JP2737568B2 - Color imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image pickup device.

[0002]

2. Description of the Related Art In recent years, black-and-white imaging apparatuses have been remarkably popularized by home automation and the like, and the flow of colorization is completely natural.

FIG. 3 shows a configuration of a conventional color image pickup apparatus.
Shown in In the figure, 1 is a subject, 2 is an imaging lens, 1
3 is an infrared cut filter, 4 is an image sensor, 7 is a signal processing circuit, 8 is an image sensor output signal, and 11 is a video output.

[0004] Here, the operation will be described. First, light coming from the subject 1 enters the imaging lens 2, passes through the infrared cut filter 13, and forms an image on the imaging device 4. Then, the image sensor 4 outputs an image sensor output signal 8
Is output and input to the signal processing circuit 7, from which a video signal 11 of the NTSC system or the like is output.

[0005] The infrared cut filter 13 is for removing an infrared component contained in the light incident on the lens 2 from the subject 1, and uses a color CCD image sensor generally used at present. This is essential for a color imaging device. If this infrared cut filter 13
If there is no infrared light, the image sensor 4 has sensitivity to infrared light. Therefore, if the incident light includes infrared light, the image sensor output signal 8 includes not only a visible light component but also an error component due to infrared light. Will be. This is particularly true for light generated by a heat source such as light from a bulb, and color reproduction cannot be accurately performed.

[0006]

As described above, conventionally, it was necessary to provide an infrared cut filter in the optical system. However, the infrared cut filter is expensive and needs to be located in the optical system. This imposes restrictions on the design of the system, and it is difficult for the filter to purely remove only infrared light, so that the input of visible light is attenuated, and the sensitivity of the imaging device is reduced accordingly. Also, nighttime illumination using an infrared irradiator conventionally used in a black-and-white imaging device cannot be used because infrared components are cut off, which is very inconvenient.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, an object of the present invention is to provide a color image pickup apparatus which does not require an infrared cut filter and can be used for nighttime infrared illumination.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and is arbitrarily set after subtracting the output signal of the infrared light receiving element from the output signal of the image sensor and the infrared light receiving element. An arithmetic circuit for outputting an arithmetic value in comparison with a threshold value is provided, and the color signal component is suppressed when the arithmetic value becomes smaller than an arbitrarily set value.

[0009]

According to the above arrangement, it is possible to remove the infrared component contained in the output signal of the imaging device, and the infrared cut filter in the optical system of the imaging device becomes unnecessary. Further, when the illuminance is lower than the minimum illuminance at which the image sensor can capture an image, the output signal of the image sensor includes an infrared component, so that the infrared irradiation device can be used at night or the like.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a color image pickup apparatus according to the present invention will be described below.

In FIG. 1, 1 is a subject, 2 is an image pickup lens, 3 is a prism, 4 is an image pickup element, 5 is an infrared light receiving element, 6 is an arithmetic circuit, 7 is a signal processing circuit, 8 is an image pickup element output signal, 9 Is an infrared light receiving element output signal, 10 is a calculated value,
11, a video signal; and 12, a chrominance signal suppression signal.

The operation of the embodiment constructed as described above will be described below. First, the light incident from the imaging lens 2 passes through the prism 3 and is divided into two parts.
Is incident on the infrared light receiving element 5. Here, upon receiving the light, an image sensor output signal 8 is output from the image sensor 4, and an infrared sensor output signal 9 is output from the infrared sensor 5, and each is input to the arithmetic circuit 6.

Here, the operation of the arithmetic circuit 6 will be described with reference to the flowchart of FIG. When the power is turned on, first, the infrared light receiving element output signal 9 is subtracted from the imaging element output signal 8 to obtain a subtraction value. Here, the imaging device 4 has sensitivity to visible light and infrared light, and the infrared light receiving device 5 has sensitivity only to infrared light. By making the sensitivity distributions of these two infrared rays the same, by subtracting the infrared light receiving element output signal 9 from the image sensor output signal 8, only the visible light component input to the image sensor 4 can be extracted. Here, it is determined whether or not the obtained subtraction value is equal to or larger than an arbitrarily set threshold value. Normally, this threshold value is set to the output signal value at the time of the lowest illuminance of the image sensor 4, so that if the subtraction value is equal to or more than the threshold value, there is incident light having the minimum illuminance of the image sensor 4 or more. This means that imaging with visible light is possible. Therefore, the arithmetic circuit 6 outputs a value obtained by subtracting the infrared light receiving element output signal 9 from the image sensor output signal 8 as an arithmetic value 10 and is input to the signal processing circuit 7 at the next stage, from which the video signal 11 is output. . When the subtraction value is less than the threshold value, it means that imaging with visible light is impossible, and the arithmetic circuit outputs the image sensor output signal 8 as an arithmetic value. At this time, the calculated value power contains only the visible light component less than the minimum subject illuminance, the infrared light is the main component, and if normal color signal processing is performed, unnatural color reproduction will occur. Arithmetic circuit 6
Sends a chrominance signal suppression signal to the signal processing circuit 12 and suppresses the chrominance signal normally generated by the signal processing circuit 12 at the next stage, thereby outputting only a luminance signal component to the video signal output. Therefore, at night or the like, the image sensor output signal 8
Even if the value obtained by subtracting the output signal 9 of the infrared light receiving element from the image signal is equal to or less than the minimum illuminance, it is possible to capture an image by providing the infrared irradiation device.

By continuing the above-mentioned determination loop until an arbitrarily set time elapses, it is possible to always obtain an optimal video signal regardless of the amount of incident light until the power is turned off.

[0015]

According to the present invention, an image pickup element and an infrared light receiving element are provided, and the infrared light receiving element output signal is subtracted from the image pickup element output signal. This eliminates the need for an expensive infrared cut filter normally required. In addition, when light less than the minimum illuminance is incident, the infrared component is used together to capture the infrared component and suppress the color signal component of the video signal, thereby preventing unnatural color reproduction. In addition to being able to take images at night, the sensitivity can be increased because there is no infrared cut filter. Also,
Since the infrared cut filter is not required, the filter is not broken, and the imaging device is resistant to mechanical vibration.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of one embodiment of the present invention.

FIG. 3 is a configuration diagram illustrating an example of a conventional imaging device.

[Description of Signs] 1 subject 2 imaging lens 3 prism 4 imaging element 5 infrared light receiving element 6 arithmetic circuit 7 signal processing circuit

Claims (1)

(57) [Claims] An imaging device having a sensitivity distribution to both visible light and infrared light; an infrared light receiving device having the same sensitivity distribution as the infrared sensitivity distribution of the imaging device; and receiving the infrared light from an output signal of the imaging device. An arithmetic circuit for subtracting an output signal of the element and outputting a subtraction value, wherein a color signal suppression signal for suppressing a color signal component is output from the arithmetic circuit when the subtraction value becomes smaller than an arbitrarily set value. A color imaging device characterized by the above-mentioned.