JPH08224943A - Printer device - Google Patents

Abstract

PURPOSE: To obtain a printer device capable giving an alarm if its power is ON with the connected external host device turned OFF. CONSTITUTION: A printer device comprises a CPU 1, an image-forming part 9, an interface 7 communicating with an external host device 19, an operation panel 8 containing an operation switch and the like, and an alarm circuit 10. In addition, a voltage-monitoring circuit 15 for monitoring a signal level change of a strobe signal from the external host device 19 is provided. When the strobe signal is at an intermediate level between a first reference voltage V1 and a second reference voltage V2, the power source of the external host device 19 is judged to be interrupted, and the alarm circuit 10 is actuated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer device for forming images such as characters and figures on a recording medium, and more particularly to a printer device capable of monitoring the power state of an external host device.

[0002]

2. Description of the Related Art Conventionally, a printer such as a serial dot printer is roughly classified into a built-in type integrated with a host device such as a word processor and an external type connected to a separate host device by a signal cable. . The built-in printer is
Generally, the power supply circuit is shared, and when the power of the host device is turned off, the power of the printer device is automatically cut off. On the other hand, the external printer has a dedicated power supply circuit, so it is necessary to perform the power operation of the host device and the power operation of the printer separately, and the printer automatically turns off even when the host device is turned off. do not become.

The printer is often operated in an online mode in which it operates according to a command from the host device, and the user rarely operates the printer directly. Therefore, when the power of the host device is turned off, the printer often forgets to turn off the power, which is not preferable in terms of energy saving.

As a prior art for solving such a problem, a data terminal device designed to reduce power consumption (Japanese Patent Application Laid-Open No. Sho 5)
No. 7-155633) and a printer device (Japanese Patent Laid-Open No. Hei 4-
No. 354017) is disclosed.

[0005]

In the conventional printer, it is possible to provide a mechanism for automatically interlocking the power operation of the external host device with the power operation of the printer.
The circuit configuration and control of the device becomes complicated.

Further, in Japanese Patent Laid-Open No. 4-354017, the strobe signal is judged simply by the high level or the low level. However, that alone does not correspond to the actual external host device, and the power state is actually changed. Cannot be detected.

An object of the present invention is to provide a printer device capable of reliably preventing forgetting to turn off the power supply on the printer side when the power supply of the external host device is turned off.

[0008]

The present invention comprises host monitoring means for monitoring the power supply state of an external host device, and alarm means for issuing an alarm when the power supply of the external host device is cut off. Is a printer device. Further, the present invention provides an interface means for receiving a host-side signal output from an external host device, an image forming means for forming an image on a recording medium, and an interface means and an image forming means. In a printer device including a main control unit that transmits and receives a signal and performs signal processing according to a predetermined program, a voltage monitoring unit that monitors a voltage of a host-side signal, and the host-side signal is a first reference voltage or less and a second reference voltage. The printer device is provided with an alarm means for issuing an alarm when the voltage is equal to or higher than the reference voltage.

[0009]

According to the present invention, since it is possible to notify the user by an alarm that the power supply of the external host device is in the cut-off state, it is possible to surely prevent the printer device from forgetting to turn off the power supply and waste power consumption. Can be suppressed.

Further, according to the present invention, by monitoring the voltage of the signal on the host side and comparing it with two reference voltages, it is possible to detect even an intermediate potential other than the high level and the low level. By thus issuing an alarm when the host-side signal is lower than or equal to the first reference voltage and higher than or equal to the second reference voltage, the user can be surely notified that the power supply of the external host device is in the cutoff state.

[0011]

1 is a block diagram showing the electrical construction of an embodiment of the present invention. This printer device includes a CPU (central processing unit) 1 that manages the operation of the entire device, a ROM (read only memory) 2 that is a non-volatile memory, and a RAM (random access memory) that can rewrite data.
3, an interface (I / F) 7 for connecting to an external host device 19, a panel unit 8 incorporating signal input means such as operation switches and signal display means such as a display LED (light emitting diode), An image forming unit 9 for forming an image on a recording medium, a control circuit 4 for controlling the image forming unit 9, and the like.

The CPU 1 performs signal processing such as data input / output, data transfer, calculation, etc. according to a program stored in the ROM 2. The ROM 2 stores programs and data necessary for the operation of the CPU 1 and data necessary for printing such as character codes and character fonts. RAM3 is CP
It is used for temporary storage of data received from the U1 work area and external host device, development of document data, and the like. The interface 7 exchanges data with the external host device 19. Further, the interface 7 is provided with a voltage monitoring circuit 15 for monitoring the level change of the strobe signal.

CPU 1, ROM 2, RAM
3, the interface 7, the panel unit 8 and the control circuit 4 are connected to each other by a bus BUS including an address bus, a data bus, a control bus and the like.

The image forming section 9 has a drive section 6 and a drive circuit 5. The drive unit 6 includes a print head that prints on a recording medium, a CR motor that moves a carriage (CR) equipped with the print head in the width direction of the recording medium, and a PF (paper feed) that conveys the recording medium by a fixed amount. It has a drive unit such as a motor. The drive circuit 5 is the control circuit 4
Each drive unit of the image forming unit 9 is driven based on the control signal from.

An alarm circuit 10 for issuing an alarm to the user is connected to the control circuit 4. Alarm circuit 10
As such, a buzzer or a voice synthesizing circuit that informs by sound can be used, and an LED that informs by light can also be used.

FIG. 2 is a block diagram showing the interface 7 of FIG. The external host device 19 and the interface 7 are connected via a connector 21. Here, a parallel interface system based on Centronics is used, and a data signal Da is used as a typical signal line.
ta1 to 8 (positive logic), a busy signal BUSY (positive logic), a strobe signal STROBE (negative logic), an acknowledge signal ACK (negative logic), and the like are defined.

The data latch circuit 22 receives the data signal Da.
The print code and the print control code transmitted from the external host device 19 via ta1 to 8 are stored in 8-bit units, and the data is latched when the strobe signal falls. The latched data is RA under the control of the CPU 1.
It is stored in the print buffer of M3. Busy flag 23
Is composed of a flip-flop or the like, becomes a high level at the falling edge of the strobe signal, and outputs it as a busy signal to the external host device 19 as it is and is taken into the CPU 1 via the general-purpose input / output circuit (I / O) 24. .
The external host device 19 constantly monitors the busy signal and waits for the next data transmission until it becomes a low level. When the data latched in the data latch circuit 22 is taken into the CPU 1 via the bus, the CPU 1 outputs the clear signal CLEAR via the general-purpose input / output circuit 24 to invert the busy flag 23 to the low level.

FIG. 3 is a circuit diagram showing various examples of the power supply monitoring circuit 15. FIG. 3A shows two comparators 15.
This is an example using a window comparator composed of a and 15b, and FIG. 3B is an example using an AD converter 15c for converting an analog signal into a digital signal.

In FIG. 3A, in order to monitor the voltage level change of the strobe signal, a comparator 15a for comparing with the first reference voltage V1 and a comparator 15b for comparing with the second reference voltage V2 are provided, and each output is provided. Is an open collector type and is pulled up to the power supply line. The first reference voltage V1 and the second reference voltage V2 are supplied from a reference power source (not shown) and are set to 4V and 1V, respectively.

When the voltage of the strobe signal is 1) higher than the first reference voltage V1, the output of the comparator 15a becomes low level. 2) When the voltage of the strobe signal is lower than the first reference voltage V1 and higher than the second reference voltage, the comparator 15a, The output of 15b becomes high level, and 3) when it is lower than the second reference voltage V2, the output of comparator 15b becomes low level. In this way, a window comparator is constructed, and its output is read by the CPU 1 through the general-purpose input / output circuit 24 shown in FIG.

Further, in FIG. 3B, in order to monitor the voltage level change of the strobe signal, for example, an 8-bit AD converter 15c is provided, and the digital output is shown in FIG.
It is read into the CPU 1 via the general-purpose input / output circuit 24 of.

FIG. 4 is a circuit diagram showing an example of a connection system between the external host device and the printer device, which is equivalent to the input signal when the external host device is powered off and the printer device is energized. It is a figure which shows a circuit. The external host device 19 and the printer device are connected via a connector 21, and an input buffer Q1 is provided on the input side of the interface 7.
(For example, TTL-IC model number “LS14” or the like) is provided. The signal line has a pull-up resistor R to prevent noise.
1 (for example, 1.5 kΩ to 4.7 kΩ) is connected to the power supply line (for example, 5 V). Similarly, on the output side of the external host device, pull-up resistors and pull-down resistors are connected to the respective signal lines, and they can be represented by the combined impedance Z in terms of an equivalent circuit.

When the external host device is energized,
The voltage level of the signal line is stable at a high level or a low level according to the output from the external host device. Also,
When not connected to the external host device, the signal line is stabilized at a high level due to the presence of the pull-up resistor R1. However, when the external host device is not energized and the printer device is energized, it can be considered that the output side of the host device is grounded through the combined impedance Z as shown in FIG. Therefore, the voltage level of the signal line depends on the pull-up resistor R1 and the combined impedance Z.
Since it is determined by the voltage division ratio of, it becomes an intermediate value between high level and low level.

FIG. 5 is a graph showing an example of the voltage change of the strobe signal. When the external host device 19 and the printer device are connected and the external host device 19 is not transmitting data, the strobe signal is held at a high level (for example, 5V). When the power supply of the external host device is turned off in this state, the voltage level of the strobe signal exponentially decreases as the power supply voltage decreases, and the intermediate potential determined by the voltage division ratio of the pull-up resistor R1 and the combined impedance Z (see FIG. 5 settles down to about 3.3V). Next, when the external host device 19 is energized again, the signal level rises from the intermediate potential toward the high level and stabilizes at a constant voltage.

As described above, when the power source of the external host device 19 is off, since the combined impedance Z has a constant value, the intermediate potential is generally within the range of 1.5V to 4V. When the input buffer Q1 is a TTL-IC, the low level threshold is 0.8V to 1.1V. Therefore, even if the power of the external host device 19 is turned off, the strobe signal does not become low level, and the situation in which the printer device receives data by mistake can be avoided. In the present invention, the power supply state of the external host device is detected by utilizing such circuit characteristics.

FIG. 6 is a flow chart showing an example of the operation of the printer device. Here, an example using the window comparator of FIG. 3A will be described. First, when the printer is powered on, the RAM 3, the interface 7, the panel section 8 and the control circuit 4 are initialized in step S101, and the drive circuit 5 and the drive circuit 5 are driven through the control circuit 4 in the next step S102. Part 6
To perform the initial operation for initializing the printing position, printing conditions, etc., and the printing standby state is entered. When a print command is received from the external host device 19 in this state, the print operation can be started.

Next, in step S103, as shown in FIG.
The output of the window comparator of (a) is determined. If the external host device 19 is energized or data is being transferred, the output of the window comparator becomes low level, and the process proceeds to step S110 to enter a normal print operation routine. Here, it is determined whether or not the data to be printed is stored in the print buffer of the RAM 3, and if there is no print data, the process returns to step S103. If there is print data, the image forming unit 9 is driven to print on the recording medium each time the print start condition is satisfied in step S111. When the completion of printing is confirmed in step S112, step S1
Return to 03. Thus, the output of the window comparator is constantly determined while executing the normal print processing routine.

On the other hand, if the output of the window comparator is at high level in step S103, the strobe signal being monitored is at the intermediate potential, and it can be determined that the power supply of the external host device 19 is in the cutoff state.
Therefore, the alarm routine after step S104 is entered, the timer is first started, the alarm circuit such as the buzzer is activated in step S105, the output of the window comparator is judged again in step S106, and if it is still high level, step The output determination in step S106 and the alarm operation by the buzzer or the like are repeated until the timer counts in S107. The alarm operates by a timer for a certain period of time to notify the user of forgetting to turn off the power of the printer.

When the timer counts over in step S107 or the output of the window comparator becomes low level during the alarm operation in step S106, the process proceeds to step S108 to stop the alarm operation by the buzzer or the like. Next, in step S109, a wait is made in a loop until the output of the window comparator becomes a low level to prevent the alarm from being issued more than necessary. When the external host device 19 is powered on during this standby,
The output of the window comparator becomes low level and the process returns to step S103.

By monitoring the voltage of the strobe signal in this manner, it is possible to determine the power-off of the external host device 19, and it is possible to notify the user to turn off the power of the printer device.

In the above embodiment, an example in which the window comparator is used to monitor the voltage of the strobe signal has been described, but it is also possible to use the AD converter 15c shown in FIG. 3B. In that case, the CPU 1 compares the output of the AD converter 15c with the first reference voltage V1 and the second reference voltage V2 stored in advance in the ROM 2 or the RAM 3 to obtain the same result as that of the window comparator.

Further, as a method of monitoring the power supply state of the external host device, a method of monitoring the voltage of the strobe signal of the host side signal has been shown. In addition, when the external host device is in the energized state, it is at high level or low level. A signal that is sure to be at a level and can be used as a monitoring target as long as it is a signal that has an intermediate potential when the power is cut off, and a dedicated signal line (wired or wireless) for transmitting the power status of the external host device. However, it is possible).

[0033]

As described above in detail, according to the present invention, it is possible to notify the user by an alarm that the power supply of the external host device is in the cutoff state, so that it is possible to surely forget to turn off the power supply of the printer device. This can be prevented, and wasteful power consumption can be suppressed.

Further, by monitoring the voltage of the signal on the host side and comparing it with two reference voltages, the power supply state of the external host device can be reliably detected, and the alarm operation by powering off is performed stably.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of an embodiment of the present invention.

2 is a block diagram showing an interface 7 of FIG. 1. FIG.

3 is a circuit diagram showing various examples of a power supply monitoring circuit 15. FIG.

FIG. 4 is a circuit diagram showing an example of a connection system between an external host device and a printer device.

FIG. 5 is a graph showing an example of a voltage change of a strobe signal.

FIG. 6 is a flowchart illustrating an example of operation of the printer device.

[Explanation of symbols]

 1 CPU 2 ROM 3 RAM 4 control circuit 5 drive circuit 6 drive unit 7 interface 8 panel unit 9 image forming unit 10 alarm circuit 15 voltage monitoring circuit 15a, 15b comparator 15c AD converter 19 external host device 22 data latch circuit 23 busy flag 24 General-purpose input / output circuit

Claims (2)

[Claims] 1. A printer device, comprising: host monitoring means for monitoring a power supply state of an external host device; and alarm means for issuing an alarm when the power supply of the external host device is cut off. 2. An interface means for receiving a host-side signal output from an external host device, an image forming means for forming an image on a recording medium, and an interface means and an image forming means. In a printer device including a main control unit that transmits and receives a signal and performs signal processing according to a predetermined program, a voltage monitoring unit that monitors a voltage of a host-side signal, and the host-side signal is a first reference voltage or less and a second reference voltage or less. A printer device, comprising: an alarm unit for issuing an alarm when the voltage is equal to or higher than a reference voltage.