JPH07191789A - Discriminating method for off state of power source in device of communication source - Google Patents

Abstract

PURPOSE:To provide a discriminating method for surely discriminating that a host is turned off by the use of a simple configuration in order to reduce the power consumption of a printer connected to the host through a signal line as much as possible. CONSTITUTION:An interface control part 4 having a receiver circuit 2, a voltage output means 9 outputting a prescribed voltage to the circuit 2 with a pull-up resistor R2 and a voltage output blocking means Tr blocking the output voltage to be outputted to the receiver circuit and also a central control part 5 having a recognizing means 5a recognizing a signal compared by the receiver circuit and a blocking signal output means 5c outputting a blocking signal to the blocking means of the interface control part are provided. Then the signal transmitted from a communication source device while the blocking signal output means is outputting the blocking signal is recognized by the above recognizing means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, in a terminal device such as a printer for processing data transmitted from a host computer (hereinafter referred to as "host"), quickly determines the state of the host when it is not operating. Regarding the determination method,
Further, it relates to a method of controlling the main power supply of the terminal device to determine the power-off state of the communication source device that saves power.

[0002]

2. Description of the Related Art Conventionally, each terminal device connected to a host operates each terminal device by its own power source. In this case, even when the power of the host is turned off, the terminal device itself cannot discriminate the fact, and wastes electric power to maintain the operation reference state.

For example, in an electrophotographic printer, which is an example of a terminal device, a large amount of electric power is required for a heater used for a fixing device, and in order to keep the printer in a printing state, the heater is kept in a constant heating state. Must be on and, as a whole, consumes considerable power. In other words, even if the printer is turned off and the host is turned off, unless the printer is turned off, the printer itself cannot determine this fact, so that a considerable amount of wasted power is consumed.

On the other hand, in consideration of only the power consumption problem, the configuration in which power is supplied from the host and the printer is turned off at the same time the host is powered off may be interrupted during printing.

Therefore, as a method of determining that the host is disconnected and controlling the power supply, a method of indirectly determining the level of the signal using an interface device can be considered. That is, as shown in the diagram for explaining the interface device X in FIG. 5, when the pull-up resistor R1 is present on the host A side, the printer B, which is a terminal device, is powered on and the host A is powered off. Then, the input voltage of the differential amplifier 2a of the printer B becomes a partial voltage of the pull-up resistor R2 of the printer B and the pull-up resistor R1 of the host A and decreases. Therefore, it is possible to determine that the power supply on the host side is off by discriminating this level change.

However, if the host A changes and the value of the pull-up resistor R1 changes, depending on the value, the input voltage of the operational amplifier 2a may be close to the threshold (reference voltage value) which is the reference for decoding the digital signal. Since the output becomes unstable, it may cause an error to judge that the power supply on the host side is off by the judgment of the voltage level drop.

Also, in recent years, CMOS has been used for the amplifier 1a on the host A side with the formation of a circuit gate array,
In order to prevent static electricity or the like, there is a case where a built-in diode or the like is installed on the output side of the amplifier 1a and the pull-up resistor R1 is not used as a host (not shown). Even in this case, when the power of the host is turned off while the printer B is on, the impedance of the host A decreases, so that a current flows from the printer B side to the host A and the voltage output to the printer decreases. If the host changes as described above, this voltage drop changes in the vicinity of the threshold, and even the same host may change due to noise or the like, so the same problems as described above cannot be avoided.

An object of the present invention is to solve the above problems and
It is to provide a determination method for quickly determining that the power of the host has been turned off.

[0009]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems, and as described in claims 1 to 3, various communications such as a host and a terminal device connected by a LAN line or the like. A signal line 3a for data to which at least data is transmitted from the original device, and a pulse-shaped signal signal (STRB) for signaling that the data is transmitted from the various communication source devices.
* Signal) (* indicates Active Low; the same applies hereinafter), and a reception block signal line that transmits a reception block signal (Busy * signal) that blocks reception of the data to the communication source device. Interface signal line 3 with 3c
A receiver circuit 2 connected to each signal line of the interface signal line 3 via a pull-up resistor R2 and outputting a predetermined voltage to stably transmit and receive signals. Voltage output blocking means Tr coupled to the voltage output means 9 for blocking the voltage application to the receiver circuit 2 and a signal signal (STRB *) coupled to the receiver circuit 2 and received from the signal line 3b.
Interface) having a comparison means 2a for comparing a signal) with a predetermined reference voltage for signal decoding, and a reception blocking signal output means 2b coupled to the receiver circuit 2 for outputting the reception blocking signal, and the receiver. Circuit 2
Recognition means 5a for recognizing the comparison signal compared by the comparison means 2a, and reception blocking signal instructing means 5 for instructing the reception blocking signal output means 2b to output the reception blocking signal.
b and a central control unit 5 having a blocking signal output unit 5c for outputting a signal for blocking voltage application to the voltage output blocking unit Tr of the receiver circuit 2, and a reception blocking signal of the central control unit 5 While the reception inhibiting signal (Busy *) is being output by the instructing means 5b, the inhibiting signal outputting means 5c is provided.
Is output, and the signal means (STRB *) compared by the comparison means 2a is recognized by the recognition means 5a.

Further, as described in claim 4, the recognition by the recognition means 5a may be performed a plurality of times so that the off state of the communication source device can be surely determined. Further, even if the above-mentioned recognizing means 5a recognizes the off state of the communication source, the data processing of the receiving device may not be completed to the end. Therefore, the data processing confirming means 5d may be provided.

[0011]

According to the constitution of the present invention, as shown in FIGS. 2 and 4, the blocking signal output means 5c outputs the blocking signal to block the output voltage to the receiver circuit 2 of the interface control section 4 and When the power supply of A is off, the output voltage of the differential amplifier 2a of the printer B is, for example, a signal state H (High) that the recognizing unit 5a recognizes when communicating with a signal of negative logic. In this case, the L (Low) state is surely recognized. Therefore, if the blocking signal output is sent, ST
Since no voltage is applied to the RB * signal line, the signal sent from the host A connected to this line is the pull-up resistor R2.
The comparison is performed directly by the comparison means 2a without being affected by the above. At this time, the recognizing means 5a of the CPU 5 operates to recognize the level of the output voltage, and the current state of the host A can be surely and quickly determined. It is also possible to carry out the recognition a plurality of times in order to make a more reliable determination. In this case, the power consumption can be reduced by configuring the printer to enter the consumption saving mode. In addition, if the signal voltage level of the STRB * signal is recognized while the Busy * signal is being output, this off-state discrimination method will not cause data acquisition due to malfunction even if the off-state is discriminated using the STRB * signal line 3b. Can be prevented. Further, data processing confirmation means 5d
With the configuration, the recognition unit 5a recognizes the off state of the communication source, and then enters the consumption saving mode after the data processing of the receiving device is completed.

[0012]

Embodiments of the present invention will be described with reference to the drawings. Figure 1
FIG. 3 is a block diagram illustrating an outline of the present invention. In the present embodiment, an example using a parallel interface device will be described, but the present invention is not limited to this.

Such an interface device is a host A
Side driver circuit 1, a receiver circuit 2 on the printer B side, an interface control unit 4 including a voltage output means 9 for outputting a predetermined voltage to the receiver circuit 2, and a plurality of interface signals connecting these circuits. Line 3
It consists of and. The voltage output unit 9 includes a blocking unit Tr that blocks the output voltage to the receiver circuit 2. The interface signal line 3 is composed of a parallel data signal line 3a for data transmission and a plurality of signal lines 3b, 3c, 3d for control information transmission.

The parallel data signal line 3a is, for example, (0-7).
Is a signal line for transmitting DATA *, and the signal line 3b is STRB.
* (* Indicates active low; same below) (Strobe)
This STRB * signal line is a signal line for transmitting a signal, and is a signal for instructing the start of data reception using the parallel data signal line 3a from the host. The signal line 3c is a signal line for transmitting a Busy * (busy) signal that informs the host that the printer B side cannot receive data, and is output by the Busy * signal output means 2b. The signal line 3d is an Ack * (acknowledge) signal line for transmitting a confirmation signal to that effect to the host when the data received from the parallel data signal line 3a is received. When this signal is output, it is taken into the printer B. The data is output to the engine control unit 8 and the processing is started. Reference numeral 5 denotes a CPU for controlling the entire printer, etc., and at least a recognition means 5a for recognizing a signal compared by an operation output device 2a, which is a comparison means of a receiver circuit 2 described later, and a Busy * signal to a host A described later. It has a Busy * signal instructing means 5b for instructing output and a blocking signal output means 5c for outputting a blocking signal to the voltage output blocking means Tr of the interface control section 4. Reference numeral 6 denotes a ROM in which a program necessary for controlling the CPU, for example, a program for setting the engine control unit 8 in a power saving mode, is stored, and 7 is an R storing font data for printing.
In the case of an electrophotographic printer, AM and 8 are engine control units that drive a photoconductor, a fixing device, and the like to perform printing, and include a power supply control unit 8a that controls the power supply of the engine. It should be noted that although the power supply control means 8a has been described as an example in which the power supply control means 8a is installed in the engine control unit 8 in the present embodiment, it is not limited to this.
The power supply for the printer B itself may be controlled, or the power supply configured for each circuit may be controlled.

Next, the communication procedure of the interface device will be described. The data input from the host A sends a STRB * signal to the printer B before sending the data to the printer via the parallel data signal line 3a. Then, the comparison means 2a of the receiver circuit 2 compares the signal with a predetermined signal voltage of a threshold, and the compared result is C
CP5 that the STRB * signal is input to PU5
When recognized by the recognition means 5a of U5, the data is transferred to the printer B.
, And the Busy * signal output instructing means instructs the host to output the Busy * signal. When the signal is output, the latched data described above is input to an input buffer (not shown). The data is accumulated and output to the engine control unit 8 at a timing to start data processing. Busy at this time
* Is output until the aforementioned input buffer is ready to receive the next data, and comes from the next host A during output
STRB * signal and DATA * are not accepted. When data is ready to be received, the Busy * signal is stopped, the ACK * signal is output to host A, and the next STRB * is waited for. These are repeated and all the data is transmitted.

On the other hand, when the print image data is transmitted through the parallel data signal line 3a in this manner, the CP is determined based on the data and the corresponding font data in the RAM 7.
The printing section is driven by the engine control section 8 by the operation instructing means 5b of U5 to print on the recording paper.

Next, the configuration of the device for detecting that the host A side is in the off state will be described. FIG. 2 is a diagram for explaining the configuration of the interface device X, which is a simplified version of the block diagram of FIG. 1. One of the signal lines selected from the control signal lines in the interface signal line 3 to which the host A and the printer B are connected. (3b-3c, etc.), specifically, the STRB * signal line is used.

To the host A side of the interface device X, a power source 10 of the driver circuit 1 and a signal line 3b from the power source 10 are connected via a pull-up resistor R1. 1a is an amplifier such as TTL.

The voltage output means 9 on the printer B side is
A power supply 9a for supplying power to the interface section is connected to the collector of the transistor Tr, while the base is C
The PU5 is connected to the recognition means 5a, and the emitter is connected to the signal line 3b through the pull-up resistor R2. The data signal line 3a and other control signal lines 3c,
3d also supplies the power source 10 via the pull-up resistor R2.
However, the configuration is omitted in FIG. 2 for convenience of description. Here, the pull-up resistor is used conventionally, and is for stable signal transmission / reception.

Reference numeral 2a is a differential amplifier which is connected to various signal lines and is provided for comparing an input signal with a reference voltage for signal decoding, and a threshold value is appropriately changed as described later. It is configured to be possible.

Next, the operation procedure of the present invention will be described based on the flowchart of FIG. 3 and the timing chart of FIG. It should be noted that this description shows an example in which communication is performed using a signal of negative logic. The power of the printer A is turned on, and the operation of each device is checked so that the printer is ready for printing (step 1). At this time, the blocking signal output means 5c of the CPU 5 sends an H signal to the transistor Tr, which is the voltage output blocking means, and the voltage is output to the receiver circuit 2 to enable communication.

Next, when the printable state is reached, the CPU 5 waits for STRB * from the host A, the receiver circuit 2 receives this signal, and the comparison means 2a compares it with a predetermined reference voltage for signal decoding, When the result is output to the recognition means 5a of the CPU 5 and the STRB * signal is recognized as coming from the host A, communication is performed as described in the communication procedure described above.
(step 2). Next, an ACK * signal is output and it is checked whether the communication is completed (step 3). Step 2 if communicating
This loop operation is repeated until the return communication is completed (until ACK * is output). When ACK * is output and the communication is completed, the CPU 5 outputs the Busy * signal to the host A by the Busy * signal output means 2b. Then, the STRB * signal, DATA * signal, etc. coming from the host A are blocked (set to H) to enter the saving mode routine (step 4).

In the saving mode routine, as shown in period a of FIG. 4, the ACk * signal is detected, the Busy * signal is first output (step 4), and then the blocking signal output means 5 of the CPU 5 is output.
c outputs an L signal to the transistor Tr, which is a voltage output blocking means, to block the output voltage to the interface controller 2 (step 5). Then, the recognition means 5a of the CPU 5 is operated to enable the signal level of the STRB * signal to be recognized even while the Busy * signal is being output, and the comparison signal output from the operation output device 2a which is the recognition means of the interface control unit 2 is checked. (step 6). At this time, by checking a plurality of times, it is possible to accurately and accurately determine the off state. Next, in step 7, the recognition means 5a determines whether the result of the comparison means 2a is H or L. In this case, in order to surely discriminate between H and L by the recognizing means 5a, the comparing means 2a is provided with a varying means (not shown) for changing the threshold to a value which makes it easy to discriminate.

As a result of checking by the recognition means 5a in step 7, if the signal is H, the CPU 5 determines that the transistor Tr
The H signal is output to (step 10), the Busy * signal is released (set to L) (step 11), the STRB * signal from the host A is waited for a certain time (step 12), and the certain time elapses. Even if the communication is not started and the CPU 5 cannot recognize the STRB * signal, the process returns to step 4 (step 13), the Busy * signal is output again, and the host A is checked again for disconnection.
On the other hand, when the STRB * signal is recognized, it is determined that the power of the host A is turned on, the process returns to step 2, and the communication processing described so far is repeated.

On the other hand, from Step 4 shown in the period b of FIG.
If the STRB * signal is L after the process of Step 6 is completed,
(step 7), judging that the power of the host is off,
After the processing of the printer is completed, it is confirmed by the data processing confirmation means 5d whether all the input data have been printed.
(Step 8), after confirmation, enter power saving mode (Step
9). Here, in the power saving mode, the CPU 5 informs the engine control unit 8 that the power of the host A is off, and the power control means 8a in the engine control unit 8 turns off the power connected to the engine. Take action. Although the present embodiment has described the operation of turning off the power, the present invention is not limited to this.
It is also possible to reduce the output voltage of a part of the power supplies, resulting in low power consumption. The operating method is
The present invention is not limited to the one described in this embodiment, and for example, step 1
Up to step 3 may be repeated at all times to communicate data, and only when the STRB * signal cannot be recognized for a certain period of time during this communication, the saving mode routine of the present invention may be entered and controlled.

[0026]

According to the structure of the present invention, by providing the voltage blocking means for blocking the voltage output means to the interface, it is possible to promptly recognize that the host is reliably disconnected in a stable state. Moreover, since the voltage blocking means can be composed of at least only the transistor, it is possible to simply configure without using a complicated control device. Furthermore, if the operation of the power saving mode is performed for each data sent from the host, it is possible to quickly determine that the host is dead, and a great saving can be achieved in the printer using the electrophotographic method that consumes a considerable amount of power. It will be possible. On the other hand, if the method for discriminating the off-state of the present invention is configured to recognize the level of the signal voltage of the STRB * signal during Busy * signal output, even if the off-state is discriminated using the STRB * signal line, it may cause a malfunction. Data capture is prevented.

Further, if the data processing confirmation means is added to the method of the present invention, it is consumed after the data processing such as printout of the receiving device is completed after the off state of the communication source is recognized by the recognition means. It can be developed and improved to enter the saving mode.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating an outline of the present invention.

FIG. 2 is an explanatory diagram for explaining the configuration of the interface device by simplifying FIG.

FIG. 3 is a flowchart illustrating an operation procedure of the present invention.

FIG. 4 is a timing chart.

FIG. 5 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 A host computer B printer 1 driver circuit 2 receiver circuit 2a actuation output device (comparing means) 2b reception blocking signal output means (Busy *) 3 interface signal line 4 interface control unit 5 central control unit (CPU) 5a recognition unit 5b reception blocking Signaling means 5c Blocking signal outputting means 5d Data processing confirmation means 9 Voltage outputting means 9a, 10 Power supply Tr Voltage output blocking means (transistor)

Claims (4)

[Claims] 1. An interface signal line having at least a data signal line for transmitting data from various communication source devices and a plurality of control information transmitting signal lines for transmitting various control information, and the interface signal. A receiver circuit connected to each signal line of the line through a pull-up resistor and connected to a voltage output unit for outputting a predetermined voltage to stably transmit and receive a signal, and the receiver circuit coupled to the voltage output unit. Voltage output blocking means for blocking voltage application to the circuit, and comparing means for coupling the control signal coupled to the receiver circuit and received from the control information signal line with a predetermined reference voltage for signal decoding. An interface control unit having; a recognition unit for recognizing the comparison signal compared by the comparison unit of the receiver circuit; and a receiver circuit of the receiver circuit. A central control unit having a blocking signal output unit for outputting a signal for blocking voltage application to the pressure output blocking unit, and the blocking signal output unit of the central control unit outputs an application blocking signal, and A method for determining an off state of a communication source device, wherein the recognizing means recognizes the control signal compared by the comparing means while the application blocking signal is being output. 2. The off-state determination method for a communication source device according to claim 1, wherein the control signal is a signal transmitted from the communication source device prior to data transmission. 3. A reception blocking signal for blocking the reception of data from a communication source device is output from the receiving device, and
3. The off-state determination method for a communication source device according to claim 2, wherein the application inhibition signal is output during the output of the reception inhibition signal. 4. The off-state determination method for a communication source device according to claim 1, wherein the recognition means that operates during the output of the blocking signal recognizes a plurality of times.