JP3628817B2 - Printer interface switching device and printer using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printer interface switching device and a printer using the same.
[0002]
[Prior art]
In general, a printer is often connected as a peripheral device of a personal computer (hereinafter simply referred to as a personal computer), but as a form thereof, there is a one-to-one connection relationship for connecting one personal computer and one printer. The majority. As the interface for connecting a personal computer and a printer, a Centronics standard interface is the mainstream, and normally, both are coupled using a Centronics standard connector (including Centronics compliance).
[0003]
Here, there are various types of printers including laser printers and ink jet printers, and there are also those with monochrome specifications and those with color specifications. However, various types of printers have merits and demerits, and there is an increasing need for coexistence of different types of printers for one personal computer. For example, a black and white laser printer and a color ink jet printer will be described as typical examples. In the case of this example, if only a black and white laser printer is used, the demand for color printing cannot be met, and a color ink jet printer is required for a user who desires color printing. On the other hand, if only a color ink jet printer is used, color printing as well as black and white printing are possible. There is a disadvantage that it is quite bad, and it can be said that it is preferable to provide a black and white laser printer in consideration of black and white printing which occupies most.
[0004]
[Problems to be solved by the invention]
However, looking at the usage mode when two printers coexist on a single personal computer, only one printer can be connected to a single personal computer. Most of the systems dealt with by replacing standard connectors. However, this is troublesome to switch the printer and is extremely inconvenient.
[0005]
In addition, there is a switcher on the market that allows one PC and two printers to be connected to each other. According to this switcher, although it is not necessary to replace the connector, it can be controlled by control from the PC side. The present situation is lacking in reliability regarding the selection of the printer side. Originally, the interface between the personal computer side and the printer side is based on the Centronics standard. This is due to the fact that there are many cases where the compatibility of is often poor. Considering the case where the above-mentioned switch is used under such circumstances, since two printers connected to the switch are unspecified when viewed from a personal computer, it can be versatile. It is difficult and lacks the reliability of the switching function.
[0006]
Therefore, the present invention provides a highly reliable printer interface switching that can reliably select a desired printer by control on the personal computer side when two printers coexist on a single personal computer. An object is to provide an apparatus and a printer using the same.
[0007]
[Means for Solving the Problems]
Printer interface switching device of the invention described in claim 1 includes a first connector to which the connector for the computer is coupled to connecting only ship the printer directly to the computer, other machine to the computer A second connector to which a connector for the other printer is coupled in order to connect a printer via the own printer, and an own device side signal transmission / reception for connecting between the first connector and the own printer a path, and the other-side signal transmitting and receiving path connecting between said first connector and said second connector, at the time of power on the is initially set to the own device side signal transmitting and receiving path becomes effective, the a route state switching means either between the other-side signal transmitting and receiving paths own device side signal transmitting and receiving path is switched so that the effective, the own apparatus from the computer side When the printer selection code is sent at an arbitrary timing via the signal transmission / reception path, the path state switching means is switched so that the other apparatus side signal transmission / reception path becomes valid, and the own apparatus side signal transmission / reception path is switched from the computer side. A control unit that outputs a switching signal for switching the path state switching means so that the signal transmission / reception path for the own device becomes valid and returns to the same state as when the power is turned on. The state of the switching signal for the path state switching means from the controller for enabling the other apparatus side signal transmission / reception path built in the printer is the state of the switching signal generated when the power of the own printer is turned off. Set the same.
[0008]
Therefore, when the power is turned on, the own-side signal transmission / reception path becomes valid according to the initial setting, so that the computer and the own-printer are in an effective connection state, and the print output can be performed using the own-machine printer. When attempting to use other machine printer in this state, when sending a printer selection code by escape sequences in the multifunction peripheral printer through own device side signal transmission and reception path from the computer, the own device printer control unit By determining that an understandable command has been received and operating the path state switching means, the other apparatus side signal transmission / reception path is switched to become effective. As a result, the computer and the other printer are in a valid connection state, and a print output is possible using the other printer. On the other hand, if it is desired to return to the own printer side in such a state, the command on the other printer side should be used according to the above, but the command standard of the other printer is not necessarily the same. Most of the printers do not match the printer and are different, and it is unclear whether the printer can understand the command. If it cannot be understood, it cannot be restored. When such a signal is sent using a signal that can be understood by the control unit built in the printer, the route state switching means is operated to switch the own-side signal transmission / reception route to be effective. As a result, a switching device is provided that can arbitrarily switch the use of the own machine / other machine printer under the control of the computer. The switching signal for the path status switching means does not operate if the printer of the own printer is turned off, but the switching signal status for the path status switching means for validating the signal transmission / reception path on the other machine side is not controlled. Since the switching signal generated when the printer power is off is set to the same state, the signal transmission / reception path on the other device side becomes valid when the printer power is off and the printer power on. It is possible to switch between them, and even when the power of the printer of the own machine is off and only the power of the personal computer and the printer of the other machine is on, the interface between the two is possible.
[0009]
Here, for example, a printer initialization signal (/ INIT), which is a signal assigned to a predetermined pin in a Centronics standard connector and used to return the printer to an initial state, is used as a signal that can be recognized by the own printer. However, the present invention is not limited to the printer initialization signal, and for example, some recognizable signal may be placed on the data bus. In short, any signal that can be recognized by the own printer may be used, and a signal generated by clicking an icon on the computer may be transmitted.
[0010]
According to a second aspect of the present invention, in the printer interface switching apparatus according to the first aspect, the printer selection code is a printer selection code by an escape sequence, and the recognizable signal is a printer initialization signal .
[0012]
According to a third aspect of the present invention, in the printer interface switching device according to the first or second aspect, a power source for operating the path state switching means is connected to the first printer and the other printer. and a second connector side so as to disjunctive supply.
[0013]
When supplying power for operating the path status switching means only from the own printer side, if the power of the own printer is off, the path status switching means should be operated even if the power of the other printer is on. I can't. However, because it is providing power from the second connector side to the other machine printer is connected, Ru can be operated route state switching device by its power supply if the power of the other machine printer is on.
[0014]
A printer according to a fourth aspect of the present invention includes the printer interface switching device according to the first , second or third aspect, wherein the computer is coupled via the first connector, and the other printer via the second connector. Are combined. Therefore, since the printer itself incorporates the printer interface switching device according to the first, second, or third aspect, even if the specifications of other printers are not specified, the printer itself is controlled by the computer. The printer can surely switch between enabling the printer side and enabling the other printer side.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. In the present embodiment, for example, as shown in FIG. 2, two printers, a black and white laser printer (hereinafter referred to as “own printer”) 1 and a color inkjet printer (hereinafter referred to as “other printer”) 2, In the system coexisting with one personal computer 3 as described above, it relates to the own printer 1 part.
[0016]
The personal computer 3 and the other printer 2 are connected via the own printer 1, and a printer interface switching device 4 is built in a part of the own printer 1. This printer interface switching device 4 is basically a Centronics standard interface and is configured as shown in FIG. First, a first connector 5 to which a Centronics standard connector (not shown) for the personal computer 3 is coupled, and a second connector to which a Centronics standard connector (not shown) for the other printer 2 is coupled. 6 are provided. Since this printer interface switching device 4 is built in the own printer 1 and is fixedly connected to the own printer 1, it is connected by internal wiring and does not have a connector for the own printer. The own printer 1 has a built-in controller 8 including a CPU 7, and a self-side signal transmission / reception path 9 that connects between the first connector 5 and the controller 8 is formed. This own-side signal transmission / reception path 9 is formed by an eight-line data bus 9a, a four-line reception control line 9b, and a five-line transmission control line 9c. Further, the other-device-side signal transmission / reception path 10 for connecting between the first connector 5 and the second connector 6 (accordingly, the other-device printer 2) is also formed. The other-device-side signal transmission / reception path 10 is a data bus 10a in which the data bus 9a, the reception control line 9b, and the transmission control line 9c drawn from the first connector 5 side are branched to the second connector 6 side. These are formed by a reception control line 10b and a transmission control line 10c.
[0017]
These signal transmission / reception paths 9 and 10 are switched in accordance with a switching signal given from the controller 8 side, and a switching unit serving as a path state switching means for enabling any one of the signal transmission / reception paths 9 or 10. 11 is provided. The switching unit 11 is provided on each of the data bus 9a, the reception control line 9b, and the transmission control line 9c, and can take an operation state and a non-operation state, and buffers 12a, 12b, and 12c. Buffers 13b and 13c that are provided on each of the line 10b and the transmission control line 10c and can be activated and deactivated, and a switch 14 that is provided on the data bus 10a and is on / off controlled. It is configured. The buffer 12a is a bidirectional buffer. Also, a control line 15b for supplying a switching signal for selectively operating the buffers 12b and 13b, a control line 15c for supplying a switching signal for alternatively operating the buffers 12c and 13c, and the buffer A control line 15a for supplying a switching signal for controlling the operating state of the switch 12a and a control line 15d for supplying a switching signal for controlling on / off of the switch 14 are provided, and control lines 15b for the buffers 13b and 13c are provided. Inverters 16b and 16c for inverting the signal are interposed on 15c. A power supply 17 for operating the switching unit 11 is supplied from the power supply line 18 of the controller 8 and a second power supply for checking whether or not the power supply on the other printer 2 side is on. P. of connector 6 L. Also supplied from an H (peripheral logic high) line 19. Specifically, a minute power supply current is allocated from the other printer 2 to the Centronics interface. Here, the diodes 20 and 21 are interposed on these lines 18 and 19 so as to be logically connected.
[0018]
Here, when the printer 1 is turned on, the state of the switching signal given from the controller 8 to the control lines 15a to 15c is H level (the state of the switching signal given to the control line 15d is L level). The initial setting is made. In this state, since the buffers 12a to 12c are in the operating state, the switch 14 is in the OFF state, and the buffers 13b and 13c are in the inactive state, the own signal transmission / reception path 9 side is set to be valid.
[0019]
In such a configuration, when all the power supplies are turned on in a system in which two printers 1 and 2 coexist on one personal computer 3, the state of the switching signal given to the control lines 15a to 15c by the controller 8 is shown. Becomes H level (the state of the switching signal applied to the control line 15d is L level). As a result, the own-side signal transmission / reception path 9 side becomes effective as described above, which is equivalent to a state in which only the own-printer 1 is connected to the personal computer 3. Therefore, the printer 3 can print out the print data, other data, and signals from the personal computer 3 side. In the case of this embodiment, high-speed and high-quality black-and-white printing is performed.
[0020]
Further, when it is desired to use the other printer 2 at an arbitrary time, an ESC command as a printer selection code by an escape sequence is transmitted by an operation on the personal computer 3 side. On the side of the control 8 that has received this ESC command through its own signal transmission / reception path 9, the CPU 7 determines that the command has come, and the switching signal given to the control lines 15a to 15c is at the L level and the switching signal given to the control line 15d. Is switched to H level. Thereby, instead of the buffers 12a to 12c, the buffers 13b and 13c are activated, and the switch 14 is closed and turned on, and the other-device-side signal transmission / reception path 10 side becomes effective. That is, this is equivalent to a state in which only the other printer 2 is connected to the personal computer 3 via the connectors 5 and 6. Therefore, the printer 1 can print out by sending print data, other data, and signals from the personal computer 3 side. In the case of this embodiment, full-color printing is performed.
[0021]
On the other hand, when it is desired to return to the own printer 1 side in such a state that the other printer 2 can be used, the printer initialization signal (/ INIT) is sent through the first connector 5 by the operation on the personal computer 3 side. To the interface switching device 4 side. Such a printer initialization signal (/ INIT) is a signal in accordance with the Centronics standard, and is a signal that can be recognized by the CPU 7 in the printer 1 itself. Therefore, the processing in accordance with the printer initialization signal (/ INIT) is performed. That is, the switching unit 11 is operated so as to return to the same state as when the power is turned on, so that the own device side signal transmission / reception path 9 side is switched to the valid state again instead of the other apparatus side signal transmission / reception path 10 side. That is, even when such switching is performed, the command on the other machine printer 2 side should be used according to the above, but this other machine printer 2 is unspecified when viewed from the own machine printer 1. The command standard does not necessarily match that of the own printer 1 and is often different, and it is unknown whether the command can be understood by the own printer 1 and cannot be returned if a command that cannot be understood is sent. In this case, the command is returned to the self printer 1 side using a signal that can be understood by the self printer 1 as described above without using the command of the other printer standard. Accordingly, the use of the own printer / other printers 1 and 2 can be arbitrarily switched by the control on the personal computer 3 side.
[0022]
By the way, although the power of the own printer 1 is off, there are cases where both the personal computer 3 and the other printer 2 are on. Even in such a case, it is desirable that the interface between the personal computer 3 and the other printer 2 is possible. However, the printer interface switching device 4 is built in the own printer 1, and the own printer 1 Is switched off and the switching unit 11 and the like cannot be operated. However, in the present embodiment, since the power supply 17 is also supplied to the switching unit 11 from the second connector 6 side to which the other printer 2 is connected, if the power of the other printer 2 is on. The switching unit 11 can be operated by supplying electric power. In addition, the controller 8 does not operate if the power of the printer 1 is off and the control does not work if the power of the printer 1 is off, but the switch 11 for enabling the other-device-side signal transmission / reception path 10 is also effective. Since the state of the switching signal (L level) is set to be the same as the state of the switching signal (ground level) generated when the printer 1 is turned off, the controller 8 functions when the printer 1 is turned off. Even when the other printer 2 is powered on, the other device side signal transmission / reception path 10 can be switched to be effective. Therefore, even when the power of the own printer 1 is off and only the power of the personal computer 3 and the other printer 2 is on, the interface between the two is possible.
[0023]
Next, the configuration and operation of the switch 14 portion will be described. The switch 14 can be configured using a mechanical switch, but it is on / off switching on the data bus 10a, and an analog switch 22 having an IC configuration is often used. In this case, in order to protect the analog switch 22 from an external surge voltage or the like, protection diodes 23a to 23d are usually interposed between the signal terminal of the input / output stage and the power supply as shown in FIG. However, in the case of such a configuration, when the power of the printer 1 is turned off and the power supply of the personal computer 3 is turned on, the power supply for the analog switch 22 shown in FIG. There is a possibility that a reverse current flows. If a reverse current flows, the IC (analog switch 22) is destroyed, which is not preferable. In this respect, in the present embodiment, as shown in FIG. 3, a diode 24 (which may be the diode 20 in FIG. 1) serving as a backflow prevention element is connected to the power supply line 18 in the opposite direction to the protection diode 23. Therefore, even if the printer 1 is turned off and the personal computer 3 is turned on, a reverse current does not flow from the signal line, so that the IC or the like can be reliably protected.
[0024]
【The invention's effect】
According to the first aspect of the present invention, the first connector to which the connector for the computer is coupled to directly connect only the own printer to the computer, and the other printer to the computer. A second connector to which a connector for the other printer is coupled for connection via a printer, a own-side signal transmission / reception path connecting the first connector and the own printer, The other apparatus side signal transmission / reception path connecting between the first connector and the second connector and the other apparatus side signal are initialized so that the own apparatus side signal transmission / reception path becomes valid when the power is turned on. a route state switching means to be switched to any one of the transmitting and receiving paths own device side signal transmitting and receiving path is valid, optionally via the own device side signal transmission and reception path from the computer side When the printer selection code is transmitted at the timing, the path state switching means is switched so that the other apparatus side signal transmission / reception path becomes valid, and a signal that can be recognized from the computer side via the own apparatus side signal transmission / reception path is transmitted. Since the self-machine side signal transmission / reception path becomes valid and a control signal for outputting a switching signal for switching the path state switching means so as to return to the same state as when the power is turned on is built in the self-machine printer. , A switching device capable of arbitrarily switching between the use of the own printer and the other printer by the control on the computer side, and further, from the control unit for enabling the other device side signal transmission / reception path The state of the switching signal for the path state switching means is set to be the same as the state of the switching signal generated when the printer power is turned off. Therefore, even if the power of the own printer is off, it can be switched so that the signal transmission / reception path of the other device is valid when the power of the other printer is on. Even when only the power supply to the other printer is turned on, the interface between the two can be made possible.
[0026]
According to the printer interface switching device of the third aspect of the present invention, the power source for operating the path state switching means is logically ORed from the own printer side and the second connector side to which the other printer is connected. Even if the power of the own printer is off, when the power of the other printer is on, it can be switched so that the signal transmission / reception path of the other device is valid, and the power of the own printer is Even when the computer is turned off and only the power of the printer is turned on, the interface between the two can be made possible.
[0027]
According to a fourth aspect of the invention, the printer interface switching device according to the first, second, or third aspect is built-in, the computer is coupled through the first connector, and the other is coupled through the second connector. Since the printers are combined, even if the specifications of other printers are unspecified, switching between enabling the own printer side or enabling the other printer side by control on the computer side It is possible to provide a printer that can be surely performed.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention mainly using a printer interface switching device.
FIG. 2 is a connection diagram showing a system configuration.
FIG. 3 is a circuit diagram showing the vicinity of a switch.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Self-machine printer 2 Other machine printer 3 Computer 4 Printer interface switching device 5 1st connector 6 2nd connector 9 Own machine side signal transmission / reception path 10 Other machine side signal transmission / reception path 11 Path state switching means 22 Analog switch 23 Protection Diode 24 Diode

Claims (4)

A first connector to which a connector for the computer is coupled in order to directly connect only the own printer to the computer;
A second connector to which a connector for the other printer is coupled to connect the other printer to the computer via the own printer ;
A self-device side signal transmission / reception path connecting the first connector and the self-printer;
Other device side signal transmission / reception path connecting between the first connector and the second connector,
A path state that is initially set so that the own device side signal transmission / reception route becomes valid when the power is turned on, and is switched so that either the other device side signal transmission / reception route or the own device side signal transmission / reception route becomes valid Switching means;
When the printer selection code is sent from the computer side via the own device side signal transmission / reception route at an arbitrary timing, the route state switching means is switched so that the other device side signal transmission / reception route becomes effective, and the computer side When a signal that can be recognized is sent from the own device side signal transmission / reception route, a switching signal for switching the route state switching means is output so that the own device side signal transmission / reception route becomes valid and returns to the same state as when the power is turned on. A control unit,
Is built into the printer.
The state of the switching signal for the path state switching means from the control unit for validating the other apparatus side signal transmission / reception path is set to be the same as the state of the switching signal generated when the printer power is turned off .
An interface switching device for a printer. 2. The printer interface switching apparatus according to claim 1 , wherein the printer selection code is a printer selection code based on an escape sequence, and the recognizable signal is a printer initialization signal . Claims, characterized in that the power for operating the route state switching device to the supply from the ship the printer side to the other machine printer connected to said second connector side disjunctive The printer interface switching device according to 1 or 2 . A printer having a built-in printer interface switching device according to claim 1 , wherein a computer is coupled through a first connector, and another printer is coupled through a second connector. .

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