JP3940940B2 - Automatic discrimination device for serial communication - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a serial communication presence / absence automatic determination device, and more particularly to a serial communication presence / absence automatic determination device which is mounted on a lens device of a television camera and determines whether or not the television camera body has a function of performing serial communication.
[0002]
[Prior art]
A lens device that can be attached to and detached from a television camera is connected to the camera body by an electrical connector and exchanges various signals with the camera body. The camera has a serial communication function for transmitting and receiving a plurality of pieces of information as digital serial signals in one line, and a plurality of pieces of information on a plurality of lines for each type, with L level and H level or analog signals ( Some of them have a control function for transmitting and receiving with a level signal).
[0003]
For this reason, the lens device is equipped with both the serial communication function and the level signal control function, and the same lens device is controlled by a camera with a different control method by switching the control method of the lens device according to the control function of the camera body. It is possible to use it for general purposes.
In such a lens device, when automatically switching the control method according to the control method of the camera body, a serial command is transmitted to the camera body when the lens device is turned on, and the camera body responds within a specified time. It is a generally considered method to determine whether the camera body performs serial communication or performs control using a level signal depending on whether or not there is.
[0004]
[Problems to be solved by the invention]
However, when the control method of the lens apparatus is switched according to the response to the serial command as described above, there is a problem that the control method is not always switched appropriately.
In other words, even if the camera body performs serial communication, if there is a mismatch in the control method that the lens device is set to be controlled by the level signal for some reason, the lens device may generate a serial command in this state. In addition, since the serial signal transmitted from the camera body is simply recognized as a level signal by the lens device, the lens device cannot switch from the control based on the level signal to the serial communication.
[0005]
Thus, for example, when the power of the camera body is turned on after the power of the lens device is turned on, the lens device is first set to control by the level signal because there is no response from the camera body, and then the camera body The above-described problem occurs when the power is turned on and the camera body starts serial communication.
In addition, when the camera body switches between serial communication and level signal control, the camera body forcibly terminates serial communication once, performs control by level signal, and then starts serial communication again. The above-described problem that the apparatus cannot resume the serial communication again after switching to the control by the level signal occurs.
[0006]
This is a problem that occurs not only when the television camera is used, but also when other devices communicate with each other.
The present invention has been made in view of such circumstances, and automatically determines whether a communication partner device is performing serial communication or performing control based on a level signal, and the device has a serial communication function. It is an object of the present invention to provide a serial communication presence / absence automatic discrimination device that automatically discriminates whether or not there is a serial communication.
[0007]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention can be attached to and detached from the camera body, serial communication function for performing serial communication with the mounted camera body, and level signals transmitted on different lines for each type of information. a presence or absence discrimination system serial communication mounted in the lens apparatus and a level signal transmission and reception functions for transmitting and receiving, in the line where the serial communication function receives a transmission signal by serial communication from the camera body, said camera when the counting means for counting the number of pulses per predetermined time of the transmission signal transmitted from the main body, the value counted by said counting means is a predetermined value or more, it is determined that the camera body is performing serial communications When the value counted by the counting means is less than the predetermined value, the camera body is And the determination means are transmitting or receiving items, when the camera body by the determination means determines that the performed serial communications, to enable serial communication by the serial communication function in the lens apparatus, A communication function switching means for enabling the level signal transmission / reception by the level signal transmission / reception function in the lens device when the determination means determines that the camera body is transmitting / receiving a level signal; It is characterized by that.
[0008]
According to the present invention, the number of pulses per predetermined time of a transmission signal transmitted from the target device is measured, and when the number of pulses is equal to or greater than a predetermined value, it is determined that the target device is performing serial communication. If it is less than the predetermined value, it is determined that the target device is not performing serial communication. As a result, the device that communicates with the target device can automatically determine the communication function of the target device, and can appropriately switch to the communication function corresponding to the communication function to appropriately communicate with the target device.
[0009]
In addition, by constantly monitoring the communication function of the target device, even if the target device switches the communication function during communication, the communication function of its own device can be automatically switched accordingly.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of an automatic serial communication presence / absence discriminating apparatus according to the present invention will be described in detail below with reference to the accompanying drawings.
FIG. 1 is a configuration diagram showing a configuration of an invention for automatically determining whether or not serial communication is applied to a lens device of a television camera. As shown in the figure, the television camera includes a camera body 10 and a lens device 12, and the lens device 12 is mechanically connected to the camera body 10 and connected to the camera body 10 via a connector (not shown). Are electrically connected. The connector has a plurality of terminals, and the camera body 10 and the lens apparatus 12 transmit and receive signals through a plurality of lines. The configuration diagram shown in FIG. The line 13 is shown paying attention to the line 13, and this line 13 is a line through which a transmission signal is transmitted from the camera body 10 to the lens device 12.
[0011]
The signal transmitted from the camera body 10 is a serial signal composed of a periodic pulse train as shown in FIG. 2A, and the L level (0 V) and H as shown in FIG. There may be a case where the level signal is switched aperiodically at the level (5 V). That is, the camera body 10 has a serial communication function for converting a parallel signal into the serial signal depending on the model, and does not have a serial communication function, and the parallel signal is used as it is for the level signal (or analog signal). ), And the lens device 12 switches the control method according to the control method of the camera body regardless of the presence or absence of the serial communication function of the camera body. It can be connected to either.
[0012]
A transmission signal transmitted from the camera body 10 is input to the lens device 12 via the line 13, and is input to the MPU (microprocessor unit) 16 via the receiver (CMOS) 14 in the lens device 12.
The transmission signal input to the MPU 16 is input to the serial communication reception input port (serial input port) 20 or the level input input port (level input port) 22 via the changeover switch 18.
[0013]
The changeover switch 18 is controlled by the CPU 26 mounted on the MPU 16 (the changeover control will be described later). When a serial signal is input from the camera body 10, the changeover switch 18 is connected to the serial input port. When the level signal is input from the camera body 10, the changeover switch 18 is connected to the level input port 22. As a result, the serial signal is input to the serial input port 20 and the level signal is input to the level input port 22.
[0014]
A counter 24 is connected to the subsequent stage of the receiver 14 in parallel with the changeover switch 18. The transmission signal that has passed through the receiver 14 is input to the changeover switch 18 and simultaneously to the counter 24.
The counter 24 counts up at the rising or falling edge of the pulse of the transmission signal from the camera body 10 and counts the number of pulses of the transmission signal. The CPU 26 reads the count value in the counter 24 at predetermined time intervals (for example, every several ms), and determines whether the transmission signal from the camera body 10 is a level signal or a serial signal.
[0015]
That is, since the serial signal has an extremely large number of pulses per predetermined time compared to the level signal, if the number of pulses per predetermined time exceeds a certain set value, it is determined that the transmission signal is a serial signal, Conversely, when the number of pulses per predetermined time is equal to or less than the set value, it is determined that the transmission signal is a level signal.
Then, the CPU 26 performs switching control of the changeover switch 14 based on the determination result. When it is determined that the signal is a serial signal, the changeover switch 18 is connected to the serial input port 20 and is input to the serial input port 20. A transmission signal is read from the serial input port 20. On the other hand, when it is determined as a level signal, the changeover switch 18 is connected to the level input port 22, and the transmission signal input to the level input port 22 is read from the level input port 20.
[0016]
Next, the processing procedure of the CPU 26 will be described. First, when the camera body 10 and the lens device 12 are powered on, the CPU 26 resets (initializes) the counter 24 and a timer built in the CPU 26 (step S10). Then, the timer is started (step S12), and the counter 24 is started to start counting the number of pulses of the transmission signal from the camera body 10 (step S14).
[0017]
Next, it is determined in step S16 whether or not a timer interrupt has occurred. While the interrupt does not occur, other processes in the main routine are repeatedly executed (step S18).
When the predetermined time is measured by the timer and an interrupt is generated by the timer in step S16, the CPU 26 inputs the count value from the counter 24 and determines whether or not the count value exceeds the set value (step S20). If the count value does not exceed the set value, it is determined that the transmission signal from the camera body 10 is a level signal, the changeover switch 18 is connected to the level input port 22, and the control of the CPU 26 confidence is controlled by the level signal. And the input terminal of the connection connector of the lens device 12 connected to the camera body 10 is set as the input terminal for the level signal (step S22).
[0018]
On the other hand, if the count value exceeds the set value, it is determined that the transmission signal from the camera body 10 is a serial signal, the changeover switch 18 is connected to the serial input port 20, and the control of the CPU 26 is controlled by serial communication. The mode is set, and the input terminal of the connection connector of the lens device 12 connected to the camera body 10 is used as the input terminal of the serial signal (step S24).
[0019]
When the above settings are made, the process returns to step S18 again, and the processes in steps S16 and S18 are repeated. And the process of said step S20-step S24 is repeatedly performed by the interruption of the timer which generate | occur | produces every predetermined time.
As described above, it is possible to automatically determine whether the camera body 10 is performing serial communication or performing control based on the level signal.
[0020]
In addition, by repeatedly executing the processing of step S20 to step S24, when the camera body 10 is turned on after the lens apparatus 12 is turned on, or when the control mode of the camera body 10 is in the middle of operation, serial communication is performed. Even when control is switched from level signal control to level signal control or level signal control to serial communication, the control mode of the camera body 10 can be switched to appropriately correspond to the control mode of the lens device 12. Thereby, the trouble of re-powering the lens device 12 can be prevented.
[0021]
In the above embodiment, the case where the present invention is applied to a lens device of a television camera has been described. However, the present invention is not limited to this and can be applied to other arbitrary devices.
[0022]
【The invention's effect】
As described above, according to the serial communication presence / absence automatic determination device according to the present invention, the number of pulses per predetermined time of the transmission signal transmitted from the target device is measured, and when the number of pulses is equal to or larger than the predetermined value, It is determined that the target device is performing serial communication. If the target device is less than the predetermined value, it is determined that the target device is not performing serial communication. Thereby, the device that communicates with the target device can automatically determine the communication function of the target device and appropriately switch to the communication function corresponding to the communication function.
[0023]
In addition, by constantly monitoring the communication function of the target device, even if the target device switches the communication function during communication, the communication function of its own device can be automatically switched accordingly.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of a serial communication presence / absence automatic discrimination device according to the present invention applied to a lens device of a television camera.
FIG. 2A illustrates an example of a serial signal, and FIG. 2B is an explanatory diagram illustrating an example of a level signal.
FIG. 3 is a flowchart showing a control procedure of a CPU in the lens apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Camera body 12 ... Lens apparatus 16 ... MPU main body 18 ... Changeover switch 20 ... Serial input port 22 ... Level input port 24 ... Counter 26 ... CPU

Claims (2)

A serial communication function that can be attached to and detached from the camera body and performs serial communication with the mounted camera body, and a level signal transmission / reception function that transmits and receives level signals transmitted on different lines for each type of information A serial communication presence / absence discriminating device mounted in a lens device,
Counting means for measuring the number of pulses per predetermined time of the transmission signal transmitted from the camera body in a line where the serial communication function receives a transmission signal by serial communication from the camera body ;
When the value counted by the counting means is greater than or equal to a predetermined value, it is determined that the camera body is performing serial communication . When the value counted by the counting means is less than the predetermined value, the camera body Determining means for determining that the level signal is transmitted and received,
When it is determined by the determination means that the camera body is performing serial communication, serial communication by the serial communication function is enabled in the lens device, and the camera body transmits and receives level signals by the determination means. Communication function switching means for enabling transmission and reception of level signals by the level signal transmission and reception function in the lens device,
An apparatus for automatically determining the presence / absence of serial communication. 2. The serial communication presence / absence automatic determination device according to claim 1, wherein the determination means repeatedly determines whether the camera body is performing serial communication or transmitting / receiving the level signal at regular intervals. .

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