JP2003069865A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device in which an insertion and extraction mechanism of an infrared cut-off filter in each photographing mode is eliminated, which automatically switches photographing modes and in which sensitivity in each photographing mode is also improved more. SOLUTION: In this imaging device, a lens unit is arranged at an object side, a luminous flux from the lens unit is divided into two directions, the first luminous flux is coupled to a first solid-state image pickup device as it is, and the second luminous flux is coupled to a second solid-state image pickup device through the infrared cut-off filter. A means for dividing the luminous flux into two parts and the infrared cut-off filter are configured on one and the same base material. The output signal levels of a brightness sensor or the two solid-state image pickup devices are detected to automatically switch photographing modes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus suitable for use in a surveillance camera or the like.

[0002]

2. Description of the Related Art In recent years, as imaging devices such as surveillance cameras,
In the daytime normal shooting mode, color light is captured by supplying the imaging light from the subject to the solid-state image sensor through the infrared cut filter, and in the dark night vision mode, the subject is exposed to infrared rays. An imaging device has been proposed which is capable of irradiating and imaging light from the subject to enter the above-mentioned solid-state imaging device so that imaging can be performed even in darkness.

Switching between the normal photographing mode and the night-vision photographing mode of such an image pickup device is realized by changing the presence or absence of an infrared cut filter in front of the same solid-state image pickup device.

[0004]

However, such an image pickup apparatus is provided on the optical path (in front of the solid-state image pickup element) for each photographing mode.
A combination of mechanisms for inserting and removing the infrared cut filter is required. Also, since the same solid-state image sensor is used and the shooting mode is switched only with or without the infrared cut filter,
There is a problem that the sensitivity in the normal photographing mode and the night-vision photographing mode is determined by the characteristics of the solid-state image sensor. Further, it is necessary to switch the shooting mode manually or by turning the switch on and off.

The present invention has been made to solve such a problem, and eliminates the mechanism for inserting and removing the infrared cut filter for each photographing mode, automatically switches the photographing modes, and improves the sensitivity for each photographing mode. An object is to provide an improved imaging device.

[0006]

In the image pickup apparatus of the present invention, a lens unit is arranged on the object side, a light beam from the lens unit is split into two directions, and the first light beam is directly passed to the first solid-state image pickup device. And the second light flux is coupled to the second solid-state imaging device via the infrared cut filter.

Further, the means for splitting the luminous flux into two and the infrared cut filter are constructed on the same substrate. Also, the output signal level of the brightness sensor or the two solid-state image pickup devices is detected and the photographing mode is automatically switched.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram schematically showing an example of the configuration of the present invention. The image pickup device 10 includes a half mirror 2 that reflects the light flux from the lens unit 1 on the subject side.
In this embodiment, the first light flux is coupled as reflected light (R) to the first solid-state image sensor 3 having high infrared sensitivity, and the second light flux is As the transmitted light (T), it is configured to be coupled to the second solid-state imaging device 5 for color photographing through the infrared cut filter 4.

For the half mirror 2, for example, glass BK7 or the like having excellent optical characteristics, on which a metal such as Al or Ag is thinly deposited, is used. Alternatively, a half mirror formed by alternately forming TiO2 and SiO2 with a predetermined film thickness on glass BK7 or the like having excellent optical characteristics may be used. still,
A combination of a high refractive index material H such as TiO2 or ZrO2 and a low refractive index material L such as MgF2 or SiO2 results in transmittance:
Reflectance (T: R) 70:30, 65:35, 60: 4
It can be changed like 0. Confirm the sensitivity characteristics of the solid-state image sensor for color photography and the solid-state image sensor for night-vision photography and select an appropriate half mirror.

The infrared cut filter is formed by alternately depositing TiO2 and SiO2 with a predetermined film thickness on glass BK7 having excellent optical properties, and cutting the low wavelength side of 400 nm or less at a half value.
The one that can cut 650 nm high wavelength side at half value was used. In this case as well, the spectral characteristic is adjusted by the solid-state image sensor selected.

In this apparatus 10, the brightness of the subject is detected by the brightness sensor 7 at the start of photographing. When the brightness sensor 7 detects a brightness equal to or higher than a predetermined value, by selecting the signal output from the second solid-state image sensor 5 side through the infrared cut filter 4, color shooting with good color reproducibility can be achieved. I can do it. When the brightness sensor 7 does not detect brightness equal to or higher than a predetermined value at the time of shooting, the first
The signal on the solid-state image sensor 3 side is selected. Since the first solid-state image pickup element 3 is selected to have a high sensitivity characteristic to infrared light, black-and-white night-vision photography can be performed. Further, by irradiating the subject with infrared light by the infrared irradiation device 6 as necessary, it is possible to perform photographing with higher sensitivity. Although not shown, a brightness detection circuit, a signal processing circuit, a processing microcomputer, etc. are built in.

In this embodiment, the switching of the photographing signal is carried out by the brightness sensor 7. However, at the start of photographing,
The signal output levels of the first solid-state image sensor 3 and the second solid-state image sensor 5 are confirmed, and if the signal of the second solid-state image sensor 5 performing color photographing is higher than a predetermined signal level, the second It is also possible to select the output signal of the solid-state image sensor 5 side for color photographing, and if the signal level is lower than a predetermined signal level, select the signal of the first solid-state image sensor 3 side for monochrome photographing. If the signal level of the first solid-state image sensor 3 is lower than a predetermined value, the infrared irradiation device irradiates infrared rays.

Next, another embodiment of the device of the present invention will be described with reference to FIGS. FIG. 2 is a schematic diagram schematically showing a second embodiment of the present invention. FIG. 3 is a schematic diagram when the half mirror and the infrared cut filter are formed on the same base material. The half mirror 2 and the infrared cut filter 4 in the embodiment shown in FIG.
As described above, a half mirror is formed on the surface a of the glass substrate, and an infrared cut filter is formed on the surface b on the opposite side, so that a member having both functions is formed by one member. As described above, a half mirror and an infrared cut filter can be manufactured by combining a glass substrate with a high refractive index substance H such as TiO2 or ZrO2 and a low refractive index substance L such as MgF2 or SiO2, and controlling the respective film thicknesses. It is possible. For this member, first, glass such as BK7 having excellent optical characteristics is cut into a size capable of vapor deposition and washed. After that, the substrate is set in the vapor deposition device and vapor deposition is performed. At this time, although it depends on the film design, the number of layers of the vapor deposition film of the half mirror is smaller than the number of layers of the infrared cut filter and the residual stress is small, so that it is preferable to perform the half mirror first. The vapor-deposited substrate is divided by dicing or the like into the size of an actually used state to be manufactured. The half mirror side is arranged on the lens side and the infrared cut filter side is arranged on the second solid-state imaging device 5 side of the member of FIG. Others are the same as those in FIG.

[0014]

As described above, according to the present invention, the image pickup apparatus performs color photographing using a signal from the solid-state image pickup device side through the infrared cut filter in the normal photographing mode and infrared cut in the night vision mode. By using a solid-state image pickup device having a sensitivity characteristic on the infrared side without using a filter, black-and-white photographing (night-vision photographing) with high sensitivity can be performed, and at the same time, the photographing mode can be automatically switched.
Further, by constructing the two members of the half mirror and the infrared cut filter on the same base material, the two members become one, so that the mechanism can be made small and easy to design.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a second embodiment of the present invention.

FIG. 3 is a schematic diagram when a half mirror and an infrared cut filter are formed on the same substrate.

[Explanation of symbols]

1 lens unit 2 half mirror 3 First solid-state image sensor (high infrared sensitivity) 4 infrared cut filter 5 Second solid-state image sensor (for color photography) 6 Infrared light irradiation means 7 Brightness sensor 10 Imaging device

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 11/00 G03B 11/00 5C054 15/00 15/00 S 17/17 17/17 // H04N 7/18 H04N 7 / 18 EF term (reference) 2H042 DA02 DA04 DA08 DA12 DB01 DC02 DE00 2H048 FA05 FA09 FA12 FA22 FA24 GA04 GA33 2H083 AA04 AA26 AA32 AA48 AA54 AA58 2H101 FF00 FF06 FF07 5FF022 A18A04 AC05 AC18 A04 AC05 AC4 A51 AC04 5

Claims (5)

[Claims] 1. An image pickup apparatus comprising at least a lens unit, a light splitting means, and two solid-state image pickup elements, wherein the lens unit is arranged on a subject side, and a light beam from the lens unit is divided into two directions by the light splitting means. Split into
The first light flux is directly coupled to the first solid-state image sensor, and the second light flux is transmitted through the infrared cut filter to the second light flux.
An image pickup device characterized by being coupled to the solid-state image pickup element of. 2. The image pickup device according to claim 1, wherein a light splitting means for splitting the light flux into two and an infrared cut filter are formed on the same base material. 3. The image pickup device according to claim 1, further comprising a brightness sensor, wherein the first solid-state image pickup device or the second solid-state image pickup device is selected by the output of the brightness sensor to pick up an image. apparatus. 4. The image pickup device according to claim 1, wherein the first solid-state image pickup device or the second solid-state image pickup device is selected and picked up according to the output signal level of the first or second solid-state image pickup device. Imaging device. 5. The image pickup apparatus according to claim 1, wherein the first solid-state image sensor and the second solid-state image sensor have different sensitivity characteristics to infrared light.