JP2017146325A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device capable of suppressing an undershoot at voltage switching while suppressing time required for switching the voltage, when switching power supply which supplies power to an interchangeable lens, from a higher voltage to a lower voltage, regardless of a load capacity and load current of the interchangeable lens.SOLUTION: An interchangeable lens capable of communicating at a first voltage and an interchangeable lens capable of communicating at the first voltage and a second voltage lower than the first voltage are selectively mounted to the imaging device. The imaging device includes a terminal for supplying power to the interchangeable lens and a power supply unit for supplying power to the terminal for supplying power. The power supply unit includes a voltage switching section for selectively switching the voltage to be supplied to the interchangeable lens, and a discharge section capable of selecting a current value for extracting charges from a load capacity of the interchangeable lens. When switching the voltage to be supplied to the interchangeable lens from a first voltage to a second voltage lower than the first voltage, the current value of the discharge section is selected on the basis of the load capacity and the load current of the interchangeable lens.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging device, and in particular, an interchangeable lens that can communicate at a first voltage, and an interchangeable lens that can communicate at a second voltage lower than the first voltage and the first voltage are selectively mounted. The present invention relates to a possible imaging device.

  The interchangeable lens attached to the imaging device operates by receiving a voltage supply from the imaging device. However, the operating voltage of the interchangeable lens may vary depending on the type. In order to allow a plurality of different types of interchangeable lenses to be attached to the imaging device, a technique for switching the voltage supplied to the interchangeable lens by the imaging device according to the type of the attached interchangeable lens is disclosed.

  In Patent Document 1, when an imaging device once supplies an interchangeable lens with a power supply voltage at which all types of interchangeable lenses can operate, and the subsequently mounted interchangeable lens can operate with a lower power supply voltage, the interchangeable lens The power supply voltage supplied to is switched to a lower voltage.

  In Patent Document 2, when an interchangeable lens is mounted, the type of the interchangeable lens is determined before the imaging apparatus supplies a voltage to the lens, and a corresponding communication voltage is supplied.

JP-A-9-90488 JP 2013-231946 A

  However, in the conventional technique disclosed in Patent Document 1, when the voltage supplied from the imaging device to the interchangeable lens is lowered from a high voltage to a low voltage, the load capacity and load current of the interchangeable lens cause the load capacity of the interchangeable lens. The time required for the charge to escape is different.

  Therefore, the slew rate of voltage switching differs depending on the load capacity and load current of the interchangeable lens. When the slew rate is slow, the time required to complete voltage switching increases. When the slew rate is steep, there is a concern that the microcomputer in the lens may be reset or malfunction due to undershoot of the lens power supply voltage.

  The prior art disclosed in Patent Document 2 determines voltage to be supplied to the power supply of the interchangeable lens before the imaging apparatus supplies power to the interchangeable lens, so that voltage switching is not necessary in the first place.

  However, in order to discriminate the type of the interchangeable lens before supplying power, it is necessary to provide a mount terminal dedicated to discriminating the lens type as a discriminating means, and compatibility with an imaging device having a conventional mount or an interchangeable lens is lost.

  The object of the present invention is to suppress undershoot at the time of voltage switching while suppressing the time required for voltage switching, regardless of the load capacity and load current of the interchangeable lens, when switching the power supplied to the interchangeable lens from a high voltage to a low voltage. An object of the present invention is to provide an imaging apparatus that can be suppressed.

In order to achieve the above object, an imaging apparatus according to the present invention includes:
An imaging device in which an interchangeable lens that can communicate at a first voltage and an interchangeable lens that can communicate at a first voltage and a second voltage lower than the first voltage can be selectively mounted. An interchangeable lens having a terminal for supplying a voltage to the lens, a voltage switching portion for selectively switching the voltage to be supplied to the interchangeable lens, and a discharge portion capable of selecting a current value for extracting charge from the load capacity of the interchangeable lens When switching the voltage to be supplied from the first voltage to the second voltage lower than the first voltage, the current value of the discharge unit is selected according to the load capacity and load current of the interchangeable lens. To do.

  According to the present invention, imaging capable of suppressing undershoot at the time of voltage switching while suppressing the time required for switching the voltage supplied to the interchangeable lens regardless of the load capacity and load current of the mounted interchangeable lens. An apparatus can be provided.

1 is a block diagram of an imaging apparatus 1 (hereinafter referred to as a camera 1) and an interchangeable lens 2 in Embodiment 1 of the present invention, and a diagram showing details of a voltage supply unit 6. FIG. In the camera 1 and the interchangeable lens 2 according to the first exemplary embodiment of the present invention, after the camera 1 detects the mounting of the interchangeable lens 2, the setting of the VDD terminal voltage is completed and the camera 1 and the interchangeable lens 2 start communication. Flowchart showing the operation of Time chart showing the operation of the control signal DIS_ON output from the MIF terminal 3e, the VDD terminal 3a, and the camera microcomputer 4 in the camera 1 and the interchangeable lens 2 according to the first embodiment of the present invention. In the camera 1 and the interchangeable lens 2 according to the second exemplary embodiment of the present invention, the setting of the VDD terminal voltage is completed after the camera 1 detects the mounting of the interchangeable lens 2, and the camera 1 and the interchangeable lens 2 start communication. Flowchart showing the operation of In the camera 1 and the interchangeable lens 2 according to the third exemplary embodiment of the present invention, after the camera 1 detects the mounting of the interchangeable lens 2, the setting of the VDD terminal voltage is completed and the camera 1 and the interchangeable lens 2 start communication. Flowchart showing the operation of Time chart showing operations of the control signal DIS_ON output from the MIF terminal 3e, the VDD terminal 3a, and the camera microcomputer 4 in the camera 1 and the interchangeable lens 2 according to the third embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  The embodiment described below is an example as means for realizing the present invention, and may be appropriately modified or changed depending on the configuration of the apparatus to which the present invention is applied and various conditions. Each embodiment can also be combined as appropriate.

  FIG. 1A is a block diagram of a camera 1 and an interchangeable lens 2 according to the present invention.

  The camera 1 and the interchangeable lens 2 each have a mount 3 that electrically connects each other.

<Configuration of mount 3>
The mount 3 includes a VDD terminal 3a, an LCLK terminal 3b, a DCL terminal 3c, a DLC terminal 3d, an MIF terminal 3e, and a GND terminal 3f.

  The VDD terminal 3 a is a terminal for supplying power from the camera 1 to the interchangeable lens 2.

  The LCLK terminal 3b, the DCL terminal 3c, and the DLC terminal 3d are terminals for performing communication between the camera 1 and the interchangeable lens 2. The LCLK terminal 3 b is a terminal for a clock signal output from the camera 1 to the interchangeable lens 2. The DCL terminal 3 c is a data signal terminal from the camera 1 to the interchangeable lens 2. The DLC terminal 3 d is a data signal terminal from the interchangeable lens 2 to the camera 1.

  The MIF terminal 3e is a terminal for detecting that the interchangeable lens 2 is attached to the camera 1. The GND terminal 3f is a ground terminal. When the interchangeable lens 2 is attached to the camera 1, the MIF terminal 3e and the GND terminal 3f are electrically connected.

<Configuration of camera 1>
Inside the camera 1, there are a camera microcomputer 4, a power generation unit 5, a voltage supply unit 6, a level shifter unit 7, a current measurement unit 12, and a current detection unit 11.

  The camera microcomputer 4 is a microcomputer such as a CPU, for example, and controls the operation of each unit in the camera 1. Further, communication with the lens microcomputer 8 in the interchangeable lens 2 is performed via the level shifter unit 7, the mount 3, and the level shifter unit 10.

  The power supply generation unit 5 is a power supply circuit such as a switching regulator or a linear regulator, for example, and generates power necessary for the operation of each circuit in the camera 1 or power supplied to the interchangeable lens 2 via the VDD terminal 3a. .

  The voltage supply unit 6 supplies power to the VDD terminal 3a. Further, the voltage of the VDD terminal 3a is switched. Details of the configuration of the voltage supply unit 6 will be described later.

  The level shifter unit 7 is a level shift circuit, for example, and converts the 3.3V clock signal and data signal output from the camera microcomputer 4 into the same voltage as the voltage of the VDD terminal 3a output from the voltage supply unit 6. , Output to the LCLK terminal 3b and the DCL terminal 3c. In addition, the data signal input from the DLC terminal 3d at the same voltage as the VDD terminal 3a is converted into a voltage of 3.3V that can be input to the camera microcomputer 4.

  The voltage detection unit 11 is a comparator, for example, and detects the voltage at the VDD terminal 3 a and transmits it to the camera microcomputer 4.

  The current measuring unit 12 is, for example, a shunt resistor, converts a current value flowing into the VDD terminal 3 a into a voltage, and outputs the voltage to the input terminal of the camera microcomputer 4.

  The camera microcomputer 4 can measure the current value flowing into the VDD terminal 3a by monitoring the voltage at the input terminal.

<Configuration of interchangeable lens 2>
Inside the interchangeable lens 2, there are a lens microcomputer 8, a power generation unit 9, and a level shifter unit 10.

  The lens microcomputer 8 is a microcomputer such as a CPU, for example, and controls the operation of each unit in the lens. Further, it communicates with the camera microcomputer 4 in the camera 1 via the level shifter unit 10, the mount 3, and the level shifter unit 7.

  The power supply generation unit 9 is a power supply circuit such as a switching regulator or a linear regulator, for example, and generates power necessary for the operation of each circuit in the lens from the power supplied to the VDD terminal 3a.

  The level shifter unit 10 is, for example, a level shift circuit, converts a 3V data signal output from the lens microcomputer 8 into a voltage supplied from the VDD terminal 3a, and outputs the voltage to the DLC terminal 3c. Further, the clock signal input from the LCLK terminal 3 b and the data signal input from the DCL terminal 3 c at the same voltage as the VDD terminal 3 a are converted into a voltage of 3 V that can be input to the lens microcomputer 8.

<Configuration of voltage supply unit 6>
FIG. 1B is a diagram showing the voltage supply unit 6 in the camera 1 shown in FIG.

  The voltage supply unit 6 includes a voltage switching unit 20, a discharge unit 21, and a resistance value selection unit 22.

  The voltage switching unit 20 includes a switch 20a and a switch 20b. The switch 20a is controlled to be turned on / off by a control signal SWA_ON from the camera microcomputer 4. The switch 20b is controlled to be turned on / off by a control signal SWB_ON from the camera microcomputer 4. The voltage switching unit 20 is supplied with a voltage of 5 V and a voltage of 3.3 V from the power generation unit 5 in FIG. 1A, and only one of the switch 20a and the switch 20b is turned on to input the voltage. Is supplied to the VDD terminal 3a. Moreover, the voltage supplied to the VDD terminal 3a can be cut off by turning off both the switch 20a and the switch 20b.

  When the voltage switching unit 20 switches the voltage from 5 V to 3.3 V, the discharge unit 21 discharges the charge charged in the load capacity (not shown) of the interchangeable lens 2 connected to the VDD terminal 3 a. The discharge unit 21 includes a plurality of discharge paths having different resistance values, and the resistance value selection unit 22 sets which path is to be discharged.

  The resistance value selection unit 22 is composed of, for example, a register and a CMOS logic circuit, receives a control signal DIS_SEL from the camera microcomputer 4, and discharges at any path among a plurality of discharge paths with different resistance values provided in the discharge unit 21. Set whether to perform. Further, upon receiving the control signal DIS_ON from the camera microcomputer 4, the discharge unit 21 is controlled so that the discharge is performed only when the DIS_ON signal is High.

<Flow chart, time chart>
FIG. 2 shows the camera 1 and the interchangeable lens 2 according to Embodiment 1 of the present invention, from when the camera 1 detects the mounting of the interchangeable lens 2 until the voltage supplied to the VDD terminal 3a is determined and communication is started. It is a flowchart which shows operation | movement.

  FIG. 3 is a time chart of the control signal DIS_ON in the MIF terminal 3e, the VDD terminal 3a, and the voltage supply unit 6 in the camera 1 and the interchangeable lens 2 according to the first embodiment of the present invention.

  The operation of the camera 1 and the interchangeable lens 2 in the first embodiment of the present invention will be described below with reference to FIGS.

  First, in S101 of FIG. 2 (corresponding to t101 of FIG. 3), the camera microcomputer 4 detects that the interchangeable lens 2 is mounted by detecting that the MIF terminal is electrically connected to the GND terminal.

  Next, in S102 of FIG. 2 (corresponding to t102 of FIG. 3), the voltage supply unit 6 starts supplying a voltage of 5 V to the VDD terminal 3a.

  In S103 of FIG. 2, the camera microcomputer 4 starts supplying a voltage of 5V to the VDD terminal 3a at t102 of FIG. 3, and then the voltage detection unit 11 reaches 5V of the VDD terminal voltage 3a at t103 of FIG. The camera microcomputer 4 measures the time tchg until this is detected. Further, the camera microcomputer 4 periodically measures the current value flowing into the VDD terminal voltage 3a by the current measuring unit 12 during the period from t102 to t103 in FIG. 3, and calculates the average value Ichg.

  In S104 of FIG. 2, the load capacity value C of the interchangeable lens 2 is calculated by substituting the time tchg measured in S103 and the current value I measured in S103 into the following equation (1). However, V1 represents the voltage (5V) after charge.

In S105 of FIG. 2, the camera 1 determines whether the mounted interchangeable lens 2 is compatible only with 5V or both 5V and 3.3V by the interchangeable lens type determining means.

  If the mounted interchangeable lens 2 can handle only 5V, the voltage setting is completed while the voltage at the VDD terminal 3a remains at 5V. Thereafter, the camera 1 and the interchangeable lens 2 start 5V communication.

  When the mounted interchangeable lens 2 is an interchangeable lens that can handle both 5V and 3.3V, the current measurement unit 12 measures the load current value IL of the interchangeable lens 2 in S106 of FIG.

  In S107 of FIG. 2, the camera microcomputer 4 sets the current value Idis that needs to be discharged by the discharge unit 21 in the camera 1 in order to switch the voltage at the VDD terminal 3a from 5V to 3.3V at the target time tsw. This is calculated using Equation (2). Here, C represents the load capacity value of the interchangeable lens, V1 represents the voltage before voltage switching (5V), V2 represents the voltage after voltage switching (3.3V), and IL represents the load current of the interchangeable lens 2.

In S108 of FIG. 2, the camera microcomputer 4 has a resistance value that allows a current closest to the current value calculated in S107 of FIG. 2 among a plurality of discharge paths having different resistance values prepared in the discharge unit 21. The resistance value selection unit 22 is set so as to perform discharge by pass. However, when the calculation result of the current value calculated in S107 of FIG. 2 is 0 or less, the discharge unit 21 does not perform discharge at the time of voltage switching.

  It should be noted that the discharge unit 21 needs to have a resistance value so that the voltage can be switched at the target time tsw even with the interchangeable lens 2 having the maximum value that the load capacity C is assumed and the minimum value that the load current IL is assumed. There is. For example, when the assumption of the maximum value of the load capacity C of the interchangeable lens 2 is 100 uF and the assumption of the minimum value of the load current IL is 0 mA, a current of about 170 mA is used to switch the voltage at the target time tsw from the equation (2). It is necessary to provide a discharge path with a resistance value that can flow the current. Therefore, it is necessary to provide the resistance value of the discharge unit 21 so that a maximum current of about 170 mA can flow. For example, as shown in Table 1, a plurality of discharge paths having a resistance value capable of flowing about 170 mA and a plurality of discharge paths having a resistance value capable of flowing a current smaller than that are provided.

In S109 of FIG. 2 (corresponding to t109 of FIG. 3), the voltage switching unit 20 switches the voltage supplied to the VDD terminal 3a from 5V to 3.3V. At the same time, the camera microcomputer 4 sets DIS_ON to High, and the discharge 21 starts discharging on the resistance value path set by the resistance value selection unit 22.

  In S110 of FIG. 2 (corresponding to t110 of FIG. 3), after the camera microcomputer 4 times that a certain time has elapsed from the start of the discharge, DIS_ON is set to Low, and the discharge unit 21 stops the discharge.

  Thus, the voltage setting of the VDD terminal 3a is completed, and then the camera 1 and the interchangeable lens 2 start 3.3V communication.

  In Example 1 of the present invention, the load capacity and load current of the interchangeable lens 2 were measured and calculated by a circuit in the camera 1. Therefore, a circuit for measuring and calculating the load capacity and load current of the interchangeable lens 2 is required in the camera 1.

  However, if the interchangeable lens 2 can store the load capacity and load current values in advance and notify the camera 1, a circuit for measuring the load capacity and load current of the interchangeable lens 2 is not necessary in the camera 1. It becomes.

  Therefore, in this embodiment, an example in which the camera 1 is notified of the load capacity and the load current value stored in advance in the interchangeable lens 2 will be described.

  FIG. 4 shows the camera 1 and the interchangeable lens 2 according to Embodiment 2 of the present invention, from when the camera 1 detects the mounting of the interchangeable lens 2 until the voltage supplied to the VDD terminal 3a is determined and communication is started. It is a flowchart which shows operation | movement.

  The operation of the camera 1 and the interchangeable lens 2 in the second embodiment of the present invention will be described below with reference to FIG.

  S201, S202, S205, S207, S208, S209, and S210 in FIG. 4 are the same as S101, S102, S105, S107, S108, S109, and S110, respectively, in FIG.

  In FIG. 4, steps corresponding to S103, S104, and S106 in FIG. 2 are deleted.

  In S <b> 206 of FIG. 4, the camera 1 acquires the load capacity of the interchangeable lens 2 and the value of the load current of the interchangeable lens 2 through communication with the interchangeable lens 2.

  In this embodiment, since the load capacity value and the load current value of the interchangeable lens 2 are acquired by communication in S206 of FIG. 4, a circuit for measuring the load capacity value and the load current value becomes unnecessary, and the circuit scale is reduced. I can do it.

  In the first and second embodiments of the present invention, after the discharge by the discharge unit 21 is started, the camera microcomputer 4 stops after a certain time has elapsed.

  However, if the voltage switching of the VDD terminal 3a is completed before a certain time elapses, the discharge unit 21 draws an unnecessary discharge current after the voltage switching is completed, causing an undershoot or an unnecessary discharge period. In some cases, the power consumption is excessive.

  Therefore, in this embodiment, an example will be described in which the discharge by the discharge unit 21 is stopped simultaneously with the completion of the voltage switching of the VDD terminal 3a.

  FIG. 5 shows the steps from when the camera 1 detects the mounting of the interchangeable lens 2 until the voltage to be supplied to the VDD terminal 3a is determined and the communication is started in the camera 1 and the interchangeable lens 2 according to the third embodiment of the present invention. It is a flowchart which shows operation | movement. FIG. 6 is a time chart of the control signal DIS_ON in the MIF terminal 3e, the VDD terminal 3a, and the voltage supply unit 6 in the camera 1 and the interchangeable lens 2 according to the third embodiment of the present invention.

  The operation of the camera 1 and the interchangeable lens 2 in the second embodiment of the present invention will be described below with reference to FIGS.

  S301, S302, S305, S306, S307, S308, and S309 in FIG. 5 are the same as S201, S202, S205, S206, S207, S208, and S209 in FIG. 4, respectively. The time chart from t301 to t309 in FIG. 6 is the same as the time chart from t101 to t109 in FIG.

  In S311 of FIG. 5, the voltage detection unit 11 determines whether the voltage at the VDD terminal 3a has decreased to 3.3 V or less. When the voltage at the VDD terminal 3a is higher than 3.3V, the discharge unit 21 continues to discharge.

  If the voltage of the VDD terminal 3a is 3.3V or less, the camera microcomputer 4 sets DIS_ON to Low in S312 of FIG. 5 (corresponding to t312 of FIG. 6), and the discharge unit 21 stops the discharge.

  In the present embodiment, the discharge unit 21 stops discharging after the voltage detection unit 11 detects that the voltage at the VDD terminal 3a has dropped to a predetermined value in S311 and S312 of FIG. For this reason, it is possible to prevent unnecessary discharge current from being drawn after voltage switching is completed, thereby causing undershoot or excessive power consumption.

  In the first embodiment, the second embodiment, and the third embodiment of the present invention, the lens type is determined by the determination unit. However, the camera microcomputer 4 communicates with the lens microcomputer 4 and exchanges information for determining the lens type. By doing so, the type of lens may be determined.

1 camera, 2 interchangeable lens, 3 mount

Claims (3)

Imaging capable of selectively mounting the interchangeable lens (2) communicable with the first voltage and the interchangeable lens (2) communicable with the first voltage and the second voltage lower than the first voltage. A device (1) having a terminal (3a) for supplying power to the interchangeable lens (2) and a power supply unit (6) for supplying power to the terminal (3a) for supplying power; The supply unit (6) is a voltage switching unit (20) that selectively switches the voltage supplied to the interchangeable lens (2), and a discharge unit that can select a current value for extracting charge from the load capacity of the interchangeable lens (2). When the voltage supplied to the interchangeable lens is switched from the first voltage to a second voltage lower than the first voltage, the current value of the discharge unit (21) is changed to the interchangeable lens (2). Image pick-up characterized by selection according to the load capacity and load current of Location (1). The imaging device according to claim 1, wherein information including a load capacity and a load current of the interchangeable lens (2) is acquired in communication between the interchangeable lens (2) and the imaging device (1). (1). A voltage detector (11) for monitoring the voltage supplied to the interchangeable lens (2), and the voltage detected by the voltage detector (11) when the voltage supplied to the interchangeable lens is switched to a predetermined value; The imaging device (1) according to claim 1, wherein when detected, the discharge by the discharge unit (21) is stopped.