera unit is converted into digital data by noise reduction and digital data through the camera signal processor, more specifically, the signal corrector 30. The luminance signal is separated from the digital data by the luminance / color signal separation unit 40 and input to the luminance signal level calculation unit 50. Then, only the high frequency component of the luminance signal is extracted by the high pass filter of the luminance signal level calculating unit 50, and the high frequency component is integrated through the integrating circuit so that the controller 60 can read the luminance signal level of the captured image. Will be.

When the luminance signal level of the captured image is read as described above, the controller 40 compares the read level value with one or more reference values obtained by experiment in advance (step 90), and varies the camera driving clock according to the comparison result. The clock variable control signal for outputting is output (step 100).

More specifically, for example, if the read luminance signal level has a value greater than or equal to a predetermined first reference value, the controller 40 determines that there is no movement of the current subject (auto focusing state) and is lower than the default value. The clock variable control signal is output so that the camera driving clock is oscillated. The first reference value may be defined as a reference signal for determining an auto focusing state using a value obtained by an experiment.

On the other hand, if the read luminance signal level is less than the second reference value having a value smaller than the first reference value, the controller 40 determines that the current subject is moving fast and the camera driving clock higher than the default value is oscillated. Output the clock variable control signal,

If the read luminance signal level has a value between the first reference value and the second reference value, the clock variable control signal is output such that the camera driving clock has a default intermediate frequency value.

As such, the camera driving clock oscillated at different frequencies according to the luminance signal level is then applied to the CCD 20, the signal corrector 30, and the luminance / color signal separator 40, thereby transmitting signals between the blocks. Is influenced by the camera driving clock, and as a result, the frame rate of the captured image is varied according to the camera driving clock.

Accordingly, the present invention changes the camera driving clock by comparing the luminance signal level with one or more reference values. When photographing a subject without motion, the present invention reduces power consumption by reducing the camera driving clock frequency, while photographing a subject with a lot of motion. In this case, by increasing the camera driving clock frequency (frame rate), it is possible to obtain an effect of preventing the deterioration of the image quality of the preview image.

In the above embodiment, the camera driving clock is varied according to the comparison of the luminance signal level and the reference value obtained in the auto focusing mode. However, the camera driving clock may be changed according to a camera driving clock adjustment command manually input by a user.

 As described above, the present invention has an effect of reducing power consumption during preview operation by relatively lowering the camera driving clock frequency when photographing a subject without motion.

When photographing a subject with a lot of motion, the camera driving clock frequency (frame rate) is increased, and as a result, the image quality of the preview image can be prevented.

On the other hand, the present invention has been described with reference to the embodiments shown in the drawings, which are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be defined only by the appended claims.

Claims (6)

A CCD for converting and outputting an optical signal into an electrical imaging signal, a signal correction unit for removing noise included in the imaging signal and converting the signal into digital data, and separating the luminance signal and the color signal from the digital data. In the camera driving clock variable device comprising a luminance / color signal separation unit for, A luminance signal level calculator for extracting only a high frequency component of the separated luminance signal components and integrating the same to output a luminance signal level; A control unit for outputting a clock variable control signal for generating a camera driving clock having a different frequency by comparing the luminance signal level with one or more stored reference values; And a timing signal generator for outputting camera driving clocks of different frequencies oscillated according to the clock variable control signal to the CCD, the signal correcting unit, and the luminance / color signal separating unit. The apparatus of claim 1, wherein the controller outputs a clock variable control signal for generating three different frequencies. The apparatus of claim 1, wherein the camera driving clock variable device is embedded in a camera phone. In the camera driving clock variable method of the device comprising a timing signal generator capable of oscillating the camera driving clock having a different frequency, A first step of separating the luminance signal and the color signal from the signal captured by the camera unit; Extracting and integrating only the high frequency component among the separated luminance signal components; A third step of comparing the integrated luminance signal level with at least one reference value previously stored; And generating a clock variable control signal for generating camera driving clocks having different frequencies according to the comparison result and outputting the clock variable control signal to the timing signal generator. The method of claim 4, wherein the first to fourth steps are performed in an auto focusing (AF) setting mode. The method of claim 4, further comprising: generating a clock variable control signal for generating a camera driving clock having a different frequency according to a camera driving clock adjustment command manually input by a user and outputting the clock variable control signal to the timing signal generator; Camera driving clock variable method, characterized in that.

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