In an information apparatus such as copier or printer, usually, a plurality of motors are mounted as mentioned above. In particular, such information apparatus handling documents is advanced in color display, multiple functions, and high precision, and the number of motors installed in one apparatus tends to increase. As a result, the control method of each motor is complicated, and the signal wires for controlling each motor are increased in number.
For example, in the case of a brushless DC motor coming to be used widely recently because it is easy to control the rotation, it is a general configuration to compose a motor device by integrally forming a motor main body and a motor drive control circuit, and rotate and control the motor by connecting a microcomputer and a motor drive control circuit by various signal wires. At this time, between the microcomputer and the motor drive control circuit, various signal lines are connected for start/stop, brake action/release, normal rotation/reverse rotation, rotating speed command, rotating speed monitor, rotating speed phase lock detection, control gain changeover, etc. Accordingly, when the number of motors increases, the number of required signal wires increases. As a result, the wiring space increases, which brings about various demerits, such as difficulty in downsizing of the apparatus, increase of port load and control load of main controller such as microcomputer provided at the apparatus side, and increase of the necessary system cost.
Recently, to suppress such increase in the number of signal wires, it has been widely attempted to control the objects of control by using serial communication in various devices. The serial communication in devices is realized by connecting the microcomputer and the objects of control by a serial communication bus in the devices. The serial communication bus is a data bus composed of several signal wires for transmitting serial data. At this time, in order to identify each object of control, each one is assigned with an identification number such as an address. The microcomputer sends and receives necessary data while designating the identification number, and the data can be transmitted individually to each object of control. Thus, while suppressing the increase in the number of signal wires, various data can be exchanged with a plurality of objects of control, and the microcomputer can control each object of control by using such data.
In such apparatus having a plurality of motors, similarly, the technology utilizing such serial communication has been proposed.
One of such technologies is a proposal of a driving system of a plurality of motors by connecting the serial communication buses serially and sequentially to compose a cascade connection so as to enhance the wiring efficiency, in a conventional drive control circuit of motors (see, for example, patent literature 1).
Such conventional driving system is composed as follows. That is, data for driving the plurality of motors individually is sent out as serial data via serial communication buses. The motor drive control circuits provided in individual motors are connected serially via serial communication buses. Therefore, in each motor drive control circuit, addresses for identifying each one are set by bit switches or the like. First, out of the plurality of motor drive control circuits, a first motor drive control circuit receives data. At this time, the first motor drive control circuit refers to the transmitted address via the serial communication bus, and extracts only the data for the first motor drive control circuited sent to the own address, and stores in the register. At the same time, the first motor drive control circuits transfers other data not sent to the own address to a next motor drive control circuit. Hereinafter, by processing same as in the first motor drive control circuit, the plurality of motors can be driven and controlled. In the conventional driving system, in such configuration, a simple structure is realized by a small number of wires.
Or, when controlling a plurality of motors, it is often required to control so that each motor may work cooperatively. Therefore, in a conventionally proposed driving system, a simultaneous control mode for controlling the plurality of motors simultaneously is provided, and the operation of each motor is synchronized and changed, and a cooperative working of each motor is realized (see, for example, patent literature 2).
On the other hand, in these conventional driving systems, to judge if the received data is the data sent to the own address or not, as mentioned above, each motor drive control circuit needed bit switches or the like for setting individual addresses, and when the number of motor devices increases, the number of parts such as bit switches also increases. Further, it is required to set individually in each motor drive control circuit, and the setting takes much time, or setting errors may be involved.
Hence, conventionally, another communication control device has been proposed, in which the host device can communicate with individual slave devices selectively and serially without requiring setting of individual addresses in the slave devices corresponding to the motor devices (see, for example, patent literature 3).
Such conventional communication control device is composed as follows. That is, the host device and the slave devices are sequentially connected in link state via shift pulse lines. From the host device to the slave devices, or from a slave device of upstream side to a slave device of downstream side, shift pulses are transferred sequentially according to a shift clock. In an input state of this shift pulse, when a slave device receives a shift clock signal, it is judged that a serial communication state is established. At this time, this slave device starts serial communication with the host device via a serial communication line. For example, when the shift clock is sent out twice from the host device, the shift pulse is entered only in a second slave device. As a result, only the second slave device is selected, and the serial communication is established between the host device and the second slave device.
However, in such conventional communication control device, for example, when sending same data to individual slave devices, the communicating slaves devices are selected one by one. Accordingly, it is required to repeat transmission of shift pulse from upstream side to downstream side, and to desired slave devices, and it is not suited to a system for controlling a plurality of motor devices at high speed.    Patent literature 1: Unexamined Japanese Patent Application No. 2001-161095    Patent literature 2: Unexamined Japanese Patent Application No. 2008-22638    Patent literature 3: Unexamined Japanese Patent Application No. 2007-73238