A filter switching device and a smart camera for day and night monitoring using the device.

Abstract

This invention discloses a filter switching device and a smart camera for day and night monitoring using the device. The filter switching device includes a dual bandpass filter, a left-hand circularly polarized light (CLC), and a right-hand circularly polarized light (CLC) stacked sequentially. The left-hand and right-hand CLCs are connected to a driving circuit via electrodes. The driving circuit controls the power supply to the left-hand and right-hand CLCs. The dual bandpass filter allows both band A and band B to pass through. The left-hand CLC is configured to reflect left-hand circularly polarized light of band A and transmit right-hand circularly polarized light of band A when power is off. The right-hand CLC is configured to reflect right-hand circularly polarized light of band A and transmit left-hand circularly polarized light of band A when power is off. Both the left-hand and right-hand CLCs allow both band A and band B to pass through when power is on. This invention's filter switching device achieves efficient switching between visible and infrared light through an electrically controlled filter, replacing the traditional mechanical filter structure.

Description

Technical Field

[0001] This utility model belongs to the technical field of surveillance cameras, and relates to a filter switching device and a smart camera for day and night monitoring using the device. Background Technology

[0002] Currently, outdoor surveillance cameras typically use a mechanical motor to drive an infrared filter (IR-Cut) to achieve day / night mode switching, with a structure as follows: Figure 1 :

[0003] During the day: An infrared filter is inserted to block near-infrared light (above 700nm) and allow only visible light (400-700nm) to pass through, thus avoiding infrared light interference with color reproduction.

[0004] At night: The infrared filter is removed to allow near-infrared light (such as 800-900nm) to pass through, which, together with the infrared supplement light, enables night vision.

[0005] Disadvantages of existing technology:

[0006] Complex mechanical structure: Components such as motors and filter brackets occupy a lot of space, increasing the size and cost of the camera.

[0007] Low reliability: Mechanical parts are prone to wear and jamming, especially in extreme temperature or dusty environments.

[0008] Slow response time: Filter switching takes hundreds of milliseconds, affecting real-time monitoring performance. Utility Model Content

[0009] The purpose of this invention is to address the problems of large size, high cost, poor reliability, and slow response speed of traditional mechanical IR-Cut filters in the prior art. It proposes a filter switching device and a smart camera for day and night monitoring using this device. The filter switching device of this invention achieves efficient switching between visible light and infrared light through an electrically controlled filter, replacing the traditional mechanical filter structure.

[0010] To achieve the aforementioned technical objective, the technical solution adopted by this utility model is as follows:

[0011] A filter switching device includes a dual bandpass filter, a left-hand circularly polarized light (CLC), and a right-hand circularly polarized light (CLC) stacked sequentially. The left-hand and right-hand CLCs are connected to a driving circuit via electrodes. The driving circuit controls the power supply to and off of the left-hand and right-hand CLCs. The dual bandpass filter allows both band A and band B to pass through. The left-hand CLC is configured to reflect left-hand circularly polarized light of band A and transmit right-hand circularly polarized light of band A when powered off. The right-hand CLC is configured to reflect right-hand circularly polarized light of band A and transmit left-hand circularly polarized light of band A when powered off. Both the left-hand and right-hand CLCs allow both band A and band B to pass through when powered on.

[0012] To optimize the aforementioned technical solution, the specific measures also include:

[0013] The aforementioned band A is the near-infrared band, and band B is the visible light band.

[0014] The aforementioned dual bandpass filter is bonded and fixed to the left-hand CLC, and the left-hand CLC is bonded and fixed to the right-hand CLC using optical adhesive.

[0015] The aforementioned day and night monitoring smart camera uses a filter switching device, which includes a camera body and the filter switching device is installed at the front end of the camera body.

[0016] The aforementioned camera body is also equipped with an infrared fill light in front of the filter switching device. The infrared fill light is connected to the driving circuit. When the driving circuit powers the left-hand CLC and the right-hand CLC, it simultaneously powers the infrared fill light.

[0017] CLC stands for "Cholesteric Liquid Crystal".

[0018] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0019] 1. The filter switching device of this utility model has no mechanical structure: the motor and moving filter are eliminated, the volume is reduced by more than 20%, and the cost is reduced.

[0020] 2. The filter switching device of this utility model can respond quickly: the electronic switching time can be shortened to the millisecond level (the traditional mechanical type requires more than 100ms).

[0021] 3. The filter switching device of this utility model has high reliability: no mechanical wear, and is suitable for harsh environments such as high and low temperatures and high humidity. Attached Figure Description

[0022] Figure 1 It is the traditional mechanical IR-Cut filter mentioned in the background section;

[0023] Figure 2 This is a structural diagram of the filter switching device of this utility model;

[0024] Figure 3 This is a simplified diagram of a smart camera that monitors day and night.

[0025] Figure 4 These are the spectra of the CLC when it is powered on and off;

[0026] Figure 5 This is the spectrum of a dual bandpass filter.

[0027] The attached labels in the figure are: dual bandpass filter 1, left-handed CLC 2, right-handed CLC 3, optical adhesive 4, and camera body 5. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0029] Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0030] like Figure 2 As shown, the filter switching device of this utility model includes a dual bandpass filter 1, an optical adhesive 4, a left-handed CLC 2, another optical adhesive 4, and a right-handed CLC 3 stacked sequentially.

[0031] The dual-bandpass filter 1 can be a coating or a lens. The characteristics of the dual-bandpass filter 1 are: it allows the 400–700 nm (visible light) and 800–900 nm (near-infrared light) wavelengths to pass through, while cutting off other wavelengths. For example... Figure 5 As shown in the figure, parameter "θ" represents the viewing angle. The left-handed CLC2 and right-handed CLC3 reflection bands are designed for near-infrared (e.g., 800–900 nm). Figure 4 As shown.

[0032] The characteristics of the filter switching device of this utility model are as follows:

[0033] Power-on state: Allows 400-700nm (visible light) and 800-900nm (near-infrared light) to pass through, while other wavelengths are cut off.

[0034] Power off state: Only 400-700nm (visible light) is allowed to pass through, other wavelengths are cut off.

[0035] 2. Control logic for day and night monitoring smart cameras:

[0036] Daytime mode: The filter switching device is powered off, allowing only visible light to pass through, avoiding infrared interference.

[0037] Night mode: When the filter switching device is powered on, the infrared fill light is turned on simultaneously, and the night vision effect is enhanced by the use of both visible and near-infrared light.

[0038] The following explains the working principles of left-handed CLC2 and right-handed CLC3:

[0039] When CLC2 and right-handed CLC3 are energized: the strong electric field forces the two CLC layers into a uniform transparent state, losing polarization selectivity and reflectivity.

[0040] Power off (voltage returns to zero): The electric field disappears, and the two CLC layers relax back to the plane state, restoring their inherent selective reflection capability for light of specific wavelengths and directions.

[0041] CLC pitch design: When the two CLC layers are in a planar state, their reflection bands precisely cover the 800-900nm wavelength band (left-handed CLC reflects left-handed light, right-handed CLC reflects right-handed light), while being transparent to the visible light band (400-700nm).

[0042] The polarization combination "switch" of the double CLC layer:

[0043] When power is off (planar state), the two CLC layers with opposite rotation directions combine to act as a "circularly polarization-independent" mirror / optical shutter for the 800-900nm wavelength band. Regardless of the polarization state of the incident near-infrared light, its left-handed component is reflected by the first layer, and its right-handed component is reflected by the second layer, effectively blocking (cutting off) this wavelength band. Visible light, however, passes through unimpeded.

[0044] When powered on (in a homogeneous state), both CLC layers become transparent "windows," allowing visible and near-infrared light, which are permitted by the filter, to pass through freely.

[0045] It should be noted that the embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model, and all such modifications and substitutions should be covered within the scope of the claims of this utility model.

[0046] The embodiments described are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited to the embodiments described. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present utility model shall be considered equivalent substitutions and shall be included within the protection scope of the present utility model.

Claims

1. A filter switching device, characterized in that, The device includes a dual bandpass filter (1), a left-hand circularly polarized light (CLC) (2), and a right-hand circularly polarized light (CLC) (3) stacked in sequence. The left-hand CLC (2) and the right-hand CLC (3) are connected to a driving circuit via electrodes. The driving circuit controls the power supply of the left-hand CLC (2) and the right-hand CLC (3). The dual bandpass filter (1) allows band A and band B to pass through. The left-hand CLC (2) is configured to reflect left-hand circularly polarized light of band A and transmit right-hand circularly polarized light of band A when the power is off. The right-hand CLC (3) is configured to reflect right-hand circularly polarized light of band A and transmit left-hand circularly polarized light of band A when the power is off. Both the left-hand CLC (2) and the right-hand CLC (3) allow band A and band B to pass through when the power is on.

2. The filter switching device according to claim 1, characterized in that, The band A is the near-infrared band, and the band B is the visible light band.

3. The filter switching device according to claim 1, characterized in that, The dual bandpass filter (1) and the left-hand CLC (2), and the left-hand CLC (2) and the right-hand CLC (3) are bonded and fixed together by optical adhesive (4).

4. A smart camera for day and night monitoring, characterized by: The application of the filter switching device as described in claim 2 includes a camera body (5), and the filter switching device is installed at the front end of the camera body (5).

5. The intelligent surveillance camera for day and night monitoring according to claim 4, characterized in that: The camera body (5) is also equipped with an infrared fill light in front of the filter switching device. The infrared fill light is connected to the driving circuit. When the driving circuit powers the left-hand CLC (2) and the right-hand CLC (3), it simultaneously powers the infrared fill light.

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