JP2009027310A - Detection method for forgetting of lens cap removal and video recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide detection method for forgetting of lens cap removal by which opening/closing of a lens cap is electronically and accurately judged taking leaking light of the lens cap into consideration without adding a special switch for detecting the opening/closing of the lens cap, thereby an erroneous operation due to power disconnection is notified to user. <P>SOLUTION: The opening/closing of the lens cap can be highly accurately detected by taking into consideration a detection result of an AGC signal and a detection result of luminance average, and useless battery consumption is suppressed by displaying warning to a user, and at the same time automatically disconnecting the power for a user who is not aware of the warning. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a video camera having a lens cap, and can determine whether or not the lens cap is closed without turning on a special switch. The lens cap is in a state in which the video camera is turned on. This can be suitably used to warn the user that it is closed.

It is common to take a lens cap to protect the lens from scratches and dust after shooting with a video camera, etc., but if the lens cap is mistaken with the video camera turned on When the next recording is attempted, there is a problem that is inconvenient for the user because the battery is exhausted and recording cannot be performed for the intended time. To solve this problem, determine whether the lens cap is closed, notify the user with a sound or a warning, and perform control to turn off the power and reduce battery consumption in case the user does not notice it. Can be considered. Under such circumstances, it is conceivable to use a specific detection switch to determine whether the lens cap is closed. However, such a mechanical switch has a problem that the material cost is increased or the mechanical switch is easily broken. . To solve such a problem, a method of electronically determining whether or not the lens cap is closed has been devised (for example, see Patent Document 1).
JP-A-6-22198

  However, in the conventional configuration, since the presence / absence of the lens cap is detected only by the AGC signal output from the AGC (Auto Gain Controller) circuit, it is very difficult to set a threshold value to be compared with the AGC signal. When the threshold is set low, a warning display is always displayed when shooting in a slightly dim situation, depending on the shooting conditions at that time, even though the lens cap is not attached due to the amplification process of the AGC circuit. In addition, when the threshold value is set high, there is a problem that light leaks from the gap due to inadequate lens cap, etc., and the AGC circuit amplification is suppressed and the warning display is not displayed even though the lens cap is attached. Had a problem to do.

  The present invention solves the above-described conventional problems, and includes a lens cap warning display for the purpose of appropriately determining whether or not the lens cap is closed even if there is a photographing condition or light leakage of the lens cap. Another object of the present invention is to provide a video recording method and apparatus.

In order to solve the conventional problem, the video recording apparatus of the present invention includes:
An imaging unit that converts light imaged by the lens into an electrical signal;
An automatic gain control unit that always keeps the video signal output from the imaging unit constant;
A gain comparison unit that compares the gain value output from the automatic gain control unit with a gain threshold that is held in advance;
A luminance average region selection unit that extracts a predetermined region from the video signal output from the imaging unit;
A luminance average value calculation unit that calculates an average value of the signal output from the luminance average region selection unit, and a light amount measurement unit that measures ambient brightness;
A luminance comparison unit that selects and compares the average luminance calculated by the luminance average value calculation unit and at least one average luminance threshold held in advance based on the output of the light amount measurement unit;
A warning display determination unit that determines whether or not a lens cap is attached using output results of the gain comparison unit and the luminance signal comparison unit, and a warning unit that prompts the display device to warn according to the determination result It is characterized by that.

Furthermore, in the video recording apparatus of the present invention,
When the luminance average area selection unit divides the image signal for one screen input from the imaging unit into at least two areas and detects an area having pixels with high luminance, the luminance average area selection unit selects the area. It is characterized by exclusion.

Furthermore, in the video recording apparatus of the present invention,
The light quantity measuring unit is an IR sensor.

Furthermore, in the video recording apparatus of the present invention,
The warning display determination unit attaches the lens cap when the gain value is larger than the gain threshold value as a result of the gain comparison unit and the average luminance value is smaller than the average luminance threshold value as a result of the luminance signal comparison unit. It is characterized in that it is judged.

Moreover, in the detection method forgetting to remove the lens cap of the present invention,
A gain value calculating step for automatically controlling and calculating the gain value of the video signal;
A gain value comparison step for comparing the calculated gain value with a gain threshold stored in advance;
A light intensity measuring step for measuring the brightness of outside light;
A luminance selection step of selecting from at least two luminance thresholds based on the brightness of the external light;
A luminance calculation area selection step for selecting an area for calculating the luminance average value;
A luminance average value calculating step for calculating an average luminance of the selected area;
A luminance comparison step for comparing the calculated average luminance value and the luminance threshold;
A warning display determination step of determining whether or not a lens cap is attached using output results of the gain value comparison step and the luminance comparison step;
A warning display step for displaying a warning on the display device when the lens cap is mounted;
It is characterized by having.

Furthermore, in the detection method of forgetting to remove the lens cap of the present invention,
The luminance calculation area selection step is characterized in that the average luminance is calculated from the signal values of the entire screen or only a specific area when the average luminance is performed.

Moreover, in the detection method forgetting to remove the lens cap of the present invention,
The warning display determination step includes attaching a lens cap when the gain value is larger than the gain threshold value as a result of the gain comparison step and the average luminance value is smaller than the average luminance threshold value as a result of the luminance comparison step. It is characterized by judging that it exists.

  According to the video recording method and apparatus having the lens cap warning display of the present invention, the opening and closing of the lens cap is determined electronically without adding a special switch, and light leakage occurs when the lens cap is closed. Can be detected with high accuracy, and unintended battery consumption can be suppressed.

  Hereinafter, embodiments of a video recording method and apparatus having a lens cap warning display according to the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a configuration diagram of a video recording apparatus provided with a lens cap warning display according to the first embodiment of the present invention.

  In FIG. 1, reference numeral 1000 denotes a configuration diagram for detecting the lens cap of the video recording apparatus of the present invention and notifying the user of a warning. The light that enters from the lens group 1001 is imaged on the imaging unit 1090 and is output from there as a video signal 1002. Thereafter, the input signal 1002 is input to the AGC circuit unit 1050. The AGC circuit 1050 controls the gain value for the input signal. In other words, if the video signal level is low, the video signal is determined to be dark and the video signal is amplified. . The amplification value at that time is output as a gain value 1004.

  Further, the gain threshold value 1003 is provided as a determination reference value for detecting opening / closing of the lens cap. The gain comparison unit 1020 outputs a gain state flag 1008 that is a first determination criterion as to whether or not the lens is opened and closed based on both the gain value 1004 and the gain threshold 1003.

  On the other hand, even when the lens cap is closed, if the exterior is distorted, or if the lens cap is closed halfway, a small amount of light leaks into the lens cap and the lens from the gap, causing false detection. Therefore, in the present invention, in order to overcome the problem, the luminance average is taken, and when the calculation result is low, it is determined that the lens cap is closed. However, the area for calculating the average luminance can be selected. is doing. For example, the IR sensor 1080 detects whether the video recording apparatus of the present invention is in a dark place or a bright place. If the IR sensor 1080 is in a dark place, the brightness threshold A1005 is selected. B1006 is selected and determined as the luminance threshold value used in the luminance signal comparison unit.

  In addition, the luminance average region selection unit 1060 determines for which region the luminance average is calculated.

Based on the information determined by the luminance average region selection unit 1060, the luminance average value calculation unit 1070 calculates the average value of luminance in the region.
Next, the lens cap is closed by the luminance signal comparison unit 1010 that receives both the luminance threshold selected based on the ambient brightness measured in advance by the IR sensor 1080 and the result calculated by the luminance average value calculation unit 1070. Is output as a luminance state flag 1009 which is the second determination criterion.

  Next, the warning display determination unit 1030 determines that the lens cap is closed when the gain state flag 1008 has a gain value 1004 larger than the gain threshold 1003 and the luminance state flag 1009 has a luminance average value smaller than the luminance average value. The warning display presence / absence determination signal 1007 is output. When the warning display determination unit 1030 determines that the lens cap is closed, the warning display unit 1040 warns the user that the power is on. Although the warning display unit is used here, attention may be urged by sounding a sound. If the user still does not notice, the power can be forcibly turned off to reduce battery consumption.

(Embodiment 2)
FIG. 2 is a flowchart of the lens cap removal forgetting detection method according to the second embodiment of the present invention.

  First, the gain value of the video signal input from the imaging unit is calculated (2101). Next, the gain value calculated from the video signal is compared with a gain threshold value stored in advance (2102). Here, when the lens cap is closed, the AGC circuit amplifies the signal so as to increase the gain, and thus exceeds a preset gain threshold value. Therefore, when the gain threshold is exceeded in this way, TRUE is stored (2104). Otherwise, FALSE is stored (2103).

  In parallel, the external brightness is measured by the IR sensor (2105). When the measured brightness is less than or equal to a predetermined brightness judgment value, the brightness threshold A is selected because the surroundings are dark, such as indoors or at night (2107). Otherwise, the brightness threshold B is selected because the surroundings are bright in the outdoors and daytime (2107).

  Next, a region to be used when calculating the average luminance value is selected (2109). Details of this processing will be described with reference to FIG. First, one screen is divided at a predetermined interval, and a histogram is created for each region (2201). When the difference between the dark pixel and the bright pixel is larger than a predetermined value for each area, the area is excluded (2203). When the determination for all the areas is completed (2204), the remaining area becomes an area for calculating the average luminance. By making it possible to select the area to be calculated in this way, it becomes possible to detect leaked light with high accuracy.

  Next, the average luminance value in the selected area is calculated (2110).

  Next, the previously selected luminance threshold value is compared with the calculated luminance average value (2111). If the luminance average value is lower than the luminance threshold value, it is determined that the lens cap is closed and TRUE is stored (2113). . Otherwise, FALSE is saved (2112).

  If the result of the gain state flag and the result of the luminance state flag are both TRUE (2114), a warning is displayed (2115).

The method for detecting forgetting to remove the lens cap and the video recording apparatus according to the present invention determine whether the lens cap is opened or closed electronically without adding a special switch, and even if there is light leakage when the lens cap is closed, it is accurate For video cameras with a lens cap that can detect and suppress unintended battery consumption, a special switch is attached to determine whether the lens cap is closed or open. This can be suitably used when warning the user that the lens cap is closed with the video camera powered on.

1 is a configuration diagram of a recording apparatus according to Embodiment 1 of the present invention. Flowchart in Embodiment 2 of the present invention Region selection flowchart according to the second embodiment of the present invention

Explanation of symbols

1000 Video recording apparatus 1001 Lens group 1002 Video signal 1003 Gain threshold 1004 Gain value 1005 Luminance threshold A
1006 Luminance threshold B
1007 Warning display presence / absence determination signal 1008 Gain state flag 1009 Luminance state flag 1010 Luminance signal comparison unit 1020 Gain comparison unit 1030 Warning display determination unit 1040 Warning display unit 1050 AGC circuit 1060 Luminance average region selection unit 1070 Luminance average value calculation unit 1080 IR sensor 1090 Imaging unit

Claims (7)

An imaging unit that converts light imaged by the lens into an electrical signal;
An automatic gain control unit that always keeps the video signal output from the imaging unit constant;
A gain comparison unit that compares the gain value output from the automatic gain control unit with a gain threshold that is held in advance;
A luminance average region selection unit that extracts a predetermined region from the video signal output from the imaging unit;
A luminance average value calculating unit for calculating an average value of a signal output from the luminance average region selecting unit, and a light amount measuring unit for measuring ambient brightness;
A luminance comparison unit that selects and compares the average luminance calculated by the luminance average value calculation unit and at least one average luminance threshold value held in advance based on the output of the light amount measurement unit;
A warning display determination unit that determines whether or not a lens cap is attached using output results of the gain comparison unit and the luminance signal comparison unit, and a warning unit that prompts the display device to warn according to the determination result A video recording apparatus characterized by that. When the luminance average area selection unit divides the image signal for one screen input from the imaging unit into at least two areas and detects an area having pixels with high luminance, the luminance average area selection unit selects the area. The video recording apparatus according to claim 1, wherein the video recording apparatus is excluded. The video recording apparatus according to claim 1, wherein the light quantity measurement unit is an IR sensor. The warning display determination unit attaches the lens cap when the gain value is larger than the gain threshold value as a result of the gain comparison unit and the average luminance value is smaller than the average luminance threshold value as a result of the luminance signal comparison unit. The video recording apparatus according to claim 1, wherein it is determined that the video recording is performed. A gain value calculating step for automatically controlling and calculating the gain value of the video signal;
A gain value comparison step for comparing the calculated gain value with a gain threshold stored in advance;
A light intensity measuring step for measuring the brightness of outside light;
A luminance selection step of selecting from at least two luminance thresholds based on the brightness of the external light;
A luminance calculation area selection step for selecting an area for calculating the luminance average value;
A luminance average value calculating step for calculating an average luminance of the selected area;
A luminance comparison step for comparing the calculated average luminance value and the luminance threshold;
A warning display determination step of determining whether or not a lens cap is attached using output results of the gain value comparison step and the luminance comparison step;
A warning display step for displaying a warning on the display device when the lens cap is mounted;
A method for detecting forgetting to remove a lens cap, comprising: 6. The method of detecting forgetting to remove a lens cap according to claim 5, wherein the luminance calculation area selecting step calculates the average of the luminance from the signal value of the entire screen or only a specific area when the luminance is averaged. The warning display determination step includes attaching a lens cap when the gain value is larger than the gain threshold value as a result of the gain comparison step and the average luminance value is smaller than the average luminance threshold value as a result of the luminance comparison step. 6. The method for detecting forgetting to remove a lens cap according to claim 5, wherein:

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