JP3200304B2 - Liquid remaining amount detection device in tank and ink jet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a remaining amount of liquid in a tank, for example, for detecting a remaining amount of ink in an ink tank, and an ink jet recording apparatus provided with the detecting device.

[0002]

2. Description of the Related Art Conventionally, there are the following types of detection devices for detecting the presence or absence of the remaining amount of ink in an ink tank of an ink jet device.

FIG. 18 shows a detection apparatus of a system for detecting light by entering light into a transparent ink tank. 7 is 4 in total
Two translucent ink tanks, 1 is a carriage on which each ink tank 7 is mounted, 1a is a calibration reflector provided on the carriage 1, and 81 is four types of ink contained in each ink tank 7. . An ink jet recording head capable of discharging ink 81 in each ink tank 7 is mounted on the carriage 1. The carriage 1 scans in the left and right direction in FIG. 18 while the recording head discharges the ink 81. To record an image on a recording medium such as paper.

6c is an LED (light emitting diode) as a light emitting portion, 6d is a phototransistor as a light receiving portion, 87 is an LED current limiting variable resistor, 89 is an LED on / off transistor, and 80 is a phototransistor load resistor. , 82 are A / D converters, 83 is a CPU, 84
Is an LED on / off signal, and 86 is a phototransistor raw output voltage.

LED on / off signal 8 from CPU 82
4 turns on the transistor 6d.
The ED 6c lights up. When the ink 81 is present in the transparent ink tank 7, since light is not reflected at the boundary between the ink 81 and the inner surface of the ink tank 7, the difference between the bright voltage and the dark voltage of the output voltage 86 from the phototransistor 6d is obtained. That is, the output voltage 86 (bright voltage) when the LED 81 is on and L
The difference from the output voltage 86 (dark voltage) when the ED 81 is off (hereinafter, simply referred to as “the output of the phototransistor 6d”) is small. On the other hand, when there is no ink 81 in the ink tank 7, the light is reflected at the boundary between the ink 81 and the ink tank 7, so that the output of the phototransistor 6d increases. Therefore, the presence / absence of the ink 81 can be detected by detecting the output voltage 86 with the A / D converter 82.

Next, a method of detecting the presence or absence of ink will be described with reference to the flowchart of FIG.

Step S61: LED on ink tank 7
The carriage 1 is moved by a carriage moving mechanism (not shown) so that the light from 6c is irradiated.

Step S62: The output voltage 86 is detected while the LED 6c is off.

Voff: Output voltage (dark voltage) when LED is off Step S63: Output voltage 86 when LED 6c is on
Is detected.

Von: Output voltage (bright voltage) in LED ON state Step S64: Output is calculated.

V: Output (= Voff-Von) Step S65: It is checked whether the output V is higher than a predetermined comparison reference voltage. If smaller, it is determined that there is ink, and if larger, it is determined that there is no ink.

Vth: Output threshold value for judging presence / absence of ink Step S66: Processing such as display according to the result of detection of presence / absence of ink is performed.

As the LED 6c and the phototransistor 6d, a photointerrupter 6 in which a light emitting and receiving unit is housed in one package is usually used. Generally, the life of the photointerrupter 6 is shorter than the life of the printer. Therefore, the LED 6c is turned on by the LED on / off transistor 89 only when the presence or absence of ink is detected, so that the energization time of the photointerrupter 6 is reduced. .

Generally, the photo interrupter 6
Since both the light emission amount of the LED 6c and the sensitivity of the phototransistor 6d vary, the combined photocurrent output characteristics of the LED 6c and the phototransistor 6d have a difference of about 2 to 4 times at the upper and lower limits. For this reason, when used as an ink presence / absence detection device, adjustment for keeping the output of the photointerrupter 6 within a certain range, that is, so-called calibration is required.

As an example of the calibration, there is the following method. That is, as shown in FIG. 18, the carriage 1 is provided with a calibration reflector 1a having a certain reference reflectance. Then, the carriage 1 is set so that the light from the LED 6c is applied to the reflecting portion 1a.
Is shifted by a carriage moving mechanism (not shown),
The reflected light from a is detected by the phototransistor 6d.
The LED current limiting variable resistor 87 is adjusted so that the output of the phototransistor 6d at this time falls within a certain range.

[0016]

However, the above-mentioned prior art has the following problems.

The task of calibrating the output of the photointerrupter 6 by adjusting the LED current limiting variable resistor 87 is difficult to automate and increases man-hours.

In addition, if the adjustment error of the photointerrupter output due to the above operation is large, there is a risk of erroneous detection of the presence or absence of ink, so that accurate adjustment is required and the number of steps further increases.

Since the above operation is performed in the printer adjustment process in the factory, if there is a change in the light emission amount of the LED 5 with time or an output change due to contamination of the photo interrupter 6 after the shipment from the factory, the output of the photo interrupter changes. As a result, accurate detection of ink presence cannot be performed.

An object of the present invention is to provide an apparatus for detecting the remaining amount of liquid in a tank and an ink jet recording apparatus capable of automatically adjusting a means for optically detecting the remaining amount of liquid such as ink. .

[0021]

According to the present invention, there is provided a device for detecting a remaining amount of liquid in a tank, which irradiates light from a light emitting portion through a light-transmitting wall of an ink tank having an ink absorber therein, and the wall and the ink. By detecting means for detecting the amount of reflected light at the boundary with the absorber, in a liquid remaining amount detection device in the tank for detecting the remaining amount of liquid in the tank, the drive signal of the light emitting unit is pulse width modulated, It is characterized by comprising adjusting means capable of adjusting the light emission amount of the light emitting section.

An ink jet recording apparatus according to the present invention comprises an ink jet recording head for discharging ink, a translucent ink tank containing ink to be supplied to the ink jet recording head, and a relative position between the ink jet recording head and a recording medium. Moving means for irradiating light from a light emitting unit through a wall surface of the ink tank, and detecting a reflected light amount at a boundary portion between the wall surface and the ink absorber; and Adjusting means for adjusting the light emission amount of the light emitting unit by pulse width modulation of the drive signal of the unit.

[0023]

According to the present invention, a drive signal of a light emitting unit such as an LED is transmitted by PW
By performing the M control and changing the light emission duty ratio of the light emitting unit, the light emission amount of the light emitting unit can be automatically adjusted.

For example, an input signal to an LED on / off transistor that controls on / off of an LED as a light emitting unit is a PWM signal, and the LED is turned on / off at an interval sufficiently shorter than a response time of a phototransistor as a light receiving unit. Turn off the LED and change the light emission duty ratio to change the apparent LE
Make D light quantity variable. As a result, the calibration can be automatically performed. For example, if a sequence such as performing the calibration operation immediately after the power is turned on is added to the software, the calibration can be performed even after the product is shipped to the market.

At the time of calibration, the carriage is displaced so that light from the LED is irradiated to the calibration reflecting section, and the reflected light is detected by the phototransistor. At this time, the duty ratio of the PWM signal is adjusted so that the output of the phototransistor falls within a certain range. At this time, the duty ratio is set using Expression 1.

[0026]

[Expression 1] Duty ← Duty * Vtarget / V (Equation 1) where Duty is the duty ratio of the PWM signal VTarget is the output target value at the time of calibration V: output the output is within a certain range with respect to the output target value at the time of calibration If so, the duty ratio at that time is stored in the nonvolatile storage element as the duty ratio at the time of detecting the presence or absence of ink, and the calibration is completed. At this time, the output at the time of detecting the presence or absence of ink is corrected by one of the following methods.

In the first method, the final output at the time of calibration is stored as a parameter for calculating an output ratio in a nonvolatile storage element, and the presence or absence of ink is determined using the magnitude of the output ratio obtained by equation (2). Do.

[0028]

A = V / Vcal (Equation 2) where Vcal: Output ratio calculation parameter A: Output ratio In the second method, a correction coefficient is obtained by using Expression 3 and stored in the nonvolatile storage element at the time of calibration. Keep it. At the time of ink presence / absence detection, the presence / absence of ink is determined by a value obtained by multiplying the output by the correction coefficient.

[0029]

K = V / VTarget (Equation 3) K: Correction coefficient In both the first method and the second method, accurate determination of the presence or absence of ink even if the output during calibration deviates from the output target value. It becomes possible.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG.
FIG. 4 is a schematic perspective view of an embodiment of an ink jet recording apparatus in which the present invention is applied to the ink tank and the ink jet recording apparatus proposed in No. 43.

In FIG. 4, reference numeral 8 denotes a chassis to which various components are attached. Reference numeral 9 denotes a paper feed roller provided in the longitudinal direction of the apparatus and for conveying a recording paper (not shown). Reference numeral 10 denotes a paper feed roller provided in parallel with the paper feed roller 9 to feed the recording paper. Is a pinch roller for pressing the sheet. Reference numeral 2 denotes a guide shaft which is provided in parallel with the paper feed roller 9 and reference numeral 11 denotes a scale portion of a magnetic linear encoder which is provided in parallel with the guide shaft 2.

Reference numeral 1 denotes a carriage that moves along the guide shaft 2. Reference numeral 12 denotes a head cover for fixing an ink jet head (not shown) to the carriage 1, and 13 denotes a flexible substrate, which sends a recording data signal from the apparatus control unit to the ink jet recording head mounted on the carriage 1, and An output signal from a sensor (not shown) of a magnetic linear encoder provided in the device can be sent to the device control unit.

3 is provided in parallel with the guide shaft 2,
A support shaft that maintains the posture of the carriage 1 that is provided rotatably about the guide shaft 2,
Reference numeral 14 denotes a carriage motor for scanning the carriage 1 along the guide shaft 2, and reference numeral 15 denotes a timing belt for transmitting the driving force of the carriage motor 14 to the carriage 1. Reference numeral 16 denotes a transmission type photo interrupter provided in the scanning area of the carriage 1 for setting a reference position in the scanning of the carriage 1.

Reference numeral 17 denotes a suction cap used to prevent ejection failure of the ink jet recording head or to recover them, and reference numeral 18 denotes an inside of an ejection port (hereinafter also referred to as a nozzle) of the ink jet recording head when the ink jet recording head is on standby. It is a protective cap for preventing the drying of the water.
5 is a paper position switching lever provided on the carriage 1 for switching the clearance between the recording paper and the ink jet head according to the thickness of the recording paper.
Denotes a reflective photo-interrupter as an ink sensor provided near the home position of the carriage 1;
Reference numeral 9 denotes a preliminary ejection hole for receiving ink droplets at the time of performing preliminary ejection prior to recording such as printing in order to prevent clogging of the nozzle portion of the ink jet recording head.

FIG. 1 is a side view of the carriage 1, FIG. 2 is a view showing a state in which the ink tank is mounted in FIG. 1, and FIG. 3 is a view of the carriage shown in FIG. It is a figure showing a state.

The positional relationship between the carriage 1 and the photo-interrupter 6 and the principle of detection by the photo-interrupter 6 will be described with reference to FIGS. 1, 2 and 3.

In FIGS. 1, 2 and 3, reference numeral 1b denotes a hole provided on the bottom of the carriage 1 for transmitting light from the photo interrupter 6.

In FIG. 2, reference numeral 21 denotes a nozzle 2 at the tip thereof.
2 is a print head for performing printing by discharging ink from the print head 2. Reference numeral 7 denotes an ink tank mounted on the carriage 1, 7a denotes an absorber as a negative pressure generating member provided in the ink tank 7, and 7b denotes a connection between the absorber 7a in the ink tank and an outer wall 7e of the ink tank 7. A boundary portion 7c is an ink storage portion (hereinafter also referred to as a raw ink storage portion) for storing the ink in the ink tank 7 as it is (hereinafter, also referred to as a raw ink) without being mixed with other members, and 7d is a raw ink storage portion. This is the boundary between the raw ink in the ink tank 7 and the outer wall 7e of the ink tank. The material of the ink tank 7 is transparent to the detection light of the photo interrupter 6 such as transparent plastic. Reference numeral 24 denotes a supply port for supplying ink to the print head 21, and reference numeral 28 denotes an air communication port for performing gas-liquid exchange accompanying consumption of ink.

The head 21 and the ink tank 7 are integrally mounted on the carriage 1, and are scanned in the direction perpendicular to the plane of FIG.

FIG. 5 is a plan view of the substrate on which the photo interrupter 6 is mounted, where 6c denotes a light emitting unit and 6d denotes a light receiving unit. In FIG. 1, reference numeral 6a denotes light emitted from the light emitting unit 6c, and 6b denotes an optical path that is reflected and returned (hereinafter, also referred to as a return optical path), and is received by the light receiving unit 6d shown in FIG. . This optical path may be a reflection surface in the plane of FIG. 1 as shown in FIG. 1 or a reflection plane perpendicular to the plane of FIG. However, when the posture of the carriage 1 is largely changed by the operation of the above-described paper position switching lever 5, the influence of the posture difference is less likely to be obtained by setting the reflection surface in the direction perpendicular to the paper surface of FIG. Also, in FIG. 1, this optical path is drawn as a simple straight line so as not to complicate the drawing, but is actually a light beam having a certain spread.

The photo-interrupter 6 is installed so as to irradiate a detection light to a portion of the absorber 7a in the ink tank 7 slightly closer to the raw ink storage portion 7c. This position affects the remaining number of printable sheets at the time of detection as described later. Regarding the position of the photo-interrupter 6 in the height direction, it is desirable to arrange the photo-interrupter 6 such that the boundary 7b between the wall surface 7e of the ink tank 7 and the absorber 7a comes near the focal position of the photo-interrupter 6. If the detection light deviates from the focus position of the photo interrupter 6, the spread of the detection light increases, and the S / N of the detection is lowered due to the light reflected and scattered at the edge of the hole 1b of the carriage 1 or the like. .

In this embodiment, as shown in FIG. 4, a color ink jet recording apparatus configured to be capable of discharging a plurality of different color inks will be described as an example.

A plurality of inks of different colors are stored in the corresponding ink tanks 7 and the carriage 1
Mounted on top. Therefore, the ink absorbed by the absorber 7a is one of the four colors of black, cyan, magenta, and yellow that are usually used in a color printer. The ink is supplied from the absorber 7a to the supply port 24 and the flow path 3 in the head 21.
0, the thermal energy is applied by a heat generating means (hereinafter, also referred to as a heater) 31 provided in the nozzle 22 as an ejecting means. Discharge from outlet. Printing such as printing is performed by the ink ejected in this way adhering to a medium such as paper.

As described above, the photo interrupter 6 is formed by integrating the LED, which is the light emitting element 6c of the light source, with the light receiving element 6d. This LED emits infrared light that is transparent to any of the four color inks, and the light receiving element 6d also has sufficient sensitivity to the wavelength of the LED.

The photo-interrupter 6 is provided separately from the carriage 1, and irradiates infrared light to the bottom surface of the absorber 7a through a hole 1b formed in the carriage 1 and a wall 7e of the transparent ink tank 7, and reflects the light. The detected light is detected by the light receiving element 6d. By disposing the photo-interrupter 6 as a detection system separately from the carriage in this way, a power supply line and a signal line from the main body of the recording apparatus to the carriage 1 as a movable portion become unnecessary, and the configuration is reduced. Simplification can be achieved and cost reduction can be achieved.

FIG. 6 is an enlarged view of the vicinity where the photointerrupter 6 irradiates light to the lower surface of the absorber 7a when there is sufficient ink in the ink tank 7, and FIG. 7 shows the case where the ink is exhausted at the same position. FIG. FIG. 8 is a graph showing a change in the output of the light receiving unit 6d of the photo interrupter 6 according to the remaining ink amount.

Next, the principle of detecting the remaining amount of ink according to the present invention will be described.

In general, Fresnel's formula indicating the amplitude reflectance of light at the interface between the media 1 and 2 having different refractive indices is:

[0050]

(Equation 4)

In this embodiment, if the light from the light emitting section 6c of the photo interrupter 6 is incident on the ink tank 7 at an angle close to the vertical, it can be considered that cos θ = 1, and the amplitude reflectance In order to describe by energy reflectance instead of squaring,

[0052]

(Equation 5)

Is as follows.

First, when there is sufficient ink in the ink tank 7, the gap between the wall 7e of the ink tank 7 and the absorber 7a is filled with ink as shown in FIG. The ink tank 7 and the absorber 7a are plastic and have a refractive index of about 1.5,
Since the refractive index of the ink is about 1.4, the reflectance on the inner wall 7e of the ink tank 7 and the surface of the absorber 7a is about 0.1 from the above equation.
There is only%.

Next, as the ink is consumed, air enters into the gap between the wall 7e of the ink tank 7 and the absorber 7a through the atmosphere communication port 8 in FIG. 6, as shown in FIG. The reflectance on the surface of the tank inner wall 7e and the surface of the absorber 7a when the ink is exhausted is about 4%. That is, when the ink runs out, the amount of reflected light increases about 40 times. (However, in reality, the output difference is not detected due to the influence of light other than the reflected light of the boundary portion 7c such as the reflected light from the outer bottom surface of the ink tank 7 or the electric noise.) Even if detection is performed at the boundary portion 7d between the raw ink storage portion 7c and the raw ink storage portion 7c, a difference in reflectance occurs. However, as compared with that case, there is the following difference in the number of reflection elements.

[0056]

[Table 1]

As described above, when the detection is performed by the absorber 7a, the number of the reflection elements is three times as large, and the amount of reflected light itself is increased by that amount, and the detection which is strong against the above-described noise can be performed.

As shown in FIG. 7, air that has entered between the absorber 7a and the ink tank 7 often exists as a number of fine bubbles as it passes through the absorber 7a. The reflected light amount further increases due to the light scattering effect.

As described above, these reflectances are represented by cos θ =
The value is 1 in the case of 1. However, in other cases, there is a considerable difference in reflectance with and without ink. In either case, a large output difference occurs in the light receiving portion 6d of the photointerrupter 6 in accordance with the reflectance difference, so that the presence or absence of ink in the ink tank 7 can be detected based on the output difference.

Actually, the area where the photo interrupter 6 irradiates light is not a point even at its focal position.
It has a certain size, and the output of the photointerrupter 6 changes continuously as the ink gradually escapes from that area.

In FIG. 8, the horizontal axis represents the remaining number of printable sheets from the time when the ink is exhausted to the time when the ink is not ejected. Based on this output change curve, when the threshold level is exceeded (in FIG. 8, the remaining amount capable of printing about 15 remaining sheets is set as the threshold), the amount of ink in the ink tank 7 decreases. Judge that Then, by illuminating a warning display LED or the like on the display panel of the ink jet recording apparatus main body, it is possible to inform the user that the remaining amount of ink is low.

The remaining number of sheets when displaying that the remaining ink amount is low can be increased or decreased by changing the threshold level. However, as can be seen from FIG. 8, it is difficult to display the number before the output rises (about 30 remaining in FIG. 8). In response to this, the number of printable sheets when the output rises can be changed by changing the position where the photo interrupter 6 performs detection. In this way, a warning can be issued with a desired remaining number.

Alternatively, the printing operation may be stopped instead of issuing a warning or simultaneously with the warning in order to surely prevent a printing failure from occurring. In this case, there is an effect that a stronger warning is given by temporarily stopping.

As described in detail above, according to this embodiment,
The reflected light of the light emitted from the light emitting unit 6c is detected by the light receiving unit 6d with respect to the ink tank 7 in which the absorber 7a is disposed as a negative pressure generating member, and the remaining ink in the ink tank 7 is detected based on the output level. It can be detected that the amount has become smaller than the predetermined amount. In other words, by detecting a change in the light reflectance according to the state of the remaining amount of ink, it is possible to detect that the remaining amount of ink has decreased.

At this time, the absorber 7a functions as a negative pressure control member for controlling the negative pressure of the ink supplied from the ink tank 7, and a reflection control member for controlling the amount of light reflected by the light emitting section 6c. , It is possible to accurately detect a decrease in the remaining amount of ink in the ink tank 7 in which the absorber 7a is disposed.

This embodiment is applied to a color printer as described above, and four ink tanks 7 are arranged side by side in correspondence with four colors. Therefore, the carriage 1
, The ink tanks 7 of the respective colors are sequentially made to face the photointerrupter 6, and the remaining ink amount in each ink tank 7 is detected. Since it is necessary to individually track output changes in the ink tanks 7 of each color, a memory means is provided for the change. In this case, it is desirable that the indication that the remaining amount of ink is low is displayed separately for each of the four colors, but it is simply said that one of the colors has been reduced simply because the display panel of the ink jet recording apparatus main body becomes complicated. Only the display may be performed.

According to the configuration described above, the remaining amount of ink in each of the four color ink tanks can be accurately detected by one detection system with respect to the ink tank containing the ink absorber of the color ink jet recording apparatus.

In this embodiment, the detection is performed from the bottom of the ink tank 7. However, the present invention is not limited to the configuration in which the detection is performed from the bottom surface of the ink tank 7, and the detection may be performed from the side surface or the upper surface.

However, for the following reason, the ink tank 7
It is more desirable to perform detection from the bottom surface.

The density distribution of the absorber 7a is usually not uniform, and the ink is spotted as the ink runs out. Therefore, even if there is still ink in the surroundings, only the place where the photo interrupter 6 happens to detect the ink is exhausted first, or vice versa. The number of sheets varies, and in the worst case, the ink may run out without warning.

However, since the bottom of the ink tank 7 is apt to collect ink by the action of gravity, the ink
The influence of the density distribution of a is reduced. Therefore, by performing detection from the bottom surface of the ink tank 7, it is possible to detect the remaining amount of ink with high accuracy.

FIG. 9 is a schematic diagram showing the configuration of an ink presence / absence detecting apparatus according to the present embodiment applied to a color ink jet recording apparatus.

Reference numeral 7 denotes a transparent ink tank, 1 denotes a carriage on which the ink tank 7 is mounted, 1a denotes a calibration reflector provided on the carriage 1, 81 denotes ink, 6
c is an LED as a light emitting unit, 6d is a phototransistor as a light receiving unit, 87 is an LED current limiting resistor, 89 is L
ED on / off transistor, 80 is a phototransistor load resistance, 91 is a low-pass filter, 82 is an A / D
Converter, 83 is a CPU, 95 is a PWM signal for LED on / off, 86 is a phototransistor raw output voltage, 9
0 is the output voltage after the low-pass filter.

FIG. 10 is a timing chart showing the relationship among the PWM signal 95, the duty ratio, the on / off state of the LED, the raw output voltage 86 from the phototransistor 6d, and the output voltage 90 after the low-pass filter 91. Here, TP: PWM cycle TL: LED on time TD: Time until measurement after LED on Voff: Output voltage in LED off state Von: Output voltage in LED on state V: Output duty ratio = TL / TP.

In response to the PWM signal 95 from the CPU 83, the transistor 89 is turned on / off at a period of several kHz to several hundreds kHz to turn on the LED 6c. When the ink 4 is present in the transparent ink tank 7, as described above, light is not reflected at the boundary between the ink 81 and the transparent ink tank 7, so that the output from the phototransistor 6d is small. Since light is reflected at the boundary between the ink 81 and the transparent ink tank 7, the output increases. Therefore, the presence / absence of ink can be detected by detecting the output voltage 90 with the A / D converter 82.
The low-pass filter 91 is for removing a periodic component of the PWM signal 95 superimposed on the raw output voltage 86.

The calibration method will be described with reference to the flowchart of FIG.

Step S1: The carriage 1 is moved by a carriage moving mechanism (not shown) so that the light from the LED 6c is applied to the calibration reflecting section 1a.

Step S2: The output voltage 90 is detected with the LED off.

Voff: output voltage in the LED off state Step S3: It is checked whether Voff is higher than a certain voltage. If it is smaller, it is considered that the leakage current of the phototransistor is larger than the standard, and is set to NG.

Vmax0: output voltage (Vcc−maximum leakage current × times) obtained from the maximum leakage current of the phototransistor
(Current limiting resistance value) Step S4: The duty ratio stored in the nonvolatile RAM is set as the initial duty ratio of the PWM signal 95.

Duty: Duty ratio of the PWM signal D0: Duty ratio stored in the non-volatile RAM (duty ratio used when detecting the presence or absence of ink) Step S5: Set the duty ratio of the PWM signal 95.

Step S6: The output voltage 90 is detected while the LED is on.

Von: Output voltage in LED off state Step S7: Output is calculated.

V: Output (Voff-Von) Step S8: It is checked whether the output V is higher than a certain voltage. If it is smaller, it is regarded as a failure or disconnection of the LED 6c or the phototransistor 6d, and is determined to be NG.

Vmin0: threshold value for failure determination Step S9: It is checked whether the output V is within a certain voltage range. If it is, the PWM signal 95
It is assumed that the duty ratio has been adjusted, and the process exits the loop.

Vmin1: output adjustment lower limit value Vmax1: output adjustment upper limit value Step S10: The duty ratio of the next PWM signal 95 is calculated from the ratio between the output V and the output target value.

Next duty ratio Duty ← Current duty ratio Duty × (Output target value Vtarget / Current output V) Vtarget: Output target value during calibration Step S11: It is checked whether the duty ratio is within a certain range. If not, LED6
c and the phototransistor 6d do not satisfy the standard, or the reflector 1a for calibration or the LED 6c or the phototransistor 6d
Is judged to be NG because it is considered that the sample is dirty and the reflectance changes and accurate detection cannot be performed.

Dmin: lower limit of duty ratio adjustment Dmax: upper limit of duty ratio adjustment Step S12: It is checked whether the number of retries in the duty ratio adjustment loop is too large. If not, the process returns to step S5. If exceeded, it will be NG. Step S13: The duty ratio used at the time of detecting the presence or absence of ink is set as the duty ratio calibrated this time. The final output in the current calibration is used as an output ratio calculation parameter.

Vcal: Output ratio calculation parameter Step S14: The duty ratio and the output ratio calculation parameter used at the time of ink presence / absence detection are stored in a nonvolatile storage element (not shown).

Step S15: The state of the ink detection device is set.

Next, a method of detecting the presence or absence of ink will be described with reference to the flowchart of FIG.

Step S21: LED on ink tank 7
The carriage 1 is moved by a carriage moving mechanism (not shown) so that the light from 6c is irradiated.

Step S22: The output voltage 90 is detected with the LED off.

Voff: output voltage in the LED off state Step S23: The duty ratio stored in the nonvolatile RAM is set as the initial duty ratio of the PWM signal 95.

Duty: Duty ratio of PWM signal D0: Duty ratio stored in nonvolatile RAM (duty ratio used for detecting presence / absence of ink) Step S24: Sets duty ratio of PWM signal 95.

Step S25: The output voltage 90 is detected while the LED is on.

Von: output voltage of LED on state Step S26: Output is calculated.

V: Output (= Voff-Von) Step S27: Output ratio is calculated.

A: Output ratio (= V / Vcal) Step S28: It is checked whether the output ratio A is larger than a certain value. If smaller, it is determined that there is ink, and if larger, it is determined that there is no ink.

Ath: threshold of output ratio for judging presence / absence of ink Step S29: The result of detection of presence / absence of ink is set.

By calculating the ratio of the output at the time of detecting the presence or absence of ink to the output at the time of calibration, it is possible to cancel the change over time of the light emission amount of the LED 6c and the output change due to the contamination of the photo interrupter 6. Further, since the output adjustment lower limit value and the upper limit value can be set wider than the calibration target output value, the number of calibration loops can be reduced.

(Second Embodiment) FIG. 13 is a flowchart for explaining a calibration method according to a second embodiment of the present invention. The circuit configuration is the same as in the first embodiment. Steps S31 to S42 are the same as steps S1 to S12 in FIG. 11 of the first embodiment described above, and thus the description will be started from step S43.

Step S43: The duty ratio used at the time of detecting the presence or absence of ink is set as the duty ratio calibrated this time. Further, a correction coefficient is calculated.

K: Correction coefficient (= Vtarget / V) Step S44: The duty ratio and the correction coefficient used at the time of detecting the presence or absence of ink are stored in a non-volatile RAM (not shown).

Step S45: The state of the ink detection device is set.

Next, a method for detecting the presence or absence of ink will be described with reference to the flowchart of FIG. Steps S51 to S56
Until step S2 of the ink presence detection method of the first embodiment
Steps S57 will be described since they are the same as steps 1-26.

Step S57: The output is obtained by multiplying the output by a correction coefficient.

Step S58: It is checked whether or not the output V is larger than a certain value. If smaller, it is determined that there is ink, and if larger, it is determined that there is no ink.

Vth: threshold value of output ratio for judging presence / absence of ink Step S59: The result of detection of presence / absence of ink is set.

By multiplying the output at the time of detecting the presence or absence of ink by the correction coefficient, the output at the time of detecting the presence or absence of ink when the output at the time of calibration matches the target value at the time of calibration can be calculated. An output change due to contamination of the interrupter 6 can be canceled.
Further, since the output adjustment lower limit value and the upper limit value can be set wider than the calibration target output value, the number of calibration loops can be reduced. In this embodiment, the output can be corrected only by multiplying the output at the time of detecting the presence or absence of ink by the correction coefficient, so that the division as in the first embodiment is unnecessary, and the load on software is reduced.

(Third Embodiment) As described above, in the configuration shown in the first embodiment, it may be difficult to perform accurate detection due to the non-uniformity of the density of the absorber 7a. FIG. 15 shows a third embodiment of the present invention in which another measure for the non-uniformity of the density of the absorber 7a described in the first embodiment is taken.

In FIG. 15, the same components as those in FIG. 2 are denoted by the same reference numerals. Reference numeral 6 'denotes a photo interrupter arranged as a second ink sensor, which is the same as the photo interrupter 6. In this embodiment, the photointerrupter 6 is also referred to as a first photointerrupter for convenience of explanation.

In the first embodiment, the remaining amount of ink is determined only from the output of the photo interrupter 6. In this embodiment, the average value of the outputs of the first and second photo interrupters 6 and 6 'is used. To detect that the remaining amount of ink has decreased. This average value may be a simple average or a weighted average. In the present embodiment, the second photo-interrupter 6 ′ has a larger supply port 2 than the first photo-interrupter 6.
Since it is close to 4, an output change occurs after the remaining number of printable sheets becomes smaller. Therefore, which weight is to be determined more depends on the remaining number of sheets to be detected.

As described above, by providing sensors for detecting the remaining amount of ink at a plurality of points and using the average value of the measured values at the plurality of detection points, even if the density of the absorber 7a is not uniform, the effect is not affected. Thus, the remaining amount can be detected with high accuracy.

As means for reducing the variation in the detected value due to the influence of the non-uniformity of the density of the absorber 7a, FIG.
It is also conceivable to make the photointerrupter 6 movable as described in, and to detect the remaining amount of ink at a plurality of points in the ink tank.

Further, the present invention is not limited to the example in which the photo interrupter 6 is configured to be movable, and a plurality of points may be measured while the carriage 1 is moved while the photo interrupter 6 is fixed. However, in this case, if the ink tank 7 does not have a certain thickness in the moving direction of the carriage 1, the effect achieved by increasing the number of detection points is small.

In this embodiment, the remaining amount of ink is detected at a plurality of points while the photointerrupter 6 and the carriage 1 are relatively moved, and the average value of the measured values at the plurality of detection points is used. The absorber 7a as described above
Even if the density is uneven, the effect can be reduced, and the remaining amount can be detected with high accuracy.

(Fourth Embodiment) In the first embodiment described above, a warning or a stop of the printing operation is performed when the output of the photointerrupter 6 exceeds a predetermined threshold.

In this embodiment, when the output of the sensor exceeds the threshold value, no warning or stop of the printing operation is performed, and instead, a display corresponding to the output of the photo interrupter 6, that is, the output of the photo interrupter 6 is displayed. A display that changes proportionally or monotonically is performed.

As is clear from FIG. 8, the ink tank 7
The output of the photointerrupter 6 changes continuously as the remaining ink amount in the inside decreases. Therefore, by displaying the remaining amount corresponding to the output change, it is possible to continuously perform display substantially corresponding to the remaining number of printable sheets. By doing so, more detailed ink remaining amount information can be given to the user.

FIG. 16 shows an example in which the remaining amount of ink in the ink tank 7 is displayed on the display panel. The display in the display panel may be one in which the level of the digital meter changes according to the number of remaining printable sheets as shown in FIG.
Further, as the display panel, generally used display devices such as those using liquid crystal may be used.

The present invention is not limited to the display means to be visually recognized, but may be a method of guiding the remaining printable number by voice or a method of changing the length and the number of times of the buzzer sound according to the remaining printable number.

With the above configuration, the photo interrupter 6
, It is possible to inform the user of detailed ink remaining amount information. According to the present embodiment, when the remaining amount of ink in the ink tank 7 decreases, the user can know the detailed remaining ink amount, and can perform maintenance such as replacement of the ink tank 7 at an appropriate time. .

(Fifth Embodiment) In the first embodiment described above, the ink tank 7 includes the absorber 7a and the raw ink storage 7
However, the present invention is not limited to this configuration, but is also applicable to an ink tank having a configuration as shown in FIG.

In the ink tank shown in FIG. 17, an absorber 7a is arranged over the whole area inside the ink tank 7.

17, 24 is a supply port, 28 is an air communication port, and 6 is a photo interrupter, as in FIG. The photo interrupter 6 is arranged to detect a change in the reflectance of the bottom surface of the absorber 7a as in the first embodiment.

(Sixth Embodiment) According to the present invention, when there is no ink tank 7, there is no reflected light from the photo interrupter 6, so that the output level is much lower than the output level when there is sufficient ink. Becomes

In this embodiment, the presence or absence of the ink tank 7 is determined by the photointerrupter 6, utilizing the configuration of the ink remaining amount detection shown in the first embodiment.

Using the photo interrupter 6, the presence or absence of the ink tank 7 can also be detected from the difference in detection level between when the ink tank 7 is mounted and when it is not mounted.

Further, in this embodiment, the presence or absence of the ink tanks 7 of each color in the case of a color printer can be individually detected, and recording is not performed when the ink tanks 7 are not mounted.

Therefore, according to the above configuration, the presence / absence of the ink tank 7 can be detected without providing a special configuration for detecting the presence / absence of the ink tank 7, and the ink tank 7 can be configured with a simple configuration without increasing the cost. 7, the detection of the remaining amount of ink and the detection of the presence or absence of the ink tank can be performed.

(Others) The present invention particularly provides an excellent effect in a recording apparatus using an ink jet type recording head which forms a flying liquid by utilizing thermal energy and performs recording among ink jet recording methods. It is.

The typical structure and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to recording information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal transducer, and film boiling occurs on the heat acting surface of the recording head. Liquid (ink) corresponding to the drive signal
This is effective because air bubbles in the interior can be formed. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

The structure of the recording head may be a combination of a discharge port, a liquid path, and an electrothermal converter (a linear liquid flow path or a right-angled liquid flow path) as disclosed in the above-mentioned specifications. U.S. Pat. No. 4,558,333 and U.S. Pat.
A configuration using the specification of Japanese Patent No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Application Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, according to the present invention, recording can be reliably and efficiently performed regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium on which a recording apparatus can record. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads, or a configuration as one integrally formed recording head.

In addition, even in the case of the serial type as described above, the recording head fixed to the apparatus main body or the electric connection with the apparatus main body or the ink from the apparatus main body is mounted on the apparatus main body. The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is provided integrally with the recording head itself is used.

It is preferable to add a recording head ejection recovery unit, a preliminary auxiliary unit, and the like as the configuration of the recording apparatus of the present invention since the effects of the present invention can be further stabilized. If these are specifically mentioned, the recording head is heated using capping means, cleaning means, pressurizing or suction means, an electrothermal transducer, another heating element or a combination thereof. Pre-heating means for performing the pre-heating and pre-discharging means for performing the discharging other than the recording can be used.

Further, the type and number of the recording heads to be mounted may be two or more corresponding to a plurality of inks having different recording colors and densities. That is, for example, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, but may be any of integrally forming a printing head or a combination of a plurality of printing heads. The present invention is also very effective for an apparatus provided with at least one of the recording modes of full color by color mixture.

In addition, the form of the ink jet recording apparatus of the present invention is not limited to those used as image output terminals of information processing equipment such as computers, copying apparatuses combined with readers and the like, and facsimile apparatuses having a transmission / reception function. It may take a form.

[0140]

As described above, the present invention relates to an LED
The light emission amount of the light emitting unit can be automatically adjusted by changing the light emission duty ratio of the light emitting unit by performing PWM control of the drive signal of the light emitting unit such as, for example, immediately after the power of the device is turned on. Thus, the adjustment work can be performed even after the device is shipped to the market, and the remaining ink amount can be detected stably.

[Brief description of the drawings]

FIG. 1 is a side view of a carriage according to a first embodiment of the present invention.

FIG. 2 is a side view of the carriage shown in FIG. 1 in a tank mounted state.

FIG. 3 is a schematic view of the carriage shown in FIG. 1 as viewed from the bottom.

FIG. 4 is a schematic perspective view of the entire apparatus according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of the ink sensor shown in FIG.

FIG. 6 is a diagram for explaining the principle of detecting the remaining amount of ink according to the present invention.

FIG. 7 is a diagram for explaining the principle of detecting the remaining amount of ink according to the present invention.

FIG. 8 is a diagram for explaining an output of the photointerrupter according to the first embodiment of the present invention.

FIG. 9 is a schematic block diagram of an ink remaining amount detecting device according to the first embodiment of the present invention.

FIG. 10 is a timing chart for explaining the operation of the remaining ink amount detecting device shown in FIG. 9;

FIG. 11 is a flowchart for explaining a calibration method in the remaining ink amount detection device shown in FIG. 9;

12 is a flowchart illustrating a method of detecting the presence or absence of ink in the remaining ink amount detection device illustrated in FIG. 9;

FIG. 13 is a flowchart illustrating a calibration method of the ink remaining amount detecting device according to the second embodiment of the present invention.

FIG. 14 is a flowchart illustrating a method of detecting the presence or absence of ink in an ink remaining amount detecting device according to a second embodiment of the present invention.

FIG. 15 is a diagram illustrating a configuration of an ink sensor according to a third embodiment of the present invention.

FIG. 16 is a diagram illustrating a display unit of a detection result of a remaining amount of ink in a fourth embodiment of the present invention.

FIG. 17 is a diagram illustrating a configuration of a carriage and an ink sensor according to a fifth embodiment of the present invention.

FIG. 18 is a schematic block diagram of a conventional ink remaining amount detecting device.

FIG. 19 is a flowchart illustrating a method of detecting the presence or absence of ink in the remaining ink amount detection device illustrated in FIG. 18;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carriage 1a Calibration reflection part 6 Photointerrupter 6c LED 6d Phototransistor 7 Ink tank 7a Absorber 21 Recording head 80 Phototransistor load resistance 82 A / D converter 83 CPU 86 Phototransistor raw output voltage 88 LED current limiting resistance 89 LED ON / OFF transistor 90 Phototransistor output voltage 91 Low pass filter 95 PWM signal

Continuation of the front page (72) Inventor Toshiharu Ina 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Masaya Uezuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor: Fumiyuki Mikami, 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor: Yasuhiro Unosawa 3-30-2, Shimomaruko, Ota-ku, Tokyo Canon Inc. ( 56) References JP-A-8-112908 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01F 23/00-25/00

Claims (10)

(57) [Claims] 1. A detecting means for irradiating light from a light emitting portion through a light-transmitting wall surface of an ink tank containing an ink absorber and detecting a reflected light amount at a boundary between the wall surface and the ink absorber. An apparatus for detecting the remaining amount of liquid in a tank, comprising: an adjusting unit configured to adjust a light emission amount of the light emitting unit by pulse width modulation of a drive signal of the light emitting unit. Characteristic device for detecting remaining amount of liquid in tank. 2. An adjusting reflector for reflecting light from the light emitting unit to the light receiving unit during an adjusting operation of the adjusting unit, wherein the adjusting unit adjusts a duty ratio of pulse width modulation. 2. The liquid remaining amount detection in the tank according to claim 1, wherein a value of a detection signal when the light receiving unit detects the reflected light from the adjusting reflecting unit can be adjusted to a predetermined target value. apparatus. 3. A storage unit for storing a duty ratio of pulse width modulation and a value of a detection signal of the light receiving unit at the time of an adjustment operation of the adjustment unit, wherein the detecting unit detects the remaining amount of liquid in the tank. The duty ratio of the pulse width modulation by the adjusting unit is set as the duty ratio stored in the storage unit, and the value of the detection signal of the light receiving unit at that time is compared with the value of the detection signal stored in the storage unit. 3. A device for detecting a remaining amount of liquid in a tank according to claim 2, further comprising means for detecting a remaining amount of liquid in said tank. 4. A storage for storing a duty ratio of pulse width modulation and a correction coefficient obtained from a ratio between a target value of the detection signal and a value of a detection signal of the light receiving unit during an adjustment operation of the adjustment means. Means, when detecting the remaining amount of liquid in the tank, the duty ratio of the pulse width modulation by the adjusting means as the duty ratio stored in the storage means, the detection signal of the light receiving unit at that time 3. The apparatus according to claim 2, further comprising a unit configured to detect a remaining amount of the liquid in the tank based on a value and a correction coefficient stored in the storage unit. . 5. The apparatus according to claim 1, wherein said detecting means includes a light emitting element and a light receiving element. 6. An ink jet recording head for discharging ink, a translucent ink tank containing ink to be supplied to the ink jet recording head, and means for relatively moving the ink jet recording head and a recording medium. In the ink jet recording apparatus, a light emitting unit irradiates light from a light emitting unit through a wall surface of the ink tank to detect a reflected light amount at a boundary portion between the wall surface and the ink absorber. An ink jet recording apparatus comprising: an adjusting unit that can adjust a light emission amount of the light emitting unit by performing width modulation. 7. An adjusting reflector for reflecting light from the light emitting section to the light receiving section during the adjusting operation of the adjusting section, wherein the adjusting section adjusts a duty ratio of pulse width modulation. 7. The ink jet recording apparatus according to claim 6, wherein a value of a detection signal when the light receiving section detects the reflected light from the adjustment reflecting section can be adjusted to a predetermined target value. 8. A storage unit for storing a duty ratio of pulse width modulation and a value of a detection signal of the light receiving unit at the time of adjustment work of the adjustment unit, and detecting a remaining amount of ink in the ink tank.
The duty ratio of the pulse width modulation by the adjusting unit is set as the duty ratio stored in the storage unit, and the value of the detection signal of the light receiving unit at that time is compared with the value of the detection signal stored in the storage unit. 8. An ink jet recording apparatus according to claim 7, further comprising means for detecting a remaining amount of ink in said ink tank. 9. A storage for storing a duty ratio of pulse width modulation and a correction coefficient obtained from a ratio between a target value of the detection signal and a value of a detection signal of the light receiving unit during an adjustment operation of the adjustment means. Means, when detecting the remaining amount of ink in the ink tank,
The duty ratio of the pulse width modulation by the adjusting unit is a duty ratio stored in the storage unit, and the ink ratio based on the value of the detection signal of the light receiving unit at that time and the correction coefficient stored in the storage unit. The ink jet recording apparatus according to claim 7, further comprising means for detecting a remaining amount of the ink in the tank. 10. An ink jet recording apparatus according to claim 6, wherein said detecting means has a light emitting element and a light receiving element.