JP2007268959A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of performing self-standing operation even when a signal from an external apparatus can not be detected in the image forming apparatus carrying a power source circuit to be started by detecting the signal from the external apparatus. <P>SOLUTION: An inkjet printer 100 is equipped with a self-holding circuit 40a applying a starting electric voltage of 5 V to a relay switch 49a for starting when various electric power sources 42, 43, 45 and 46 of the inkjet printer 100 are started in the image forming apparatus in which the starting electric voltage of 5 V is inputted from a PC 30 connected through a USB cable 31 and the controlling side electric power sources 42 and 43 and the driving side electric power sources 45 and 46 are started through relay switches 49a and 49b for starting. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that receives a signal from an external connection device such as a personal computer and performs power ON / OFF.

In recent years, an image forming apparatus that is connected to a personal computer (hereinafter referred to as a PC), receives a power ON signal from the PC, and activates the apparatus by an internal power circuit is used.
For example, Patent Document 1 discloses a power supply device including a power supply control unit that detects a signal input from an external device such as a PC and operates a main power supply circuit.

According to this, it is possible to smoothly return from the power saving state and to minimize the power consumption in the power saving operation state.
JP 2005-57500 A (published March 3, 2005)

However, the conventional power supply apparatus has the following problems.
That is, although the power supply device disclosed in the above publication is effective for suppressing power consumption in the power saving mode, for example, when the USB cable connecting the external device and the main device is disconnected or externally No particular consideration has been given to measures for the case where the device shuts down first. For this reason, a signal cannot be detected from an external device such as a PC, and the main device cannot operate independently.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus equipped with a power supply circuit that detects and activates a signal from an external device, and can operate independently even when a signal from the external device cannot be detected. There is to do.

  An image forming apparatus according to a first aspect of the present invention is an image forming apparatus that receives a signal input from an external device and performs a startup process in a power supply circuit, and includes a control system power supply circuit, a drive system power supply circuit, and a control unit And a self-holding circuit. The control system power supply circuit supplies power to the control unit. The drive system power supply circuit supplies power to the drive unit. The control unit receives a signal from the external device, and relay-drives the control system power supply circuit and the drive system power supply circuit with the drive voltage supplied from the external device side. The self-holding circuit applies a driving voltage to the control system power supply circuit and the drive system power supply circuit after being relay-driven by the control unit.

Here, for example, a signal (command) input from an external device such as a PC via a USB cable or the like is received, and a relay drive voltage is applied to the control system power supply circuit and the drive system power supply circuit from the external device side. In the image forming apparatus to be activated, after the control system power supply circuit and the drive system power supply circuit are activated by relay driving, a drive voltage is applied from the self-holding circuit to each of the power supply circuits.
As a result, even after the start-up, even when the connection with the external apparatus is cut off or the power supply of the external apparatus is turned off, the image forming apparatus can continue to drive independently.

  An image forming apparatus according to a second aspect of the present invention is an image forming apparatus that receives a signal input from an external device and performs a startup process in a power supply circuit, and includes a control system power supply circuit, a drive system power supply circuit, and a control unit And a signal monitoring unit. The control system power supply circuit supplies power to the control unit. The drive system power supply circuit supplies power to the drive unit. The control unit receives a signal from the external device, and relay-drives the control system power supply circuit and the drive system power supply circuit with the drive voltage supplied from the external device side. The signal monitoring unit detects the presence or absence of a drive voltage supplied from an external device.

  Here, for example, a signal (command) input from an external device such as a PC via a USB cable or the like is received, and a relay drive voltage is applied to the control system power supply circuit and the drive system power supply circuit from the external device side. In the image forming apparatus to be activated, after the control system power supply circuit and the drive system power supply circuit are activated by relay driving, the application state of the drive voltage supplied to each of the power supply circuits is monitored.

  As a result, by monitoring the application state of the drive voltage from the external device, for example, a USB cable or the like for connecting the external device such as a PC and the image forming device is disconnected, or more than when the image forming device is shut down. It can be easily recognized on the image forming apparatus side that the power supply to the external apparatus side is turned off first and the connection with the external apparatus is cut off. As a result, when the connection with the external device is cut off, it is possible to perform control such as taking a measure of spontaneous shutdown without leaving the power on as it is.

An image forming apparatus according to a third aspect of the present invention is the image forming apparatus according to the first aspect of the present invention, further comprising a signal monitoring unit that detects the presence or absence of a signal input from an external device.
Here, after the control system power supply circuit and the drive system power supply circuit are activated by relay driving, the application state of the drive voltage supplied to each of the power supply circuits is monitored.
Accordingly, in the image forming apparatus having a self-holding circuit that applies a driving voltage to the control system power supply circuit and the driving system power supply circuit, the application state of the driving voltage from the external device is monitored, for example, a PC The USB cable that connects the external device to the image forming device is disconnected, or the power to the external device is turned off before the image forming device shuts down. This can be easily recognized on the image forming apparatus side. As a result, when the connection with the external device is disconnected, control is performed such as taking a measure of spontaneous shutdown without leaving the power source maintained in the ON state by the self-holding circuit. be able to.

An image forming apparatus according to a fourth aspect is the image forming apparatus according to the second or third aspect, wherein the control unit voluntarily turns off the power when the drive voltage is no longer detected by the signal monitoring unit. I do.
Here, when the signal monitoring unit detects that the connection with the external device is disconnected, control is performed so that the shutdown operation is spontaneously performed.

  Accordingly, in an image forming apparatus that receives various signals (commands) from an external device such as a PC and performs various operations, the power of the external device is turned off before the image forming apparatus is turned off. Even when a cable or the like is disconnected and a signal from an external device cannot be received, the power can be turned off and the process can be terminated. As a result, it can be avoided to leave the power on for a long time.

An image forming apparatus according to a fifth aspect of the present invention is the image forming apparatus according to the first aspect of the present invention, wherein the ink head ejects ink onto the photographic paper, and ejects ink from the ink head at a standby position of the ink head. And a cap member that covers the portion.
Here, the present invention is applied to an ink jet printer that forms an image by ejecting ink from an ink head.

  Thus, for example, even when an external device such as a PC is forcibly terminated before the image forming apparatus is shut down, the image forming apparatus can be continuously operated by the self-holding circuit. As a result, the power of the image forming apparatus was turned off together with the forced termination of the external device. As a result, the ink head of the ink jet printer was left unattended for a long time, causing ink clogging. Can be prevented.

According to the image forming apparatus of the first aspect of the present invention, even after the start-up, even when the connection with the external device is disconnected or the power supply of the external device is turned off, the image forming apparatus is driven independently. Can continue.
According to the image forming apparatus of the second aspect of the invention, when the connection with the external device is disconnected, the control is performed such as taking a measure of spontaneously shutting down without leaving the power on as it is. It can be carried out.

According to the image forming apparatus of the third aspect of the present invention, when the connection with the external device is cut off, the power supply is left as it is without being left as it is, and measures are taken to shut down spontaneously. Control can be performed.
According to the image forming apparatus of the fourth aspect of the present invention, it is possible to avoid leaving for a long time with the power on.

  According to the image forming apparatus of the fifth aspect of the invention, it is possible to prevent the occurrence of problems such as the ink head of the ink jet printer being left for a long time without being in the cap position and causing ink clogging. .

An inkjet printer (image forming apparatus) 100 according to an embodiment of the present invention will be described below with reference to FIGS.
[Configuration of Inkjet Printer 100]
As shown in FIG. 1, the ink jet printer 100 is connected to a personal computer (hereinafter referred to as a PC) 30 as an external device via a USB cable 31, and various types of devices mounted therein. The mechanism performs printing by ejecting ink onto the set paper (printing paper) P.

The ink jet printer 100 includes a housing 15, a magazine 21, a printing unit 200, and an ink storage unit 210.
The housing 15 has a discharge port 19 and a paper discharge tray 18 at the top. The discharge port 19 discharges the paper P to the outside of the inkjet printer 100. The paper discharge tray 18 receives the paper P discharged from the discharge port 19.

Two magazines 21 are arranged at the bottom of the casing 15 and hold a roll of paper P that is wound so that the stamp screen is on the outside.
The printing unit 200 is disposed in the upper center portion of the housing 15 and prints image data on the paper P. The print unit 200 includes a print head (ink head) 4a (see FIG. 2) for each color in order to form an image by ejecting ink onto the paper P.

  The ink storage unit 210 stores ink ejected during the printing process. Here, ink cartridges 23 having different hues (ink cartridges 23C, 23M, 23Y, and 23K shown in FIG. 2) are accommodated in the door 15a so that they can be inserted and removed. In these ink cartridges 23, for example, inks such as cyan (C), magenta (M), yellow (Y), and black (K) are sealed. Each ink cartridge 23 is replaced with a new ink cartridge 23 when all of the sealed ink is consumed. The door 15a is attached to the housing 15 so as to be openable and closable around an axis extending in the vertical direction.

[Configuration of Print Unit 200]
As shown in FIG. 2, the print unit 200 mainly includes a transport unit 2, two rails 3, a carriage 4, a platen 5, and a control unit 6.
The transport unit 2 transports the paper P drawn from the magazine 21 (see FIG. 1). Specifically, the paper P is transported by a pair of rollers 25 and 26 arranged upstream and downstream in the transport direction of the paper P with respect to the print unit 200.

The roller pair 25 is configured such that the paper P is sandwiched between two rollers, and the paper P is conveyed to the downstream side when one roller side rotates counterclockwise.
The roller pair 26 guides the paper P that has undergone the printing process between the two rollers, and conveys the paper P further downstream. Each roller is arranged such that its axial direction intersects at right angles to the transport direction of the paper P.

As shown in FIG. 2, the two rails 3 are arranged so as to be substantially parallel to each other in the direction intersecting the paper P transport direction. Here, the rail 3 passes through the carriage 4.
As shown in FIG. 2, the carriage 4 has a shape in which a convex portion is provided on a substantially rectangular parallelepiped, and has a print head 4 a that prints on the paper P on the bottom surface of the convex portion. The carriage 4 is disposed so that its longitudinal direction is perpendicular to the transport direction of the paper P, and is further slidably attached to the rail 3 so that the bottom surface of the convex portion faces the paper P. Further, the print head 4 a portion of the carriage 4 includes a nozzle (not shown) that ejects ink onto the paper P. On the upper surface of the carriage 4, a projecting cylinder portion 10 is opened so as to be open at both ends. One open end of each protruding cylinder 10 is connected to the ink cartridges 23C, 23M, 23Y, and 23K of the ink reservoir 210 via tubes 9C, 9M, 9Y, and 9K, respectively. The other open end communicates with the nozzles of the print head 4a.

  The print head 4a has a space partitioned to correspond to the respective color inks and a plurality of nozzles from which the respective color inks are ejected. The spaces are arranged in the longitudinal direction of the carriage 4. Ink is ejected by ejection means (not shown). Here, as the ejection unit, for example, a piezoelectric element such as a piezoelectric element that ejects ink from the nozzle at a predetermined amount and at an appropriate timing can be used. The piezoelectric element is configured to push the ink in the print head 4a toward the nozzle when a voltage is applied. Further, the print head 4a is moved to a standby position except when printing is performed, and is protected by a cap 4b for covering a nozzle portion that ejects ink.

  The nozzle is configured such that one open end coincides with the bottom surface of the planar print head 4a. Further, the other open end of the nozzle is connected to a plurality of connection holes (not shown) branched from the inner hole of the protruding cylinder portion 10, and the nozzle communicates with the protruding cylinder portion 10 through the connection holes. Has been. Thereby, the ink supplied from each tube can be ejected from a plurality of nozzles. In the longitudinal direction of the carriage 4, nozzle rows corresponding to the inks of the respective colors are formed, and each nozzle row has a plurality of nozzles. When ejecting ink in the printing process, the nozzle is controlled by the control unit 6 so as to protrude from the paper P.

The platen 5 is disposed at a position facing the carriage 4 and the print head 4a. The paper P that is conveyed is conveyed along the platen surface of the platen 5 that faces the print head 4a when printing.
As shown in FIG. 2, the control unit 6 is connected to the transport unit 2, the rail 3, the print head 4a, and the like, and gives control instructions such as supply and stop to these. The control unit 6 is connected to the power supply circuit 40, and power for the control system and the drive system is supplied from the power supply circuit 40. The configuration of the power supply circuit 40 mounted on the inkjet printer 100 according to the present embodiment will be described in detail later.

[Description of Operation of Print Unit 200]
The printing unit 200 of the inkjet printer 100 scans the carriage 4 that moves in a direction orthogonal to the transport direction of the paper P to print an image for one line, and then transports the paper P for one line and stops it. Subsequently, the next row of images is printed in the same manner, and image formation is performed while repeating the same transport operation, and the printing process is terminated. In order to obtain a high-quality image in this printing process, it is necessary to accurately spray ink onto a predetermined position of the paper P from the nozzles mounted on the print head 4a.

  First, the paper P drawn out from the magazine 21 is conveyed to the gap between the print head 4 a and the platen 5 in the printing unit 200 on the downstream side in the conveyance direction by the roller pair 25 of the conveyance unit 2. Further, the roller pair 25 conveys the paper P while maintaining a predetermined platen gap along the surface of the platen 5 as it is due to the characteristic of the thickness of the paper P.

  When the printing portion of the paper P reaches the substantially central portion of the platen surface, the carriage 4 continuously reciprocates on the rail 3. At that time, the ink supplied from the ink cartridge 23 to the print head 4a via the tubes 9C, 9M, 9Y, and 9K is ejected from the nozzles toward the paper P by the operation of an ejection unit (not shown). Subsequently, the transport unit 2 transports the paper P corresponding to the reciprocating timing of the print head 4a. As a result, the line-like print becomes a continuous state and becomes a plane, and an image is formed on the print screen (the surface facing the print head 4a) on the paper P.

When printing is completed, the paper P is further conveyed along the platen surface, and is sandwiched between the rollers in the roller pair 26 and pushed downstream. Then, it is cut into a predetermined size by a cutter.
Then, when printing is completed, the print head 4a moves to a predetermined standby position along the rail 3, and the nozzle portion is covered and protected by the cap 4b at this standby position.

[Configuration of Power Supply Circuit 40]
As described above, the inkjet printer 100 according to this embodiment includes the power supply circuit 40 that is driven by being applied with a Vbus voltage of 5 V from the PC 30 connected via the USB cable 31 through the Vbus line.
As shown in FIG. 3, the power supply circuit 40 includes a self-holding circuit 40a, a Vbus signal detection unit (signal monitoring unit) 40b, a CPU (control unit) 41, control-side power supplies (control system power supply circuits) 42 and 43, and an interlock. Power supply 44, drive side power supply (drive system power supply circuit) 45 and 46, AC power supply 47, interlock relay switches 48a and 48b, start relay switches 49a and 49b, and interlock switch 50.

  The self-holding circuit 40a applies a starting voltage of 5V to the starting relay switch 49a as a local power supply after the power supply circuit 40 is started by the starting voltage of 5V supplied from the PC 30 side via the Vbus line of the USB cable 31. 5V power supply 40aa. As a result, after the inkjet printer 100 is activated, the operation of the inkjet printer 100 can be performed even if the USB cable 31 is disconnected or the PC 30 is shut down first on either the inkjet printer 100 side or the PC 30 side. Can be held. For this reason, it is possible to effectively prevent the occurrence of problems such as clogging of ink in the nozzle portion as a result of the print head 4a being left without returning to the standby position during the above-described printing process.

The Vbus signal detector 40b is a current detector such as a diode arranged in parallel with the activation relay switch 49a, and is a Vbus signal (applied from the PC via the USB cable 31 (Vbus line)). The presence or absence of a 5V drive voltage) is detected and transmitted to the CPU 41.
The CPU 41 determines whether or not to hold the operation of the inkjet printer 100, that is, the power supply from the power supply circuit 40, according to the presence or absence of the Vbus signal received from the Vbus signal detection unit 40b. Specifically, when the Vbus signal applied from the PC 30 is received, the CPU 41 holds the operation of the inkjet printer 100 (power supply from the power supply circuit 40) as it is. On the other hand, when the Vbus signal from the PC 30 is not received, the CPU 41 shifts to the end mode so as to shut down the inkjet printer 100 spontaneously. In this way, when the Vbus signal is no longer detected, control is performed so as to enter the shutdown operation by itself, so that even when the connection with the PC 30 side is disconnected due to the disconnection of the USB cable 31 or the like, the inkjet printer It is possible to avoid 100 being left for a long time while the power is on.

The control-side power supplies 42 and 43 are power supplies of 5V and 42V, respectively, for supplying power to the control system circuit. A Vbus signal, that is, a startup voltage of 5V is applied from the PC 30, and the startup relay switch 49a. , 49b is activated by receiving power supply from the AC power supply 47.
The interlock power supply 44 is disposed downstream of the control power supply 43 described above, and is connected to an interlock switch 50 described later.

  The drive-side power supplies 45 and 46 are power supplies of 24V and 36V, respectively, for supplying power to the drive system circuit. A Vbus signal, that is, a startup voltage of 5V is applied from the PC 30, and the startup relay switch 49a. , 49b is activated by receiving power supply from the AC power supply 47, and when the interlock relay switches 48a, 48b function, the power supply from the AC power supply 47 is stopped.

The AC power supply 47 supplies power to the above-described control system and drive system power supplies 42, 43, 45, and 46, respectively.
The interlock relay switches (X1) 48a and 48b are safety switches arranged respectively between the drive side power supplies 45 and 46 and the AC power supply 47 on the downstream side of the interlock switch 50 and on the drive system power supply circuit side. . The interlock relay switches 48a and 48b are configured such that when the interlock switch 50 is activated by opening the door 15a of the casing 15 of the ink jet printer 100 or the like, no current flows through the interlock relay switch 48a (X1). The lock relay switch 48b is turned off, and power supply from the AC power supply 47 to the drive side power supplies 45 and 46 is stopped.

  The activation relay switches (X2) 49a and 49b are respectively connected between the USB port to which the USB cable 31 connected to the PC 30 is connected and the CPU 41 described above, and between the AC power supply 47 and the control power supplies 42 and 43, respectively. Has been placed. When the activation relay switches 49a and 49b receive the Vbus signal as the activation voltage of 5V applied from the PC 30, a current flows through the activation relay switch (X2) 49a and the activation relay switch 49b is turned on. Then, electric power is supplied from the AC power source 47 to the control side / drive side power sources 42, 43, 45, 46, respectively.

  The interlock switch 50 is a switch for operating the interlock relay switches 48a and 48b. For example, a magnet reed switch (proximity sensor) that operates when the door 15a of the casing 15 of the inkjet printer 100 is opened. It is. For example, when the door 15a of the casing 15 of the ink jet printer 100 is opened, the interlock switch 50 is activated to be in an OFF state, no current flows through the interlock switch 48a, and the interlock relay switch 48b is in an OFF state. The power supply to the side power supplies 45 and 46 is stopped.

<Starting Operation and Ending Operation in Power Supply Circuit 40>
In the inkjet printer 100 of the present embodiment, the start operation and the end operation are performed according to the flowchart shown in FIG.
That is, in step S1, first, when connected to the PC 30 via the USB cable 31, a startup voltage of 5 V is applied from the PC 30.

In step S2, by applying this starting voltage, a current flows through the starting relay switch 49a, and the starting relay switch 49b is shifted to the ON state.
Furthermore, in step S3, the Vbus voltage is detected by the Vbus signal detection unit 40b by applying the activation voltage, and the detection result is sent to the CPU 41.
On the other hand, when the above-described activation relay switch 49b is turned on, the control-side power sources 42 and 43 and the interlock power source 44 are driven in step S5 by the power supplied from the AC power source 47 in step S4. The side power supplies 45 and 46 are activated.

  At this time, the interlock relay switch 48b disposed on the upper side of the drive side power supplies 45 and 46 is in the ON state. When the interlock switch 50 is activated due to the door 15a of the casing 15 of the inkjet printer 100 being opened, the interlock relay switch 48b is shifted to the OFF state via the interlock relay switch 48a. Thus, the power supply from the AC power supply 47 to the drive side power supplies 45 and 46 is stopped.

  Here, when the USB cable 31 that supplies the 5V start-up voltage from the PC 30 is disconnected from the insertion port on the PC 30 side or the inkjet printer 100 for some reason, or the PC 30 issues an end command to the inkjet printer 100. If the computer is shut down before transmission, the supply of the starting voltage from the PC 30 via the USB cable 31 is stopped.

At this time, the ink jet printer 100 of the present embodiment has a self-holding circuit 40a including a 5V power supply 40aa for applying a voltage of 5V to the activation relay switch 49a in the power supply circuit 40.
As a result, even when the supply of the startup voltage of 5V from the PC 30 is stopped for some reason, the operation of the inkjet printer 100 can be held by supplying the voltage of 5V from the self-holding circuit 40a. Therefore, for example, even when the supply of the starting voltage from the PC 30 is stopped during the printing process in the ink jet printer 100, the printing process is continued as it is and the printing process is completed, and then the print head 4a is moved to the standby position where the cap 4b is located. And can be moved. As a result, the supply of the starting voltage from the PC 30 is stopped during the printing process in the ink jet printer 100, and the print head 4a is left for a long time without returning to the standby position where the cap 4b is located. It is possible to avoid the occurrence of problems such as

Furthermore, in this embodiment, in step S6, the CPU 41 monitors whether or not a 5V start-up voltage (Vbus signal) is input via the Vbus signal detection unit 40b.
Thereby, when the supply of the startup voltage of 5V from the PC 30 is stopped, the operation of the inkjet printer 100 is held by the voltage of 5V supplied from the self-holding circuit 40a in step S7. Note that the 5V voltage supplied from the self-holding circuit 40a is not applied after the Vbus signal is no longer detected, but in parallel with the Vbus signal from the time when the inkjet printer 100 is activated by the Vbus signal. It is assumed that a voltage of 5V is continuously applied to the starting relay switch 49a.

  Then, in step S8 and step S9, the CPU 41 can confirm the print processing status in the ink jet printer 100 and the like, and in step S10, can perform control so as to enter the end operation spontaneously. Therefore, after the printing process in the ink jet printer 100 is completed and the print head 4a returns to the standby position, the ink jet printer 100 enters the end operation spontaneously, thereby avoiding the occurrence of ink clogging in the nozzle portion, and the ink jet printer for a long time. It is possible to prevent the 100 from being left inoperable when the power is on.

[Features of Inkjet Printer 100]
(1)
As shown in FIG. 3, the inkjet printer 100 according to the present embodiment receives a 5V start-up voltage from the PC 30 connected via the USB cable 31 and connects the control-side power sources 42 and 43 and the drive-side power sources 45 and 46. An image forming apparatus that is activated via activation relay switches 49a and 49b. When various power sources 42, 43, 45, and 46 of the inkjet printer 100 are activated, the activation relay switch 49a is activated by 5V. A self-holding circuit 40a for applying a voltage is provided.

  As a result, when the USB cable 31 is disconnected or the PC 30 is shut down before the end command is transmitted to the inkjet printer 100, the startup voltage or operation command is not input via the USB cable 31. However, since the 5V voltage is applied to the activation relay switch 49a from the 5V power supply 40aa of the self-holding circuit 40a, the operation of the inkjet printer 100 can be held.

(2)
In the inkjet printer 100 according to the present embodiment, as shown in FIG. 3, the control power supply 42, 43 and the drive power supply 45, 46 are connected when a startup voltage of 5 V is input from the PC 30 connected via the USB cable 31. An image forming apparatus that is activated via the activation relay switches 49a and 49b, and for monitoring whether or not the activation voltage of 5V is continuously applied from the PC 30 via the USB cable 31, the Vbus signal detection unit 40b. It has.

  As a result, when the USB cable 31 is disconnected or the PC 30 is shut down before the end command is transmitted to the inkjet printer 100, the startup voltage or operation command is not input via the USB cable 31. However, this situation can be easily recognized on the inkjet printer 100 side. As a result, by recognizing that the instruction input from the PC 30 is no longer transmitted, take subsequent measures such as spontaneously shifting to the shutdown operation without being disabled while the power is on. Is possible.

(3)
In the inkjet printer 100 of the present embodiment, when the Vbus signal is not detected by the Vbus signal detection unit 40b, the CPU 41 spontaneously shifts to the end mode and shuts down the inkjet printer 100 as shown in FIG.
As a result, even when the operation command from the PC 30 cannot be received due to the USB cable 31 being unplugged from the insertion port due to the non-detection of the Vbus signal, it is left in an inoperable state with the power on. Can be prevented, and the shutdown operation can be voluntarily entered.

(4)
The ink jet printer 100 according to the present embodiment performs printing processing by ejecting ink from the nozzles of the print head 4a onto the paper P. After the printing processing is completed, the print head 4a is returned to the standby position to return the nozzle portion. Is covered with a cap 4b.
As a result, as described above, in the inkjet printer 100, when the USB cable 31 is disconnected from the insertion port and the startup voltage, the operation command, etc. from the PC 30 cannot be received, the self-holding circuit 40a is used for autonomous operation. Therefore, even if the Vbus signal from the PC 30 is cut off during the printing process in the inkjet printer 100, the printing process is continued. Can do. As a result, it is possible to prevent the print head 4a from stopping at a place other than the standby position due to the inability to receive the Vbus signal from the PC 30. Therefore, it is possible to prevent ink clogging at the nozzle portion of the print head 4a. Can be prevented.

[Other Embodiments]
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention.
(A)
In the above embodiment, an example in which the present invention is applied to the power supply circuit 40 mounted on the inkjet printer 100 has been described. However, the present invention is not limited to this.

For example, in addition to an ink jet printer, the present invention can naturally be applied to a power supply circuit mounted on various image forming apparatuses including a photographic processing apparatus that forms an image by exposure processing and development processing. is there.
(B)
In the above embodiment, the PC 30 has been described as an example of the external device. However, the present invention is not limited to this.

For example, in addition to a PC, an external device that inputs instructions to an image forming apparatus such as an ink jet printer can also be used.
(C)
In the above embodiment, an example in which the PC 30 as an external device and the inkjet printer 100 are connected by the USB cable 31 has been described. However, the present invention is not limited to this.

  In addition to the USB cable, for example, a PC and an inkjet printer may be connected via an IEEE 1394 cable, a LAN cable, or the like, and a startup voltage or various operation signals may be input.

  The image forming apparatus of the present invention has an effect that the image forming apparatus can continue to drive independently even when the connection with the external apparatus is disconnected or the power of the external apparatus is turned off. Therefore, the present invention can be widely applied to various devices that start up and operate in response to an instruction input from the outside.

1 is an external perspective view of an ink jet printer including a printing unit according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of a print unit and its periphery according to an embodiment of the present invention. FIG. 2 is a circuit diagram showing a configuration of a power supply circuit mounted on the inkjet printer of FIG. 1. 4 is a flowchart showing a flow of start and end operations in the power supply circuit of FIG. 3.

Explanation of symbols

2 Conveying section 3 Rail 4 Carriage 4a Print head (ink head)
4b Cap 5 Platen 6 Control unit 10 Projection cylinder 15 Case 15a Door 18 Paper discharge tray 19 Paper outlet 21 Magazine 23 Ink cartridges 25 and 26 Roller pair 30 Personal computer (PC)
31 USB cable 40 Power supply circuit 40a Self-holding circuit 40aa 5V power supply 40b Vbus signal detection unit (signal monitoring unit)
41 CPU (control unit)
42, 43 Control side power supply (control system power supply circuit)
44 Interlock power supply 45, 46 Drive side power supply (drive system power supply circuit)
47 AC power supply 48a, 48b Interlock relay switch 49a, 49b Start relay switch 50 Interlock switch 100 Inkjet printer (image forming apparatus)
200 Print unit 210 Ink storage unit

Claims (5)

An image forming apparatus that receives a signal input from an external device and performs startup processing in a power supply circuit,
A control power supply circuit for supplying power to the control unit;
A drive system power supply circuit for supplying power to the drive unit;
A controller that receives the signal from the external device and relay-drives the control system power supply circuit and the drive system power supply circuit using a drive voltage supplied from the external device;
A self-holding circuit that applies the drive voltage to the control system power supply circuit and the drive system power supply circuit after being relay-driven by the control unit;
An image forming apparatus. An image forming apparatus that receives a signal input from an external device and performs startup processing in a power supply circuit,
A control power supply circuit for supplying power to the control unit;
A drive system power supply circuit for supplying power to the drive unit;
A controller that receives the signal from the external device and relay-drives the control system power supply circuit and the drive system power supply circuit using a drive voltage supplied from the external device;
A signal monitoring unit for detecting the presence or absence of the drive voltage supplied from the external device;
An image forming apparatus. A signal monitoring unit for detecting the presence or absence of the signal input from the external device;
In addition,
The image forming apparatus according to claim 1. When the driving voltage is no longer detected by the signal monitoring unit, the control unit voluntarily performs power-off processing.
The image forming apparatus according to claim 2. An ink head for ejecting ink to photographic paper;
A cap member that covers a portion of the ink head that ejects ink at the standby position of the ink head;
Further equipped with,
The image forming apparatus according to claim 1.

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