JP2002072660A - Electrophotographic system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic sensitizing system for improving toner concentration control accuracy, in the case that an image resolution setting is changed, that is, a printing speed setting is changed. SOLUTION: Toner concentration in a mixing area 3 is detected by a magnetic permeability sensor 5 and the concentration is compared with a threshold. When a detection voltage is equal to or below the threshold, a digital voltage Vdig is outputted to a CPU 9. In the case of detecting that the toner runs short based on the Vdig, the toner is supplied by the CPU 9. Besides, an input voltage Vcont applied on the detection voltage is switched by the CPU 9 in accordance with the printing speed, that is, based on printing quality such as image resolution, monochromatic printing and color printing, and the variance of the toner concentration. Then, the linearity of the detection voltage is obtained all over the toner concentration detection extent. Besides, the reduction time of the toner concentration is counted by the CPU 9, and the Vcont is switched, then, the concentration is highly accurately detected so as to correct the concentration to the prescribed one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic system used for an electrophotographic printer such as a laser printer, and more particularly to an electrophotographic system for improving control of toner density.

[0002]

2. Description of the Related Art In an electrophotographic printer such as a laser printer, a printing process is performed by transferring toner charged on a photosensitive drum onto paper. Therefore, the density of the toner supplied to the photosensitive drum is controlled in order to improve the finishing quality of the characters to be printed. Normal,
In the two-component developing system, a two-component developer in which a nonmagnetic or weak magnetic toner and a magnetic carrier are mixed is used, and the toner density is detected and managed by a magnetic permeability sensor.

That is, when the toner concentration is low, the amount of the toner adhering to the magnetic carrier is small and the amount of the magnetic substance per unit volume of the developer increases, and the magnetic permeability sensor detects a high voltage level. On the other hand, when the toner concentration is high, the amount of toner adhering to the magnetic carrier is large, and the amount of magnetic substance in a unit volume of the developer decreases, so that the magnetic permeability sensor detects a low voltage level. Therefore, the magnetic permeability sensor outputs the toner density information by comparing these detection voltage levels in advance with a threshold voltage, and controls the toner density to be constant based on this information.

[0004]

However, the relationship between the toner concentration and the detection voltage depends on the magnetic permeability characteristic (ie, BH characteristic) of the magnetic permeability sensor, and has a linear region and a saturated region. ing. FIG. 7 is a characteristic curve showing the relationship between the toner density detected by the magnetic permeability sensor and the detection voltage of the sensor. That is, as shown in the drawing, when the toner density is in the area A, a detection voltage proportional to the toner density is output, but in the area B where the toner density is low and the area C where the toner density is high, the toner density is low. Even if it changes, the detection voltage hardly changes, so that the detection accuracy of the toner density becomes extremely poor. For this reason, the conventional detection method cannot detect a state where the toner concentration is high or low, and particularly cannot detect an empty state where the toner concentration is low.
An empty sensor must be provided separately from a normal density detection sensor.

In normal printing, the toner density is detected while toner is supplied from the toner tank to the mixing area and the toner and the carrier are agitated. For this reason, according to the conventional detection method, printing was performed at high speed or high density, and the toner concentration in the mixing area was reduced due to temporary supply of toner, or the toner amount was insufficient in the toner tank. It is not possible to determine whether the toner concentration in the mixing area has dropped.

Further, some electrophotographic printers such as a laser printer have a function of changing the resolution by a user. In such an electrophotographic printer, a plurality of printing speed levels corresponding to each resolution are provided, and printing is performed at a printing speed corresponding to the set resolution. Further, the above-described printing speed changes depending on color printing and black-and-white printing.

However, even when the printing speed is changed as described above, the toner density control is a control corresponding to the normal printing. Therefore, there is a problem that the toner density is erroneously detected and the toner supply accuracy is reduced. .

The present invention has been made in view of such circumstances, and an electrophotographic system in which the accuracy of toner density control is improved when the setting of printing speed is changed, such as when the setting of resolution is changed. The purpose is to provide.

[0009]

In order to solve the above-mentioned problems, an electrophotographic system according to the present invention comprises a toner density detecting means for outputting an output signal proportional to a toner density based on an input signal level; Printing speed detecting means for detecting a change in speed; input switching means for switching an input signal level input to the toner density detecting means based on an output signal of the toner density detecting means and a detection result of the printing speed detecting means; It is characterized by having.

Further, in the electrophotographic system according to the present invention, in the above invention, a plurality of the input signal levels are provided for each printing speed, and at least the toner empty is detected in the plurality of the input signal levels. And an empty input signal level.

More specifically, the input switching means detects that the output signal of the toner density detecting means has become equal to or less than a threshold for a set time set in correspondence with each input signal level. Of the plurality of input signal levels at the currently set print speed, select an input signal level which is set to detect the next lower toner density level, and change the print speed by the print speed detecting means. Is detected, the input signal level corresponding to the current toner density level is selected from the input signal levels set according to the detected printing speed. Further, the input switching means may be configured such that, when the empty input signal level is selected as the input signal level, the output signal of the toner density detection means is kept below a threshold for a predetermined time or more. Has a function of determining that the toner is empty and notifying the user of the determination.

Further, the printing speed is changed according to the setting of resolution, the setting of color printing or the setting of black and white printing.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the electrophotographic system according to the present invention will be described in detail with reference to the drawings. Figure
FIG. 1 is a schematic configuration diagram of a toner supply portion for explaining an electrophotographic system applied to an embodiment of the present invention. That is, in the figure, the configuration of the entire electrophotographic printer is omitted because it is a known technique. Therefore, only the developing unit 1 and the toner density sensor unit 4 of the electrophotographic system are displayed.

That is, the developing unit 1 includes a toner tank 2 and a mixing area 3. Also,
The toner density sensor unit 4 includes a magnetic permeability sensor 5 for detecting the toner density in the mixing area 3 and a sensor controller 6. Further, when the toner density in the mixing area 3 decreases, the toner feeder 8 is driven by the motor 7 to supply toner from the toner tank 2 to the mixing area 3.

The toner density in the mixing area 3 is
After being detected by the magnetic permeability sensor 5 as an analog voltage (hereinafter, referred to as Vana), it is compared with a predetermined threshold voltage. When Vana falls below the threshold voltage, a digital voltage (hereinafter, referred to as Vdig) is detected. It is output to the CPU 9 of the controller 6. Then, the CPU 9 generates a predetermined signal waveform based on the input Vdig, and quantitatively determines the density of the toner density. Furthermore, CP
U9 sends a signal to the motor 7 when the toner concentration becomes low, and drives the toner feeder 8 to drive the toner tank 2
The control is performed so that the toner is supplied to the mixing area 3 more.

Further, a resolution setting section 20a and a print switching setting section 20n are provided outside. The user changes the resolution level from the resolution setting unit 20a, for example, from 600 dpi to 1200 dpi,
The change from 00 dpi to 2400 dpi becomes possible.

From the print switching setting section 20b, it is possible to select between monochrome printing and color printing. Then, by changing these settings, a desired print quality can be obtained. And a resolution setting unit 2
0a, the setting change of the printing speed setting unit 20b is detected by the CPU 9, and the CPU 9 controls the printing linear speed, the paper feeding speed, and the like based on the printing speed corresponding to each newly set printing condition. .

The CPU 9 controls the input voltage (hereinafter referred to as Vcont) to be input to the magnetic permeability sensor 5 in accordance with the density of the toner density and the printing speed corresponding to each resolution, and selects one of V1 to Vn. Is going. Thus, C
The PU 9 switches the input voltage Vcont stepwise according to the density of the toner density and the printing speed, and always performs high-precision toner irrespective of whether the toner density is low or high, or even if the printing setting conditions are changed. Control is performed so that the concentration can be detected. The switching voltage of Vcont is
An arbitrary number of stages can be provided. Vcc in the sensor controller 6 is a power supply voltage of the sensor controller 6 and the magnetic permeability sensor 5.

FIG. 4 shows the drive signal Vm of the electrophotographic system and the toner detection operation start timing waveform V
7 is a waveform showing a relationship with n. That is, as shown in the drawing, after the electrophotographic system is driven by the drive signal Vm to start toner supply, a certain period is set as a toner detection impossible period i, and the detection function is stopped. Then, after the period i, the toner detection operation start timing waveform Vn rises to start the toner density detection. This is because the density is detected after the mixer 10 in the mixing area 3 in FIG. 1 has rotated several times to stir the toner, thereby detecting the density accurately.

Next, the operation of detecting and controlling the toner density will be described in detail with reference to the control block diagram of the toner density sensor and the waveforms of various parts. FIG. 2 is a control block diagram of the toner density sensor. FIG. 3 shows voltage signal waveforms at various points in the block diagram of FIG. Therefore, FIGS. 2 and 3
This will be described with reference to FIG.

First, the toner density is detected by an analog voltage detection circuit 21 composed of a transformer or the like, converted into Vana, and input to a comparison circuit 22.
Further, as shown in the waveform of FIG.
Is compared with a predetermined threshold voltage Vs. Here, Vana shows a sinusoidal waveform because the mixer 10 rotating in the mixing area 3 in FIG.
This is because the toner on the magnetic permeability sensor 5 is removed in synchronization with the rotation cycle by the mixer cleaner 10 ′.

Next, the waveform compared by the comparison circuit 22 is
As shown in the waveform of FIG. 3B, in a period in which Vana is lower than Vs, a pulsed digital voltage Vdig is generated in synchronization with the peak value of Vana. Furthermore, this Vdig is O
As shown in each waveform of FIG. 3 (c), each of the waveforms rises in synchronization with the rising waveform of the Vdig pulse in each cycle, and falls in synchronization with the falling waveform of the next Vdig pulse. An OR waveform is generated by taking a high-level OR of the waveforms 1, 2,... N. As a result, the waveform of Vdig · Hsig is output to the output of the OR circuit 23, as shown in FIG. That is, a period in which Vdig · Hsig is “high” is a period in which the toner density is reduced.

The signal Vdig · Hsig is input to the motor control circuit 24 to generate a drive signal Vm for the motor 7 for toner supply shown in FIG. The motor control circuit 24
Is a circuit provided in the CPU 9 shown in FIG. That is, as shown in the waveform of FIG. 3E, the motor 7 is driven during the period g in which Vm is "high" to supply toner. Then, during the period when Vdig · Hsig is “high”, that is, during the period when the toner density is decreasing, the drive signal TFsig is generated every g period in the cycle of the interval h to drive the motor 7 to replenish the toner. Is going. The toner supply period g and interval h are determined by the CPU 9 shown in FIG.
Can be set arbitrarily.

Next, returning to the block diagram of FIG. 2, the input voltage switching circuit 25, which is a major feature of this embodiment, will be described. The input voltage switching circuit 25 changes the input voltage Vcont to different voltages V1 to Vn by the switch SW.
, The bias level of the analog voltage Vana output from the analog voltage detection circuit 21 is changed. That is, the input voltage V supplied to the analog voltage detection circuit 21 according to the toner density and the printing resolution.
The level of cont is changing. As a result, the toner density can be detected with high accuracy from the low density state to the high density state of the toner, and the detection voltage can be changed according to the resolution. The input voltage switching circuit 25
Is a circuit provided in the CPU 9.

FIG. 5 is a characteristic diagram showing the relationship between the toner density and the detection voltage realized in the embodiment of the present invention. In the figure, the horizontal axis represents the toner concentration, the vertical axis represents the detection voltage of the magnetic permeability sensor, that is, Vana, and the characteristic diagram when the input voltage Vcont is changed is shown. In the following description, it is assumed that the resolution is set to, for example, 600 dpi.

First, the case where the toner density is about the standard is shown. In the block diagram of FIG.
5 switches the switch SW to set the resolution to 600d
The reference voltage V3 at pi is supplied to the analog voltage detection circuit 21 as the input voltage Vcont. By this Vana
Has an intermediate height, and the characteristic curve in FIG. 5 becomes Vcont3.

On the other hand, when the toner concentration becomes higher than the standard, the input voltage switching circuit 25 switches the switch SW to set the highest voltage V1 at the resolution setting of 600 dpi as the input voltage Vcont, and the analog voltage detection circuit 2
Feed to 1. As a result, the bias level of Vana becomes the highest, and the characteristic curve in FIG. 5 is shifted rightward in the figure as Vcont1.

When the toner density is lower than the standard, the switch SW is switched to set the resolution to 600 dp.
Let the lowest voltage V5 at i be the input voltage Vcont,
It is supplied to the analog voltage detection circuit 21. This allows V
The bias level of ana becomes the lowest, and the characteristic curve in FIG. 5 is shifted to the left of the figure like Vcont5.

As a result, when the resolution is set to 600 dpi, as shown in the characteristic diagram of FIG.
In the C region where the toner concentration is high, the detection voltage, that is, Vana is output in the linear region of the characteristic of Vcont1. In the A region where the toner concentration is standard, Vana is output in the linear region of the characteristic of Vcont3. In the B region where the toner density is low, Vana is output in the linear region having the characteristic of Vcont5. Therefore, the detection voltage, that is, Vana, can maintain high detection accuracy from the region B having a low toner concentration to the region C having a high toner concentration.

The voltages V1, V3, and V5 are input voltages Vcont set according to the respective toner densities when the resolution is set to 600 dpi. This voltage is provided corresponding to each resolution level, that is, each printing speed level. For example, when the resolution is set to 1200 dpi, the voltage V2 is used instead of the highest voltage V1 of the above-described resolution 600 dpi.
However, V4 is used instead of the reference voltage V3, and the voltage V6 is used instead of the lowest voltage V5.

As a result, when the resolution is set to 1200 dpi, as shown in the characteristic diagram of FIG. 5, in the C region where the toner density is high, the detection voltage, that is, Vana is output in the linear region of the characteristic of Vcont2. And
In the region A where the toner density is standard, Vcont4
Vana is output in the linear region having the characteristic of Vcont, and in the B region where the toner density is low, Vana is output in the linear region having the characteristic of Vcont6. As described above, the higher the resolution, the higher the value of Vcont set according to the respective toner densities, and the areas A to C shown in FIG. Shift toward

As described above, V is set according to each setting.
By setting the cont levels in multiple values and using them appropriately according to the settings, it is possible to maintain high detection accuracy in the toner density detection under various setting conditions from the low B area to the high toner density C area. . Furthermore, if the value of the above-mentioned input voltage Vcont is set in consideration of the setting change of color or black-and-white printing in addition to the setting change of the resolution, it is possible to accurately detect the toner density corresponding to any setting. Becomes possible.

In the example of this embodiment, the case where the input voltage Vcont is switched in three steps in setting each resolution has been described. However, linear characteristics can be obtained over the entire detection range of the toner density. Vcont can be switched to an arbitrary number of stages according to the width of the linear region characteristic of the magnetic permeability sensor.

FIG. 6 is a flowchart showing the flow of the detection control process of the toner density sensor according to the embodiment of the present invention. Therefore, the flow of the detection control process of the toner density sensor will be described with reference to FIG. In the following description, it is assumed that the resolution is set to the standard 600 dpi.

First, a normal toner supply mode is performed as a first step. In this mode, the printer main body performs normal printing, and toner is replenished based on the detection voltage (Vana) of the toner density sensor (magnetic permeability sensor 5). Further, the input voltage Vcont to the analog voltage detection circuit 21 is supplied with the reference level Vcont3 (step S1).

Then, the operation of determining the toner density is performed, and it is detected whether or not the toner density is equal to or less than the determination value (step S2). Here, if Vdig · Hsig shown in FIG. 3D is continuously longer than a1 (sec), for example, longer than 5 seconds (step S2, YES), the process proceeds to the next step S3.
If the continuous time of dig · Hsig is not more than a1 (sec), for example, not more than 5 seconds (step S2, NO), it is determined that the decrease in the toner concentration is primary, and the process returns to step S1. One-step operation is continuously performed.

That is, if Vdig · Hsig> a1 (step S2, YES), the toner density return mode 1 of the (2-1) th stage is performed. In this mode, printing of the printer body is stopped, and the motor 7 is driven to supply toner in the maximum supply mode. Then, the input voltage Vcont to the analog voltage detection circuit 21 is switched to a low level Vcont5, so that highly accurate detection can be obtained with a low toner concentration (step S3).

Then, in step S3, the input voltage
After c1 (sec) from the voltage switching of Vcont5, for example, 25
After a lapse of seconds, the process proceeds to step S4, and the toner density return mode 2 of the 2-2 stage is performed. In this mode, printing of the printer body is continuously stopped, and the motor 7 is driven to supply toner in the maximum supply mode (step S4).
Then, at the low-level input voltage Vcont5, it is detected whether or not the toner density has returned to the normal value (step S5).

If the result of the determination operation indicates that the toner density has not returned and has fallen below the minimum value, the duration below the minimum value, ie, Vdig · Hsig shown in FIG.
Is continuously less than a2 (sec), for example, less than 10 seconds (step S5, YES), it is determined that the density decrease is temporary, and the toner density return mode 3 in the 2-3 step of step S6 is performed. Move to

That is, in the toner density return mode 3 of 2-3 steps in step S6, step S4
The printing of the printer main body is stopped continuously from the mode 2 of FIG. In addition, the motor 7 is stopped to stop toner supply. Then, the input voltage V to the analog voltage detection circuit 21
The cont is switched from the low level Vcont5 to the normal level Vcont3, and after the switching time c2 (sec), for example, after 25 seconds, returns to mode 1 of the first stage of step S1, and shifts to the same normal operation as described above (step S6) ).

On the other hand, in step S5, the time during which the toner density is lower than the minimum value, that is, Vdig · Hsig shown in FIG.
If it is longer than the second (step S5, NO), step S7
The operation shifts to the toner empty detection mode, which is the operation mode of the third stage. In this mode, printing is continuously stopped, and the motor 7 is driven to supply toner in the maximum supply mode. Also, the input voltage V to the analog voltage detection circuit 21
The cont performs the density detection operation in the low density region in the state of the low level Vcont5 (step S7).

Then, at the low level input voltage Vcont5, it is determined whether the toner density is equal to or lower than the minimum value, that is, whether the toner is in an empty state (step S8). Then, the time during which the toner density is lower than the minimum value, that is, Vdig · Hsig shown in FIG.
(Sec), for example, less than 15 seconds (step S
8, NO), the process shifts to the toner density return mode 2 of the 2-2 stage of step S4, and the above-described processes after step 4 are repeated.

On the other hand, in step S8, the time during which the toner concentration is lower than the minimum value, that is, FIG.
If Vdig · Hsig shown in (1) is continuously longer than a3 (sec), for example, longer than 15 seconds (step S8, YES), it is determined that there is no toner in the toner container, and the toner empty recovery in the fourth step of step S9 is performed. Go to mode. That is, in this mode, the printing is continuously stopped, the driving of the motor 7 is stopped, and the supply of the toner is stopped. Then, the input voltage Vcont to the analog voltage detection circuit 21 outputs an error message indicating that the toner is empty, and waits for a toner container replacement signal while performing the density determination at the low level Vcont5 (step S9).

Then, it is determined whether or not the toner has been supplied to the toner container (step S10). If the toner has not been supplied (step S10, NO), the error message is continued, and if the toner has been supplied (step S10, YES). ),
Toner density return mode 2 of the 2-2 stage of step S4
Then, the above-described processing after step S4 is repeated.

The input voltage Vcont (V3 as the reference voltage and V5 as the low-level voltage) selected in each of the above-described processes is a voltage value set corresponding to each density at a resolution of 600 dpi. Resolution 1
If it is set to 200 dpi, 120
The input voltage Vcont (reference voltage V4, low level voltage V6) set corresponding to 0 dpi is applied. Also,
Even when the resolution setting is changed during the above-described processing procedure, the toner density is accurately detected by changing the input voltage Vcont to a value provided corresponding to the set resolution. be able to.

More specifically, if the resolution setting is changed from 600 dpi to 1200 dpi during the processing shown in FIG. 6, for example, during the empty detection mode which is the operation mode of the third stage in step S7, the input is performed. The input voltage Vcont is set to 600 dpi by the voltage switching circuit 25.
From the low level voltage Vcont5 at 1200 dpi to the low level voltage Vcont6 at 1200 dpi. As a result, even when the resolution setting is changed, erroneous detection of the toner density can be prevented, and the toner density can be accurately detected.

Similarly, when the setting is changed from black and white to color, the erroneous detection of the toner density is performed by switching the input voltage set corresponding to each print quality setting as described above. Can be prevented, and the toner density accuracy can be improved.

The embodiment is an example for describing the present invention, and the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the invention. For example, the density detection sensor is not limited to the magnetic permeability sensor, and any sensor may be used as long as the control always shifts so that the linear region becomes the detection region. Further, the sensor undetectable period from the start of motor driving described in the embodiment is not limited to the rotation cycle of the mixer,
It can also be set arbitrarily in consideration of other mechanical conditions, humidity of the toner atmosphere, and the like. Further, the reason why the input voltage is switched in a cycle longer than the cleaning cycle of the mixer cleaner is that the input voltage can be arbitrarily changed according to the detection situation.

[0049]

As described above, according to the electrophotographic system of the present invention, based on the input signal level, a toner density detecting means for outputting an output signal proportional to the toner density, and detecting a change in printing speed. And an input switching means for switching an input signal level input to the toner density detecting means based on an output signal of the toner density detecting means and a detection result of the printing speed detecting means.

As described above, when the printing speed changes due to a change in the printing quality such as resolution, color, monochrome printing, etc., the input voltage at each toner density is set to a multi-value in accordance with each printing speed. By changing these input voltages in accordance with the above conditions, that is, the printing speed and the density of the toner, the density can be detected with high accuracy from the empty state to the full state of the toner.

A plurality of input signal levels are provided for each printing speed, and the plurality of input signal levels include:
Since at least the empty input signal level for detecting the toner empty is included, it is automatically determined whether the density has temporarily decreased or the density has permanently decreased due to the absence of toner in the toner tank. You can judge. This makes it possible to perform an appropriate density return process according to the situation, so that it is possible to provide an electrophotographic printer or the like that is extremely easy to use. Further, it is not necessary to separately provide an empty sensor, and normal density detection and empty detection can be performed by one sensor, so that the cost of a printer or the like can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a toner supply portion for explaining an electrophotographic system applied to an embodiment of the present invention.

FIG. 2 is a control block diagram of a toner density sensor.

FIG. 3 is a voltage signal waveform of each part in the block diagram of FIG. 2;

FIG. 4 is a waveform showing a relationship between a drive signal Vm of a motor 7 and a toner detection operation start timing waveform Vn.

FIG. 5 is a characteristic diagram illustrating a relationship between a toner concentration and a detection voltage realized in the embodiment of the present invention.

FIG. 6 is a flowchart illustrating a flow of detection control processing of a toner density sensor according to the embodiment of the present invention.

FIG. 7 is a characteristic curve showing a relationship between a toner concentration and a detection voltage detected by a magnetic permeability sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Development unit 2 Toner tank 3 Mixing area 4 Toner density sensor unit 5 Magnetic permeability sensor 6 Sensor controller 7 Motor 8 Toner feeder 9 CPU 10, 11 Mixer 10 'Mixer cleaner 20a Resolution setting unit 20b Printing speed setting unit 21 Analog voltage detection circuit 22 Comparison circuit 23 OR circuit 24 Motor control circuit 25 Input voltage switching circuit

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shinobu Yamamoto 2-7 Sugasawa-cho, Tsurumi-ku, Yokohama-shi, Kanagawa F-term (reference) 2E053 AA29 AB07 BA05 CA02 CB19 2H027 DA17 DD07 FA28 FA30 FA35 2H077 DA10 DA16 DA44 DA52 DA86 GA04

Claims (3)

[Claims] 1. A toner density detecting means for outputting an output signal proportional to a toner density based on an input signal level, a printing speed detecting means for detecting a change in printing speed, an output signal of the toner density detecting means, An electrophotographic system comprising: an input switching unit that switches an input signal level input to the toner density detection unit based on a detection result of the printing speed detection unit. 2. A plurality of input signal levels are provided for each printing speed, and the plurality of input signal levels include:
The electrophotographic system according to claim 1, further comprising at least an empty input signal level for detecting toner empty. 3. The electrophotographic system according to claim 1, wherein the printing speed is changed according to a setting of resolution, a setting of color printing or a setting of black and white printing.