Abstract:
A printer is communicatively connected to a host device. A first transmitter is operable to transmit an inquiry to the printer for acquiring a status of the printer, and to transmit a printing request to the printer. A detector is operable to detect the inquiry and the printing request from the host device. A printing section is operable to perform printing with respect to a printing medium, in accordance with the printing request. A second transmitter is operable to transmit the status to the host device in response to the inquiry. A power saving controller is operable to switch the printer between a first state in which the second transmitter is activated and a second state in which the second transmitter is deactivated. The first transmitter is operable to transmit the inquiry every first time period in a case where the printer is in the first state. The first transmitter is operable to transmit the inquiry every second time period which is longer than the first time period or to stop transmitting the inquiry in a case where the printer is in the second state.

Description:
[0001]     The disclosure of Japanese Patent Application No. 2005-285932 filed Sep. 30, 2005 including specification, drawings and claims is incorporated herein by reference in its entirety.  
       BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to technology for suppressing power consumption of a printer.  
         [0003]     There has been known a printer which, in case that it does not accept a printing request for a predetermined time in a power-on state, shifts to a power saving mode in order to reduce the power consumed quantity. Particularly, there is a printer which deactivates CPU in this power saving mode.  
         [0004]     On the other hand, there is a printer host device which inquires of the printer a status periodically. The printer, upon reception of the inquiry about the status from such the host device, must respond to an inquiry request about the status after restoring the CPU. Therefore, there is a problem that a power saving effect of the printer is reduced. In view of such the problem, some inventions have been made, for example, Japanese Patent Publication NO. 11-219263 and Japanese Patent Publication No. 2004-34488.  
         [0005]     In Japanese Patent Publication No. 11-219263, technology is described in which a period of making a status inquiry for the printer by the host device can be changed by user&#39;s setting.  
         [0006]     In Japanese Patent Publication No. 2004-34488, a printer is described, which deactivates a main CPU in a power saving mode, and includes a sub-CPU for responding to a status inquiry in this time.  
         [0007]     However, in the technology in Japanese Patent Publication No. 11-219263, to utilize the printer comfortably while increasing the power saving effect, the user must set and release the period. Therefore, in order to increase the power saving effect, the user must frequently set and release the period, which is troublesome.  
         [0008]     Further, the printer in Japanese Patent Publication No. 2004-34488 has the sub-CPU, which causes increase of cost.  
       SUMMARY OF THE INVENTION  
       [0009]     Therefore, it is an object of the invention to increase a power saving effect of a printer without giving a load to a user and increasing the number of parts.  
         [0010]     In order to achieve the above objects, according to the invention, there is provided a printing system comprising: 
        a host device;     a printer, communicatively connected to the host device, wherein:     the host device includes: 
            a first transmitter, operable to transmit an inquiry to the printer for acquiring a status of the printer, and to transmit a printing request to the printer;    
            the printer includes: 
            a detector, operable to detect the inquiry and the printing request from the host device;     a printing section, operable to perform printing with respect to a printing medium, in accordance with the printing request;     a second transmitter, operable to transmit the status to the host device in response to the inquiry; and     a power saving controller, operable to switch the printer between a first state in which the second transmitter is activated and a second state in which the second transmitter is deactivated;    
            the first transmitter is operable to transmit the inquiry every first time period in a case where the printer is in the first state; and     the first transmitter is operable to transmit the inquiry every second time period which is longer than the first time period or to stop transmitting the inquiry in a case where the printer is in the second state.        
 
         [0022]     According to the invention, there is also provided a host device adapted to be communicatively connected to a printer, the host device comprising: 
        a transmitter, operable to transmit an inquiry to the printer for acquiring a status of the printer, wherein:     the transmitter is operable to transmit the inquiry every first time period in a case where the printer is in a first state in which the printer is operable to transmit the status; and     the transmitter is operable to transmit the inquiry every second time period which is longer than the first time period or to stop transmitting the inquiry in a case where the printer is in a second state in which the printer is not operable to transmit the status.        
 
         [0026]     According to the invention, there is also provided a method performed by a host device for inquiring a status of a printer which is communicatively connected to the host device, the method comprising: 
        transmitting an inquiry to the printer; and     acquiring the status from the printer in response to the inquiry, wherein:     the inquiry is transmitted every first time period in a case where the printer is operable to transmit the status; and     the inquiry is transmitted every second time period which is longer than the first time period in a case where the printer is not operable to transmit the status.       
 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0031]     The above object and advantages of the invention will become more apparent by describing in detail preferred and exemplary embodiments with reference to the accompanying drawings.  
         [0032]      FIG. 1  is a diagram showing the constitution of a printing system according to an embodiment of the invention;  
         [0033]      FIG. 2  is a diagram showing the functional constitution of the printing system according to the embodiment of the invention;  
         [0034]      FIG. 3  is a flowchart of a host device;  
         [0035]      FIG. 4  is another flowchart of the host device;  
         [0036]      FIG. 5  is a flowchart of a printer; and  
         [0037]      FIG. 6  is a flowchart of the printer. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0038]     Hereinafter, a printing system according to one embodiment of the invention will be described with reference to drawings.  
         [0039]      FIG. 1  is a diagram showing the constitution of a printing system according to one embodiment of the invention.  
         [0040]     This system includes a printer  1  and a printer host device (hereinafter referred to as a host device)  3 .  
         [0041]     The printer  1  includes a printing mechanism  11  having a print head, a carriage on which the print head is mounted, and a paper feed mechanism; a CPU  12  which executes a program stored in a ROM  13  and controls the printing mechanism  11 ; a RAM  14  which is used when the CPU  12  executes the program; and an interface  15  with the host device  3 .  
         [0042]     The host device  3  may be constituted by a general-purpose computer machine such as a personal computer. Namely, the host device  3  includes a CPU  31  which executes a predetermined program stored in a ROM  32 ; a RAM  33  which is used when the CPU  21  executes the program; and an interface  34  with the printer  1 .  
         [0043]      FIG. 2  is a diagram showing the functional constitution realized by executing the respective predetermined programs by the printer  1  and the host device  3  which include the above hardware construction.  
         [0044]     The host device  3 , as shown in  FIG. 2 , includes a status inquiry means  301  which inquires of the printer  1  about a status, and a printing request means  302  which generates printing data, transmits the printing data to the printer  1 , and requests printing. The status inquiry means  301  and the printing request means  302  are implemented by the CPU  31 .  
         [0045]     The status inquiry means  301  transmits a status inquire request to the printer  1 , and acquires information indicating the status of the printer  1  as a response to the inquire request. Timing in which the status inquiry for the printer  1  is made may be arbitrary timing such as when an instruction is given by a user, or may be periodical timing at predetermined intervals. The control of the status inquiry timing will be described later.  
         [0046]     The printing request means  302  generates printing data, transmits this printing data to the printer  1 , and makes a printing request.  
         [0047]     The printer  1 , as shown in  FIG. 2 , includes a request detecting means  101  which detects the request transmitted from the host device  3 , a printing means  102  which executes printing on the basis of the printing data transmitted from the host device  3 , a status response means  103  which transmits the status of the printer  1  in response to the status inquiry from the host device  3 , and a power saving control means  104  which controls operation modes of the printer in order to save electric power consumed by the printer  1 .  
         [0048]     The request detecting means  101  is implemented by the interface  15  (refer to  FIG. 1 ), and detects, upon reception of any request from the host device  3 , its request. For example, in the embodiment, since the host device  3  transmits the status inquiry request and the printing request to the printer  1 , the interface  15  (request detecting means  101 ), upon reception of either request from the host device  3 , detects its request, and interrupts the CPU  12  (refer to  FIG. 1 ). The CPU  12  knows from this interruption that the request from the host device  3  has been received.  
         [0049]     In case that the received request is the printing request, the printing means  102  implemented by the CPU  12  and the printing mechanism  11  executes printing processing. Further, in case that the received request is the status inquiry request, the status response means  103  implemented by the CPU  12  transmits a present status of the printer  1  to the host device  3 .  
         [0050]     The power saving control means  104 , which is implemented by the CPU, controls the operation modes of the printer  1  thereby to reduce power consumption of the printer  1 . Here, the operation modes of the printer  1  include the following three kinds.  
         [0051]     (1) Normal operation mode (hereinafter referred to as a normal mode) in which all of the request detecting means  101 , the printing means  102  and the status response means  103  are activated.  
         [0052]     (2) Sleep mode in which the printing means  102  is deactivated, and the request detecting means  101  and the status response means  103  are activated.  
         [0053]     (3) Standby mode in which the printing means  102  and the status response means  103  are deactivated, and only the request detecting means  101  is activated.  
         [0054]     The normal mode indicates an immediate response-enabled state in relation to the status inquiry request and the printing request from the host device  3 . The normal mode is largest in power consumption of the three modes. In the normal mode, when a waiting state where the printing request from the host device  3  is waited continues for a predetermined time (T 1 ) or more, the printer  1  shifts to the sleep mode.  
         [0055]     The sleep mode is a first power saving mode in which the printing means  102  is deactivated and the power consumption is reduced. In the sleep mode, for example, a not-shown panel lighting for interface is turned off, or each motor included in the printing mechanism  11  (refer to  FIG. 11 ) is unexcited. Further, at this time, a clock of the CPU  12  is operating.  
         [0056]     When the printer  1  receives the printing request in the sleep mode, the power saving control means  104  restores the printer  1  to the normal mode, and the printing means  102  executes printing in accordance with the printing request. Therefore, it takes more time to make the response than in the normal mode by the time necessary for the printer  1  to be restored from the sleep mode to the normal mode.  
         [0057]     On the other hand, even in the sleep mode, the status response means  103  is operating. Therefore, the status response means  103 , upon reception of the status inquiry request from the host device  3 , immediately responds to the inquiry and transmits the status in that time (i.e., “sleep”).  
         [0058]     In the sleep mode, when the printer  1  does not accept any request from the host device  3  for a predetermined time (T 2 ) or more, it shifts to the standby mode.  
         [0059]     The standby mode is a second power saving mode in which the printing means  102  and the status response means  103  are deactivated. In the standby mode, in addition to the state in the sleep mode, the clock of the CPU  12  is also deactivated. Namely, substantially, only the host device  3  and interface  15  (request detecting means  101 ) of the components which the printer  1  has are operating. Therefore, the standby mode is lower in power consumption than the sleep mode.  
         [0060]     When the request detecting means  101  interrupts the CPU  12  in the state where the printer  1  is in the standby mode, the clock of the CPU  12  restarts to operate, and the printer  1  enters the sleep mode. Here, when the request detected by the request detecting means  101  is the status inquiry request, the status response means  103  transmits the status in that time (i.e., “sleep”) in the state where the printer is in the sleep mode.  
         [0061]     On the other hand, when the detected request is the printing request, the printer  1  is further restored from the sleep mode to the normal mode, and the printing means  102  performs printing processing of printing data relating to the printing request.  
         [0062]     Next,  FIG. 3  shows a flowchart of processing executed by the host device  3 .  
         [0063]     The host device  3  checks whether or not there is a printing request for the printer  1  (S 101 ). When there is no printing request (S 101 : No), the host device  3  counts elapsed time. When the time set as a normal period elapses, the status inquiry means  301  transmits a status inquiry request to the printer  1  and acquires the status of the printer  1  (S 102 , S 103 ).  
         [0064]     Here, in case that the status of the printer  1  is the “normal mode”, the host device  3  returns to the step S 101  (S 104 ).  
         [0065]     In case that the status of the printer  1  is “error”, the host device  3  executes error processing (S 110 ).  
         [0066]     In case that the status of the printer  1  is the “sleep mode”, the host device  3  checks whether or not there is the printing request for the printer  1  (S 105 ). Here, when there is no printing request, the host device  3  counts elapsed time after the last status acquiring time. When time in a period which is longer (long period) than the normal period in the step S 102  passes, the status inquiry means  301  transmits the status inquiry request to the printer  1  and acquires the status of the printer  1  (S 106 , S 107 ). Next, the host device  3  returns to the step S 105  and repeats processing from the step S 105  on.  
         [0067]     When there are the printing requests in the step S 101  and in the step S 105 , the status inquiry means  301  transmits the status inquiry request to the printer  1  and acquires the status of the printer  1  (S 108 ). In case that the acquired status is “error” (S 109 : Yes), the host device  3  executes error processing (S 110 ).  
         [0068]     In case that the acquired status is not “error” (S 109 : No), the printing request means  302  generates printing data and transmits its data to the printer (S 111 ). Next, the host device returns to the step S 101  and continues the processing.  
         [0069]     As described in the above processing, the host device  3 , when the printer  1  is in the sleep mode, inquires about the printer status in the time period which is longer than the time period in the normal mode. Namely, according to the embodiment, the host device  3 , in accordance with the status of the printer  1 , can change the time period in which the status is acquired.  
         [0070]     Further,  FIG. 4  shows a flowchart of another processing executed by the host device  3 .  
         [0071]     In this procedure, as shown in  FIG. 4 , the steps S 106  and S 107  in  FIG. 3  are omitted. Namely, the host device  3 , when detecting that the status of the printer  1  is the sleep mode, does not perform the status acquirement till a next printing request occurs. Further, the status acquirement may be performed when an event to inquire about the status of the printer occurs in the printer host device. As the event, a case where a next printing request occurs, or a case where a user gives an instruction of displaying the newest status of the printer on a screen of the printer host is thought.  
         [0072]     According to the above embodiment, when the printer is in the power saving mode, the time period of the status inquiry for the printer is made longer, or the inquiry is not made. In this result, because of the later described reasons, the printer  1  can be power-saved more.  
         [0073]     Next,  FIGS. 5 and 6  show flowcharts of processing executed by the printer  1 .  
         [0074]     Firstly, when the printer  1  is switched on, it enters a waiting state where it waits a request from the host device  3  (S 201 ). Next, the printer  1  counts elapsed time after the waiting state. In case that the elapse time is below the predetermined time (T 1 ) (S 202 : No), the printer  1  checks whether or not there is reception of any request from the host device  3  ( 203 ).  
         [0075]     When the host device  3  has not received any request from the printer  1  (S 203 : No), the printer returns to the step S 202 .  
         [0076]     On the other, when the printer  1  has received any request from the host device  3 , it judges a kind of its request (S 204 ). When the received request is a printing request, the printer executes printing in accordance with the printing data received by the printing means  102  and returns to the step S 201  (S 205 ). To the contrary, when the received request is a status acquirement request, the status response means  103  transmits the present status of the printer  1  i.e., “normal”) to the host device  3  in response to the request and returns to the step S 202  (S 206 ).  
         [0077]     In the step S 202 , when the elapsed time after the waiting state of the printer  1  exceeds T 1  (S 202 : Yes), the printer  1  shifts to the sleep mode (S 208 ).  
         [0078]     Referring to  FIG. 6 , the printer  1  counts elapsed time after the sleep mode. When the elapsed time exceeds a predetermined time (T 2 ) (S 209 : Yes), the printer  1  shifts to the standby mode (S 210 ).  
         [0079]     Here, the printer  1 , till the request detecting means  101  accepts the request from the host device  3 , continues the standby mode state (S 211 ). When the request detecting means  101  detects the request from the host device  3  (S 211 : Yes), the printer  1  is restored to the sleep mode and returns to the step S 209 .  
         [0080]     Namely, when the printer  1  is in the standby mode in which the power saving effect is largest, it continues the standby mode state till it accepts any request from the host device  3 . Therefore, as described above, when the host device  3  detects that the printer  1  has entered the sleep mode, the time period of the status inquiry made for the printer  1  becomes long. Therefore, the time period in which the printer  1  is in the standby mode becomes long, so that power-saving effect becomes larger.  
         [0081]     Here, as clear from the above description, since the response to the status inquiry is impossible in the standby mode, the power saving mode detected by the host device  3  is always the sleep mode. However, such setting of T 2  as to become shorter greatly than the long period of the status inquiry, when the host device  3  detects the sleep mode, makes it possible that the printer is substantially in the standby mode.  
         [0082]     Continuing the description of the flowchart, when the continuation time of the sleep mode is below T 2  (S 209 : No), the printer judges the presence or absence of the request from the host device  3  (S 221 ). When the printer has not received any request from the host device  3  (S 221 : No), it returns to the step S 209 .  
         [0083]     On the other, when the printer has received the request from the host device  3 , it judges a kind of its request (S 222 ). When the received request is a printing request, the status of the printer  1  is restored to the normal mode, and the printer executes printing in accordance with the printing data received by the printing means  102  (S 223 , S 224 ). After completion of printing, the printer returns to the step S 201 . When the request from the host device  3  is a status acquirement request, the printer  1  transmits the present status to the host device  3  in response to the request, and the printer returns to the step S 209  (S 225 ).  
         [0084]     In the above embodiment, a plurality of the means (status inquiry means  302 , printing request means  302 ) provided for the host device correspond to the CPU  31 . Further, the request detecting means provided for the printer corresponds to the interface  15 , and the status response means and the power saving control means correspond to the CPU  12 . The function of each means may be realized by execution of the programs by one CPU or plural CPU&#39;s, or may be realized by one hardware unit or plural hardware units.  
         [0085]     In the above embodiment, as the power-saving states of the printer  1 , there are the sleep mode in which the printing means  102  is deactivated, and the status response means  103  is activated; and the standby mode in which the printing means  102  and the status response means  103  are deactivated. Namely, at least the state where the printing means  102  is deactivated is set as the power saving state. However, regardless of the operation of the printing means  102 , the state where the status response means  103  is deactivated may be set as the power saving state, or the state where at least either the printing means  102  or the status response means  103  is deactivated may be set as the power saving state.  
         [0086]     In the above embodiment, the power saving mode which is detected by the host device  3  is the “sleep mode”. However, the printer  1 , before shifting to the “standby mode” (or example, immediately before shifting thereto), may transmit a fact of shifting to the standby mode as the status to the host device  3 , whereby the host device  3  can judge the printer  1  to be in the “standby mode”.  
         [0087]     In the above embodiment, a condition that the printer shifts to the power saving state is that the waiting state in which the printer is waiting for the printing request from the host device  3  continues for the predetermined time (T 1 ) or more. However, the condition that the printer  1  shifts to the power saving state may be a predetermined condition consisting of an internal factor in the printer or/and an external factor outside the printer. For example, by a command from the host device  3 , the printer may be caused to shift to the power saving state. In this case, the host device  3 , regardless of the status information from the printer  1 , can grasp the power saving state of the printer  1 .  
         [0088]     In the above embodiment, the host device  3  judges the power saving state of the printer  1  on the basis of the status information transmitted from the printer  1 . However, the host device  3  may judge the power saving state on the basis of a predetermined command transmitted from the printer  1  in place of the status. Further, the host device may judge, by a response time till the printer  1  transmits the status to the host device in response to the status inquiry transmitted by the host device, that the printer  1  is in the standby mode.  
         [0089]     The above described embodiment of the invention is an illustration for description of the invention, and does not limit the scope of the invention to only this embodiment. It will be obvious to those skilled in the art that the invention can be embodied in several forms without departing from the spirit of the invention.