JPH10136349A - Focus adjustment method for video doorphone system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make focus position deviation small by adjusting the focus by using a colored stripe chart so as to provide a peak at a certain wavelength of spectroscopic characteristics which is the product of the spectroscopic light transmission characteristics of a light source and the spectroscopic sensitivity characteristics of an image pickup element. SOLUTION: The lens focus position of a camera is determined at an appropriate position between the respective lens focus positions of the lens focus position 15 by a fluorescent lamp light source 12 and the lens focus position 16 by an infrared LED light source 11. Thus, well-balanced focusing is performed under either one of the light source 12 and the light source 11 and clear video images are projected to a monitor under either one of the light sources. The stripe chart of red and black is illuminated by the light source provide with the spectroscopic light transmission characteristics only in a visible light area, it is image picked up and the wavelength of red which is a single wavelength is focused. Thus, the lens focus position of the camera at the appropriate position between the lens focus positions of both light sources of a fluorescent lamp and an infrared LED is determined. Thus the deviation in the lens focus position due to change in time is made small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting the focus of a television doorphone device comprising a slave unit with a camera and a master unit with a television monitor connected to the slave unit with a camera via a transmission line.

[0002]

2. Description of the Related Art In general, a handset equipped with a camera of a conventional TV door phone apparatus is provided with several semiconductor infrared light emitting elements (hereinafter referred to as infrared LEDs) for securing shooting at night. It was used to project nighttime images.

Further, as a focus adjustment method for a television door phone apparatus, that is, a focus adjustment method for a slave unit with a camera, a black-and-white stripe chart is imaged, and the level of a video (luminance) signal corresponding to the stripe portion of the stripe chart is changed. The focus was adjusted by moving the position of the lens mounted on the camera back and forth so as to take a peak value.

Further, when the stripe chart is imaged, an incandescent lamp,
The fringe chart is illuminated using fluorescent light or infrared LED light, thereby increasing the level of the corresponding video (luminance) signal, thereby making it easier to find the position where the peak value is obtained. The focus of the handset was adjusted.

[0005]

In the above-described focus adjustment method for a TV door phone apparatus, an incandescent lamp, a fluorescent lamp, or an infrared LED light is used as illumination for imaging a black-and-white stripe chart. When the adjustment is performed under the infrared LED light source due to the difference, the image is clear under the infrared LED light source, but the image is slightly blurred under the fluorescent light source, and conversely, the adjustment is performed under the fluorescent light source When
Clear image under fluorescent light source, but infrared LED
There is a drawback that an image is slightly blurred under a light source.

This is because the peak wavelengths in the spectral characteristics (shown in FIG. 10) obtained by multiplying the spectral emission characteristics of each light source by the spectral sensitivity characteristics of the imaging device (CCD) are different.
In particular, in the case of a lens having a large chromatic aberration such as a plastic lens (a lens having a large change in the just focus position due to a difference in the wavelength of the incident light), the problem is remarkable.

Further, as can be said from the spectral characteristics shown in FIG. 10, especially when the adjustment is performed under an incandescent light source, the curve of the wavelength versus the spectral output is obtained by using another fluorescent lamp or infrared LED light as a light source. Since it is not critical compared to the case, the change in the amplitude level of the image when the lens is moved back and forth is small, and it is difficult to obtain the true peak value, so that the following adjustment variation occurs.

[0008] That is, there have been ones adjusted to the infrared LED light side and those adjusted to the fluorescent lamp side. The former produces a sharp image when imaged under an infrared LED light source, but the image becomes greatly blurred when imaged under a fluorescent light source, and the opposite is true for the latter. As described above, the variation at the time of the focus adjustment is large, and as a result, some of the images after the focus adjustment are such that, depending on the type of the light source at the time of imaging, the image appears to be out of focus. Even when the adjustment is performed under the fluorescent light source, there is a variation in the adjustment although not as much as under the incandescent light source. This is because incandescent lamps and fluorescent lamps are not light sources having spectral emission characteristics of a single wavelength like infrared LED light sources, but light sources whose spectral emission characteristics are spread over a certain wavelength range.

Further, even if a fluorescent lamp is selected as a light source for illuminating the black-and-white fringe chart at the time of focus adjustment, its spectral emission characteristics are different from each other, and there is a temporal change, so that the focus position is shifted. I was afraid.

In view of the above problems, the present invention focuses on a well-balanced image under light sources of incandescent lamps, fluorescent lamps, and infrared LED light, and as a result, a clear image can be displayed on a television under any of the light sources. It can be projected on the parent machine with a monitor, and when adjusting the focus with a light source such as an incandescent lamp or a fluorescent lamp whose spectral emission characteristics are spread over a certain wavelength range, the dispersion during focus adjustment is reduced. Another object of the present invention is to provide a focus adjustment method for a TV door phone device, which can reduce a shift of a focus position due to a difference in spectral emission characteristics of light sources or a change with time.

[0011]

SUMMARY OF THE INVENTION A focus adjusting method for a television door phone apparatus according to the present invention achieves the above object, and the invention according to claim 1 is directed to a slave unit with a camera and a slave unit with a camera. In a method of adjusting the focus of a TV door phone including a master unit with a TV monitor connected by a transmission line, the spectral emission characteristics of a light source and the spectral sensitivity characteristics of an imaging device (CCD) are multiplied in order to reduce variations during focus adjustment. The focus adjustment is performed using a colored stripe chart so that the combined spectral characteristics have a sharp peak at a specific wavelength.

Therefore, when a black-and-white stripe chart is used, white reflects light of all wavelengths in the visible light region (black absorbs all light in the visible light region), so that the spectral light emission of the light source is obtained. Light of all wavelengths appearing in the characteristics will contribute to the focusing of the lens. When coloring such as red and blue is used instead of white or black and white of this black and white stripe chart, only light of a specific wavelength such as red and blue is reflected among all wavelengths in the visible light region, so that the light source If the spectral emission characteristics are limited to the visible light region, only light of a specific wavelength such as red and blue contributes to the focus adjustment of the lens. In the latter case, the change in the amplitude of the image when the lens is moved back and forth becomes much more critical than in the former case, and variations in focus adjustment can be reduced. Further, a part depending on the light source such as a difference in spectral emission characteristics of the light source or a change with time can be removed at a considerable rate.

According to a second aspect of the present invention, there is provided a method for adjusting the focus of a television doorphone comprising a slave unit with a camera and a master unit with a television monitor connected to the slave unit with a camera via a transmission line. Using red and black as the colors of the specific colored stripe chart in the invention according to claim 1,
By illuminating the red-black stripe chart with a light source having a spectral emission characteristic only in the visible light region and performing focus adjustment, it is possible to focus on a single wavelength, that is, a red wavelength (about 650 nm). It is characterized in that it is possible to focus on an appropriate position between the position of the focal point under the lamp light source and the position of the focal point under the infrared LED light source.

As a result, in imaging under each light source of incandescent light, fluorescent light, and infrared LED light, a well-balanced focus is achieved,
Under any light source, clear images can be projected on the master unit with a TV monitor.

The fourth and fifth aspects of the present invention relate to a means for detecting an amplitude level of a video (luminance) signal of a stripe portion of a stripe chart used for focus adjustment. According to a fourth aspect of the present invention, in the focus adjustment method for a television door phone apparatus according to the third aspect, the whole image is used as a means for detecting a peak value of a level of an image (luminance) signal corresponding to a stripe portion of the stripe chart at the time of focus adjustment. (Luminance) In order to extract the part corresponding to the stripe part from the signal,
6. The method according to claim 5, wherein a high-frequency component is extracted from the video (luminance) signal, and the peak value is evaluated as a value averaged over the entire area of the screen or a specific selected area. According to the invention described in the first aspect, in the focus adjustment method for a television door phone apparatus according to any one of the first to third aspects, the peak value of the level corresponding to the striped portion of the striped chart of the video signal is adjusted at the time of focus adjustment. As means for detecting, a point where the level of the luminance component of the video (luminance) signal changes in the horizontal direction and the vertical direction of the imaging screen is extracted, and the change level at each point is determined over the entire area of the screen or a specific selected area. In the above, the evaluation is performed using the averaged value.

Therefore, according to the fifth aspect of the present invention, the striped chart according to the first or second aspect of the present invention does not need to be arranged vertically with respect to the imaging screen of the camera, and can be arranged horizontally or obliquely. Becomes When high-frequency correction is performed in a circuit by a camera circuit, it may be easier to adjust the horizontal direction than the vertical direction as an arrangement of a focus adjustment stripe chart. (If the fringe chart is arranged vertically, and the high-frequency correction is performed in a circuit, the amplitude level of the video (luminance) signal corresponding to the fringe portion will not change even if the focus is slightly shifted from the just focus position. Due to the high-frequency correction on the circuit, the level does not change much from the level at the just focus position, and it may be difficult to adjust.) According to the invention described in claim 5, a subject other than the stripe chart can be used as a subject at the time of focus adjustment. Become like

According to a sixth aspect of the present invention, there is provided a method for adjusting the focus of a television doorphone comprising a slave unit with a camera and a master unit with a television monitor connected to the slave unit with a camera via a transmission line. The colored stripe chart of the invention according to claim 1, as described above,
Further, in place of the red-black stripe chart of the invention according to claim 2, a fine and uniform pattern composed of a specific color or red and black, a character or a symbol is used. The focus of the camera is adjusted so that the average value of the change level at the change point of the luminance level in the horizontal direction and the vertical direction of the imaging screen is the largest, and the subject is displayed as the clearest image. It is.

Therefore, compared with the method of adjusting the amplitude level of the video (luminance) signal of the corresponding stripe portion to take the peak value using the stripe chart, the focus is actually adjusted by the human eyes at the time of focus adjustment. There is a merit that you can realize that

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a focus adjustment method for a television intercom apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a television door phone apparatus for explaining an embodiment of the focus adjusting method of the video door phone apparatus of the present invention, and FIG. 2 is a slave unit with a camera of the TV door phone apparatus of FIG. FIG. 3 is a schematic view showing the lens used in the camera-equipped child device of FIG. 1 as viewed from above, and FIG. 4 is used in the camera-equipped child device of FIG. FIG. 5 is a schematic view of the lens viewed from the side, FIG. 5 is a schematic view showing that the position of the lens of the camera is different between the fluorescent light source and the infrared LED light source, and FIG. It is a schematic diagram.

FIG. 7 is a schematic diagram of a video signal waveform of a corresponding fringe portion when a fringe chart is picked up during focus adjustment.
FIG. 8 is a schematic diagram showing a black-and-white chart at the time of focus adjustment in the related art, in which white and black are vertically arranged at equal intervals vertically, and a resolution of 150 TV or more can be confirmed. FIG. 3 is a schematic diagram showing a red-black chart at the time of focus adjustment according to the present invention, in which red and black are vertically arranged at equal intervals and a resolution of 150 TV lines or more can be confirmed.

FIG. 10 is a diagram showing the spectral characteristics obtained by multiplying the spectral emission characteristics of the light source and the spectral sensitivity characteristics of the image pickup device (CCD). FIG. 11 corresponds to the stripe portion of the stripe chart during focus adjustment. FIG. 12 is a block diagram showing a method for generating a signal representing the definition of an image of a subject in focus adjustment.

First, as shown in FIG. 1, the TV intercom apparatus has a camera-equipped slave unit 1 and a television monitor-equipped master unit 3 connected by a transmission line 2. In the figure, reference numeral 4 denotes a television monitor. The slave unit 1 with a camera has an internal structure shown in FIG.
As shown in FIG. 4 to FIG. 4, the lens barrel 8 of the lens is rotated counterclockwise with respect to the substrate 5, that is, the lens is slid forward and backward by rotating the lens barrel 8 so that the focus can be adjusted. A lens 7 and an infrared LED 6 which can fix the master flange 9 and the lens barrel 8 of the lens with a lens fixing screw 10 provided above the flange 9 are provided.

As shown in FIG. 5, if the spectral emission characteristics of the light source incident on the lens 13 are different, the focal position of the lens 13 will be different due to the difference in the chromatic aberration of the lens 13. For example, the upper part of FIG. 5 shows the focal position when the light source is infrared LED light, and the lower part shows the focal position when the light source is a fluorescent lamp. FIG.
When focusing on the upper position, a clear image is obtained under the fluorescent light source, but a blurred image is obtained under the infrared LED light source. Focusing on the lower position of FIG. 5,
The image is clear under the infrared LED light source, but blurred under the fluorescent light source.

Accordingly, the lens focal position of the present camera is set at an appropriate position between the lens focal position 15 of the fluorescent lamp light source 12 and the lens focal position 16 of the infrared LED light source 11, as shown in FIG. As a result, a well-balanced focus is obtained under both the fluorescent light source 12 and the infrared LED light source 11, and a clear image is projected on the monitor 4 of the main unit 3 of the TV door phone apparatus under either light source. Becomes possible.

The red and black stripe chart is illuminated by a light source having a spectral emission characteristic only in the visible light region, and the image is taken and focused on a single red wavelength, thereby obtaining the fluorescent lamp and the infrared LED. The lens focal position of the camera at an appropriate position between the lens focal positions of the two light sources is determined. Further, the wavelength of the light incident on the lens is a single wavelength of red in the stripe chart, and the shift of the focal point of the lens becomes small due to a difference in illumination light source or a change with time.

FIG. 6 shows an example of a focus adjustment jig based on the present invention. A focus adjustment jig 17 provided in a dark box includes a slave unit 1 with a camera, an illumination light source 25 and a light source as shown in FIG. The object is provided with a stripe chart 24 in which red and black are arranged at a predetermined distance from the camera-attached slave unit 1 and are arranged in vertical columns. As the illumination light source, one having a spectral emission characteristic only in the visible light region is used. In the case of a light source that includes infrared light and ultraviolet light in addition to visible light, an optical filter 19 that cuts them is provided. For example, when a fluorescent lamp is used, infrared light is not included but ultraviolet light is included, and therefore, an ultraviolet light cut filter is provided. However, a red-black stripe chart is used as the stripe chart. In this case, since both red and black do not reflect ultraviolet light, the optical filter 19 is unnecessary when the illumination light source is a fluorescent lamp.

When the fringe chart 24 is imaged using the focus adjustment jig 17 of the present invention, a video signal waveform 20 shown in FIG.
Is output. The focus is adjusted by moving the lens 7 back and forth so that the amplitude level 22 of the video (luminance) signal 21 corresponding to the stripe portion of the red-black stripe chart 24 takes a peak value while observing the waveform 20. At this time, when the lens 7 moves back and forth, the video (luminance) signal 2 corresponding to the chart stripe portion
Since the change of the amplitude level 22 of 1 is very large, that is, the change is critical, the variation in adjustment is small.

Here, the stripe chart 24 is a red-black stripe chart in which red and black are vertically arranged at equal intervals and a resolution of 150 TV lines or more can be confirmed. Brightness) The amplitude waveform of the signal is almost the same and periodic on each line of the screen,
This is because it is easy to check the level with a measuring instrument such as an oscilloscope, and it is easy to find the peak value of the level.

If a method is used in which a signal representing the definition of an image obtained when the subject is imaged is extracted from the entire video signal, and the magnitude of this signal is searched for its peak value, the non-object is determined as a non-object. In addition to being able to use striped charts at equal intervals, striped charts arranged horizontally, etc., not limited to charts, repetitive or non-repeated patterns, letters, and symbols arranged finely and uniformly can be used. Looks like

Also, the reason why red and black are used as the two kinds of colors in the stripe chart is that black absorbs light of all wavelengths in the visible light range, so that only red light is used in focus adjustment. And it is easy to focus on this wavelength. In addition to black, other colors such as blue and yellow can be used. In this case, light of two wavelengths is present and the amplitude level 22 of the video (luminance) signal 21 corresponding to the stripe portion of the stripe chart is 2. Care should be taken because two peaks are formed, but if they are adjusted so that they are not mistaken, the reduction in variation in the focus position during focus adjustment and the independence on the illumination light source are the same as in the case of the red-black stripe chart .

As a method of detecting the peak value of the video (luminance) signal corresponding to the stripe portion of the above-described stripe chart, the peak value of the video (luminance) signal corresponding to the stripe portion is used without processing. There is a method of searching for the peak value and a method of searching for the peak value by processing. FIG. 11 shows an example of the latter method. By inputting the image (luminance) signal a of the entire stripe chart to the high-pass filter 31, only the stripe portion of the stripe chart, which is a high-frequency component, is extracted, and the average is averaged by the detector 32 and the smoother 33. Obtain b. The average value b is the average value of the amplitude level 22 of the video (luminance) signal 21 corresponding to the stripe portion of the stripe chart, and the magnitude is searched for the peak value.

The method for generating the above-mentioned signal representing the definition of the image is as follows. The image (luminance) signal c of the entire subject is subjected to A / D conversion by the A / D conversion unit 34, and then temporarily taken into the memory A35, and the luminance level in the memory A35 in the horizontal and vertical directions of the screen is equal to or higher than a certain level. The changing points are sequentially scanned and searched, and the change level d is stored in another memory B36.
I will remember above. When the average value e is obtained from the change level at each change point stored in the memory B36, the average value e becomes a signal representing the definition of the screen, and the focus may be adjusted so as to maximize the signal. When calculating the average value, it is also possible to adopt a method in which weighting is performed so that the weight near the center of the screen is increased and the weight around the periphery is reduced, and focusing is performed with emphasis on the center of the screen.

[0034]

As described above, the present invention relates to a method for adjusting the focus of a TV door phone apparatus, wherein a specific colored stripe chart or a specific colored stripe chart is used instead of a conventional black and white stripe chart as a subject to be used when adjusting the focus of a camera. By using a fine colored object, it is possible to focus on a specific wavelength, reduce the dispersion of the focal position when adjusting the focus, and use the spectral emission of the light source that illuminates the object. It is possible to reduce the shift of the focal position due to a difference in characteristics or a change over time, and it is possible to reduce the dependence of the light source on the adjustment of the focal position.

If red is selected as the specific wavelength, and focus adjustment is performed using a red-black stripe chart or a fine red-black subject, a visible light range to an infrared LED light range like a camera of a TV door phone can be obtained. For cameras that require a wide range of light wavelengths up to a wide range of light wavelengths, sharp images can be displayed on a television monitor under light sources of any wavelength. In addition, this focus adjustment method can be sufficiently applied not only to a TV door phone camera but also to other cameras.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a video doorphone apparatus for describing an embodiment of a focus adjustment method for a video doorphone apparatus of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a sub-unit with a camera of the television door phone apparatus of FIG.

FIG. 3 is a schematic plan view of a lens used in a slave unit with a camera of the television door phone device of FIG. 1;

FIG. 4 is a schematic side view of a lens used in a slave unit with a camera of the television door phone apparatus of FIG. 1;

FIG. 5 is a schematic diagram showing a lens focal position by a fluorescent lamp light source and an infrared LED light source for describing an embodiment of a focus adjustment method of the TV door phone apparatus of the present invention.

FIG. 6 is a schematic diagram showing a focus adjustment jig of the television door phone apparatus of FIG. 1;

7 is a schematic diagram illustrating a waveform of a video signal output from a slave unit with a camera of the television door phone device of FIG.

FIG. 8 is a schematic diagram showing a stripe chart in which white and black are vertically arranged as subjects, for explaining an embodiment of a focus adjusting method of the television door phone apparatus of the present invention.

FIG. 9 is a schematic diagram showing a stripe chart in which red and black are vertically arranged as subjects for explaining an embodiment of the focus adjustment method of the television door phone apparatus of the present invention.

FIG. 10 is a diagram illustrating spectral characteristics obtained by multiplying spectral emission characteristics of a light source and spectral sensitivity characteristics of an imaging device for describing an embodiment of a focus adjustment method for a TV door phone apparatus of the present invention.

FIG. 11 is a block diagram illustrating a method of searching for a peak value from a video signal corresponding to a stripe portion of a stripe chart for describing an embodiment of a focus adjustment method for a television doorphone apparatus of the present invention.

FIG. 12 is a block diagram illustrating a method of generating a signal representing the definition of an image of a subject for describing an embodiment of a focus adjustment method of the television door phone apparatus of the present invention.

[Explanation of symbols]

 Reference Signs List 1 slave unit with camera 2 transmission line 3 master unit with television monitor 4 television monitor 5 board

Claims (6)

[Claims] 1. A television intercom apparatus comprising a slave unit with a camera and a master unit with a television monitor connected by a transmission line, wherein stripes are arranged at a predetermined distance from the camera using two kinds of specific colors. Then, a colored stripe chart in which adjacent stripes are different in color from each other is placed, and this is illuminated with a light source having spectral emission characteristics only in the visible light region, and the level of the video signal corresponding to the stripe portion of the colored stripe chart has a peak value. To reduce the variation of the focus position during focus adjustment by adjusting the focus of the camera so that the colored stripe chart is projected as the clearest image,
Further, there is provided a focus adjustment method for a TV door phone apparatus, characterized in that a difference in focus position due to individual differences in spectral emission characteristics of a light source to be illuminated or a change with time is reduced. 2. The focus adjusting method for a television intercom apparatus according to claim 1, wherein the camera is positioned at a predetermined distance from the camera.
Arrange the stripes using red and black and place adjacent red and black stripe charts of different colors from each other, illuminate this with a light source having spectral emission characteristics only in the visible light region, and check the stripes of the red and black stripe chart. By adjusting the focus of the camera so that the level of the video signal corresponding to the portion takes a peak value and the red-black stripe chart is displayed as the clearest image, the position of the focus under the fluorescent light source and the semiconductor infrared A focus adjustment method for a video door phone apparatus, wherein the camera is focused on an appropriate position between the focus positions under a light emitting element light source. 3. A focus adjustment method for a television doorphone device according to claim 1, wherein the stripe chart used is such that stripes are vertically arranged at equal intervals and a resolution of 150 TV lines or more can be confirmed. A focus adjustment method for a TV door phone device. 4. A focus adjusting method for a television door phone apparatus according to claim 3, wherein said means for detecting a peak value of a level of a video signal corresponding to a striped portion of a striped chart at the time of focus adjustment is a striped portion based on the entire video signal. In order to extract a portion corresponding to, a high-frequency component is extracted from the video signal,
A focus adjustment method for a video door phone apparatus, wherein the peak value is evaluated as a value averaged over the entire area of the screen or a specific selected area. 5. A focus adjustment method for a television intercom apparatus according to claim 1, wherein a peak value of a level of a portion corresponding to a stripe portion of a stripe chart of a video signal is adjusted at the time of focus adjustment. As means for detecting, the points where the level of the luminance component of the video signal changes in the horizontal direction and the vertical direction of the imaging screen are extracted, and the change level at each point is averaged over the entire area of the screen or a specific selected area. A focus adjustment method for a TV intercom apparatus, characterized in that the evaluation is performed using a set value. 6. A focus adjustment method for a TV door phone apparatus according to claim 1, wherein two specific colors or red and black are used instead of a colored stripe chart or a red-black stripe chart at the time of focus adjustment. Image of a subject consisting of a series of finely and uniformly distributed repetitive or non-repetitive patterns, characters, and symbols, and the luminance level change points in the horizontal and vertical directions of the imaging screen with respect to the subject The focus of the camera is adjusted so that the average value of the change level in is largest and the image is displayed as the clearest image.