# US 8,540,352 B2 · Inkjet recording apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,540,352 B2 - Document ID: US8540352B2 - Status: Granted - Kind: B2 - Application number: 12/873,778 - Filed: 2010-09-01 - Published: 2011-03-10 - Granted: 2013-09-24 - Earliest claimed: 2009-09-04 - Assignees: Ricoh Company, Ltd. - Applicants: Masanori Igarashi - Inventors: Masanori Igarashi - Web page: https://patentgrep.com/patent/US8540352B2 ## CPC - B41J 2/17596: {Ink pumps, ink valves} - B41J 2/175: Ink supply systems {; Circuit parts therefor} - B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS ## Abstract An inkjet recording apparatus is disclosed. The inkjet recording apparatus includes a droplet ejecting head which has multiple nozzles for ejecting ink, multiple head tanks which generate a negative pressure at the droplet ejecting head and temporarily store a predetermined amount of ink, an ink cartridge which stores the ink, multiple liquid sending pumps which perform a forward transfer liquid process which sends the ink from the ink cartridge to the multiple head tanks, or a backward transfer liquid process which sends the ink from the multiple head tanks to the ink cartridge, and an ink supply channel being branched from the ink cartridge to multiple head tanks to supply ink from the ink cartridge to multiple head tanks by the corresponding one of multiple liquid sending pumps. ## Claims ### Claim 1 An inkjet recording apparatus, comprising: a droplet ejecting head which has multiple nozzles for ejecting ink, multiple head tanks which generate a negative pressure at the droplet ejecting head and temporarily store a predetermined amount of ink, an ink cartridge which stores the ink, multiple liquid sending pumps which perform a forward transfer liquid process which sends the ink from the ink cartridge to the multiple head tanks, or a backward transfer liquid process which sends the ink from the multiple head tanks to the ink cartridge, an ink supply channel being branched from the ink cartridge to multiple head tanks to supply ink from the ink cartridge to multiple head tanks by the corresponding one of multiple liquid sending pumps, and an ink liquid level sensing unit which senses a height of an ink liquid level within each of the head tanks, wherein, when the height of the ink liquid level within the head tanks that is sensed by the ink liquid level sensing unit provided at any one of the multiple head tanks across the multiple liquid sending pumps being branched is less than a predetermined height, the backward transfer liquid process of each of the liquid sending pumps is not performed, and wherein at least one of the multiple liquid sending pumps performs the forward transfer liquid process when there is a short supply of ink in the ink cartridge without being able to send the ink from the ink cartridge to one of the head tanks, and then each of the multiple liquid sending pumps performs the backward transfer liquid process for a predetermined ink amount. ### Claim 2 (depends on 1) The inkjet recording apparatus as claimed in claim 1, wherein the predetermined ink amount in the backward transfer liquid process is set according to a storage volume of one of the head tanks. ### Claim 3 (depends on 1) The inkjet recording apparatus as claimed is claim 1, wherein the predetermined ink amount in the backward transfer liquid process is set according to an amount of ink used that is measured by a soft counter. ### Claim 4 (depends on 1) The inkjet recording apparatus as claimed in claim 1, wherein the predetermined ink amount in the backward transfer liquid process is set according to an environmental temperature. ### Claim 5 (depends on 1) The inkjet recording apparatus as claimed in claim 1, wherein, when the height of the ink liquid level within the head tanks that is sensed by the ink liquid level sensing unit provided at any one of the multiple head tanks across the multiple liquid sending pumps being branched is less than a predetermined height, the backward transfer liquid process of each of the liquid sending pumps only to one of the head tanks is not performed. ### Claim 6 (depends on 1) The inkjet recording apparatus as claimed in claim 1, wherein one of the liquid sending pumps is a tube pump. ### Claim 7 (depends on 1) The inkjet recording apparatus as claimed in claim 1, wherein, when the height of the ink liquid level within the head tanks, that is sensed by the ink liquid level sensing unit provided at any one of the multiple head tanks across the multiple liquid sending pumps being branched from the ink cartridge, is less than a predetermined height, the backward transfer liquid process of each of the liquid sending pumps is not performed. ### Claim 8 An inkjet recording apparatus, comprising: a droplet ejecting head which has multiple nozzles for ejecting ink, multiple head tanks which generate a negative pressure at the droplet ejecting head and temporarily store a predetermined amount of ink, an ink cartridge which stores the ink, multiple liquid sending pumps which perform a forward transfer liquid process which sends the ink from the ink cartridge to the multiple head tanks, or a backward transfer liquid process which sends the ink from the multiple head tanks to the ink cartridge, and an ink supply channel being branched from the ink cartridge to multiple head tanks to supply ink from the ink cartridge to multiple head tanks by the corresponding, one of multiple liquid sending pumps, wherein at least one of the multiple liquid sending pumps performs the forward transfer liquid process when there is a short supply of ink in the ink cartridge without being able to send the ink from the ink cartridge to one of the head tanks, and then each of the multiple liquid sending pumps performs the backward transfer liquid process for a predetermined ink amount, and wherein the predetermined ink amount in the backward transfer liquid process corresponds to an ink amount when a position of a negative pressure lever for sensing a state of a negative pressure within one of the head tanks that is displaced in response to an amount of ink stored in one of the head tanks reaches a limit position such that the negative pressure within one of the head tanks is not lost. ### Claim 9 (depends on 8) The inkjet recording apparatus as claimed in claim 8, wherein the predetermined ink amount in the backward transfer liquid process is set according to a storage volume of one of the head tanks. ### Claim 10 (depends on 8) The inkjet recording apparatus as claimed in claim 8, wherein the predetermined ink amount in the backward transfer liquid process is set according to an amount of ink used that measured by a soft counter. ### Claim 11 (depends on 8) The inkjet recording apparatus as claimed in claim 8, wherein the predetermined ink amount in the backward transfer liquid process is set according to an environmental temperature. ### Claim 12 (depends on 8) The inkjet recording apparatus as claimed in claim 8, wherein, when the height of the ink liquid level within the head tanks that is sensed by the ink liquid level sensing unit provided at any one of the multiple head tanks across the multiple liquid sending pumps being branched is less than a predetermined height, the backward transfer liquid process of each of the liquid sending pumps only to one of the head tanks is not performed. ### Claim 13 An inkjet recording apparatus, comprising: a droplet ejecting head which has multiple nozzles for ejecting ink, multiple head tanks which generate a negative pressure at the droplet ejecting head and temporarily store a predetermined amount of ink, an ink cartridge which stores the ink, multiple liquid sending pumps which perform a forward transfer liquid process which sends the ink from the ink cartridge to the multiple head tanks, or a backward transfer liquid process which sends the ink from the multiple head tanks to the ink cartridge, and an ink supply channel being branched from the ink cartridge to multiple head tanks to supply ink from the ink cartridge to multiple head tanks by the corresponding one of multiple liquid sending pumps, wherein at least one of the multiple liquid sending pumps performs the forward transfer liquid process when there is a short supply of ink in the ink cartridge without being able to end the ink from the ink cartridge to one of the head tanks, and then each of the multiple liquid sending pumps performs the backward transfer liquid process for a predetermined ink amount, and wherein one of the liquid sending pumps is a tube pump in which a direction of sending ink is controlled by conducting forward transfer of ink in which the ink is sent from an ink cartridge to a head tank and by conducting backward transfer of ink in which the ink is sent from the head tank to the ink cartridge by locally squeezing, with a rotor, a tube which crawls inside a pump and rotating the rotor forward or backward. ### Claim 14 (depends on 13) The inkjet recording apparatus as claimed in claim 13, wherein, when the height of the ink liquid level within the head tanks, that is sensed by the ink liquid level sensing unit provided at any one of the multiple head tanks across the multiple liquid sending pumps being branched from the ink cartridge, is less than a predetermined height, the backward transfer liquid process of each of the liquid sending pumps is not performed. ### Claim 15 (depends on 13) The inkjet recording apparatus as claimed in claim 13, wherein the predetermined ink amount in the backward transfer liquid process is set according to a storage volume of one of the head tanks. ### Claim 16 (depends on 13) The inkjet recording apparatus as claimed in claim 13, wherein the predetermined ink amount in the backward transfer liquid process is set according to an amount of ink used that is measured by a soft counter. ### Claim 17 (depends on 13) The inkjet recording apparatus as claimed in claim 13, wherein the predetermined ink amount in the backward transfer liquid process is set according to an environmental temperature. ### Claim 18 (depends on 13) The inkjet recording apparatus as claimed in claim 13, wherein, when the height of the ink liquid level within the head tanks that is sensed by the ink liquid level sensing unit provided at any one of the multiple head tanks across the multiple liquid sending pumps being branched is less than a predetermined height, the backward transfer liquid process of each of the liquid sending pumps only to one of the head tanks is not performed.