JP2012053144A - Video camera apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video camera apparatus in which current flowing to an LED for illumination can be effectively utilized for a video camera unit, the operation of the apparatus can be kept even when a power supply voltage drops, and a reduction in light emission amount is suppressed.SOLUTION: The video camera apparatus comprises: a power supply input section 40 which is connected to a power supply 100 outside the apparatus; an illumination unit 20 which has multiple LEDs (D1, D2 and D3) for illumination and multiple switches S1 to S6; a video camera unit 30 which photographs an area illuminated with the LEDs for illumination of the illumination unit 20 to output a video signal; a voltage generation section 50 which generates voltage needed for the video camera unit 30; and a power supply voltage monitoring section 70 which monitors a voltage value of the power supply outside the apparatus. When the power supply voltage is normal, all the multiple LEDs are connected in series between the power supply input section and the voltage generation section. When the power supply voltage monitoring section detects a reduction in the power supply voltage, a part of or all the multiple LEDs are so changed as to be connected in parallel by operating the switches.

Description

  The present invention relates to a video camera device, and more particularly to a video camera device with an illumination function that performs shooting while illuminating a shooting range with LED illumination.

  In recent years, video cameras have been miniaturized and installed and used in various places. For example, cameras for crime prevention in shops, cameras for monitoring factory lines, etc. for commercial and industrial purposes, cameras installed on intercoms etc. to photograph visitors, vehicles installed to project the driver's vision There is no limit to enumerating home use such as cameras.

  Some of these video cameras have an illumination function to illuminate the shooting range so that a good image can be obtained when using at night or in a dark place. . As an illumination function, an LED (Light Emitting Diode) is generally used because of its advantages such as low cost, small size, light weight, and long life. For example, Patent Document 1 describes that a video camera device in which a video camera and an infrared LED are integrated is attached to a vehicle door mirror or the like for use in monitoring the side of a vehicle or the like.

  In a conventional video camera device having an illumination function, as disclosed in Patent Document 1, a current is separately supplied to the LED illumination unit and the video camera unit from a power source outside the device, respectively. It was. That is, the current flowing through the illumination unit is used only for lighting the illumination LED, and there is a problem in the effective use of the current.

  The present invention can effectively use the current flowing in the lighting LED even in the video camera unit, and can maintain the operation of the apparatus even when the power supply voltage is reduced, and can suppress the decrease in the light emission amount. An object of the present invention is to provide a video camera device with a lighting function.

  In order to achieve the above object, a video camera device with an LED illumination function according to the present invention includes a power input unit connected to a power supply outside the device, an illumination unit having an illumination LED, and an illumination LED of the illumination unit. A video camera unit that shoots an illuminated area and outputs a video signal, and a voltage generation unit that generates a voltage required by an internal circuit of the video camera unit. The basic configuration is that it is inserted in series between the voltage generator and the voltage generator. This makes it possible to effectively use the current flowing through the illumination LED even in the video camera unit.

  The video camera device with an LED illumination function of the present invention further includes a power supply voltage monitoring unit that monitors a voltage value of a power supply outside the device, and the illumination unit changes a plurality of LEDs and a connection state of the plurality of LEDs. Switching means for performing the operation. When the power supply voltage is normal, the plurality of LEDs are connected in series with each other so as to be connected between the power supply input unit and the voltage generation unit, and when the power supply voltage monitoring unit detects a decrease in the power supply voltage, By the operation of the switching unit, a part or all of the plurality of LEDs are changed so as to be connected in parallel to each other. As a result, the operation of the apparatus can be maintained even when the power supply voltage is lowered. In addition, since the plurality of LEDs all maintain the lighting state, it is possible to suppress a decrease in the light emission amount.

  According to the video camera device with an illumination function of the present invention, the current for turning on the illumination LED is obtained by inserting the illumination LED in series between the power input unit and the voltage generation unit. It can also be used as a current necessary for operating the unit to perform shooting. In addition, a small and inexpensive linear regulator can be used as a voltage generation unit that generates a voltage required by the internal circuit of the video camera unit. In addition, when the power supply voltage outside the apparatus is reduced, the input voltage to the voltage generator is minimized by changing the plurality of LEDs so that some or all of them are connected in parallel to each other. It is possible to ensure a voltage higher than a necessary voltage and maintain the operation of the apparatus, and to suppress a decrease in the amount of light emission.

  When such a video camera device with a lighting function of the present invention is installed in a vehicle and used, it becomes even more effective.

It is a figure which shows the structural example of the video camera apparatus with the conventional illumination function. It is a figure which shows the basic composition of the video camera apparatus with an illumination function of this invention. It is a figure which compares the characteristic of the linear regulator used for a voltage generation part, and a DC / DC converter. It is a figure for demonstrating the forward direction voltage drop of LED for illumination. It is a figure which shows the specific structural example of the video camera apparatus with an illumination function of this invention. It is a figure which shows the connection state of LED for illumination when a power supply voltage is normal. It is a figure which shows the connection state of LED for illumination when a power supply voltage falls. It is a figure which shows the connection state of LED for illumination when a power supply voltage further falls.

  Hereinafter, embodiments of a video camera device with an illumination function according to the present invention will be described with reference to the drawings.

  First, a conventional configuration example of a video camera device with an illumination function will be described with reference to FIG. In FIG. 1, the video camera device 10 with an illumination function is roughly divided into an illumination unit 20, a video camera unit 30, and a power input unit 40. Note that FIG. 1 shows only connection relating to the power supply, and signal lines such as video signals are omitted.

  The video camera device 10 is supplied with a current from a power source 100 outside the device via a power input unit 40. As the power supply 100 outside the apparatus, a DC power supply is generally used. For example, a battery or a battery mounted on a vehicle. When using an AC power supply, an AC adapter is used. The power input unit 40 is a connect such as a DC jack. The power input unit 40 may include an electronic circuit that protects the device from reverse insertion of connectors and static electricity.

  The illumination unit 20 is connected to the output side of the power supply input unit 40, and is configured to be grounded after an illumination LED (D1) and a current limiting resistor (R1) are connected in series. For convenience, only one LED is shown in FIG. 1, but in order to increase the amount of light emitted, a plurality of LEDs are connected in series, or a plurality of LEDs and resistors are connected in parallel. is there.

  The video camera unit 30 includes a voltage generation unit 50, an image sensor 60 such as a CCD sensor or a CMOS sensor, an image processing LSI 61, and the like.

  The voltage generation unit 50 converts the power supply voltage supplied via the power input unit 40 into a voltage required by an internal circuit (image sensor, image processing LSI, etc.) of the video camera unit 30. For the voltage generation unit 50, a linear regulator, a DC / DC converter, or the like is used. In FIG. 1, the voltage generation unit 50 is included in the video camera unit 30, but is not limited thereto. The voltage generation unit 50 may be outside the video camera unit 30.

  The image sensor 60 captures a range illuminated by the LED of the illumination unit 20 and outputs a video signal. The image processing LSI 61 inputs the video signal output from the image sensor 60 and performs necessary processing (color space conversion, MTF correction, γ correction, distortion, rotation, down-looking correction, etc.). Although omitted in FIG. 1, the video signal subjected to the necessary processing is amplified by a video amplifier and output to the outside of the apparatus.

  In the case of such a conventional video camera device with an illumination function, as indicated by an arrow in FIG. 1, the current supplied from the power supply 100 outside the device via the power input unit 40 is the same as that of the illumination unit 20 and the video. It flows separately to the camera unit 30. In other words, since the illumination unit 20 and the video camera unit 30 are connected in parallel when viewed from the power supply 100 outside the apparatus, the sum of the currents required by each is supplied from the power supply 100 outside the apparatus. become. At this time, the current flowing in the illumination unit 20 is flowing only for lighting the illumination LED (D1), and it is difficult to say that it is effectively used.

  Therefore, the present invention provides a video camera device with an illumination function that can effectively use the current flowing through the illumination unit even in the video camera unit. FIG. 2 shows a basic configuration of a video camera device with an illumination function according to the present invention. Here, only the connection relating to the power source is shown, and signal lines such as video signals are omitted.

  2, the same parts as those in FIG. 1 are denoted by the same reference numerals. The difference from the conventional configuration of FIG. 1 is that the illumination unit 20 composed of an illumination LED (D1) as a light emitting element is inserted in series between the power input unit 40 and the voltage generation unit 50. is there. Specifically, the anode electrode of the LED (D1) is connected to the output side of the power input unit 40, and the cathode electrode is connected to the input side of the voltage generation unit 50. For convenience, only one LED is shown in FIG. 2, but in actuality, a configuration in which a plurality of LEDs are directly connected to increase the amount of light emission is obtained by connecting the power input unit 40 and the voltage generation unit 50 to each other. Insert between them.

  In the case of FIG. 2, the current supplied from the power supply 100 outside the apparatus to the video camera device 10 flows through the power input unit 40 to the illumination unit 20 and the video camera unit 30 as indicated by arrows. In other words, the illumination unit 20 and the video camera unit 50 are connected in series when viewed from the power supply 100 outside the apparatus. Naturally, the current flowing through the illumination unit 20 is the same as the current flowing through the video camera unit 30. Become.

  With the configuration shown in FIG. 2, the current for turning on the LED (D1) of the illumination unit 20 can be used as a current necessary for operating the video camera unit 30 to perform photographing. become.

  In addition, when the configuration shown in FIG. 2 is used, an effect that a small and inexpensive linear regulator can be used as the voltage generation unit 50 is also obtained. This will be described in detail below.

  The voltage generation unit 50 converts the voltage supplied from the power supply 100 outside the apparatus via the power input unit 40 into a predetermined voltage required by the internal circuit (image sensor, image processing LSI, etc.) of the video camera unit 30. Is. As electronic components for converting voltage values, linear regulators and DC / DC converters are widely used. FIG. 3 shows the characteristics of the linear regulator and the DC / DC converter. The loss of the linear regulator is determined by the product of the voltage difference between input and output and the output current. The output current of the voltage generation unit in the case of the configuration of FIG. 2 is the current consumed by the video camera unit 30, and the current consumption is also during the video camera unit 30 performing a certain shooting operation. It is almost constant. Therefore, the loss when a linear regulator is used as the voltage generator 50 in FIG. 2 is determined by the voltage difference between the input and output. If the voltage drop between the input and output is small and sufficient efficiency can be obtained even with a linear regulator, it is advantageous to use a small and inexpensive linear regulator. This will be described in detail.

  The output voltage of the voltage generation unit 50 is a voltage required by the internal circuit of the video camera unit 30 in both the configurations of FIGS. On the other hand, the input voltage of the voltage generation unit 50 is different in the case of FIG. 1 and FIG. 2 due to the influence of the characteristic called forward voltage drop (hereinafter referred to as Vf) of the LED. When the diode element including the LED becomes conductive, the potential of the cathode viewed from the anode drops by Vf. For example, as shown in FIG. 4, when three LEDs are inserted in series between the power source (Vcc) and the circuit 200, the voltage applied to the circuit 200 is Vcc-3Vf (where Vcc> 3Vf). The value of Vf is about 0.7 V for a silicon diode for rectification, and LED is about 2 to 4 V, although it varies depending on the emission color. In FIG. 4, if Vcc = 12V and Vf = 2V, the voltage supplied to the circuit 200 drops to 6V.

  A circuit 200 in FIG. 4 corresponds to the voltage generation unit 50 in FIG. That is, in the configuration of FIG. 1, the input voltage to the voltage generator 50 is the voltage of the power supply 100 outside the apparatus, whereas in the configuration of FIG. 2, the input voltage to the voltage generator 50 is The voltage of the power supply 100 outside the apparatus is lowered by the amount of Vf of the illumination LED. As described above, since the output voltage of the voltage generation unit 50 is the same in FIGS. 1 and 2, the configuration of FIG. 2 is more suitable for the voltage generation unit 50 because the input voltage to the voltage generation unit 50 is lower. The voltage difference between the input and output is reduced, and the possibility that a small and inexpensive linear regulator can be used as the voltage generation unit 50 increases.

  This is more effective when the video camera apparatus is installed in a vehicle and used. When the video camera device is installed in a vehicle, a battery mounted on the vehicle is used as the power source 100 outside the device. Usually, the voltage of this battery is 12V. On the other hand, the voltage required by an element such as an image sensor or an image processing LSI inside the video camera is about 3.3 V at most in recent years. This voltage difference (12V-3.3V = 8.7V) is too large to be stepped down by the linear regulator in the configuration of FIG. On the other hand, in the case of the configuration of FIG. 2, it is possible to cope with this by inserting a plurality of illumination LEDs in series until the voltage drops to a level at which the linear regulator can be used. Further, by using a plurality of illumination LEDs, the amount of light emission is greater than that of a single configuration.

  By the way, in FIG. 2, when it is set as the structure which connected several LED for illumination in order to increase the light-emission quantity, if the power supply voltage of the apparatus exterior 100 falls more than a certain amount, the input voltage to the voltage generation part 50 will be the lowest. If the voltage is lower than the required voltage, the voltage generation unit 50 does not operate normally, and the operation of the video camera unit 30 cannot be maintained.

  In the present invention, the configuration shown in FIG. 2 is expanded so that the current flowing through the illumination LED can be effectively used also in the video camera unit 30 and the voltage generation can be performed even when the power supply voltage of the external device 100 is reduced to some extent. Provided a video camera device with an illumination function that secures an input voltage to the unit 50 to a minimum necessary voltage so that the operation of the video camera unit 30 can be maintained and a decrease in light emission amount is suppressed. There is to do.

  FIG. 5 shows a specific configuration example of the video camera device with an illumination function of the present invention. In FIG. 5, the same parts as those in FIG. The difference from FIG. 2 is that the configuration of the illumination unit 20 and the power supply voltage monitoring unit 70 are added.

  The illumination unit 20 includes three illumination LEDs (D1, D2, D3), six switches S1 to S6 as switching means for changing the connection state of these LEDs, and three resistors R1, It is composed of R2 and R3. Specific examples of the switches S1 to S6 include a semiconductor switch such as a transistor and a mechanical switch such as a relay. The resistors R1, R2, and R3 are provided to absorb the influence of the variation in Vf when the LEDs are connected in parallel to each other.

  The power supply voltage monitoring unit 70 monitors the voltage value supplied from the power supply 100 outside the apparatus via the power input unit 40, and when a decrease in the voltage value is detected, the switching instruction 1 or A switching instruction 2 is issued to the illumination unit 20. In the illumination unit 20, the switches S1 to S6 are operated according to the switching instruction 1 or the switching instruction 2 from the power supply voltage monitoring unit 70 to change the connection state of D1 to D3.

  Hereinafter, the operation of FIG. 5 will be described in detail. Here, it is assumed that the power supply voltage in a normal state is 12V, the minimum required input voltage of the voltage generation unit 50 is 5V, and the forward drop voltage Vf of one lighting LED is 2V.

  When the power supply voltage is normal (12 V), the switches S2 and S5 are in an ON (short circuit) state, and the switches S1, S3, S4, and S6 are in an OFF (open) state. At this time, all three LEDs for illumination (D1, D2, D3) are connected in series with each other. FIG. 6 shows the connection state of the illumination LEDs (D, D2, D3) at this time. In FIG. 6, switches and extra paths are omitted for easy understanding of the connection between LEDs. In the case of FIG. 6, the input voltage to the voltage generation unit 50 is 12V−3 * 2V = 6V, which exceeds the minimum required voltage (5V) of the voltage generation unit 50. Therefore, the voltage generation unit 50 operates normally, The operation of the video camera unit 30 is maintained.

  Here, if for some reason the power supply voltage drops and becomes less than 11V (for example, 10.5V), the input voltage to the voltage generator 50 is 10.5V-3 * 2V = 4.5V, and voltage generation The voltage is lower than the minimum necessary voltage (5 V) of the unit 50.

  When the power supply voltage monitoring unit 70 detects that the power supply voltage has dropped to around 11 V, it issues a switching instruction 1 to the illumination unit 20. When the lighting unit 20 receives the switching instruction 1 from the power supply voltage monitoring unit 70, the lighting unit 20 turns on the switches S1, S2, and S5 and turns off the switches S2, S4, and S6. As a result, the three lighting LEDs (D1, D2, D3) are changed so that D1 and D2 are connected in parallel with each other and D3 is connected in series. FIG. 7 shows the connection state of the illumination LEDs (D1, D2, D3) at this time. Also in FIG. 7, in order to make it easy to understand the connection between the LEDs, the switches and the extra paths are omitted.

  In the case of FIG. 7, the voltage drop due to Vf of the illumination LED is equivalent to only two LEDs, and if the power supply voltage is 10.5 V, for example, the input voltage to the voltage generator 50 is 10.5 V−2 * 2 V = 6.5V, so that the minimum required voltage (5V) of the voltage generating unit 50 can be secured, and the operation of the video camera unit 30 is maintained. Moreover, since the three illumination LEDs (D1, D2, D3) are lit as in the normal state, it is possible to suppress a decrease in the amount of light emission. However, since D1 and D2 are connected in parallel, the amount of light emission is slightly reduced as compared with the normal time.

  If the power supply voltage further decreases from this state to less than 9V (for example, 8.5V), the input voltage to the voltage generation unit 50 is 8.5V-2 * 2V = 4.5V, and the voltage generation unit The minimum required voltage (5V) of 50 is also lowered.

  When the power supply voltage monitoring unit 70 detects that the power supply voltage has dropped to around 9 V, it issues a switching instruction 2 to the illumination unit 20. When the illumination unit 20 receives the switching instruction 2 from the power supply voltage monitoring unit 70, the lighting unit 20 turns on the switches S1, S3, S4, and S6 and turns off the switches S2 and S5. As a result, all the three illumination LEDs (D1, D2, D3) are changed so as to be connected in parallel. FIG. 8 shows the connection state of the illumination LEDs (D1, D2, D3) at this time. Also in FIG. 8, in order to make it easy to understand the connection between the LEDs, the switches and the extra paths are omitted.

  In the case of FIG. 8, the voltage drop due to Vf of the LED for illumination is equivalent to only one LED, and if the power supply voltage is 8.5 V, for example, the input voltage to the voltage generator 50 is 8.5 V-1 * 2 V. = 6.5V, so that the minimum required voltage (5V) of the voltage generating unit 50 can be secured, and the operation of the video camera unit 30 is maintained. Moreover, since the three illumination LEDs (D1, D2, D3) are lit as in the normal state, it is possible to suppress a decrease in the amount of light emission. However, since all of D1, D2, and D3 are connected in parallel, the amount of light emission is further reduced as compared with the case of FIG.

In this way, with the configuration of FIG. 5, even when the voltage of the power supply 100 outside the apparatus has dropped to some extent, the input voltage to the voltage generator 50 can be secured to the minimum necessary voltage, and video The operation of the camera unit 30 can be maintained, and a decrease in the amount of light emission can be suppressed. Further, since there are a plurality of illumination LEDs, the amount of light emission is larger than that of a single configuration. Furthermore, it is also suitable to use a linear regulator as the voltage generator 50.
In FIG. 5, three illumination LEDs are used. However, the number may be two or more as long as the input voltage to the voltage generation unit 50 can be secured to a minimum necessary voltage.

  Again, this is more effective when the video camera device is installed in a vehicle and used. As described above, a battery mounted on the vehicle is used as the power source 100 outside the device when the video camera device is installed in the vehicle. However, the voltage of the battery decreases due to various causes, such as when power is supplied to many electrical devices in the vehicle at the same time, or when the vehicle is not operated for a long period of time. With the configuration shown in FIG. 5, the operation of the apparatus can be maintained even when the voltage of the battery drops to some extent.

  When the video camera device is mounted on a vehicle and used, the illumination LED irradiates light in the infrared region, and the image sensor inside the video camera unit detects light in the infrared region. It is preferable that it has sensitivity. This is because it is prohibited to irradiate visible light toward the outside of the vehicle. Moreover, if it is the light of an infrared region, even if LED lights, it will not become obstructive. Furthermore, although irradiation with visible light is not prohibited in the vehicle interior, light in the infrared region can prevent the irradiation light from interfering with driving.

DESCRIPTION OF SYMBOLS 10 Video camera apparatus 20 Illumination part 30 Video camera part 40 Power supply input part 50 Voltage generation part 60 Image sensor 61 Image processing LSI
70 Power supply voltage monitoring unit 100 Power supply outside the apparatus D1, D2, D3 LED for illumination
S1 to S6 switches (switching means)
R1-R3 resistance

JP 2002-240629 A

Claims (4)

A video camera device with an illumination function for photographing while illuminating a photographing range with LED illumination,
A power input unit connected to a power supply external to the device;
An illumination unit having an illumination LED;
A video camera unit that captures a range illuminated by the illumination LED of the illumination unit and outputs a video signal;
A voltage generating unit that generates a voltage required by an internal circuit of the video camera unit;
A power supply voltage monitoring unit for monitoring a voltage value of a power supply external to the device;
Comprising
The illumination unit includes a plurality of LEDs and switching means for changing a connection state of the plurality of LEDs,
When the power supply voltage is normal, the plurality of LEDs are connected in series with each other and connected between the power supply input unit and the voltage generation unit,
When the power supply voltage monitoring unit detects a decrease in power supply voltage, the operation of the switching unit is changed so that some or all of the plurality of LEDs are connected in parallel to each other.
A video camera device with an illumination function.   The video camera with an illumination function according to claim 1, wherein the illumination unit includes a resistor for absorbing the influence of variations in LED forward voltage drop when the LEDs are connected in parallel to each other. apparatus.   When the power supply voltage drop is small, some of the plurality of LEDs are connected in parallel to each other, and when the power supply voltage drop is large, all the plurality of LEDs are connected in parallel to each other. The video camera device with an illumination function according to claim 1 or 2. A video camera device with an illumination function according to any one of claims 1 to 3,
The illumination LED of the illumination unit emits light in the infrared region,
The video camera unit is sensitive to light in the infrared region,
The video camera device is installed in a vehicle, takes a picture while illuminating the periphery of the vehicle or the passenger compartment, and operates using a battery mounted on the vehicle as a power source.
A video camera device with an illumination function.

Images