JP2000235212A - Monitoring camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute the changeover of a photographing mode by attaching and detaching a filter with simple structure. SOLUTION: A photographing lens 4, a CCD image sensor 11 which is an image pickup means and the filter 19 cutting infrared ray are housed at the lens barrel part of a monitoring camera. Pins 21 and 23 are respectively provided at the photographing lens 4 and the filter 19. The pins 21 and 23 are respectively engaged with a cam groove 31 and an oblong hole 32 provided at a changeover plate 12. When the changeover plate 12 is rotated, the attaching and detaching of the filter 19 and the focusing of the photographing lens 4 caused by it are executed by this engagement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surveillance camera having a function of switching a photographing mode by inserting and removing a filter having wavelength selectivity.

[0002]

2. Description of the Related Art There is a surveillance camera which is installed and used at a specific place. The surveillance camera is used, for example, to monitor traffic to and from people entering and exiting the location, and the traffic conditions of cars and the like at the location. Such a surveillance camera is often used in a place where shooting light is insufficient, such as indoors or at night, or in a time zone. However, in such a case, the surveillance camera cannot use visible light such as strobe light as auxiliary light due to the nature of surveillance.
For this reason, a surveillance camera uses invisible infrared light as auxiliary light, and performs infrared imaging using this.

[0003] In such a surveillance camera, an infrared light irradiating device (infrared light flash) for irradiating an object with infrared light is provided in order to perform infrared imaging together with visible light imaging. An image sensor such as a CCD capable of capturing an optical image using both lights is provided. Thus, the photographing can be performed regardless of the brightness of the subject and without the subject being noticed.

[0004]

However, when the above-described image pickup means is used, for example, even when photographing under sunlight that does not require auxiliary light (infrared light), infrared light contained in sunlight can be used. Is exposed, and the color and contrast of an image taken during the day are far from human vision.
Therefore, when shooting is performed continuously regardless of day and night, switching of the shooting mode has been considered as a measure against the infrared light. Specifically, for example, in the daytime shooting, shooting is performed using an infrared light cut filter that reduces infrared light, and in nighttime shooting, infrared shooting is performed without using this filter. A method of switching between two shooting modes, a shooting mode and an infrared light shooting mode, has been considered.

As described above, when the photographing mode is switched depending on whether or not the infrared cut filter is used, it is necessary to insert and remove the filter on the photographing optical path. The infrared light cut filter is obtained, for example, by coating a glass substrate with a multilayer film for cutting infrared light. Since the refractive index of the glass serving as the substrate is different from that of air, the imaging optical path length changes. For this reason, it is necessary to perform focus correction with insertion and removal of the filter. Also, since the monitoring camera is usually installed in a place where no operator is present and used by remote control or automatic shooting,
It is desirable that the switching of the photographing mode be performed simply and automatically.

However, if the insertion and removal of the filter and the focus correction are to be performed automatically or by remote control, it is necessary to provide a drive motor for moving the filter and the lens. And, as a result, an increase in manufacturing cost. In addition, such a complicated structure causes an increase in the number of components, which also affects the failure rate.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems, and has as its object to be able to switch a photographing mode with a simple structure.

[0008]

In order to achieve the above object, a surveillance camera according to the present invention comprises: a photographing lens; an image pickup means for picking up an optical image formed by the photographing lens; A filter having a wavelength selectivity provided detachably, and selecting one of a first photographing mode in which the filter is inserted into the photographing optical path and a second photographing mode in which the filter is retracted outside the photographing optical path. A mode switching unit, and a focus correction unit that moves the taking lens in the optical axis direction in conjunction with the switching between the first and second photographing modes and performs focus correction of the taking lens based on the presence or absence of the filter. It is assumed that.

The imaging means has sensitivity to visible light and infrared light, and the filter comprises an infrared light cut filter for transmitting visible light and cutting infrared light. An infrared light irradiating device for irradiating infrared light toward a subject in the mode is provided.

The photographing mode switching means includes a switching member that is displaced between a first position for moving the filter into the photographing optical path and a second position for retracting the filter from the photographing optical path, and the focus correction means. Is characterized by comprising a cam formed on the switching member and a cam follower fixed to the taking lens and engaged with the cam.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A surveillance camera 2 shown in FIG. 2 is installed at a specific place and shoots a still image of the place at regular intervals, and uses a CCD image sensor as an image pickup means. Electronic still camera.

The surveillance camera 2 can perform photographing in two photographing modes. The two photographing modes include a first photographing mode (hereinafter, referred to as a normal photographing mode) in which photographing is performed using external light such as sunlight or indoor lighting, and an infrared light that is directed toward a subject. A second photographing mode for performing infrared photographing with reflected light (hereinafter referred to as an infrared photographing mode). The switching of the photographing mode is automatically performed, for example, in response to a change in the photographing light amount at the photographing place. The method of switching the shooting mode may be arbitrarily performed by remote control, or may be automatically set by setting a switching time in a built-in timer in advance.

The surveillance camera 2 comprises a main body 3 and a lens barrel 6 for housing a taking lens 4. On the front surface of the main body 3, an infrared light emitting section 5 for irradiating infrared light toward a subject is provided above the lens barrel 6.
Inside the main body 3, a lens barrel 6, an infrared light emitting section 5,
In addition to a controller consisting of a drive unit and a timer, etc., for driving the like, a memory for recording captured image data, a data transmission device for exchanging control signals and transmitting image data with a remote monitor room, a photographing mode A drive motor (13 described later) for performing the switching, a power supply and the like are incorporated.

The infrared light emitting section 5 is turned on when switched to the infrared photographing mode, and emits infrared light when photographing is performed in this mode. For this reason, even when the shooting place is dark, such as at night, shooting can be performed. In addition, since infrared light is used, shooting can be performed without noticing the subject.

A support member for fixing the monitoring camera 2 is attached to the lower surface of the main body 3. This support member is selected according to the installation location. The photographing of the monitoring camera 2 is performed, for example, automatically at regular intervals.
The time interval of this automatic photographing is set in a timer in advance.
Of course, instead of setting the time interval, a fixed time may be set in advance, and shooting may be performed at the time. The photographed image data is recorded in a memory and read out by remote control. Alternatively, the image data may be automatically sent to a remote monitor room.

As shown in FIG. 3, the lens barrel 6 includes a photographing lens 4 and an infrared light cut filter 7, and a front barrel 8 and a rear barrel 9 that movably support them. It has. The taking lens 4 is incorporated in a lens holding frame 18, and subject light enters the taking lens 4 through the opening 14 of the front lens barrel 8. The lens holding frame 18 is attached to the front lens barrel 8.
Is supported movably in the direction of the optical axis by a guide mechanism formed in the inside thereof, and a pin 21 protrudes from the outer periphery thereof. The pin 21 projects out of the front lens barrel 8 through a long hole 16 extending in the optical axis direction on the side surface of the front lens barrel 8.
By moving the lens 1 in the optical axis direction, the photographing lens 4 is moved.
Can be moved together with the lens holding frame 18 in the same direction.

The infrared light cut filter 7 is formed by coating a transparent glass substrate with a multilayer film that transmits visible light and blocks infrared light, and is mounted on a filter holding frame 19 provided with projections 22 on both side surfaces. Fixed. These projections 22
Is engaged with a guide groove 17 formed on the rear end edge of the front lens barrel 8, and moves the pin 23 protruding from the filter holding frame 19 up and down to hold the infrared light cut filter 7 in the filter. It can be moved in the vertical direction across the photographing optical axis together with the frame 19.

An opening 28 is formed on the rear surface of the rear lens barrel 9. The CCD 28 is so positioned that the light receiving surface is located in the opening 28.
The image sensor 11 is attached. The CCD image sensor 11 is an imaging unit that converts an optical image formed by the photographing lens 4 into an electric signal. This C
The CD image sensor 11 has sensitivity not only in the visible light region but also in the infrared light region, and outputs a monochrome imaging signal. Note that a color image sensor combining R, G, and B micro color filters may be used to obtain a color image signal for visible light. In this case, a red filter (for red transmission) is used for red light. What is necessary is just to have external light transmission characteristics.

The CCD image sensor 11 is
It also functions as a photometric device for the amount of photographing light, and the switching of the photographing mode is automatically performed according to a change in the amount of photographing light received by the sensor 11 through the photographing lens 4. A predetermined value is set in advance for the photographing light amount serving as a reference for switching the photographing mode. As described above, since the shooting mode is switched according to the change in the shooting light amount, unlike the case where the switching is performed by setting the timer to a fixed time, for example, when the sunrise or sunset time changes depending on the season, It is possible to respond automatically.

The switching plate 12 is rotatably mounted by inserting a bearing hole 29 provided at the center of the switching plate 12 into a shaft 26 provided in the rear lens barrel 9. The switching plate 12 has a long hole 32 extending in the radial direction and a cam groove 31 extending in the circumferential direction. The pin 23 projecting from the filter holding frame 19 is engaged with the elongated hole 32, and the pin 21 projecting from the lens holding frame 18 is engaged with the cam groove 31. When the switching plate 12 is set to the first position shown in the drawing, the infrared light cut filter 7 is in the normal photographing mode in which it is inserted in the photographing optical path, and the switching plate 12 is rotated clockwise from the position shown in the drawing to the second position. Is set to the infrared photographing mode in which the infrared light cut filter 7 descends and retreats outside the photographing optical path.

The switching plate 12 is rotated between the first position and the second position by the forward / reverse rotation of the drive motor 13, and as a result, a normal photographing mode using the infrared light cut filter 7 is provided. A photographing mode switching means for switching between an infrared photographing mode not using the infrared light cut filter 7 is constituted. The drive of the motor 13 is automatically controlled in response to a change in the amount of photographing light at the photographing place.
It is also possible to control the drive by remote control or a timer.

When the switching plate 12 is set to the first position and the normal photographing mode is selected, the photographing lens 4 is taken into consideration in consideration of the fact that the infrared light cut filter 7 is inserted in the photographing optical path. Are positioned in the optical axis direction. Then, when the switching plate 12 is rotated to the second position and the second photographing mode is selected, the lens holding frame 18 retreats on the optical axis due to the engagement between the pin 21 and the inclined portion 31a of the cam groove 31. . The amount of this retreat is taken into consideration in consideration of the fact that the optical path length from the taking lens 4 to the CCD image sensor 11 becomes shorter due to the retreat of the infrared light cut filter 7 having a constant glass thickness from the taking optical path. It is decided. Therefore, the cam groove 31 formed in the switching plate 12 and the pin 21 provided as a cam follower in the lens holding frame 18 provide focus correction for correcting the focus of the photographing lens 4 in accordance with insertion and removal of the infrared light cut filter 7. Functions as a means.

The operation of the above-described configuration will be briefly described with reference to FIG. First, in the normal photographing mode shown in FIG. 1A, the infrared light cut filter 7 is inserted on the photographing optical path, and is located behind the photographing lens 4. At this time, the switching plate 12 is set at the first position. The pin 21 is engaged at an end opposite to the inclined portion 31a. On the other hand, the pin 23 is engaged with the outer peripheral end of the long hole 32.

When a certain time has elapsed, a timer is activated and C
The CD image sensor 11 is driven to record a still image. In the normal photographing mode, infrared light included in sunlight or the like is cut by the infrared light cut filter 7. Therefore, a monochrome image can be recorded with a contrast close to human vision.

When the photographing light amount received by the CCD image sensor 11 becomes equal to or less than a predetermined value, the normal photographing mode is switched to the normal photographing mode.
Switching to the infrared photographing mode shown in (B) is performed.
By this switching, the infrared light irradiation device is turned on. In addition, the drive motor 13 is operated to rotate the switching plate 12 from the first position to the second position.

When the switching plate 12 starts rotating clockwise, the infrared light cut filter 7 starts moving downward together with the pin 23 engaging with the elongated hole 32. Switching board 1
2 rotates about 90 degrees, the infrared light cut filter 7
It is completely retracted from the shooting optical path. On the other hand, the pin 21
For a while after the start of rotation of the switching plate 12,
And the state of sliding contact continues. Until the pin 21 is engaged with the inclined portion 31a, the photographing lens 4 is naturally not moved.

When the switching plate 12 further rotates and the inclined portion 31a starts engaging with the pin 21, the pin 21 starts moving toward the center. Accompanying this, the taking lens 4
Starts moving backward along the optical axis direction. The point at which the photographing lens 4 starts moving is after the infrared light cut filter 7 has completely retracted, so that the filter 7 does not hit the photographing lens 4. And the switching plate 1
The rotation of No. 2 stops at the second position.

The rotation of the switching plate 12 retreats the infrared light cut filter 7 from the photographing optical path to switch the photographing mode, and moves the photographing lens 4 rearward to perform focus correction. In the switched infrared photographing mode, after a certain period of time, a timer is operated to perform photographing. At this time, infrared light is emitted from the infrared light emitting unit 5 toward the subject. This reflected light enters the taking lens 4. Since the infrared cut filter 7 is retracted from the photographing optical path, the light passing through the photographing lens 4 forms an image directly on the CCD image sensor 11.

Although the above embodiment has been described with reference to the drawings, the present invention is not limited to this, and various modifications can be made. In the above embodiment, an electronic still camera that records a still image has been described as an example, but a video camera may be used to record a moving image. In the case of recording with this video camera, for example, if short-time shooting is performed at regular time intervals, the amount of tape consumed can be saved, and the number of tape replacements can be reduced. At the same time, it can be used to record not only the situation of the place at a certain time but also the transition of the situation for each time zone.

Also, a filter that cuts infrared light has been described as a filter to be inserted and removed. However, other than this, for example, a filter that cuts light of a certain wavelength out of visible light and performs color correction can be used. Good. As described above, when the infrared imaging is not performed, the infrared light irradiating device is, of course, unnecessary.

[0031]

As described above in detail, the surveillance camera according to the present invention comprises a photographing lens, an image pickup means for picking up an optical image formed by the photographing lens, and a detachable and removable light in a photographing optical path. A filter having a wavelength selectivity provided; and a photographing mode switching means for selecting one of a first photographing mode in which the filter is inserted into the photographing optical path and a second photographing mode in which the filter is retracted outside the photographing optical path. , The first,
Focus correction means for moving the photographing lens in the optical axis direction in conjunction with the switching of the second photographing mode and performing focus correction of the photographing lens depending on the presence or absence of the filter is provided. Switching of the photographing mode can be performed with a simple structure, for example, by only one. This facilitates automation of the switching of the shooting mode and remote control. At the same time, cost reduction and failure rate reduction can be achieved.

Further, the photographing mode switching means includes:
A switching member displaced between a first position for moving the filter into the imaging optical path and a second position for retracting the filter from the imaging optical path, wherein the focus correction unit includes a cam formed on the switching member; Since it is composed of a cam follower fixed to the taking lens and engaged with the cam,
The number of parts can be reduced, and the structure can be further simplified. Therefore, in terms of cost and failure rate,
The effect can be further improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a positional relationship between a photographing lens and a filter in each photographing mode.

FIG. 2 is an overall perspective view of the monitoring camera.

FIG. 3 is an exploded perspective view of a lens barrel.

[Explanation of symbols]

 2 Surveillance Camera 4 Shooting Lens 7 Infrared Light Cut Filter 12 Switching Plate 21, 23 Pin 31 Cam Groove 32 Slot

Claims (3)

[Claims] 1. A photographing lens, imaging means for photographing an optical image formed by the photographing lens, a wavelength-selective filter removably provided in a photographing optical path, and a photographing optical path A photographing mode switching unit for selecting one of a first photographing mode inserted in the camera and a second photographing mode in which the filter is retracted outside the photographing optical path;
A surveillance camera, comprising: a focus correction unit that moves a photographing lens in an optical axis direction in conjunction with switching of a second photographing mode, and corrects focus of the photographing lens based on the presence or absence of the filter. 2. The image pickup means has sensitivity to visible light and infrared light, and the filter includes an infrared light cut filter that transmits visible light and cuts infrared light.
The surveillance camera according to claim 1, further comprising an infrared light irradiation device that irradiates the subject with infrared light in the second shooting mode. 3. The photographing mode switching means includes a switching member that is displaced between a first position for moving the filter into a photographing optical path and a second position for retracting the filter from the photographing optical path, and the focus correction means. The surveillance camera according to claim 1, further comprising: a cam formed on the switching member; and a cam follower fixed to a photographing lens and engaged with the cam.