Patent Publication Number: US-7583038-B2

Title: Motor-driving circuit and recording apparatus including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The present application is a continuation of U.S. patent application Ser. No. 10/899,532, filed Jul. 26, 2004, entitled “MOTOR-DRIVING CIRCUIT AND RECORDING APPARATUS INCLUDING THE SAME”, the content of which is expressly incorporated by reference herein in its entirety. Further, the present application claims priority from Japanese Patent Application No. 2003-203744 filed Jul. 30, 2003, which is also hereby incorporated by reference herein in its entirety. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a motor-driving circuit and a recording apparatus including the motor-driving circuit. 
   2. Description of the Related Art 
   The motors mainly used for printers are DC motors and stepping motors. A plurality of DC motors and stepping motors are used in accordance with the type or use of the printer. 
   To drive these motors, four transistors form an H-bridge circuit and each transistor is turned on and off to control an electric current to drive the motors (refer to, for example, Japanese Patent Laid-Open No. 05-122988, in particular, FIG. 4 and Japanese Patent Laid-Open No. 05-184194, in particular, FIG. 8). 
     FIG. 10  shows an example of the configuration to drive a printer motor. This configuration includes a printer controller  100 , DC motors  102  and  103 , stepping motors  104  and  105 , DC motor drivers  106  and  107 , and stepping motor drivers  108  and  109 . The configuration shown in  FIG. 10  requires the motor drivers to output a driving signal to each motor. 
   With reference to  FIG. 11 , motors are connected to motor drivers in accordance with the type of motor (or the properties of the motor). Progress of semiconductor process technology has allowed a motor driver to support a plurality of motors as long as the motors are of the same type. 
   Unfortunately, if several types of motor are required, as shown in  FIG. 12 , a different motor driver is required for each type of motor, even though one motor driver can drive a plurality of motors. 
   Use of a plurality of motor drivers increases the cost and size of the circuit board, and thus of an apparatus including the motor drivers, such as a motor control apparatus. 
   SUMMARY OF THE INVENTION 
   According to the present invention, a motor-driving circuit for driving motors includes a plurality of H-bridge circuits for outputting driving signals to the motors, an H-bridge controller for controlling the H-bridge circuits, an H-bridge setting section for setting up the H-bridge controller, and a plurality of terminals for inputting setting data to the H-bridge setting section. 
   Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments (with reference to the attached drawings). 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a control block diagram to drive motors according to an embodiment of the present invention. 
       FIG. 2  is a diagram for explaining a motor-driving circuit according to the embodiment. 
       FIG. 3  shows an example of the connection between motors and the motor-driving circuit according to the embodiment. 
       FIG. 4  shows another example of the connection between motors and the motor-driving circuit according to the embodiment. 
       FIG. 5  shows another example of the connection between motors and the motor-driving circuit according to the embodiment. 
       FIG. 6  shows another example of the connection between motors and the motor-driving circuit according to the embodiment. 
       FIG. 7  shows another example of the connection between motors and the motor-driving circuit according to the embodiment. 
       FIG. 8  is a diagram for explaining the transfer of setting data. 
       FIG. 9  is a diagram for explaining the setting data. 
       FIG. 10  shows an example of the connection between motors and a known motor-driving circuit. 
       FIG. 11  shows another example of the connection between motors and a known motor-driving circuit. 
       FIG. 12  shows another example of the connection between motors and a known motor-driving circuit. 
       FIG. 13  is a diagram for explaining the motor-driving circuit according to the embodiment of the present invention. 
       FIG. 14  is another diagram for explaining the motor-driving circuit according to the embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   First Exemplary Embodiment 
     FIG. 1  shows an exemplary configuration of an apparatus including a motor-driving circuit, which is also referred to as “motor driver” or “motor driver circuit”. For example, a printer (recording apparatus) having an inkjet recording head will be described below. 
   A configuration shown in  FIG. 1  includes three DC motors and two stepping motors, five motors in total, which are connected to two motor drivers of the same type. 
   As shown in  FIG. 1 , the configuration includes a (Central Processing Unit) CPU  1 , a printer controller  2 , a first motor driver  3 , a second motor driver  4 , a first DC motor  5 , a second DC motor  6 , a third DC motor  7 , a first stepping motor  8 , and a second stepping motor  9 . 
     FIG. 2  shows a block diagram of a motor driver circuit according to the present invention. The motor driver circuit is, for example, integrated into a one-chip integrated circuit (IC). In the example shown in  FIG. 2 , the motor driver circuit has four H-bridge circuits. The combination of the H-bridge circuits and the motors can be changed in accordance with the types of the connected motors. 
   The H-bridge circuit will be briefly described below. The H-bridge circuit includes four transistors, for example, field-effect transistors, to which control signals are input. In response to the control signals, the transistors are turned on or off to change the directions of currents flowing therethrough to rotate the motors in the positive direction or negative direction. 
   As shown in  FIG. 2 , a setting section  20  determines the configuration of the H-bridges. A controller-A/B  21  controls an H-bridge-A  23  and an H-bridge-B  24 . A controller-C/D  22  controls an H-bridge-C  25  and an H-bridge-D  26 . 
   In the configuration shown in  FIG. 2 , to drive a stepping motor, the H-bridge-A  23  and the H-bridge-B  24  form a pair and the H-bridge-C  25  and the H-bridge-D  26  form a pair. 
   To drive a DC motor, the H-bridge-A  23 , the H-bridge-B  24 , the H-bridge-C  25 , and the H-bridge-D  26  independently drive their respective motors. Alternatively, the pair including the H-bridge-A  23  and the H-bridge-B  24  may drive a motor and the pair including the H-bridge-C  25  and the H-bridge-D  26  may drive another motor. 
   When DC motors that do not require a high electric current (hereinafter referred to as “DC(S)”) are connected, the H-bridge-A  23 , the H-bridge-B  24 , the H-bridge-C  25 , and the H-bridge-D  26  can independently drive these motors. In contrast, when DC motors that require a high electric current (hereinafter referred to as “DC(L)”) are connected, both the H-bridge-A  23  and the H-bridge-B  24  drive one motor and both the H-bridge-C  25  and the H-bridge-D  26  drive another motor. 
   In the specifications of the DC motors, current values required for the initial torque and varistor peak current values are different for the DC(S) and the DC(L). 
   For example, a current value required for the initial torque of the DC(S) is 2.5 ampere (A), while that of the DC(L) is 3 A. 
     FIG. 8  is a timing chart of signals to set up a motor driver in accordance with the connected motors. The configuration of the motor driver is initially set up by four signals, that is, a mode signal  31 , a clock signal  32 , a data signal  33 , and a strobe signal  34 . The mode signal is, for example, a sleep signal. If the sleep signal is at a low level, the motor driver enters a low-power-consumption mode. 
   To perform the initial set-up, as shown in  FIG. 8 , the mode signal  31  is switched to a low level, that is, to a low-power-consumption mode. Since the motor driver is in a low-power-consumption mode, the H-bridges are not active. When the mode signal  31  is low, configuration data is transferred by the data signal  33  in synchronization with the clock signal  32 . The data is determined by an edge of the strobe signal  34 , for example, the falling edge of the strobe signal. Upon reception of the strobe signal  34 , if the mode signal  31  is at a low level, an initial set-up is performed. On the other hand, if the mode signal  31  is at a high level, a normal set-up, that is, a set-up for driving each motor is performed. 
   Thus, the clock signal  32 , the data signal  33 , and the strobe signal  34  for the initial set-up are also used for driving the stepping motors. 
   In this embodiment, 16-bit data is delivered to the setting section. The first three bits, that is, bit  0 , bit  1 , and bit  2 , determine the configuration of the motors. 
   For example, as shown in  FIG. 9 , a combination of bit  0 =0, bit  1 =0, and bit  2 =0 indicates that two stepping motors are connected to the motor driver. This setting allows two stepping motors to be driven, as shown in  FIG. 3 . 
   A combination of bit  0 =0, bit  1 =0, and bit  2 =1 indicates that one stepping motor and two DC(S)s are connected to the motor driver. This setting allows one stepping motor and two DC(S)s to be driven, as shown in  FIG. 5 . 
   A combination of bit  0 =0, bit  1 =1, and bit  2 =0 indicates that one stepping motor and one DC(L) are connected to the motor driver. This setting allows one stepping motor and one DC(L) to be driven, as shown in  FIG. 4 . 
   A combination of bit  0 =1, bit  1 =0, and bit  2 =0 indicates that two DC(L)s are connected to the motor driver. This setting allows two DC(L)s to be driven, as shown in  FIG. 6 . 
   A combination of bit  0 =1, bit  1 =0, and bit  2 =1 indicates that four DC(S)s are connected to the motor driver. This setting allows four DC(S)s to be driven, as shown in  FIG. 7 . 
   Also, a combination of bit  0 =1, bit  1 =1, and bit  2 =1 indicates that two DC(S)s and one DC(L) are connected to the motor driver. This setting allows two DC(S)s and one DC(L) to be driven. 
   A circuit configuration to drive the connected motors by the initial set-up will be described next with reference to  FIG. 13 . 
   As shown in  FIG. 13 , this circuit configuration includes H-bridge circuits  1300 A and  1300 B, pre-drivers PD A 1  to PD A 4  and PD B 1  to PD B 4  that drive the H-bridge circuits. Also, signal lines A 1  to A 4  are used for driving the pre-drivers PD A 1  to PD A 4 . Signal lines B 1  to B 4  are used for driving the pre-drivers PD B 1  to PD B 4 . 
   The H-bridge circuit  1300 B can select either signal lines A 1  to A 4  or signal lines B 1  to B 4  with a selector  1301 . This selection is performed based on the above-described setting for the motors. For example, if a DC(L) or a stepping motor is connected, the selector  1301  outputs signals from the signal lines A 1  to A 4  to the H-bridge circuit  1300 B. If a DC(S) is connected, the selector  1301  outputs signals from the signal lines B 1  to B 4  to the H-bridge circuit  1300 B. 
   Further, the circuit configuration to actually drive the connected motors will be described next with reference to  FIG. 14 . H-bridges  1400 A and  1400 B, pre-drivers PD A 1  to PD A 4  and PD B 1  to PD B 4 , and a selector  1401  have the same functions as described in  FIG. 13 . Accordingly, their descriptions are omitted. 
   A block  1402  will be described below. A generator circuit  1403  generates a driving signal to drive a stepping motor. Generator circuits  1404  and  1406  generate driving signals to drive DC motors. 
   A selector  1405 , for example, selects either the generator circuit  1403  or the generator circuit  1404  based on a signal SELECT 2  and then delivers input signals to the selected generator circuit. 
   With reference back to  FIG. 2 , the setting section  20  outputs a signal SELECT 1  and the signal SELECT 2 . The selector  1401  and the block  1402  together correspond to the controller  21  or  22 . Upon receipt of the signals SELECT 1  and SELECT 2 , the block  1402  generates driving signals. 
   Each generator circuit will be described next. For example, the generator circuit  1403  receives a 16-bit serial signal in synchronization with a clock signal and its latch section latches the 16-bit signal. Then, the generator circuit  1403  generates the signals A 1  to A 4  to drive a stepping motor based on the 16-bit value. These signals drive the H-bridge. 
   On the other hand, the generator circuit  1404  receives a phase signal PHASE and an enable signal, and then generates the signals A 1  to A 4  to drive a DC motor. The phase signal PHASE, for example, is a pulse-width-modulated (PWM) signal whose duty varies. 
   The generator circuit  1406  is identical to the generator circuit  1404  and, therefore, a detailed description is omitted. The generator circuit  1406  generates the signals B 1  to B 4  that drive a DC motor. 
   The motor-driving circuit includes a plurality of terminals, some of which serve as both input terminals of signals for a stepping motor and input terminals of signals for a DC motor. For example, an input terminal of a clock signal for a stepping motor serves as an input terminal of a phase signal (a signal PHASE) for a DC(S) motor. Also, an input terminal of serial data for a stepping motor serves as an input terminal of a phase signal (the signal PHASE) for a DC(L) motor. 
   Consequently, the selector  1405  selects the generator circuit for a stepping motor or the generator circuit for a DC motor based on the signal SELECT 2  depending on the type of the connected, namely, driven motor. Then, input signals are delivered to the selected generator circuit. 
   For the sake of brevity, descriptions of other signals input to the generator circuit and the motor-driving circuit without passing through the selector  1405  are omitted. A reference voltage signal from an input terminal for the DC motor is one of the examples. 
   As described above, various types of connection of the motors are possible by initial setting. Additionally, as shown in  FIGS. 4 and 5 , motors of different types can be connected to a single motor driver to be driven. 
   Therefore, the functions of most signals output from motor driver terminals vary in accordance with the initial setting. However, functions of a power-supply terminal, a ground terminal, and a mode signal terminal remain unchanged at all time. 
   At initial set-up, by assigning bit  9  to bit  12  to the corresponding motors, the damping ratio of motor reference voltage can be also set up for each motor, where bit “ 0 ” indicates a damping ratio of 1/10 and bit “ 1 ” indicates a damping ratio of 1/20. 
   When a printer is powered on, the CPU  1  directs the printer controller  2  to set up the configuration of the motor driver. The printer controller  2  transfers the setting data shown in  FIG. 9  to the motor drivers  3  and  4  by using the control signals shown in  FIG. 8 . 
   After transferring the data, the printer controller  2  changes the mode signal  31  to a high (H) level to switch the motor drivers from a low-power-consumption mode to a normal mode, and the motor drivers  3  and  4  then receive setting data for a normal mode. The H-bridge circuits operate based on the setting data and drive the motors. 
   The normal mode setting includes settings of a range of electric current for torque (four levels), the rate of decrease of electric current (decay mode), and phase information (level setting for A-phase and B-phase). 
   Additionally, the motor drivers can drive the stepping motor in a 4-bit micro-step chopper-driving mode. 
   As described above, the motor drivers can be configured in accordance with the types and the number of connected motors by carrying out setting from a printer controller. 
   As shown in  FIG. 1 , the motor driver  3  can drive three DC(S)s  5 ,  6 , and  7  while the motor driver  4  can drive two stepping motors  8  and  9 . 
   In an example in which the present invention is applied to a recording apparatus, the DC(S)  5  is used as a carriage motor which scans a carriage having a recording head, the DC(S)  6  is used as a transfer motor which transfers recording media, such as recording paper, and the DC(S)  7  is used as a paper-outputting motor which outputs the recording media. Also, the stepping motor  8  is used as a cleaning motor for cleaning the recording head. The stepping motor  9  is used as a paper-feeding motor which feeds the recording media. 
   Other Embodiments 
   Although a printer (recording apparatus) with an inkjet recording head is described as an apparatus including the motor-driving circuits in the above-described embodiment, the present invention is not limited to the printer; the present invention may be applied to any apparatus that drives a plurality of motors. 
   The configuration of motors applied to a recording apparatus is not limited to the above-described configuration. For example, a DC motor may be used as the cleaning motor. 
   While the present invention has been described with reference to what are presently considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.