JPH05298044A - Data processor - Google Patents

Abstract

PURPOSE:To prevent data from being transmitted to a device, which power source is turned off, by outputting a status signal showing that data reception is disabled to the outside in the state of turning off the power source. CONSTITUTION:In the state of turning off the power source switch of a printer, no power 32 for logic is supplied to a resistor 30 of an output circuit. As the result, a transistor 24 is turned to a non-conducted state. At such a time, auxiliary power from an auxiliary power source is supplied to a resistor 26 connected to the collector terminal of the transistor 24 as power 29 for final output terminal, and the output terminal of a busy signal outputs signals at a high (active) level. Even when a user instructs printing to this printer to a host equipment in this step, the busy signal in the active state is transmitted to the host equipment so as not to transmit printing data or the like from the host equipment. Thus, trouble caused by data transmission can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data processing apparatus such as a printing apparatus which receives a signal from the outside and processes the signal.

[0002]

2. Description of the Related Art Conventionally, a printing apparatus has been known as an apparatus for receiving data from the outside and processing the data.

Data is passed between the printing apparatus and a host apparatus (for example, a host computer) by a plurality of data signals and a plurality of control signals. Among these control signals, the host device outputs a status signal (hereinafter referred to as a busy signal) indicating that data output from the printing device cannot be received.
Is monitored, and if this signal is inactive, data is transmitted to the printing device.

According to the standard of a typical interface of a printing apparatus, this busy signal has an active level when the electrical level is high.

[0005]

However, while the power supply of the printing apparatus is cut off, the electric level of the busy signal to be output from the printing apparatus to the host apparatus cannot be determined to be high, so that it is undefined. Becomes Therefore, when the host device tries to send print data while the power switch of the printer is turned off, the voltage level of the signal line becomes low when the host device reads the busy signal status. There is. Then, the higher-level device erroneously determines that the printing device is in the data receivable state and transmits the data to the printing device.

If the power of the printing device is turned on while the upper device is transmitting data, the printing device
While the power is off, the data transmitted from the host device cannot be received, and only the data after the power is turned on will be received. As a result, the printing apparatus performs printing from the middle based on insufficient data after the power is turned on, and wastes paper or the like as a printing medium.

Further, the host device may be programmed to erase the data at the same time as the data transmission. In such a case, there has been a problem that an accident occurs such that the data is erased even though the data is not exchanged.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to activate a busy signal output to a device which transmits data during power cutoff, thereby It is an object of the present invention to provide a data processing device capable of preventing the data transmitting side from accidentally transmitting data to a device that is in a power-off state, and can prevent the above-mentioned various adverse effects.

[0009]

In order to achieve this object, the invention of claim 1 is a data processing device having a processing circuit for receiving a signal from the outside and processing the data, in a state in which the power is cut off. In the above, it is characterized by further having a status signal output means for outputting a status signal indicating that data cannot be received externally.

According to a second aspect of the present invention, in the data processing apparatus according to the first aspect, the status signal output means receives data after performing required initialization processing when power is turned on. It is characterized by automatically stopping the transmission of the status signal indicating that it is impossible.

[0011]

According to the data processing apparatus of the present invention having the above structure, when the power source of the data processing apparatus is cut off, the host apparatus is instructed to send data to the data processing apparatus. However, since the data processing device outputs a status indicating that data transmission is impossible,
No data is transmitted from the host device.

Further, in the invention of claim 2, when the power of the data processing device is turned on, the printing device appropriately performs initialization processing and the like, and then sends out a status signal indicating that data transmission is impossible. Since it is stopped, the host device can start transmitting data to the data processing device at that point. Therefore, after the power is turned on and a required initialization process is performed, the data processing device can receive data from the beginning without loss.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a data processing device of the present invention is embodied in a printing device will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a control circuit, a drive circuit, and peripheral circuits of the printing apparatus.

The control circuit 10 is an interface circuit 12
Data is received from the higher-level device via the, and the operation instructed by the data is performed. The drive circuit 14 supplies an electric signal to the print head 16 and various motors 18, which are a drive system, based on an instruction from the control circuit. The power supply unit 20 supplies logic power to the control circuit 10, the interface circuit 12 and the like, and supplies drive power to the drive circuit 14 such as the print head 16 and various motors 18.
The operation panel 22 is composed of an indicator for an operator in various setting states of the printing apparatus, a switch for the operator to change the setting of the printing apparatus, etc., and these are controlled and monitored by the control circuit 10. The power switch 23
Is connected to the power supply unit 20.

The printing device activates the busy signal to the higher-level device when the printer is initialized when the power is turned on, or when an internal failure occurs in the printing device.
For example, when the print medium is not properly set, or when the interface between the printing apparatus and the upper apparatus is disconnected by the operation of the operator's operation panel. Note that it is well known to determine whether or not to activate the busy signal while the printing apparatus is powered on, and thus detailed description thereof will be omitted.

The control circuit 10 is provided with a reset circuit which detects that the voltage of the logic power has changed from a state below a predetermined value to a predetermined value or more and outputs a known reset signal to a reset terminal of the control circuit. ing. Therefore, the control circuit is reset after the power switch 23 is turned on and the voltage of the logic power is stabilized.

FIG. 2 is a circuit diagram showing the structure of the power supply unit. The main power supply 20a is a stabilized power supply that is supplied with power from a general AC power supply and outputs a predetermined DC voltage. When the power switch 23 is on, the main power source 20a outputs an output of 5 V as logic power and a desired voltage output as driving power. However, when the power switch 23 is off, the output voltage thereof is Both fall to 0 volts. The auxiliary power supply 20b is mainly composed of a storage battery, and is charged with the power switch 23 turned on, and its output voltage is kept at 5 volts even when the power switch 23 is turned off.

The power generation circuit for the final output terminal will be described. When the power switch 23 is turned on, the logic power 32 supplied from the main power supply 20a is supplied as the final output terminal power 29 through the diode 34. .. When the power switch 23 is turned off, the auxiliary power 37 supplied from the auxiliary power supply 20b passes through the transistor 38 and the diode 40 and the final output power 2
Supplied as 9.

Transistors 42, 4 are provided in front of the transistor 38 for supplying auxiliary power from the auxiliary power source 20b.
4 and resistors 46, 48, 50, 52 are connected, and the base terminal of the transistor 42 is connected to the resistor 46 to the supply line of the logic power 32 from the power supply unit 20 during power-on.
Since it is pulled up by, it becomes conductive, and the transistor 44 becomes non-conductive, and as a result, the transistor 38 becomes non-conductive. Therefore, when the power switch 23 of the printing apparatus is turned on,
The power supply from the auxiliary power source 20b is stopped, and the waste of the auxiliary power source 20b is prevented.

FIG. 3 shows a busy signal output circuit. This circuit is included in the interface circuit 12 and controlled by the control circuit 10. An open collector transistor 24 is used for the final output terminal of the busy signal, and the collector terminal, which is the output terminal thereof, is pulled up by the resistor 26 to the supply line of the power 29 for the final output terminal. At the same time, the signal line between the control circuit 10 and the base terminal which is the input terminal of the transistor 24 at the final output end is pulled up by the resistor 30 to the supply line of the logic power 32 from the power supply unit 20. The output of the control circuit 10 to the transistor 24 is an open collector output.

When the power switch 23 of the printing apparatus is off, the logic power 32 is not supplied to the resistor 30 of the output circuit. As a result, the transistor 24
Becomes non-conductive. At this time, the auxiliary power 37 from the auxiliary power supply 20b is supplied to the resistor 26 connected to the collector terminal of the transistor as the final output power 29,
The busy signal output terminal outputs high (active).

At this stage, even if the user instructs the upper device to perform printing on the printing apparatus, since the busy signal in the active state is sent to the upper device, print data, etc. is sent from the upper device. Is never sent.

When the power switch 23 is turned on, the control circuit receives a signal from the reset circuit after the logic power voltage is stabilized, initializes the internal registers and the like, and returns the drive circuit and the like to the initial position. Initialize the entire device. Note that at this stage, the control circuit still leaves the base terminal of the transistor 24 low. As a result, the transistor 24 becomes non-conductive, and as a result, the collector terminal, which is the output terminal, becomes
Power for logic 3 from power supply unit 20 by resistor 26
Since it is pulled up to the second supply line, it outputs high. Therefore, the busy signal remains active (S1 in the flowchart of FIG. 4). When the initialization process is completed, the online state is set (S2). And after that, the transistor 24
The base of is set to high. Therefore, the busy signal becomes non-active (at step S3). In this state, the control circuit 10
Is a high level of the base potential of the transistor 24 as necessary.
Although the row is switched and the busy signal is controlled, the processing is the same as that of the conventional printing apparatus and its explanation is omitted.

Therefore, if the power switch 23 of the printing apparatus is off when the printing apparatus instructs the printing apparatus, the printing apparatus activates the busy signal output to the printing apparatus, and the printing apparatus sends the printing apparatus to the printing apparatus. Data cannot be sent, and the device enters the standby state.

Even if the user turns on the power switch 23 of the printing device after the user instructs the upper device to print, the busy signal becomes active until the initialization of the printing device is completed and the printer is switched to the online state. to continue.
Then, when switching to the online state, the busy signal automatically becomes inactive (the transmission of the status signal indicating that printing is not possible is stopped), so the host device will start transmitting data for the first time at that stage. ..

Therefore, the printing apparatus can receive data from the beginning without missing data.

In the above embodiment, the auxiliary power source 20
Although the storage battery is used as b, a large capacity condenser, a dry battery, or the like can be used instead.

Further, even if the printing device is powered off, it is not necessary to activate the busy signal output unless the printing device is connected to the host device. Therefore, if a mechanism for detecting the connection with the host device is provided and the supply of the power for the final output terminal from the auxiliary power supply 20b is stopped when the device is not connected, the power consumption of the auxiliary power supply 20b is prevented. be able to.

Further, even if the printing apparatus is connected to the host apparatus, if the power of the host apparatus is not turned on, no data is transmitted, so it is not necessary to activate the busy signal output. For this reason, a circuit for detecting the power-on state of the host device is provided, and when the power of the host device is not turned on, the power supply from the auxiliary power source 20b is stopped to prevent waste of the auxiliary power source 20b. be able to.

Further, when the interface circuit with the higher-level device supplies electric power that can be used as the auxiliary power source 20b from the higher-level device, the higher-level device does not need to prepare the auxiliary power source 20b in the printing device. The busy signal output can be high depending on the power supplied from the. In this case, the mechanism for detecting the connection with the host device and the circuit for detecting the power-on state of the host device are unnecessary.

Further, when the busy signal to the host device of the printing device is active in the low state, when the printing device and the host device are connected, the signal is set to be low without providing an electric circuit. Can be dealt with. This configuration is shown in FIG. The switch 54 is an inversion switch of the power switch 23 of the printing apparatus, and is in a connected state only when the power is cut off. If the printing apparatus is connected to the upper apparatus while the printing apparatus is powered off, the switch 54 is in the connected state and the busy signal output is set to low. While the printing apparatus is powered on, the switch 54 is not connected and the busy signal output is based on the control of the control circuit 10.

[0033]

As is clear from the above description,
According to the data processing apparatus of the invention of claim 1, even when the host apparatus is instructed to send data to the data processing apparatus when the power supply of the data processing apparatus is cut off, the data processing apparatus Outputs a status indicating that data cannot be transmitted, the data is not transmitted from the host device. Therefore, it is possible to prevent various adverse effects caused by the data being transmitted from the host device in a random manner. Also, since the data processing apparatus is powered on and becomes ready to receive data after the higher-level device starts transmitting data, incomplete data (data lacking the leading part) will not be received. Also, there is an effect that erroneous data processing or incomplete data processing is not performed.

According to the second aspect of the present invention, when the power of the data processing device is turned on, the printing device appropriately performs initialization processing and the like and then sends out a status signal indicating that data transmission is impossible. Since it is stopped, the host device can start transmitting data to the data processing device at that point. Therefore, after the power is turned on and the required initialization processing is performed, the data processing device can automatically receive data from the beginning without any trouble for the user. ..

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a control circuit of a printing apparatus.

FIG. 2 is a diagram showing a power supply unit.

FIG. 3 is a diagram showing a busy signal output circuit.

FIG. 4 is a flowchart showing control of a control circuit.

FIG. 5 is a diagram showing an embodiment in which a busy signal is low and active.

[Explanation of symbols]

 10 Control Circuit 12 Interface Circuit 20 Power Supply Unit 24 Final Output End Transistor 28 Final Output End Power Supply 32 Logic Power 20b Auxiliary Power Supply 38 Auxiliary Power Supply Transistor 54 Power Cutoff Inversion Switch

Claims (2)

[Claims] 1. A data processing device having a processing circuit which receives a signal from the outside and processes the data, and outputs a status signal indicating that the data cannot be received to the outside when the power is cut off. A data processing device comprising a status signal output means. 2. The data processing device according to claim 1, wherein the status signal output means indicates that data cannot be received after performing required initialization processing when power is turned on. A data processing device characterized by automatically stopping signal transmission.