JP2022108330A - Imaging control device, imaging device, imaging system, and charge control method - Google Patents

Abstract

To reduce the average power consumption of an imaging instrument.SOLUTION: An imaging control device comprises: a charge control unit 11 which charges DC power generated by a solar cell 10 to a secondary battery 12; an interface 16 which is connected with an imaging instrument 20 for supply and control of the DC power; a control unit 14 which drives with the DC power; and a non-volatile storage unit which stores information (table and transformation) indicating a relation between the output current or charging current and the exposure condition. The control unit 14 determines the exposure condition of the imaging instrument 20 on the basis of the output current of the charge control unit 11 or the charging current for charging the secondary battery 12, and updates the information according to the brightness of the photographed image photographed by the imaging instrument 20. The control unit 14 drives the imaging instrument 20 under the determined exposure condition and stops the drive of the imaging instrument 20 after imaging.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a photographing control device, a photographing device, a photographing system, and a charging control method, and, for example, to a surveillance camera driven by solar power generation.

River monitoring cameras are installed in rivers to grasp the situation during floods and to encourage residents to evacuate. In addition, river surveillance cameras can be installed at low cost, so there is an increasing need for wireless surveillance cameras that are powered by solar power and do not require the laying of power lines and communication lines.

Patent Document 1 describes a general-purpose camera provided with a solar cell and restricting a photographing operation due to power shortage of the solar cell. Also, it is described that when the current value or power value of the solar cell becomes equal to or less than a threshold value, the power supply to the circuit unit such as the communication unit is turned off. Furthermore, it is described that this threshold value is changed according to the luminance component of the camera unit and the brightness of the surroundings obtained by determining the exposure time.

Japanese Patent Application Laid-Open No. 2008-135846 (claims 1, 4, 8)

By the way, it is necessary to reduce the power consumption of wireless monitoring cameras as much as possible in order to reduce the size and cost of solar cells and storage batteries and to operate the cameras for a long period of time even in the absence of sunlight. In general, a camera consumes a large amount of power during operation, so it is effective to perform an intermittent operation in which the power is turned on only during shooting to shorten the operation time.

However, even with the intermittent operation, it is necessary to correct the exposure time successively not only in the bright daytime but also in the evening or in the dark such as rainy weather. In other words, it is necessary to start the camera and repeat imaging with corrected exposure time until the captured image has appropriate brightness. As a result, the operation time of the camera (photographing device) becomes longer, and the average power consumption increases. As a result, a large-capacity solar cell and a secondary battery are required, and there is a problem that the size and cost of the entire device increase.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a photographing control device, a photographing device, a photographing system, and a charging control method capable of reducing the average power consumption of photographing equipment. With the goal.

In order to achieve the above object, the imaging control device of the present invention connects a charging control unit that charges a secondary battery with DC power generated by a solar cell, and an imaging device for supplying and controlling the DC power. and a control section driven by the DC power, wherein the control section determines the exposure condition of the imaging device based on the output current of the charging control section or the charging current for charging the secondary battery. characterized by

According to the present invention, the average power consumption of imaging equipment can be reduced.

1 is a configuration diagram of a monitoring camera system that is a first embodiment of the present invention; FIG. 3 is a functional configuration diagram of a control section of the imaging device according to the first embodiment of the present invention; FIG. 4 is a flow chart for explaining the operation of the monitoring camera system of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, each figure is only shown roughly to such an extent that the embodiment can be fully understood. Moreover, in each figure, the same code|symbol is attached|subjected about a common component and a similar component, and those overlapping description is abbreviate|omitted.

(First embodiment)
FIG. 1 is a configuration diagram of a surveillance camera system according to the first embodiment of the present invention.
The monitoring camera system 100 includes an imaging device 50, a wireless master device 2, and a server 3, and the imaging device 50 and the server 3 are communicably connected. The photographing device 50 has a photographing device 20 , a solar cell 10 , a secondary battery 12 , and a photographing control device 1 . The imaging device 50 charges the secondary battery 12 with power generated by the solar cell 10, and causes the imaging device 20 to perform intermittent imaging using the charged power. The imaging control device 1 supplies power generated by the solar cell 10 to the imaging equipment 20 and controls the imaging equipment 20 .

The wireless master device 2 mediates communication between the imaging device 50 and the server 3 . The server 3 has a function of receiving and storing a photographed image, illuminance, and exposure time (first exposure setting) from the photographing device 50 (the wireless unit 17 of the photographing control device 1). The server 3 also has an exposure correction unit 3a, which analyzes the stored photographed image and its illuminance, and determines appropriate exposure conditions (for example, exposure time), and notifies the shooting control device 1 of the determined exposure condition (second exposure setting).

The solar cell 10 is a power generation member that converts light energy into electrical energy, and is, for example, an amorphous Si solar cell. The secondary battery 12 is a chargeable/dischargeable battery that stores the DC power generated by the solar battery 10. For example, the secondary battery 12 is formed by connecting two nickel-metal hydride batteries with a rated voltage of 1.2 V in series. That is, the charging voltage V1 of the secondary battery 12 is, for example, 2.4V (2V to 3.1V). Nickel-metal hydride batteries can be charged with less current than lithium-ion batteries and lithium-polymer batteries, so they are well suited to small-scale solar batteries for sensors. Also, the secondary battery 12 is a consumable item and is arranged to be replaceable.

The image capturing device 20 is a camera that captures still images and moving images, and outputs captured images (including captured images). The imaging device 20 is connected to the interface 16 by a power line indicated by a solid line and a control line indicated by a broken line. A power line indicated by a solid line is connected to the switch 15 via the interface 16 . A control line indicated by a dashed line is used for varying the exposure time (shutter speed) and the like. The control line includes a power line for control, and even if the switch 15 is in the OFF state, a small amount of power can be supplied.

In addition, although the photographing device 20 is a fixed lens with a fixed aperture amount, an actuator may be added to electrically vary the aperture amount (F value). Note that the power consumption of the imaging device 20 is, for example, about 400 mW, which is higher than that of the imaging control device 1 .

The imaging control device 1 includes a charging control unit 11, a charging current measuring unit 13, a control unit 14, a switch 15, an interface 16, a wireless unit 17, and a ROM (Read On Memory) 18 as a nonvolatile storage unit. and a RAM (Random Access Memory) 19 as a volatile storage unit.

The charging control unit 11 converts the DC voltage generated by the solar cell 10 into the charging voltage of the secondary battery 12 . The charging control unit 11 has a maximum power point tracking (MPPT) function that maximizes the power generated by the solar cell 10 by controlling the output current of the solar cell 10 . Also, since the charging voltage V1 of the secondary battery 12 is fixed, the power generated by the solar battery 10 and the output current I0 of the charging control unit 11 are proportional.

Charging current measurement unit 13 measures output current I0 of charging control unit 11 . The power generated by the solar cell 10 is proportional to the illuminance. In other words, the output current I0 of the charge controller 11, which is proportional to the power generated by the solar cell 10, is also proportional to the illuminance. Here, the output power of the charge control unit 11 is consumed by the control unit 14, the charging current measurement unit 13, the radio unit 17, etc. even when the switch 15 is in the OFF state. Therefore, the output current I0 of the charging control unit 11 is the sum of the charging current I1 flowing through the secondary battery 12 and the load current I2 flowing through the control unit 14 and the like. If the load current I2 flowing through the control unit 14 and the like is much smaller than the output current I0 of the charging control unit 11, the charging current I1 for charging the secondary battery 12 is also proportional to the illuminance.

By the way, the secondary battery 12 can be fully charged. However, load current I2 always flows. Further, since the secondary battery 12 is charged up to the upper limit voltage for charging by the charging control unit 11, a predetermined charging current I1 _MIN flows even when the secondary battery 12 is fully charged. On the other hand, since the solar cell 10 only needs to be used for intermittent photography, a small amount of generated power is sufficient. Therefore, even if the battery is fully charged, if the power generated by solar cell 10 is V1×(I1 _MIN +I2) or less, all the power generated by solar cell 10 is converted into the output current I0 of charge control unit 11. is proportional to the illuminance.

The switch 15 supplies the DC power stored in the secondary battery 12 and the output power of the charging control unit 11 to the imaging device 20 via the interface 16 or cuts off the power supply under the control of the control unit 14 . or The interface 16 connects the imaging device 20 with, for example, a control line (broken line) used for exposure setting and shutter control and a power line (solid line) connected to the switch 15 . The radio unit 17 uses the DC power stored in the secondary battery 12 and the output power of the charging control unit 11 to communicate with the external radio master device 2 .

The ROM 18 is a non-volatile storage unit that stores programs executed by the control unit 14 and information (tables, conversion formulas, etc.) indicating the relationship between the output current I0 or the illuminance of the charging control unit 11 and the exposure time of the imaging device 20. is. Information (a table, a conversion formula, etc.) indicating the relationship between the charging current I1 flowing through the secondary battery 12 and the exposure time of the imaging device 20 may be stored. A RAM 19 is used as a working memory for the control unit 14 .

FIG. 2 is a functional configuration diagram of the control section of the imaging apparatus according to the first embodiment of the present invention.
The control unit 14 is a CPU (Central Processing Unit), and by executing a program, a charging current measurement control unit 14a, an illuminance estimation unit 14b, an exposure time estimation unit 14c, an exposure time setting unit 14e, an imaging control unit 14f, A function as the server transmission unit 14g is realized.
Charging current measurement control section 14 a causes charging current measurement section 13 to measure output current I0 of charging control section 11 . The illuminance estimator 14b estimates the illuminance received by the solar cell 10 using the measured output current I0. The exposure time estimator 14c estimates the exposure time of the imaging device 20 based on the output current I0 or the illuminance using information such as tables and conversion formulas stored in the ROM 18 in advance. Note that the exposure time estimator 14 c may estimate the exposure time of the imaging device 20 based on the charging current I<b>1 flowing through the secondary battery 12 .

The exposure time setting unit 14 e sets the estimated exposure time in the imaging device 20 . The photographing control unit 14f controls the switch 15 to supply the DC power stored in the secondary battery 12 to the photographing device 20 and causes the photographing target to be photographed. Furthermore, the imaging control unit 14f controls the switch 15 after imaging to cut off the power supply to the imaging device 20. FIG. This saves power. The server transmission unit 14g controls the wireless unit 17 to transmit the captured image, the illuminance, and the exposure time to the server 3 via the wireless base unit 2. FIG.

FIG. 3 is a flow chart for explaining the operation of the monitoring camera system of the present invention.
This flow is periodically executed when the imaging device 50 monitors the monitoring target, for example, once every 15 minutes or once every 30 minutes.
The control unit 14 of the imaging device 50 causes the charging current measuring unit 13 to measure the output current of the charging control unit 11 or the charging current of the secondary battery 12 (S1). After the process of S1, the control unit 14 estimates the illuminance based on the measured current (the output current of the charging control unit 11 or the charging current of the secondary battery 12) measured by the charging current measuring unit 13 (S2). Specifically, using information (tables and conversion formulas) stored in the ROM 18, the illuminance is obtained from the measured current.

After the processing of S2, the control unit 14 calculates exposure conditions based on the measured current measured in S1 and the illuminance estimated in S2, and sets the calculated exposure conditions (exposure time and aperture amount) in the photographing device 20 ( S3). After setting the exposure conditions, the control unit 14 turns on the switch 15 to activate the photographing device 20 (S4) and to photograph (S5). When the photographing is completed, the control unit 14 turns off the switch 15 to stop the photographing device 20 (S6). This reduces the average power consumption of the imaging device 50 (FIG. 1). After the process of S6, the control unit 14 transmits the captured image, the illuminance, and the exposure condition (first exposure setting) set in S3 to the server 3 (S7).

The server 3 receives the captured image, the illuminance, and the first exposure setting, and evaluates the brightness of the captured image (S8). The brightness of the captured image may be the average brightness of the entire image or the brightness of a specific portion of the captured image. After evaluating the brightness of the photographed image, the exposure correction unit 3a (FIG. 1) calculates the average luminance of the currently received photographed image and the average luminance of previously received photographed images with appropriate brightness, and calculates the average luminance A new exposure time (second exposure setting) is calculated based on the difference between (S9).

Normally, the installation location of the photographing device 20 and the location of the object to be monitored have approximately the same illuminance. However, for example, when a new building is constructed near the subject, the illuminance at the location of the photographing device 20 does not change, but the vicinity of the subject is shaded. Sometimes it becomes That is, in S9, when the captured image received in S8 is too bright or too dark, the exposure corrector 3a (FIG. 1) calculates an appropriate exposure time (shutter speed).

After the processing of S9, the server 3 transmits the exposure time (second exposure setting) calculated in S9 to the photographing device 50 (S10).

Based on the received second exposure setting (exposure time), the control unit 14 of the photographing device 50 updates the information (coefficients and tables of the calculation formula) stored in the ROM 18 (S11), and ends this flow. In S3 from the next time onward, the updated exposure conditions are set in the photographing device 20 .

As described above, according to the monitoring camera system 100 (FIG. 1) of the present embodiment, using the output current of the charging control unit 11 corresponding to the power generated by the solar cell 10 and the charging current of the secondary battery 12, The illuminance is estimated and the exposure time is set for the imaging device 20 . As a result, even if the illuminance is insufficient due to cloudiness or rain, it is possible to acquire a photographed image with appropriate brightness.

Also, after setting the exposure time in the photographing device 20, the switch 15 is turned on to drive the photographing device 20.例文帳に追加Therefore, the operation time of the imaging device 20 can be shortened, and the average power consumption can be reduced. This reduces the required capacity of the solar cell 10 and the secondary battery 12, reduces the size and cost, and enables long-term non-sunshine operation. Furthermore, by updating the exposure time of the photographing equipment 20 using the brightness of the photographed image transmitted to the server 3, even if some environmental changes occur, the photograph can be taken under appropriate exposure conditions. You can shoot.

(Modification)
The present invention is not limited to the above-described embodiments, and for example, the following modifications are possible.
(1) In the above-described embodiment, the program executed by the control unit 14 and the information (table, conversion formula, etc.) indicating the relationship between the output current I0 or the illuminance of the charging control unit 11 and the exposure time of the photographing device 20 are non-volatile. However, the information stored in the server 3 may be received and stored in the RAM 19 .

(2) In the above-described embodiment, after setting the exposure conditions for the photographing device 20 (S3), the photographing device 20 is started (S4). I don't mind if you go. Although power consumption increases by the time the exposure conditions are set, the average power consumption is low because shooting is not repeated until the optimum exposure conditions are determined.

Reference Signs List 1 imaging control device 3 server 10 solar cell 11 charging control unit 12 secondary battery 13 charging current measurement unit 14 control unit 15 switch 16 interface 17 wireless unit 18 ROM (storage unit)
20 photographing equipment 50 photographing device 100 surveillance camera system

Claims (11)

a charging control unit that charges the secondary battery with the DC power generated by the solar battery;
an interface for connecting imaging equipment for supplying and controlling the DC power;
A control unit driven by the DC power,
A photographing control apparatus, wherein the control unit determines exposure conditions of the photographing equipment based on the output current of the charging control unit or the charging current for charging the secondary battery. The imaging control device according to claim 1,
A photographing control apparatus, wherein the control unit drives the photographing equipment under the exposure conditions, and stops driving the photographing equipment after photographing. The imaging control device according to claim 2,
further comprising a storage unit that stores information indicating the relationship between the output current or the charging current and the exposure condition;
The photographing control device, wherein the control unit updates the information according to the brightness of the photographed image photographed by the photographing device. The imaging control device according to claim 1,
The imaging control device, wherein the output current or the charging current is equal to or less than the charge termination current that flows when the secondary battery is fully charged. a charging control unit that charges the secondary battery with the DC power generated by the solar battery;
an interface for connecting imaging equipment for supplying and controlling the DC power;
A control unit driven by the DC power,
The photographing control apparatus, wherein the control unit determines exposure conditions of the photographing equipment based on power generated by the solar cell. The imaging control device according to any one of claims 1 to 5,
The imaging control device, wherein the exposure condition is either one or both of an exposure time and an aperture amount. a charging control unit that charges the secondary battery with the DC power generated by the solar battery;
a photographing device driven by the DC power;
A control unit driven by the DC power,
The photographing apparatus according to claim 1, wherein the control section determines an exposure condition of the photographing device based on an output current of the charging control section or a charging current for charging the secondary battery. a charging control unit that charges the secondary battery with the DC power generated by the solar battery;
an interface for connecting imaging equipment for supplying and controlling the DC power;
A control unit driven by the DC power,
The photographing apparatus, wherein the control unit determines exposure conditions of the photographing equipment based on the power generated by the solar cell. A photographing device, a charging control unit that charges a secondary battery with DC power generated by a solar cell, an interface that connects the photographing device for supplying and controlling the DC power, and a control that is driven by the DC power. and a server communicably connected to the imaging control device, wherein
The imaging control device further includes a non-volatile storage unit that stores a table showing the relationship between the charging current for charging the secondary battery and the exposure conditions of the imaging device,
The server receives a photographed image photographed by the photographing device, calculates the brightness of the photographed image, and uses the calculated brightness to set a first exposure condition for updating the exposure condition to the photographing control device. send to
The control unit determines a second exposure condition of the photographing device based on the output current of the charging control unit or the charging current for charging the secondary battery, and the photographing device is operated under the determined second exposure condition A photographing system, wherein an image is taken, the photographed image is transmitted to the server, and the table is updated based on the first exposure condition received from the server. The imaging system according to claim 9,
The photographing system, wherein the control unit drives the photographing equipment after determining exposure conditions of the photographing equipment, and stops driving the photographing equipment after photographing. A charging control unit that charges a secondary battery with DC power generated by a solar cell, an interface that connects a photographing device for supplying and controlling the DC power, and a control unit that is driven by the DC power. A shooting control method executed by a shooting control device,
A photographing control method, wherein the exposure condition of the photographing equipment is determined based on the output current of the charging control unit or the charging current for charging the secondary battery.

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