JPH03114371A - Data communication system for camera - Google Patents

Abstract

PURPOSE:To attain smooth communication without need of undesired processing time and malfunction of the system by using a communication word length revision command in the control communication between a camera and a lens. CONSTITUTION:A lens 1 and a camera 2 are formed freely removably with a mount section 3 and a communication transmission line 4 for various communication is formed by an electric contact arranged to the mount section 3 at connection. Then in the case of various control of the system with synchronization communication between the camera 2 and the lens 1, as a kind of initial/ control command sent from the camera 2 to the lens 1, a word length revision command having a word length used for a succeeding communication as an operand is provided, and before the communication word length is revised by using the command, the communication master sends revision of the word length to the communication slave. Thus, the defective synchronization of the communication slave or undesired increase in the processing is prevented.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is applicable to, for example, a camera with interchangeable lenses.
The present invention relates to a communication system suitable for use in communicating control information between the camera and lens.

A suitable method is one in which multiple communication master sides with different functions and multiple communication slave sides with different functions are interconnected using the same communication format, and the combination realizes various functions as a system. This provides a serial communication system in a crisis connection system.

(Background Art) In recent years, the development of cameras and video camera systems has been remarkable, and various systems have been provided that have various functions and can have interchangeable lenses.

In such a system, the camera (including video camera; hereinafter simply referred to as camera) obtains unique information indicating various characteristics and control information of the interchangeable lens unit from the lens unit, and based on that information, Predetermined control information is sent to the lens unit side, and various controls such as automatic focus adjustment (hereinafter referred to as AF), automatic exposure adjustment (hereinafter referred to as AE), and automatic angle adjustment (hereinafter referred to as AZ) are performed. It is being said. The reception and delivery of these control data and information data is generally performed by serial communication with the master on the camera side and the slave on the lens side.

By the way, in a system with interchangeable lenses, the functions on the camera side and the lens side are different, so the total function is determined by the combination of the functions on the camera side and the functions on the lens side.

Figures 1(a) and 1(b) show combinations of system configurations of such camera systems.
), consider a combination of cameras A and B, each with different functions, and lenses C and D.

As shown in FIG. 6(b), camera A performs AF.
F block 101, AE block 102 that performs AE,
The function of the AZ block 103 for performing AZ can be controlled, and camera B can control the function of the AZ block 103 for performing AE.
Assume that only one function can be controlled.

Also, looking at the lens side, the lens C has an AF block 121, an AE block 122, and an AZ block 123.
It is assumed that the lens D has an AF block 131 and an AE block 132 and is capable of operating each function.

Here, camera A and lens C are connected via serial communication line 14.
When combined by connecting with serial communication line DL, AF, AE, and AZ functions are possible; when camera A and lens D are combined by connecting with serial communication line DL, the functions are as follows. AF and AE operations are possible, and in the case of the other two combinations using camera B, only AE operation is possible.

At this time, the cameras A and B and the lenses C and D exchange data with each other based on a common format via the serial communication line DL.

(Problems to be Solved by the Invention) By the way, in various data communications in the system as described above, prior to communication of control data, initial communication for initializing the system and communication of actual control data are performed. If there is control communication, there will naturally be a point in time when switching between these communication modes.

In other words, specifically, when the camera determines the type and function of the lens through initial communication and moves to actual drive control, or when the initial data of the lens is required again on the camera side for some reason during control, etc. be. Regarding the latter, for example, a case can be assumed in which the lens is replaced during operation.

The number of words in the initial communication X is the number of words in the header part wh,
If Wi is the number of words used for the actual initial communication command, then X = W h + Wi, and the number of words Y for control communication can be controlled (or is necessary If the number of units of each function such as AF%AE, AZ (hereinafter these functions are referred to as units) is n, and the number of control words for one unit is Wc, then Y = W. h + (n X W c ).

The magnitude relationship between the number of communication words X and Y is not determined in a fixed manner.

In other words, when the number of units that can be controlled as a system is small, X > Y, when the number of units that can be controlled as a system is large, it is X × Y, and in between these, X = Y. In some cases.

In this way, when the type of communication changes from initial communication to control communication or from control communication to initial communication, the number of communication words required also changes.

Generally, in a synchronous communication system, the communication master side can always know the number of communication words, but the communication slave side cannot always know the number of communication words. For this reason, in a normal synchronous communication system, communication is performed with the number of communication words constant regardless of the presence or absence of data in order to avoid system confusion.

However, in the system as described above, if communication is performed with the number of communication words constant, the maximum value of the system must be set as the number of communication words.

Therefore, in this case, if we return to FIG. 1(b), there is no problem in cases such as the combination of camera A and lens C, but in cases such as the combination of camera B and lens D, Communication words that are not directly related to control must be transmitted, which increases unnecessary communication, and the unnecessary communication takes up processing and the time required for that processing, reducing the processing capacity that is originally required. Since it is necessary to have a microcomputer with the above capabilities, this leads to an increase in costs.

Also, if you try to minimize the number of communication words,
For example, it is possible to use means for transmitting the number of words of the communication at that time in the header part of the communication.

However, even in this case, the processing on the lens side requires decoding the communication code during the word interval of synchronous communication and changing the control to match the number of words at that time. In this case, a high processing speed is required on the lens side, and a processing system with higher performance than necessary is required, which also causes a cost increase.

(Means for Solving the Problems) The present invention was made for the purpose of solving the above-mentioned problems. - The number of communication words is made variable, and the number of communication words is increased only when necessary. If necessary, the number of communication words can be shortened (and the functions of cameras and lenses connected to the system can be reduced to the minimum necessary), and even if the number of communication words changes depending on the type of communication, the microcomputer The present invention provides a communication system that can be realized without increasing costs.

In order to achieve such an object, the present invention is characterized in that in a camera that controls functions on the lens side based on control information serially transmitted from the camera side, the control information is communicated and The present invention provides a camera system comprising: communication means capable of changing the number of communication words; and means for transmitting the changed number of communication words from the camera side to the lens side when the number of communication words is changed.

Another feature of the present invention is a camera system that controls functions on the lens side based on control information serially transmitted from the camera side. The camera system includes means for varying the number of words of control information to be transmitted, and means for transmitting the changed number of communication words to the lens side when the number of words of the control information is changed.

Another feature of the present invention is that, in a camera with a removable lens, there is provided a communication means for serially communicating control information for controlling functions on the lens side, and a communication means for serially communicating control information for controlling functions on the lens side; The camera is provided with means for determining the number of communication words of the communication means and for changing the number of communication words of the communication means, and means for transmitting information on the number of communication words to a lens side when changing the number of communication words.

Another feature of the present invention is a first communication between the master side and the slave side for recognizing the system connection and the functions of the slave side, and a first communication for controlling the functions of the slave side. a communication means that can set a second communication mode, and a communication means that can set a second communication mode; and a communication means that can set a second communication mode; The data communication system includes means for transmitting information regarding the number of words of the switched communication mode to the slave side when a mode switching operation is performed between the communication modes.

Another feature of the present invention is that in a camera system that controls a plurality of functions on the lens side based on information of each of a plurality of communication words serially transmitted from the camera side,
an initial communication mode for recognizing the connection state between the camera side and the lens side and a control target on the lens side; and a second communication for controlling the functions of the slave side using a communication word count different from the initial communication mode. When a mode switching operation is performed between the first communication mode and the second communication mode, information regarding the number of words of the communication mode after switching is sent to the slave side. and a means for transmitting data to and from the camera.

(Function) This allows synchronized communication between the camera and lens to perform various system controls, and is used as an operand from the next communication as a type of initial/control command sent from the camera side to the lens side. By providing a "word length change command" with a word length of It is possible to prevent synchronization failure or unnecessary increase in processing.

(Embodiments) Hereinafter, embodiments of the communication system according to the present invention will be described in detail with reference to the respective figures.

Figure 1 is a system configuration diagram showing the system configuration of the camera and lens as described above, Figure 2 is a timing chart explaining data communication between the camera and lens, and Figure 3 is transmission data from the camera side to the lens side. Figure 4 shows the temporal relationship between data returned from the lens side to the camera side.
The figure shows the code structure inside each communication data, Figure 5 is a flowchart to explain the control operation on the camera side and lens side, and Figure 6 is a block diagram to explain the functions on the camera side and lens side, respectively. It is.

First, the configurations on the camera side and lens side will be explained using FIG. 6.

In the figure, 1 is a lens, and 2 is a camera, which are detachably configured by a mount 3. When connected, initialization information, control information, etc. are transmitted through electrical contacts arranged on the mount 3. A communication transmission line 4 constituting the above-mentioned communication line DL for performing various communications is formed.

Inside the lens unit 1, a lens group consisting of a focusing lens 5 for adjusting the focus, a zoom lens 6 for zooming with variable magnification, an aperture 7, a relay lens 8, etc. is arranged, and the focusing lens , a zoom lens, a drive section 9, 10, and 11 each consisting of a motor and a drive circuit for driving the diaphragm. These drive units are driven and controlled by a control microcomputer 12 that performs all controls on the lens side based on control information supplied from the camera side via the communication transmission line 4. Further, the operating states of the focusing lens, zoom lens, and aperture are detected by the focus encoder 13, zoom encoder 14, and aperture encoder 15, respectively, and are input into the lens-side microcomputer 12, and after performing predetermined processing as necessary. , is transmitted to the camera side via the communication transmission line 4.

On the other hand, the camera 2 includes an image sensor 16 such as a CCD for photoelectrically converting a subject image formed by the connected lens 1 into a video signal, and a predetermined video signal output from the image sensor 16. a preamplifier 17 that amplifies the output signal to a level of A circuit 18, an AF circuit 19 that detects a focus state based on a high frequency component of a luminance signal from a video signal, compares the average value of the luminance signal level of the video signal with a preset reference level, and determines that the luminance signal level is the reference level. AE circuit 20 that outputs a signal to control the aperture so that it is always equal to switch 22,
An AZ mode setting switch 23 and the like are arranged.

The focus state detection signal outputted from the AF circuit 19, the aperture state detection signal outputted from the AE circuit 20, and the operation signals of the zoom switch 22 and AZ mode setting switch are respectively supplied to the microcomputer 21 and sent back from the lens side. After performing predetermined calculations while referring to the information on the operating state and converting it into a format for supplying to the lens side, it is transmitted to the lens side via the communication transmission line 4, and the lens side control is performed. It will be done.

To briefly explain each function here, the AF circuit 19 uses a bypass filter 191 to extract a high frequency component of a luminance signal in a video signal that changes depending on the focusing state, and extracts it using a detection circuit 192. The signal is detected and converted to a DC level, the peak value of which is detected at predetermined intervals by a peak hold circuit 193, and converted into a digital signal by an AD conversion circuit 194, which is then supplied to the microcomputer 21. The microcomputer 21 detects the peak value of the high frequency component at predetermined intervals, and provides control information for driving the focusing lens in the direction in which the peak value is maximized.
The aperture information from the lens side is referenced, the depth of field is taken into consideration, and the calculation is output to the lens side.

The AE circuit 20 also uses a comparison circuit 202 to compare light amount information obtained by integrating luminance signal components separated by YC using a low-pass filter or the like in a signal processing circuit using an integrating circuit 201 and a reference amount level set in advance. , the difference information is converted into a digital signal by the AD conversion circuit 203 and supplied to the microcomputer 21, and a control signal for driving the aperture is generated so that the luminance signal level matches the reference amount level. . On the lens side, an aperture drive section within the lens is driven based on the control signal.

As a result, the amount of light input to the camera side changes, and a control loop is formed so that an appropriate aperture value is finally achieved.

The AZ mode is activated by operating the AZ mode switch, and compensates for changes in subject distance by varying the magnification, keeping the angle of view constant.When the subject distance changes due to AF operation, etc. The microcomputer 21 determines changes in the object distance based on zoom encode information, that is, focal length information, and focus encoder information, that is, object distance information supplied from the lens side, and corrects changes in the angle of view due to the distance changes. , that is, the zoom lens control information, and transmits it to the lens side. Based on this information, the lens side drives and controls the zoom lens so as to keep the angle of view of the subject constant within the imaging screen.

The functions on the lens and camera sides are as described above, and next we will explain in order the changes in the system due to various combinations of lenses and cameras.

In FIG. 1, first consider a system in which camera A and lens C are connected.

In this case, camera A first inquires about the functions that the lens itself has, ie, the type of unit such as AF, AE, AZ, etc. Temporarily call this command "Lens specification request command"
I will call it .

In FIG. 3, D CT L (Data Came
raT.

D L T C (Data Lenz T
oCamera) indicates a reply data block from the lens side to the camera side. Communication between the camera and the lens is performed in synchronization with the vertical synchronization frequency V, and according to this embodiment, communication is performed every V. That is, when a transmission is made from the camera side to the lens side at the timing of AroV, a reply to that transmission is made at the timing of the next V.

Now, assume that the lens specification request command described above corresponds to data block DCTL-1 in the figure.

At this time, lens C receives DCTL-1 and receives the next V
At this timing, data block DLTC-2 sends back to camera A what unit it has, that is, what function it has.

Here, camera A has an AF unit 101 and an AE unit 1.
02, has an AZ unit 103, and lens C has an AF unit 121, an AE unit 122, and an AZ unit 12.
I have 3.

That is, according to this combination system, AF control,
It can be seen that AE control and AZ control are possible.

Camera A has the unit that lens C has.
Specific control cannot be performed without knowing information such as what operating range each unit has or what control method is possible. For this reason,
In response to the "lens specification request command", it is necessary to know the specifications of the unit that lens C replies that it has.

Camera A then asks lens C about its specifications for each unit. If this command is
This command will be referred to as "Unit Specification Request Command".

Looking at Figure 3, for example, the "unit specification request command" for the AF unit corresponds to DCTL-3;
The "unit specification request command" for the E unit is
Corresponds to DCTL-4. As described above, the responses from lens C are transmitted to camera A with a delay of one communication timing. The specific contents of the "unit specification request command" differ for each unit, but for the AF unit, it includes things like the maximum and minimum values of the focus distance, and the maximum and minimum values of the speed of the focus motor. , Regarding the AE unit, it is something like FNo.
Regarding the AZl unit, it is something like a telephoto end focal length or a wide end focal length.

The above ``lens specification request command'' and ``unit specification request command'' are so-called initial communications to capture necessary information prior to actual control operation, and the number of communication words for each is determined in advance. has been decided.

That is, the commands used for initial communication are in a common format no matter what combination of camera and lens is used.

Assuming that this predetermined number of communication words is Wi, if Wi = 8, and if the number of words in the header part mentioned above is Wh = 2, then the number of words X used for initial communication is X = 2 + 8. =10.

Next, the camera issues specific control commands to the lens in order to satisfy its function. This command is issued for each unit to be controlled.

Assume that the control command for the l unit is composed of, for example, four words. In the combination of camera A and lens C, the number of controlled units is 3 (AF%AE%AZ), n=3. Therefore, the number of words X during control communication is combined with the number of words Wh = 2 in the header section, and Y
=2+3X4=14.

In the case of this combination, the number of words increases when changing from initial communication (10 words) to control communication (14 words).

FIG. 2 shows a timing chart of communication performed between the camera and lens in this manner.

Here, for convenience of explanation, it is assumed that data is received and transferred between the camera and the lens using synchronous serial communication.

Communication between the camera and the lens is performed alternately by the data communication line DCTL from the camera to the lens and the data communication line DLTC from the lens to the camera.
(S6real C1ock) is a clock signal for serial synchronization, and CS (Chip 5elect) is from the camera side, which is the master side of serial communication.
This is a chip select signal that serves as a trigger signal to notify the lens, which is the slave side of serial communication, of the start of communication.

Also, as mentioned above, regarding the repetition period of communication,
AF processing using video signals in video cameras, etc.
Taking into account the E processing, it is set to the period of the vertical synchronization signal V of the video signal.

Further, serial communication uses 8 bits as a unit of one word and has a constant word interval WS so that it can be performed even with an inexpensive microcomputer.

In FIG. 2, DCTL and DLTC are expressed in positive logic, and C8 and 5CLK are expressed in negative logic.

As is clear from the figure, when the chip select signal C8 is output after a predetermined time in synchronization with the vertical synchronization signal V, the data communications DCTL and DLTC between the camera and lens are activated in synchronization with the serial clock signal 5CLK. This is repeated alternately in units of communication words.

Here, with reference to Figure 3, DCTL and DLTC.
To explain the relationship further, when the lens attempts to convey a response to a command from the camera within the same communication, the meaning of DCTL must be deciphered within the word interval WS mentioned above. In addition, data corresponding to the content must be set as DLTC in order to be sent back to the camera side.

In order to achieve this, the processing speed must be considerably faster than that of a microcomputer. Further, the processing method within the lens is also subject to considerable limitations due to its processing speed.

Therefore, as shown in Figure 3, basically DCTL
The lens will give the answer D at the next communication timing.
A method is used in which communication is alternately and repeatedly sent to the camera as LTC. For example, DCTL-
The lens side answer to 1 is DLTC-2, D
The lens side's response to CTL-2 is DLTC-3.

DLTC-1 when Naori CTL is sent for the first time
Since no data request has come from the camera side before that, it only has a formal meaning of serial communication (the contents have no meaning).

Now, in FIG. 1, the functions of camera A that can operate as a comprehensive system differ depending on whether lens C is connected to the common data line 14 or lens D is connected to the common data line.

Therefore, when camera A is connected to the common data line 14, first of all, in order to confirm what kind of function the lens is connected to the opposite side of the common data line 14, Request the unique information of the lens, and after the unique information of the lens is revealed,
In other words, after recognizing what kind of control is possible for that lens, control suitable for each lens is performed.

Now, send a message to request lens-specific information.
This will be referred to as "initial communication," and the communication for controlling the functions of the lens will be referred to as "control communication."

Initial communication is a communication from the camera to the lens that tells the lens what kind of function the lens has, how that function can be controlled from the camera side, and the operating range of that function.
As mentioned above, the inquiry is made in CTL, and the lens replies to the camera in DLTC. Since the initial communication is used to determine what kind of function the lens has, the number of words required for communication is uniquely determined regardless of the type of camera or lens (fixed word). number).

Control communication means that the camera side uses DCTL to issue specific control operation instructions for the various functions of the lens revealed through initial communication, and the lens side uses DLTC to communicate the current status of the functions to the camera. It is intended to be communicated to the public. Since the content and type of control communication differs depending on the function of the lens, the number of words cannot necessarily be uniquely determined (the number of words is variable).

Here, the content and method of control communication will be briefly explained.

In a so-called camera system that combines a camera and a lens, typical functions are known as AF, AE, and A2 functions, and these functions are performed when the camera unit generates a control code based on some information. By operating the corresponding function on the lens side based on the control code, when the state of the lens changes, the content is transmitted to the camera side for recognition.

Then, the camera side also refers to the information from that lens,
Furthermore, if necessary, a control code is generated again for the lens.

A specific example of such control will be described below regarding AE sub-control.

As mentioned above, the AE sub-control is performed as follows.

A camera converts light input through a lens (including an aperture mechanism) into an electrical signal (video signal) through an image sensor (such as a COD).

The converted video signal is converted to YC by a low-pass filter etc.
The light amount information obtained by integrating the separated luminance signal components is compared with a preset reference amount level,
A control signal for driving the diaphragm is generated so as to match the reference amount level. Based on the control signal, the lens drives an aperture mechanism within the lens to change the amount of light input to the camera side, forming a control loop so that an appropriate aperture value is finally achieved.

The above is an example of AE sub-control, but in AF control and AZ sub-control, the camera side outputs control (drive) data to the lens side based on optical and electrical information obtained through the lens, and the data is Based on this, the lens drives some kind of drive system, and as a result, the information that enters the camera changes, forming a loop that ultimately results in proper control.

Here, in the control system as described above, each functional part existing in the lens will be referred to as a unit. It is assumed that the unit has some kind of drive system for changing the control amount of its function, and some kind of encoder for detecting the state necessary to transmit the amount of change to the camera.

Returning to FIG. 1, it can be said that camera A is a camera that has the function of controlling the AF, AE, and AZ units, and camera B is a camera that can control only the AE unit. In addition, lens C has AF%AE, A
It is a lens with Z unit, and lens D has AF,
It can be said that this is a lens with an AE unit.

FIG. 4 shows the code structure of each initial communication and control communication. CT L (CameraTo L
enz) is the transmission block from the camera side to the lens side, L
TC (Lenz To Camera) is a reply block from the lens to the camera.

Each code consists of a header section and a command (in the case of CTL)/data section (in the case of LTC), and the header section indicates what kind of communication the communication is (initial communication, control communication, or other type of communication). communication), and the communication direction is LT.
This indicates the type of command or data content, such as C or CTL.

The word lengths of the header part of the CTL code and the header part of the LTC code are always constant regardless of initial communication or control communication.

Further, as described above, the command/data section is a section that represents the actual control from the camera and the driving state from the lens, and is divided into units.

When the same thing is done with the combination of camera A and lens C, the number of words for initial communication is 10 words, which is the same as for the combination of camera A and lens C, but the number of words for control communication is only for the AE unit. The number of words is 6 words because the communication is carried out for the first time, and the number of words decreases when the initial communication changes to the control communication.

The camera side, which is the master side of serial communication, can manage the number of communication words by itself, so there is no problem, but if the number of words suddenly changes on the lens side, which is the slave side of serial communication, the previous word Since communication is supported by numbers, especially when the number of words decreases, serial processing will not be completed forever, and in the worst case, the camera side will not be able to process the data sent at the next communication timing. You will end up importing it by mistake.

Therefore, in the present invention, this problem is solved by introducing a "word length change command" when the number of words in serial communication changes, and having the changed word length as an operand of this command. are doing.

Naturally, this command is assumed to be sent with the word length before the change. As for processing on the camera side, use this command when you want to change the type of command,
On the lens side, when this command is sent from the camera side, it changes the number of words for serial processing and waits for the next communication.

FIG. 5 is a flowchart showing a portion of processing related to communication between the camera side and the lens side that is related to the present invention. 3A shows the processing in camera A, FIG. 2B shows the processing in camera B, and FIG. 1C shows the processing in lens C and lens D.

In FIG. 3(a), when camera A starts a control operation, it first performs a predetermined initial process (
SL). The contents include, for example, various controls, initialization of registers used in calculations, setting of serial communication speed, etc. After the initial processing is completed, the initial communication mode is entered (S2). First, use the "lens specification request command" to check what kind of lens the currently connected partner has (S3). This determines what kind of unit the currently connected lens has. After that, the specific contents of the units existing in the lens are obtained using each "unit specification request command".

In other words, after requesting the lens specifications, first check the presence or absence of the AF unit based on the result (S4), A
If an F unit exists, the specifications of that unit are recognized by a "unit specification request command" (S5). Similarly, based on the presence or absence of the AE unit and AZ unit, the specifications of the existing units are imported from the lens side (S6 to S9).

Next, the specific control will be started. When camera A and lens C are combined, the number of communication words is 14 as described above. Therefore, set the "°° word length change command" with the operand "° word length after change = 14" (5IO) and send it to the lens (
S11).

After that, perform AP control, AE control, and AZ control respectively (
812-514).

After that, repeat AF control, AE control, and AZ control while referring to the data returned from the lens side. If some change occurs on the camera side or lens side during control and the initial information of the lens is required again, , returns to S2, and once again sends the "°° word length change command" to the lens together with the operand "word length after change=10 (initial communication)" (S15, 316).

Furthermore, when camera A is combined with lens D, the number of controllable units is n=2, so the number of words in the control communication is 10 words, the same as the initial communication. In such cases, there is no need to use the "word length change command", but there is no harm in using the "word length change command" with the operand "word length after change = 10". it is obvious. That is, no special system control changes are required.

Figure (b) shows the case of camera B; in this case, Figure (a)
The difference is that camera B only has the function of controlling the AE unit. Therefore, whether it is combined with lens C or lens D, the number of communication words for controlling it is 6 words.

Therefore, the control flow is as follows from the flowchart of FIG. 4A to step S4 regarding unit specification requests related to the AF unit and AZ unit and their control.
S5. S8,59S12. S14 is omitted. Since the other steps are the same, they are indicated by the same reference numerals and the explanation thereof will be omitted.

FIG. 4(c) shows the processing contents on the lens side, and regarding communication processing, both lenses C and D can be expressed in a common form.

After starting the operation and performing initial processing (S21), the lens side waits for the number of words of initial communication (=10). Then, the data corresponding to the transmitted "initial communication command" or "control communication command °°" is sent back to the camera side.In other words, if the transmitted command is an initial communication command, its contents are The data corresponding to the data is sent back to the camera side (S23, 524
). If it is a control communication command, data representing the status of the unit according to the control information is returned to the camera side (S25, 526).

The above flow is repeated until the word length change command is sent to control the lens side unit.

When a "word length change command" is sent, the operand is set to the "changed word length" at that point, and subsequent communication is awaited with the word length operand unchanged. As a result, even if the word length is changed during operation, communication can be continued without malfunctioning, and it is possible to respond quickly without confusing the microcomputer and disrupting control.

(Effects of the Invention) As described above, according to the present invention, by using the communication word length change command in control communication between the camera and the lens, system malfunctions may occur due to changes in the number of communication words, mode, etc. Communication can be performed smoothly without unnecessary processing time or unnecessary processing time.

In addition, this does not result in an increase in processing on the camera side and lens side (and does not particularly require processing speed on the lens side (i.e., increases the cost of the lens side processing unit (microcomputer), etc.). Instead, it is possible to realize a system with an optimal communication word length by combining various different functions.

[Brief explanation of drawings]

Figure 1 is a connection diagram of a camera system to which the present invention is applied. Figure 2 is a diagram showing a timing chart of serial communication. Figure 3 is a diagram showing the time relationship between CTL code and LTC code. Figure 4 is an initial diagram. A diagram showing the word structure of communication/control communication, Fig. 5 is a flowchart showing a processing method related to camera side and lens side communication, and Fig. 6 is a block diagram for explaining various functions on the camera and lens sides. It is. Figure LTC <Lens m-> Camera) Figure 3 DCTL DLTC Woouu DCTL: Tsu × U → Shi> again°゛DLTC: [〉Suka X Ri (α) Camera 1 law processing (Camera A) (b) Camera fl Processing (B 1st 2 3 4 6 8 q sh. S1-13 S゛將I5 1-mera B) (C) Lens side processing (Resoz C/D) Figure

Claims (1)

[Scope of Claims] (1) In a camera that controls functions on the lens side based on control information serially transmitted from the camera side, a communication means capable of communicating the control information and changing the number of communication words; A camera system comprising: means for transmitting the changed number of communication words from the camera side to the lens side when the number of communication words is changed. (2) In a camera system that controls functions on the lens side based on control information serially transmitted from the camera side, means for serially transmitting the control information word, and a control information word transmitted from the camera side. A camera system comprising: means for changing the number of words of the control information; and means for transmitting the changed number of communication words to the lens side when the number of words of the control information is changed. (3) In a camera with a detachable lens, a communication means for serially communicating control information for controlling functions on the lens side, and a communication means for determining the state of the lens side or the number of functions to be controlled. 1. A camera comprising: means for varying the number of communication words; and means for transmitting information on the number of communication words to a lens side when changing the number of communication words. (4) A first communication between the master side and the slave side of the communication for recognizing the system connection and the functions of the slave side, and a second communication mode for controlling the functions of the slave side. and a communication means that can set the number of communication words between the first communication mode and the second communication mode if the number of communication words is different between the first communication mode and the second communication mode. A data communication system comprising: means for transmitting information regarding the number of words of the communication mode after switching to the slave side when a mode switching operation is performed. (5) In a camera system that controls multiple functions on the lens side based on information of each of multiple communication words serially transmitted from the camera side, the connection state between the camera side and the lens side and the control on the lens side. an initial communication mode for recognizing a target; and a second communication mode for controlling functions on the slave side using a communication word number different from the initial communication mode.
When a mode switching operation is performed between the first communication mode and the second communication mode, information regarding the number of words of the communication mode after switching is set to the communication mode. What is claimed is: 1. A camera data communication system comprising: means for transmitting data to a slave side.