Circulating ink supply system of ink-jet printer and online ink pressure regulation and control method

Abstract

The invention discloses an ink-jet printer circulation ink supply system and an ink online pressure regulation and control method, the circulation ink supply system comprises an ink box, an ink supply pipe, a printing head and an ink return pipe, the ink supply pipe is connected between the ink box and the printing head, the ink return pipe is connected between the printing head and the ink box, and the ink return pipe is connected between the printing head and the ink box along the flowing direction of ink. An ink supply pump, an ink supply pulse damper and an ink filter are sequentially arranged on the ink supply pipe, an ink return pulse damper and an ink return pump are sequentially arranged on the ink return pipe, an ink supply pressure sensor is arranged on the ink supply pipe, an ink return pressure sensor is arranged on the ink return pipe, and the ink supply pressure sensor is located on the downstream of the ink filter and higher than the printing head. The ink return pressure sensor is located on the upstream of the ink return pulse damper and higher than the printing head, and the ink supply pressure sensor and the ink return pressure sensor are equal in height. The rotating speed of the ink supply pump and the rotating speed of the ink return pump are determined by determining the negative pressure PID loop and the pressure difference PID loop, the printing requirement is met, ink jet is stable during printing, and ink dripping is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of sand mold 3D printing, and in particular to an inkjet printer circulating ink supply system and an ink online pressure control method. Background Art

[0002] Sand mold 3D printing refers to the technology of using print heads, nozzles and other printing technologies to deposit materials to make sand molds. The print head uses piezoelectric on-demand titration, and the ejected ink is provided by a circulating ink supply system. There are high requirements for the control of the ink at the nozzle, but the ink pressure control of the circulating ink supply system has the following two problems:

[0003] (1) The current circulating ink supply system uses an air pump or a negative pressure generator to adjust the ink pressure. During inkjet printing, the pressure adjustment fluctuates greatly, the accuracy is low, the stability is poor, and ink dripping is easy to occur. The solenoid valve is frequently switched on and off, and the replacement frequency is high;

[0004] (2) Moreover, for non-recirculating ink supply systems, it is easy to generate particles or bubbles that cannot be taken away, affecting the printing quality. For changes in ink type, viscosity, environment, etc., the current circulating ink supply system has limitations and cannot adjust the ink pressure online in real time to simultaneously meet the print head's requirements for negative pressure and flow rate.

[0005] In order to meet the requirements of the print head for ink pressure, the circulating ink supply system should adopt an online adjustable pressure setting so that it can control the appropriate flow rate within the entire ink circuit pressure range and allow independent control of the pressure difference and flow rate formed at the nozzle, thereby achieving accurate and stable operation of the circulating ink supply system. Summary of the invention

[0006] In view of the above-mentioned shortcomings, the technical problem to be solved by the present invention is to provide an inkjet printer circulating ink supply system and an ink online pressure control method, which can control the ink pressure online in real time.

[0007] To solve the above-mentioned first technical problem, the technical solution of the present invention is:

[0008] A circulating ink supply system for an inkjet printer comprises: an ink cartridge, an ink supply tube, a print head and an ink return tube, the ink supply tube being connected between the ink cartridge and the print head, the ink return tube being connected between the print head and the ink cartridge, along the flow direction of the ink, the ink supply tube is sequentially provided with an ink supply pump, an ink supply pulse damper and an ink filter, the ink return tube is sequentially provided with an ink return pulse damper and an ink return pump, the ink supply tube is provided with an ink supply pressure sensor, the ink return tube is provided with an ink return pressure sensor, the ink supply pressure sensor is located downstream of the ink filter and higher than the print head, the ink return pressure sensor is located upstream of the ink return pulse damper and higher than the print head, and the ink supply pressure sensor and the ink return pressure sensor are at the same height.

[0009] Preferably, the ink cartridge is connected to a raw material barrel via a filling pipe, and the filling pipe is provided with a filling pump;

[0010] The ink cartridge is provided with a liquid level sensor. When the liquid level in the ink cartridge is lower than a set liquid level, the filling pump starts, and when the liquid level in the ink cartridge is higher than the set liquid level, the filling pump stops working.

[0011] Preferably, the ink supply tube between the ink supply pulse damper and the ink filter is connected to an air ink exhaust pipeline, and the air ink exhaust pipeline is provided with an air filter and an air valve.

[0012] To solve the above second technical problem, the technical solution of the present invention is:

[0013] An online pressure control method for inkjet printer ink comprises the following steps:

[0014] S1, the system is powered on, the circulating ink supply system is started, and the printing mode is entered:

[0015] S2. According to the average flow rate of ink, calibrate the pressure difference P of the circulating ink supply system 压差 The lower and upper limits of the ink supply system 负压 The lower and upper limits, negative pressure feedback value-time MAP and differential pressure feedback value-time MAP;

[0016] P 压差 =P 供墨 -P 回墨 , P 供墨 is the pressure of the ink in the ink supply tube, P 回墨 is the pressure of the ink in the ink return pipe, P 负压 =(P 供墨 +P 回墨 +2P 液高 ) / 2,P 负压 represents the negative pressure at the nozzle of the print head, P 液高Indicates the pressure generated by the ink between the ink supply pressure sensor and the ink return pressure sensor and the nozzle of the print head;

[0017] S3, calculate P in the negative pressure PID loop 负压参数 ;

[0018] S4. Calculate I in the negative pressure PID loop 负压参数 ;

[0019] S5. Calculate D in the negative pressure PID loop 负压参数 ;

[0020] S6. Calculate P in the differential pressure PID loop 负压参数 ;

[0021] S7, calculate I in the differential pressure PID loop 负压参数 ;

[0022] S8, calculate D in the differential pressure PID loop 负压参数 ;

[0023] S9. End.

[0024] Preferably, step S3 further includes:

[0025] S31, set the I in the negative pressure PID loop 负压参数 Parameters and D 负压参数 Parameters are set to zero;

[0026] S32, input P 负压参数 ;

[0027] S33, observe the negative pressure feedback value-time MAP, if the current negative pressure feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, execute S34, if the current negative pressure feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, increase the current P 负压参数 And as a new P 负压参数 Return to execute S32;

[0028] S34, in the current P 负压参数 Under this condition, P is obtained by negative pressure feedback value-time MAP 负压 , if P 负压 Within the range of the lower and upper limits, P 负压参数标定 =P 负压参数 / 2, if P 负压 If it is not within the calibrated lower limit and upper limit range, execute S9.

[0029] Preferably, step S4 further includes:

[0030] S41, Input I负压参数 ;

[0031] S42, observe the negative pressure feedback value-time MAP, if the current negative pressure feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, execute S43, if the current negative pressure feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, increase the current I 负压参数 And as a new I 负压参数 Return to execute S41;

[0032] S43, in the current I 负压参数 Under this condition, P is obtained by negative pressure feedback value-time MAP 负压 , if P 负压 Within the range of the lower and upper limits, I 负压参数标定 =I 负压参数 / 2, if P 负压 If it is not within the calibrated lower limit and upper limit range, execute S9.

[0033] Preferably, step S5 further includes:

[0034] S51, input D 负压参数 ;

[0035] S52, observe the negative pressure feedback value-time MAP, if the current negative pressure feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, execute S53, if the current negative pressure feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, increase the current D 负压参数 And as the new D 负压参数 Return to execute S51;

[0036] S53, in the current D 负压参数 Under this condition, P is obtained by negative pressure feedback value-time MAP 负压 , if P 负压 Within the range of the lower and upper limits, D 负压参数标定 =D 负压参数 / 2, if P 负压 If it is not within the calibrated lower limit and upper limit range, execute S9.

[0037] Preferably, step S6 further includes:

[0038] S61, set the I in the pressure difference PID loop 压差参数 Parameters and D 压差参数 Parameters are set to zero;

[0039] S62, input P 压差参数 ;

[0040] S63, observe the pressure difference feedback value-time MAP, if the current pressure difference feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, execute S64, if the current pressure difference feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, increase the current P 压差参数 And as a new P 压差参数 Return to execute S62;

[0041] S64, in the current P 压差参数 Under this condition, P is obtained by pressure difference feedback value-time MAP. 压差 , if P 压差 Within the range of the lower and upper limits, P 压差参数标定 =P 压差参数 / 2, if P 压差 If it is not within the calibrated lower limit and upper limit range, execute S9.

[0042] Preferably, step S7 further includes:

[0043] S71, Input I 压差参数 ;

[0044] S72, observe the pressure difference feedback value-time MAP, if the current pressure difference feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, execute S73, if the current pressure difference feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, increase the current I 压差参数 And as a new I 压差参数 Return to execute S71;

[0045] S73, in the current I 压差参数 Under this condition, P is obtained by pressure difference feedback value-time MAP 压差 , if P 压差 Within the range of the lower and upper limits, I 压差参数标定 =I 压差参数 / 2, if P 压差 If it is not within the calibrated lower limit and upper limit range, execute S9.

[0046] Preferably, step S8 further includes:

[0047] S81, Input D 压差参数 ;

[0048] S82, observe the negative pressure feedback value-time MAP. If the current negative pressure feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, execute S83. If the current negative pressure feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, increase the current D 压差参数 As the new D 压差参数 Return to execute S81;

[0049] S83, in the current D 压差参数 Under this condition, P is obtained by negative pressure feedback value-time MAP 负压 , if P 负压 Within the range of the lower and upper limits, D 压差参数标定 =D 压差参数 / 2, if P 负压 If it is not within the calibrated lower limit and upper limit range, execute S9.

[0050] After adopting the above technical solution, the beneficial effects of the present invention are:

[0051] The present application provides an ink supply pressure sensor and an ink return pressure sensor on the ink supply tube and the ink return tube respectively, which provide real-time feedback of the ink supply pressure and the ink return pressure, and determine the rotation speed of the ink supply pump and the ink return pump by determining the proportional parameters, integral parameters and differential parameters in the negative pressure PID loop and the pressure difference PID loop, so as to meet the printing requirements and ensure stable inkjet printing without ink dripping. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram of the principle of an embodiment of a circulating ink supply system for an inkjet printer of the present invention;

[0053] Figure 2 Schematic diagram of the control principle of an embodiment of a circulating ink supply system for an inkjet printer of the present invention;

[0054] Figure 3 This is the principle diagram of the negative pressure PID loop;

[0055] Figure 4 This is the principle diagram of the differential pressure PID loop;

[0056] Figure 5 It is a schematic flow chart of an embodiment of the method for online pressure control of ink in an inkjet printer of the present invention;

[0057] Figure 6 It is a schematic diagram of the method for confirming the proportional parameters in the negative pressure PID loop;

[0058] Figure 7 It is a schematic diagram of the method for confirming the integral parameter in the negative pressure PID loop;

[0059] Figure 8 It is a schematic diagram of the differential parameter confirmation method in the negative pressure PID loop;

[0060] Fig. 9 It is a schematic diagram of the method for confirming the proportional parameters in the differential pressure PID loop;

[0061] Fig.10 It is a schematic diagram of the method for confirming the integral parameter in the differential pressure PID loop;

[0062] Fig.11 It is a schematic diagram of the differential parameter confirmation method in the differential pressure PID loop;

[0063] In the figure: 1. ink cartridge; 2. ink supply tube; 3. print head; 4. ink return tube; 5. ink supply pump; 6. ink supply pulse damper; 7. ink filter; 8. ink return pulse damper; 9. ink return pump; 10. ink supply pressure sensor; 11. ink return pressure sensor; 12. filling tube; 13. raw material barrel; 14. filling pump; 15. air discharge pipeline; 16. air filter; 17. air valve; 18. liquid level sensor. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0065] Embodiment 1

[0066] like Figure 1 As shown, an ink-jet printer circulating ink supply system includes: an ink cartridge 1, an ink supply tube 2, a print head 3 and an ink return tube 4. The ink supply tube 2 is connected between the ink cartridge 1 and the print head 3, and the ink return tube 4 is connected between the print head 3 and the ink cartridge 1. Along the flow direction of the ink, the ink supply tube 2 is provided with an ink supply pump 5, an ink supply pulse damper 6 and an ink filter 7 in sequence, and the ink return tube 4 is provided with an ink return pulse damper 8 and an ink return pump 9 in sequence. The ink supply tube 2 is provided with an ink supply pressure sensor 10, and the ink return tube 4 is provided with an ink return pressure sensor 11. The ink supply pressure sensor 10 is located downstream of the ink filter 7 and higher than the print head 3, and the ink return pressure sensor 11 is located upstream of the ink return pulse damper 8 and higher than the print head 3. The ink supply pressure sensor 10 and the ink return pressure sensor 11 are at the same height. Figure 2 As shown, the ink supply pump 5, the ink return pump 9, the ink supply pressure sensor 10 and the ink return pressure sensor 11 are electrically connected to the control board card respectively.

[0067] When the printer is working, the ink supply pump 5 works to deliver the ink in the ink cartridge 1 to the print head 3 through the ink supply pipe 2, and the nozzle of the print head 3 ejects the ink. The ink return pump 9 works to deliver the remaining ink in the print head 3 back to the ink cartridge 1 through the ink return pipe 4 to realize the circulating ink supply. Among them, the ink filter 7 is used to filter the ink output from the ink cartridge 1 to prevent clogging the print head 3. The ink supply pulse damper 6 is used to suppress the ink pressure fluctuation in the ink supply pipe 2, the ink supply pressure is stable, and the pressure value of the ink supply pipe 1 detected by the ink supply pressure sensor 10 is basically stable within a very small range. The ink supply pressure sensor 10 detects the ink pressure of the ink supply pipe 1 in real time and feeds it back to the control board. The ink return pulse damper 8 is used to suppress the ink pressure fluctuation in the ink return pipe 4, the ink return pressure is stable, and the pressure value of the ink return pipe 4 detected by the ink return pressure sensor 11 is basically stable within a very small range. The ink return pressure sensor 11 detects the ink pressure of the ink return pipe 4 in real time and feeds it back to the control board.

[0068] The ink cartridge 1 is connected to a raw material barrel 13 via a filling pipe 12, and a filling pump 14 is provided on the filling pipe 12; the ink cartridge 1 is provided with a liquid level sensor 18, and both the liquid level sensor 18 and the filling pump 14 are electrically connected to the control board. The liquid level sensor 18 detects the liquid level of the ink cartridge 1 in real time and feeds back to the control board. When the liquid level sensor 18 detects that the liquid level in the ink cartridge 1 is lower than the set liquid level, the control board sends a command to the filling pump 14, the filling pump 14 starts, and the ink in the raw material barrel 13 is transported to the ink cartridge 1 through the filling pipe 12. When the liquid level sensor 18 detects that the liquid level in the ink cartridge 1 is higher than the set liquid level, the control board sends a command to the filling pump 14 again, and the filling pump 14 stops working.

[0069] The ink supply pipe 2 between the ink supply pulse damper 6 and the ink filter 7 is connected to an air ink discharge pipeline 15, and the air ink discharge pipeline 15 is provided with an air filter 16 and an air valve 17, and the air valve 17 is electrically connected to the control board. When the circulating ink supply system stops working, the control board sends instructions to the ink supply pump 5 and the air valve 17, the ink supply pump 5 stops working, and the air valve 17 opens. At the same time, the timing module of the control board starts timing. Under the action of the ink return pump 9, the air flow quickly enters the circulating ink supply system from the air ink discharge pipeline 15. Under the action of the air flow, the ink in the ink supply pipe 2, the print head 3 and the ink return pipe 4 flows back to the ink cartridge 1, and the residual ink in the circulating ink supply system is cleaned up. When the timing module reaches the set time, the control board sends a command to the ink return pump 9, and the ink return pump 9 stops working.

[0070] Embodiment 2

[0071] When the circulating ink supply system is working, two issues need to be paid attention to: First, the pressure difference P between the ink supply pipe 2 and the ink return pipe 4 压差 First, the pressure difference is stable so that the inkjet can be stable; second, the negative pressure P at the nozzle is accurately controlled 负压 , no ink dripping phenomenon can occur.

[0072] like Figure 3 , Figure 4 and Figure 5 As shown in the figure, a method for regulating the online pressure of ink in an inkjet printer comprises the following steps:

[0073] S1, the system is powered on, the circulating ink supply system is started, and the printing mode is entered:

[0074] S2. According to the average flow rate of ink, calibrate the pressure difference P of the circulating ink supply system 压差 The lower and upper limits of the ink supply system 负压 The lower and upper limits, negative pressure feedback value-time MAP and differential pressure feedback value-time MAP;

[0075] Among them, P 压差 =P 供墨 -P 回墨 , P 供墨 is the pressure of ink in the ink supply tube, P 回墨 is the pressure of the ink in the ink return pipe, P 负压 =(P 供墨 +P 回墨 +2P 液高 ) / 2,P 负压 Indicates the negative pressure at the nozzle of the print head, P 液高 Indicates the pressure generated by the ink between the ink supply pressure sensor, ink return pressure sensor and the nozzle of the print head, P 液高 The value is constant;

[0076] S3, calculate P in the negative pressure PID loop 负压参数 ;

[0077] S4. Calculate I in the negative pressure PID loop 负压参数 ;

[0078] S5. Calculate D in the negative pressure PID loop 负压参数 ;

[0079] S6. Calculate P in the differential pressure PID loop 负压参数 ;

[0080] S7, calculate I in the differential pressure PID loop 负压参数 ;

[0081] S8, calculate D in the differential pressure PID loop 负压参数 ;

[0082] S9. End.

[0083] like Figure 6 As shown, step S3 further includes:

[0084] S31, set the I in the negative pressure PID loop 负压参数 Parameters and D 负压参数 Parameters are set to zero;

[0085] S32, input P 负压参数 ;

[0086] S33, observe the negative pressure feedback value-time MAP, if the current negative pressure feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, execute S34, if the current negative pressure feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, increase the current P 负压参数 And as a new P 负压参数 Return to execute S32;

[0087] S34, in the current P 负压参数 Under this condition, P is obtained by negative pressure feedback value-time MAP 负压 , if P 负压 Within the range of the lower and upper limits, P 负压参数标定 =P 负压参数 / 2,P 负压参数标定 This is the proportional parameter in the required negative pressure PID loop. If P 负压 If it is not within the range of the calibrated lower and upper limits, S9 is executed to check the operation of the circulating ink supply system to see if there is any external interference or equipment failure that causes abnormal deviation. The control board is electrically connected to the host computer, and the negative pressure feedback value-time MAP is displayed by the host computer.

[0088] like Figure 7 As shown, step S4 also includes:

[0089] S41, Input I 负压参数 ;

[0090] S42, observe the negative pressure feedback value-time MAP, if the current negative pressure feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, execute S43, if the current negative pressure feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, increase the current I 负压参数 And as a new I 负压参数 Return to execute S41, the value increased each time is fixed;

[0091] S43, in the current I 负压参数 Under this condition, P is obtained by negative pressure feedback value-time MAP 负压 , if P 负压 Within the range of the lower and upper limits, I 负压参数标定 =I 负压参数 / 2,P负压参数标定 This is the integral parameter in the required negative pressure PID loop. If P 负压 If it is not within the range of the calibrated lower and upper limits, execute S9 to check the operation of the circulating ink supply system to see if there is any external interference or equipment failure that causes abnormal deviation. The negative pressure feedback value-time MAP is displayed by the host computer.

[0092] like Figure 8 As shown, step S5 also includes:

[0093] S51, input D 负压参数 ;

[0094] S52, observe the negative pressure feedback value-time MAP, if the current negative pressure feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, execute S53, if the current negative pressure feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, increase the current D 负压参数 And as the new D 负压参数 Return to execute S51, the value increased each time is fixed;

[0095] S53, in the current D 负压参数 Under this condition, P is obtained by negative pressure feedback value-time MAP 负压 , if P 负压 Within the range of the lower and upper limits, D 负压参数标定 =D 负压参数 / 2,D 负压参数标定 This is the differential parameter in the negative pressure PID loop. If P 负压 If it is not within the range of the calibrated lower and upper limits, execute S9 to check the operation of the circulating ink supply system to see if there is any external interference or equipment failure that causes abnormal deviation. The negative pressure feedback value-time MAP is displayed by the host computer.

[0096] like Fig. 9 As shown, step S6 also includes:

[0097] S61, set the I in the pressure difference PID loop 压差参数 Parameters and D 压差参数 Parameters are set to zero;

[0098] S62, input P 压差参数 ;

[0099] S63, observe the pressure difference feedback value-time MAP, if the current pressure difference feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, execute S64, if the current pressure difference feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, increase the current P压差参数 And as a new P 压差参数 Return to execute S62;

[0100] S64, in the current P 压差参数 Under this condition, P is obtained by pressure difference feedback value-time MAP 压差 , if P 压差 Within the range of the lower and upper limits, P 压差参数标定 =P 压差参数 / 2,P 压差参数标定 This is the proportional parameter in the required differential pressure PID loop. If P 压差 If it is not within the range of the calibrated lower and upper limits, execute S9 to check the operation of the circulating ink supply system to see if there is any external interference or equipment failure that causes abnormal deviation. The differential pressure feedback value-time MAP is displayed by the host computer.

[0101] like Fig.10 As shown, step S7 also includes:

[0102] S71, Input I 压差参数 ;

[0103] S72, observe the pressure difference feedback value-time MAP, if the current pressure difference feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, execute S73, if the current pressure difference feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, increase the current I 压差参数 And as a new I 压差参数 Return to execute S71;

[0104] S73, in the current I 压差参数 Under this condition, P is obtained by pressure difference feedback value-time MAP 压差 , if P 压差 Within the range of the lower and upper limits, I 压差参数标定 =I 压差参数 / 2,I 压差参数标定 This is the integral parameter in the required differential pressure PID loop. If P 压差 If it is not within the range of the calibrated lower and upper limits, execute S9 to check the operation of the circulating ink supply system to see if there is any external interference or equipment failure that causes abnormal deviation. The differential pressure feedback value-time MAP is displayed by the host computer.

[0105] like Fig.11 As shown, step S8 also includes:

[0106] S81, Input D 压差参数 ;

[0107] S82, observe the negative pressure feedback value-time MAP. If the current negative pressure feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, execute S83. If the current negative pressure feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, increase the current D 压差参数 As the new D 压差参数 Return to execute S81;

[0108] S83, in the current D 压差参数 Under this condition, P is obtained by negative pressure feedback value-time MAP 负压 , if P 压差 Within the range of the lower and upper limits, D 压差参数标定 =D 压差参数 / 2, if P 压差 If it is not within the range of the calibrated lower and upper limits, execute S9 to check the operation of the circulating ink supply system to see if there is any external interference or equipment failure that causes abnormal deviation. The differential pressure feedback value-time MAP is displayed by the host computer.

[0109] In the negative pressure PID loop, through P 负压参数 (proportional parameter), I 负压参数 (integral parameter) and D 负压参数 (Differential parameter) regulates the speed of the ink supply pump 5 and the ink return pump 9 to ensure P 负压 If the value of is within the range of the lower and upper limits, then P 供墨 With P 回墨 The sum is within a certain range; in the differential pressure PID loop, through P 压差参数 (proportional parameter), I 压差参数 (integral parameter) and D 压差参数 (Differential parameter) regulates the speed of the ink supply pump 5 and the ink return pump 9 to ensure P 压差 If the value of is within the range of the lower and upper limits, then P 供墨 With P 回墨 The difference is within a certain range; then combined with P 供墨 With P 回墨 The sum of P 供墨 With P 回墨 The difference can be obtained as P 供墨 , P 回墨 The value of is used to obtain the corresponding rotation speeds of the ink supply pump 5 and the ink return pump 9 to meet the printing requirements.

[0110] The above are examples of the best implementation of the present invention, and the parts not described in detail are common knowledge of ordinary technicians in the field. The protection scope of the present invention shall be based on the content of the claims, and any equivalent transformation based on the technical enlightenment of the present invention is also within the protection scope of the present invention.

Claims

1. An inkjet printer circulating ink supply system, comprising: An ink cartridge, an ink supply tube, a print head and an ink return tube, the ink supply tube being connected between the ink cartridge and the print head, the ink return tube being connected between the print head and the ink cartridge, along the flow direction of the ink, the ink supply tube is sequentially provided with an ink supply pump, an ink supply pulse damper and an ink filter, the ink return tube is sequentially provided with an ink return pulse damper and an ink return pump, characterized in that an ink supply pressure sensor is provided on the ink supply tube, an ink return tube is provided with an ink return pressure sensor, the ink supply pressure sensor is located downstream of the ink filter and higher than the print head, the ink return pressure sensor is located upstream of the ink return pulse damper and higher than the print head, and the ink supply pressure sensor and the ink return pressure sensor are at the same height.

2. The ink circulation supply system for an inkjet printer as claimed in claim 1, characterized in that: The ink cartridge is connected to a raw material barrel via a filling pipe, and the filling pipe is provided with a filling pump; The ink cartridge is provided with a liquid level sensor. When the liquid level in the ink cartridge is lower than a set liquid level, the filling pump starts, and when the liquid level in the ink cartridge is higher than the set liquid level, the filling pump stops working.

3. The ink circulation supply system for an inkjet printer as claimed in claim 1, characterized in that: The ink supply pipe between the ink supply pulse damper and the ink filter is connected with an air ink discharge pipeline, and the air ink discharge pipeline is provided with an air filter and an air valve.

4. A method for regulating ink pressure online in an inkjet printer, characterized in that: The following steps are involved: S1, the system is powered on, the circulating ink supply system is started, and the printing mode is entered: S2. According to the average flow rate of ink, calibrate the pressure difference P of the circulating ink supply system 压差 The lower and upper limits of the ink supply system 负压 The lower and upper limits, negative pressure feedback value-time MAP and differential pressure feedback value-time MAP; P 压差 =P 供墨 -P 回墨 , P 供墨 is the pressure of the ink in the ink supply tube, P 回墨 is the pressure of the ink in the ink return pipe, P 负压 =(P 供墨 +P 回墨 +2P 液高 ) / 2,P 负压 represents the negative pressure at the nozzle of the print head, P 液高 Indicates the pressure generated by the ink between the ink supply pressure sensor or the ink return pressure sensor and the nozzle of the print head; S3, calculate P in the negative pressure PID loop 负压参数 ; S4. Calculate I in the negative pressure PID loop 负压参数 ; S5. Calculate D in the negative pressure PID loop 负压参数 ; S6. Calculate P in the differential pressure PID loop 负压参数 ; S7, calculate I in the differential pressure PID loop 负压参数 ; S8, calculate D in the differential pressure PID loop 负压参数 ; S9. End.

5. The method for controlling the ink pressure of an inkjet printer as claimed in claim 4, characterized in that: Step S3 also includes: S31, set the I in the negative pressure PID loop 负压参数 Parameters and D 负压参数 Parameters are set to zero; S32, input P 负压参数 ; S33, observe the negative pressure feedback value-time MAP, if the current negative pressure feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, execute S34, if the current negative pressure feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, increase the current P 负压参数 And as a new P 负压参数 Return to execute S32; S34, in the current P 负压参数 Under this condition, P is obtained by negative pressure feedback value-time MAP 负压 , if P 负压 Within the range of the lower and upper limits, P 负压参数标定 =P 负压参数 / 2, if P 负压 If it is not within the calibrated lower limit and upper limit range, execute S9.

6. The method for controlling the ink pressure of an inkjet printer as claimed in claim 4, characterized in that: Step S4 also includes: S41, Input I 负压参数 ; S42, observe the negative pressure feedback value-time MAP, if the current negative pressure feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, execute S43, if the current negative pressure feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, increase the current I 负压参数 And as a new I 负压参数 Return to execute S41; S43, in the current I 负压参数 Under this condition, P is obtained by negative pressure feedback value-time MAP 负压 , if P 负压 Within the range of the lower and upper limits, I 负压参数标定 =I 负压参数 / 2, if P 负压 If it is not within the calibrated lower limit and upper limit range, execute S9.

7. The method for controlling the ink pressure of an inkjet printer as claimed in claim 4, characterized in that: Step S5 also includes: S51, input D 负压参数 ; S52, observe the negative pressure feedback value-time MAP, if the current negative pressure feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, execute S53, if the current negative pressure feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated negative pressure feedback value-time MAP, increase the current D 负压参数 And as the new D 负压参数 Return to execute S51; S53, in the current D 负压参数 Under this condition, P is obtained by negative pressure feedback value-time MAP 负压 , if P 负压 Within the range of the lower and upper limits, D 负压参数标定 =D 负压参数 / 2, if P 负压 If it is not within the calibrated lower limit and upper limit range, execute S9.

8. The method for controlling the ink pressure of an inkjet printer as claimed in claim 4, characterized in that: Step S6 also includes: S61, set the I in the pressure difference PID loop 压差参数 Parameters and D 压差参数 Parameters are set to zero; S62, input P 压差参数 ; S63, observe the pressure difference feedback value-time MAP, if the current pressure difference feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, execute S64, if the current pressure difference feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, increase the current P 压差参数 And as a new P 压差参数 Return to execute S62; S64, in the current P 压差参数 Under this condition, P is obtained by pressure difference feedback value-time MAP 压差 , if P 压差 Within the range of the lower and upper limits, P 压差参数标定 =P 压差参数 / 2, if P 压差 If it is not within the calibrated lower limit and upper limit range, execute S9.

9. The method for controlling the ink pressure of an inkjet printer as claimed in claim 4, characterized in that: Step S7 also includes: S71, Input I 压差参数 ; S72, observe the pressure difference feedback value-time MAP, if the current pressure difference feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, execute S73, if the current pressure difference feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, increase the current I 压差参数 And as a new I 压差参数 Return to execute S71; S73, in the current I 压差参数 Under this condition, P is obtained by pressure difference feedback value-time MAP 压差 , if P 压差 Within the range of the lower and upper limits, I 压差参数标定 =I 压差参数 / 2, if P 压差 If it is not within the calibrated lower limit and upper limit range, execute S9.

10. The method for controlling the ink pressure of an inkjet printer as claimed in claim 4, characterized in that: Step S8 also includes: S81, Input D 压差参数 ; S82, observe the negative pressure feedback value-time MAP. If the current negative pressure feedback value-time MAP begins to oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, execute S83. If the current negative pressure feedback value-time MAP does not oscillate with equal amplitude relative to the calibrated pressure difference feedback value-time MAP, increase the current D 压差参数 As the new D 压差参数 Return to execute S81; S83, in the current D 压差参数 Under this condition, P is obtained by negative pressure feedback value-time MAP 负压 , if P 负压 Within the range of the lower and upper limits, D 压差参数标定 =D 压差参数 / 2, if P 负压 If it is not within the calibrated lower limit and upper limit range, execute S9.

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