Electronic Apparatus Which Is Automatically Initialized When Normal Operation Is Resumed After the Apparatus Has Been in a Low Power Consumption Mode

1. Field of the Invention

The present invention relates to an electronic apparatus, and more particularly to an electronic apparatus having a driver unit such as a printer and a control unit therefor.

2. Related Background Art

The construction described above is common to various electronic apparatus. In an electronic typewriter apparatus having a driver unit such as a printer unit which consumes relatively high power, when an input or output command is not applied for more than a predetermined period, the printer unit is set in a rest condition or a low power consumption mode. The recovery from the low power consumption mode to a normal operation mode is effected in response to a predetermined operation such as an input from a keyboard.

In the low power consumption mode, control to a detector such as a photo-coupler which detects a position of the printer unit or a member for holding an element such as a solenoid is stopped. Accordingly, if the apparatus in the low power consumption mode is moved or a shock is applied thereto so that the position of the element is changed after the low power consumption mode is assumed, a malfunction may be caused when the mode is returned to the normal operation mode.

It is an object of the present invention to provide an electronic apparatus capable of switching between a low power consumption mode in which power is supplied only to a control unit and a normal operation mode in which power is supplied to the control unit and a driver unit.

It is another object of the present invention to provide an electronic apparatus in which different power supply units are used depending on whether or not a data input is supplied from input means.

It is another object of the present invention to provide an electronic apparatus which operates in a first operation mode when a data input is supplied from input means and in a second operation mode when the data input is not supplied from the input means for a predetermined time.

FIG. 1 shows a block diagram of an electronic apparatus of the present invention, and

FIG. 2 shows a flow chart for a control procedure of a control unit of FIG. 1.

In the following description of an embodiment of the present invention, an electronic typewriter is specifically explained.

FIG. 1 shows a block diagram of the electronic typewriter in accordance with the present invention. Numeral 1 denotes a printer unit having a carriage 1a, which carries a daisy wheel 1b, a platen 1c and a print hammer 1d (all schematically shown), which is driven by a control unit 4, such as a microcomputer, through a driver 2. The control unit 4 includes a ROM 4a in which a control program shown in a flow chart of FIG. 2 is stored and a low power consumption mode flag 4b which indicates a low power consumption mode. A position of the carriage 1a of the printer unit 1, a rotation angle of the platen 1c and a type of the daisy wheel 1b selected are detected by a position sensor 3 which comprises a photo-coupler, and a detected signal is fed back to the control unit 4. The control unit 4 refers the output of the position sensor 3 in accordance with an input from a keyboard 5 to drive the printer unit 1 through the driver 2.

The control unit 4 has a normal operation mode in which it controls the printer unit 1 in accordance with a command supplied from the keyboard 5 and a low power consumption mode in which it stops the detection by the position sensor 3 or control of the drive elements such as a position control unit 1e comprising a 1f solenoid and a pulse motor 1g (schematically shown ) of the printer unit 1. In the low power consumption mode, the detection of the positions of the carriage 1a and other elements and the position holding thereof are stopped and the supply of power is stopped to reduce the power consumption. This arrangement is effective particularly in a portable electronic typewriter which is powered by a battery. Numeral 6 denotes a power supply, for example, such as a battery, for supplying power to the electronic equipment, and numeral 7 denotes a power supply control unit which controls supply of the power from the power supply 6 to the driver unit 2, printer unit 1 and a position sensor 3 elements of the electronic apparatus. The control unit 4 and power supply control unit 7 are connected to the power supply 6 by an on-off switch 8.

The switching between the normal operation mode and the low power consumption is effected as shown in FIG. 2 which shows a flow chart for a control procedure of the control unit 4.

When the apparatus is started, the control unit 4 checks in a step S1 if an input from the keyboard 5 has been completed or not. If the input is applied from the keyboard 5, a recording operation is effected in the normal mode in a step S7. The control unit 4 drives the printer unit 1 through the driver 2 to record information, and the operation of the printer unit 1 is monitored by the position sensor 3.

If the input is not detected in the step S1, the process goes to a step S2. In the step S2, a time measurement counter 4c in the control unit 4 is incremented by one and the process goes to a step S3. In the step S3, whether the counter 4c has been incremented to a count corresponding to a predetermined waiting time or not is checked. If yes, the process goes to a step S8, and if not, the process goes to a step S4.

In the step S4, whether or not an input from the keyboard 5 has been received is checked again. If the input has not been received, the process returns to the step S2 where the counter 4c is incremented. If the input has been received, the process goes to a step S5 where the counter 4c is reset. In a step S6, information is recorded in the same manner as the step S7 and the process returns to the step S1.

In a step S8, reached if the counter 4c is incremented to the predetermined count, low power consumption mode flag 4b is set in response to which the power supply control unit 7 interrupts supply of power from the power supply 6 to the printer unit 1, driver 2, and position sensor 3 as shown in FIG. 1. Therefore, the detection operation of the position sensor 3 and the operation of the position control unit 1e which comprises the pulse motor 1g and solenoid 1f are stopped and a supply of power to the driver 2 is stopped to enter into the low power consumption mode. In a step S9, whether an input from the keyboard 5 has been applied or not is checked again. If the input has not been applied, the step S8 is repeated to maintain the low power consumption mode.

If an input is subsequently received from the keyboard 5, the process goes to a step S10 where initialization operation is carried out to move the carriage 1a of the printer unit 1 to the home position and return the daisy wheel 1b to the initial position. This control is done through the driver 2. After the initialization, the process returns to the step S1 and the above operation is repeated.

With the present arrangement, when the mode is changed from the low power consumption mode to the normal operation mode, the initialization is carried out in the step S10 to return the carriage 1a and the daisy wheel 1b to their home positions. Accordingly, even if the carriage 1a or the daisy wheel 1b is moved in the low power consumption mode to a different position than that it took before the low power consumption mode was assumed, an intended record operation is always attained. Thus, no malfunction occurs when the normal mode is resumed from the low power consumption mode.

While the electronic typewriter has been described in the above embodiment, the present invention is applicable to any other electronic apparatus having the low power consumption mode such as a desk-top calculator with a printer or a word processor.

As described above, according to the present invention, in the electronic apparatus which comprises the driver unit 2 and the control unit 4 and which has the normal operation mode and the low power consumption mode in which an entire or a portion of the driver unit 2 is in a rest condition, the driver unit 2 is initialized by the control unit 4 when the mode is changed from the low power consumption mode to the normal operation mode. Thus, even if the position of the elements of the driver unit 2 have been changed in the low power consumption mode, a malfunction does not occur when the mode is returned to the normal mode and the intended operation can be performed immediately after the return to the normal operation mode.