JP5111322B2 - Image forming apparatus and image forming method - Google Patents

Description

  The present invention relates to an image forming apparatus and an image forming method capable of printing barcode data.

  In this type of image forming apparatus, an electrophotographic method is used. When a charger precharges an image carrier, for example, a photosensitive drum, and the exposure unit irradiates light on the surface of the drum, the surface of the drum is exposed. An electrostatic latent image is formed. The developing unit carries toner, and when a developing bias is applied, the toner is excited and adheres to the electrostatic latent image to form a toner image. Then, this image is transferred and fixed on the paper.

Here, in recent years, the opportunity to output barcodes on paper has greatly increased. This bar code is composed of a fine line called “BAR” and a paper color (background color) called “SPACE”, and has been standardized in detail in each country.
Specifically, for example, an EAN-128 barcode is used in a convenience store and the like, and the barcode is set to 44 digits, and has a larger number of digits than a conventional barcode. Therefore, since the reading rate with a barcode reader can be reduced, a technique for improving the reading rate has been disclosed (for example, see Patent Document 1).

JP 2007-72099 A

  However, in the conventional technique described above, when barcode data is printed on a sheet, first, a test image for barcode data is output to a non-image area on the drum surface, and then a new image is supplied to the drum. Although barcode data is printed on paper using toner and the barcode quality can be improved, the toner used for the test image consumes toner that is not necessary. There is a problem that the running cost cannot be reduced.

As described above, it is necessary not only to improve the bar code quality but also to reduce the running cost. However, the conventional technique still has a problem in this respect.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus and an image forming method capable of solving the above-mentioned problems, improving the barcode quality, and reducing the running cost.

  A first invention for achieving the above object is an image forming apparatus capable of printing barcode data on a recording material, an image carrier on which an electrostatic latent image is formed, and an alternating current with a direct current component. A developing bias with superimposed components is applied, a developing unit that supplies toner to the electrostatic latent image to develop the toner image, a developing voltage control unit that controls the developing bias, and the print data is barcode data. A barcode print control unit that outputs a signal for reducing the duty value and DC component value of the development bias to 55% or less when the barcode data is not included, to the development voltage control unit. .

According to the first aspect of the invention, a developing bias in which an alternating current component is superimposed on a direct current component is applied to the developing unit, and the toner flies to the electrostatic latent image on the image carrier, and the toner image is developed.
Here, when the print data is bar code data, the bar code print control unit first reduces the duty value of the developing bias to 55% or less when the bar code data is not included. The developing voltage control unit applies the reduced developing bias to the developing unit. This is because if the duty value of the developing bias is set to be small, the developing time is shortened and the amount of toner consumption can be reduced.

Therefore, compared to the conventional case where a test image for barcode data is output to a non-image area on the drum surface, there is no consumption of toner that is not used for printing on the recording material, contributing to a reduction in running cost of the image forming apparatus. To do.
In addition, the barcode print control unit reduces the DC component value of the developing bias to 55% or less when the barcode data is not included, and the peak value of the developing bias is difficult to increase. Therefore, even if the duty value is set to be small as described above, it becomes difficult for the toner to leak toward the image carrier, and the barcode quality can be improved.

According to a second invention, in the configuration of the first invention, a charging bias having at least a DC component is applied, a charger for charging the surface of the image carrier, and a charging voltage control unit for controlling the charging bias; And the bar code print control unit sets the surface potential of the image carrier to a magnitude of 70% to 90% when the bar code data is not included when the print data is bar code data. In order to decrease the voltage, a signal for decreasing the DC component value of the charging bias is output to the charging voltage control unit.
According to the second invention, in addition to the operation of the first invention, the barcode printing control unit further reduces the DC component value of the charging bias, includes the surface potential of the image carrier, and barcode data. Decrease to 70% -90% of the case of no. As described above, since the surface potential of the image carrier is not greatly reduced, the reproducibility of one dot can be ensured even if the duty value is set small as described above, which also contributes to the improvement of the barcode quality.

According to a third aspect of the present invention, in the configuration of the first or second aspect of the present invention, the apparatus further includes a linear speed control unit that controls the rotational speed of the image carrier, and the bar code print control unit includes the bar code data. In this case, a signal for reducing the rotation speed of the image carrier compared to the case where the barcode data is not included is output to the linear speed control unit.
According to the third invention, in addition to the operation of the first and second inventions, the barcode print control unit further reduces the rotation speed of the image carrier as compared with the case where the barcode data is not included. Therefore, the system linear velocity is reduced, and even if the duty value is set to be small as described above, printing can be performed reliably. This also contributes to the improvement of barcode quality.

  A fourth invention is an image forming method for printing barcode data on a recording material. When the print data is barcode data, the rotational speed of the image carrier on which the electrostatic latent image is formed is set so as to be lower than when the barcode data is not included, In order to reduce the surface potential of the image carrier and the surface potential of the image carrier to 70% to 90% when the barcode data is not included, the DC component value of the charging bias is set small, Among the step of charging the surface of the image carrier and the developing bias in which the AC component is superimposed on the DC component, the duty value and the DC component value are set to a value of 55% or less when the barcode data is not included. The toner image is supplied to the electrostatic latent image to develop the toner image.

  According to the fourth aspect of the invention, the duty value of the developing bias is a factor that affects the developing time. For example, if the duty value decreases, the developing time for supplying the toner to the image carrier decreases, and the toner Reduces consumption. In other words, when the print data is barcode data, if the print data is reduced to 55% or less of the case where the barcode data is not included, the toner becomes difficult to adhere to the bar portion and is scattered in the space portion. It becomes difficult.

On the other hand, the peak value of the developing bias may increase if this is maintained. This causes the toner to vibrate easily and scatters toward the image carrier. Also, because the developing time is short, the developability decreases. obtain.
Here, the DC component of the developing bias is a factor that affects the developing ability. For example, the peak value can be suppressed if the DC component value is reduced. Therefore, with respect to the leak toward the image carrier, the DC component value of the developing bias is reduced to 55% or less when no barcode data is included, thereby avoiding the leak.

  The DC component of the charging bias is a factor that affects the surface potential of the image carrier. For example, if the DC component value is reduced, the surface potential is also reduced, and the reproducibility of one dot is improved. This is because the potential difference between the surface potential and the developing bias is increased, and the toner is less likely to scatter. Therefore, in order to reduce the developability described above, the DC component value of the charging bias is reduced so that the surface potential of the image carrier is reduced to 70% to 90% when the barcode data is not included. Therefore, the developability is ensured.

Furthermore, the rotational speed of the image carrier is also a factor that affects the developing ability. For example, if the rotational speed is reduced, printing is performed slowly. Therefore, since the rotation speed of the image carrier is reduced as compared with the case where the barcode data is not included with respect to the above-described deterioration in developability, the developability is further ensured.
As a result, the amount of toner adhering to the bar portion is suppressed as compared with the prior art, the running cost of the image forming method is reduced, leaks toward the image carrier are avoided, and developability is ensured. Therefore, “scattering” on the downstream side of the bar portion as viewed in the conveyance direction of the recording material and “tailing” on the upstream side of the bar portion can be avoided, and an improvement in barcode quality can be achieved. .

  According to the present invention, the barcode data is printed by lowering the duty value of the developing bias and the DC component value thereof, and the image formation that can achieve both the improvement of the barcode quality and the reduction of the running cost thereof. An apparatus and an image forming method can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows the structure of a printer 1 which is an example of an image forming apparatus. The cross section shown in the figure is seen from the right side of the printer 1. For this reason, the front of the printer 1 is located on the left side in the figure, and the back of the printer 1 is located on the right side.

  A paper cassette 3 is disposed below the inside of the apparatus main body 2 of the printer 1. As shown in the figure, the cassette 3 is configured to be able to be pulled out to the left side, and inside the cassette 3, sheets of paper (recording material) on which barcodes can be printed are stored in a stacked state. Is done. The sheets are sent one by one toward the back side of the printer 1 in the figure, and the sent sheets are reversed toward the front side inside the apparatus main body 2 and conveyed toward the front side as they are. Is done.

In the apparatus main body 2, the registration roller 24, the image forming unit 4, and the transfer unit 71 are arranged in this order on the downstream side in the sheet conveyance direction from the cassette 3.
The image forming unit 4 has a photosensitive drum (image carrier) 5 formed of amorphous silicon (a-Si). The drum 5 is rotatably installed and is driven clockwise by a driving motor (not shown). To do. A cleaning blade 8, a charger 6, an exposure unit 12 that is a laser scanner unit, a developing unit 20, and a transfer unit 71 are provided at appropriate positions around the drum 5.

  The charger 6 uniformly charges the surface of the drum 5. The exposure unit 12 irradiates the drum 5 with laser light. Further, the developing unit 20 has a developing sleeve 21, and this sleeve 21 is driven counterclockwise in FIG. The transfer portion 71 and the drum 5 form a nip portion for transferring the toner image onto the paper.

Further, a fixing unit 72 and a discharge port 75 are sequentially arranged on the downstream side of the transfer unit 71 as viewed in the sheet conveyance direction.
When the printer 1 performs printing, the sheets from the cassette 3 are separated and sent one by one. The sent paper reaches the registration roller 24. The registration roller 24 feeds the sheet toward the transfer unit 71 while correcting the oblique feeding of the sheet and measuring the image transfer timing with the toner image formed by the image forming unit 4.

On the other hand, the input port 80 in FIG. 2 is configured to be able to receive image data to be printed from the outside. This image data is obtained by converting various images such as characters, signs, figures, symbols, diagrams, and patterns into data, and the engine controller 90 controls the irradiation of laser light based on this data.
The controller 90 is an element that functions as a computer, and is electrically connected to the above-described image forming unit 4 and the like, and has hardware resources such as a CPU and a memory. Then, the controller 90 executes a predetermined program using this hardware resource. Thereby, an electrostatic latent image is formed on the surface of the drum 5 through charging and exposure.

  The developing sleeve 21 carries toner from the toner container 10. When a predetermined developing bias V is applied to the surface of the sleeve 21, the toner adheres to the surface of the drum 5 due to a potential difference from the charging bias v applied to the drum 5. Therefore, a toner image corresponding to the electrostatic latent image is formed on the surface of the drum 5.

When the sheet passes between the drum 5 and the transfer unit 71, the toner image formed on the surface of the drum 5 is transferred to the sheet at the nip portion. The toner remaining on the surface of the drum 5 is scraped off by the cleaning blade 8.
Thereafter, the sheet is fed toward the fixing unit 72 with an unfixed toner image carried thereon, and is pressed by a heat roller that has reached a predetermined temperature in the fixing unit 72 to fix the toner image. Next, the sheet sent from the fixing unit 72 is discharged from the discharge port 75 to the front side of the printer 1.

By the way, the controller 90 described above is configured to be able to execute the barcode printing mode in addition to the normal printing mode.
Specifically, the controller 90 of this embodiment includes a drum linear speed control unit (linear speed control unit) 92, a charging voltage control unit 96, a development voltage control unit 94, and a barcode print control unit 98. .

The drum linear speed control unit 92 is electrically connected to the drive motor and the drum 5. When the print data at the input port 80 does not include barcode data, the drum linear speed control unit 92 is set to the normal print mode. A signal for setting the rotation speed R1 to, for example, 306 mm / sec is output to the drive motor.
Next, the charging voltage control unit 96 is electrically connected to the power source 50 and the charger 6, and in this embodiment, the charging voltage control unit 96 is configured to be able to apply a charging bias v in which the AC component vpp is superimposed on the DC component vdc.

  The charging voltage control unit 96 outputs a signal for setting the surface potential b1 of the drum 5 to, for example, +270 V to the power supply 50 in the normal printing mode. As a result, the charger 6 uniformly charges the drum 5 to +270 V, and the exposure unit 12 forms an electrostatic latent image on the surface of the drum 5. In this embodiment, the surface potential after exposure is + 20V. Further, since this surface potential is determined by the DC component vdc, the charging bias v may be only the DC component vdc.

Further, the developing voltage control unit 94 is electrically connected to the power source 50 and the developing sleeve 21, and is configured to be able to apply a developing bias V in which the AC component Vpp is superimposed on the DC component Vdc.
More specifically, the developing voltage control unit 94, in the normal printing mode, has an alternating electric field (for example, Vdc1 = 175V, Vpp = 1.7kV) between the drum 5 and the developing sleeve 21. A signal for operating the duty value D1 = 57% and the frequency f = 2.8 kHz is output to the power supply 50. As a result, the toner flies toward the surface of the drum 5.

On the other hand, the barcode printing control unit 98 is used only in the barcode printing mode. The print mode is set when the print data at the input port 80 includes barcode data, and a signal different from the normal print mode is sent to the drum linear speed control unit 92, the charging voltage control unit 96, and the development voltage control unit 94. Output each.
Referring to FIG. 3, there is shown a printing flowchart by the controller 90, and the operation according to the present invention will be described below.

In step S <b> 301 in the same figure, a print command is issued from the outside, and print data is input to the input port 80. Next, in step S302, the controller 90 determines whether or not the print data includes barcode data.
If the barcode data is not included, that is, if NO is determined, the process proceeds to step S303, and the above-described normal printing mode is set.

  That is, as shown in FIG. 4, the drum linear speed control unit 92 sets the rotation speed R1 of the drum 5 to 306 mm / sec, for example, and the charging voltage control unit 96 sets the surface potential b1 of the drum 5 to 270 V, for example. The unit 94 sets an alternating electric field (for example, Vdc1 = 175 V, Vpp = 1.7 kV, duty value D1 = 57%, frequency f = 2.8 kHz) of the developing bias V, and proceeds to step S304.

In step S304, the image forming unit 4 or the like starts printing and exits a series of routines.
On the other hand, if it is determined in step S302 described above that bar code data is included, the process proceeds to step S305, where the bar code print control unit 98 sets the bar code print mode.

More specifically, as shown in FIG. 4, the drum linear velocity control unit 92 in this mode drives a signal for setting the rotational speed R2 of the drum 5 to half the normal printing mode, for example, 153 mm / sec. Output to the motor.
Further, the charging voltage control unit 96 in this mode outputs to the power supply 50 a signal for setting the surface potential b2 of the drum 5 to 70% to 90% of the normal printing mode, for example, 230V, which is approximately 85%. This is because, if it is less than 70%, line thickening and fogging become remarkable, and if it exceeds 90%, fogging due to reversely charged toner may occur.

  Further, the developing voltage control unit 94 in this mode also sets the alternating electric field of the developing bias V to a magnitude less than half that of the normal printing mode. More specifically, of this alternating electric field, the AC component Vpp and the frequency f are set to the same values as in the normal print mode, but the DC component Vdc2 is set to 90 V, for example, and the duty value D2 is set to 26%, for example. The signal is output to the power source 50, and the image forming unit 4 and the like start printing in step S304 and exit from the series of routines.

As described above, according to the present embodiment, when the print data is bar code data, the bar code print control unit 98 first sets the duty value D2 of the developing bias to 45.6% of the normal print mode. Reduce to the magnitude of the degree.
The duty value D of the developing bias is a factor that affects the developing time. For example, if the duty value is decreased, the developing time for supplying the toner to the drum 5 is shortened, and the toner consumption is reduced. That is, as shown in FIG. 4, when the barcode data is not included (D1 = 57%) and reduced to half or less (D2 = 26%), the toner is less likely to adhere to the bar portion. Difficult to scatter in space.

Therefore, compared to the conventional configuration, that is, when the test image for barcode data is output to the non-image area on the drum surface, there is no consumption of toner that is not used for printing on the paper, and the running cost of the printer 1 Contributes to the reduction of
On the other hand, if only the duty value D is simply reduced, the peak value of the developing bias V may increase, and this causes the toner to vibrate easily and scatter to the drum 5, and the developing time is also increased. Since it is short, developability deteriorates.

However, the bar code printing control unit 98 reduces the value of the DC component Vdc of the developing bias to about 51.4% of the normal printing mode.
The DC component Vdc is a factor that affects the developing ability. For example, if the value of the direct current component Vdc is reduced, the peak value can be suppressed. Therefore, the leak toward the drum 5 is reduced to 51.4% (Vdc2 = 90V) when the barcode data is not included (Vdc1 = 175V) as shown in FIG. Avoid leaks.

Further, the bar code printing control unit 98 reduces the value of the DC component vdc of the charging bias, and reduces the surface potential b of the drum 5 to about 85.2% of the normal printing mode.
The DC component vdc of the charging bias is a factor that affects the surface potential of the drum 5. For example, if the value of the DC component vdc decreases, the surface potential b also decreases and the reproducibility of one dot is good. Become. This is because the potential difference between the surface potential b of the drum 5 and the developing bias V increases, and the toner is difficult to scatter. Therefore, with respect to the above-described deterioration in developability, as shown in FIG. 4, in order to reduce the charging bias to 80% (b2 = + 230 V) when the barcode data is not included (b1 = + 270 V), The value of the direct current component vdc is decreased to ensure the developability.

Further, the bar code printing control unit 98 reduces the rotational speed R of the drum 5 to a size of about 50.0% of the normal printing mode.
The system linear speed, that is, the rotational speed R of the drum 5 is also a factor that affects the developing ability. For example, if the rotational speed is reduced, printing is performed slowly. Therefore, the above-described deterioration in developability is reduced to half the size (R2 = 153 mm / sec) when barcode data is not included (R1 = 306 mm / sec) as shown in FIG. The developability is further ensured.

  As a result, the amount of toner adhering to the bar portion is suppressed as compared with the conventional case, the running cost of the printer 1 and the image forming method is reduced, leaks toward the drum 5 are avoided, and developability is reduced. Therefore, “scattering” between two adjacent bars, more specifically, toner scattered points during development, and “tailing” on the downstream side of the bar portion as viewed in the paper transport direction. More specifically, a toner tail mark generated at the time of fixing is avoided, and an improvement in bar code quality can be achieved.

This point will be described in detail.
FIG. 5 shows experimental results obtained by executing barcode data in the normal printing mode and barcode printing mode described above and examining the quality of the barcode data using a barcode reading device (REA PC-Scan / LD).
Specifically, the barcode quality can be evaluated by the Symbol Grade by A to D and F by digitizing.

And in this experiment, the average value measured 10 times about one barcode data is evaluated within the range of AD and F.
A positively charged magnetic toner is used as the toner, and the average particle diameter is 5.0 to 9.0 μm (1 μm = 1.0 × 10 ⁻⁶ m). The transfer portion 71 has a negative polarity. A high voltage bias is applied from the power supply 50.

  First, as shown on the left side of the figure, when bar code data is executed in the normal print mode, the “scattering” between two adjacent bars or the downstream side of the bar portion as viewed in the paper transport direction “Tailing” was observed in some cases, and the barcode quality was D rank of 1.25. This D rank can be read, but the image quality required for the electrophotographic printer 1 is not sufficient.

On the other hand, as shown in the right side of the figure, when the barcode data is executed in the barcode printing mode, these “scattering” and “tailing” are hardly recognized, and the barcode quality is 1.93. Was raised to C rank.
That is, when the print data is barcode data, it can be understood that both the improvement of the barcode quality and the reduction of the running cost can be achieved by using the barcode printing mode described above.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the claims. For example, a part of the configurations of the above embodiments can be omitted or arbitrarily combined so as to be different from the above.
In the above embodiment, an example of a printer having a printing function is shown. However, the image forming apparatus of the present invention can be applied to a copying machine, a facsimile machine, a multifunction machine, and the like in addition to a printer.

1 is a cross-sectional view of an image forming apparatus in the present embodiment. It is a schematic block diagram of the apparatus of FIG. FIG. 3 is a printing flowchart by the controller of FIG. 2. FIG. It is explanatory drawing of the setting value by the controller of FIG. It is explanatory drawing of the experimental result by the controller of FIG.

Explanation of symbols

1 Printer (image forming device)
5 Photosensitive drum (image carrier)
6 Charger 20 Developing Unit 90 Engine Controller 92 Drum Linear Speed Control Unit (Linear Speed Control Unit)
94 Development Voltage Control Unit 96 Charging Voltage Control Unit 98 Barcode Printing Control Unit

Claims (4)

An image forming apparatus capable of printing barcode data on a recording material,
An image carrier on which an electrostatic latent image is formed; and
A developing bias in which an alternating current component is superimposed on a direct current component, and a toner image is developed by supplying toner to the electrostatic latent image;
A developing voltage controller for controlling the developing bias;
When the print data is the barcode data, a signal for reducing the duty value of the developing bias and the DC component value to 55% or less when the barcode data is not included An image forming apparatus comprising: a bar code printing control unit that outputs to a printing unit. The image forming apparatus according to claim 1,
A charging bias having at least a direct current component is applied, and charging the surface of the image carrier;
A charging voltage control unit for controlling the charging bias;
When the print data is the barcode data, the barcode print control unit reduces the surface potential of the image carrier to 70% to 90% when the barcode data is not included. In order to achieve this, an image forming apparatus is characterized in that a signal for reducing the DC component value of the charging bias is output to the charging voltage control unit. The image forming apparatus according to claim 1, wherein
A linear velocity control unit for controlling the rotational speed of the image carrier,
When the print data is the bar code data, the bar code print control unit sends a signal to the linear speed control unit to reduce the rotation speed of the image carrier compared to the case where the bar code data is not included. An image forming apparatus that outputs the image. An image forming method for printing barcode data on a recording material,
If the print data is the barcode data,
Setting the rotational speed of the image carrier on which the electrostatic latent image is formed on the surface thereof to be lower than when the barcode data is not included, and driving the image carrier;
In order to reduce the surface potential of the image carrier to 70% to 90% when the barcode data is not included, the DC component value of the charging bias is set small, and the surface of the image carrier is Charging step;
Of the developing bias in which the AC component is superimposed on the DC component, the duty value and the DC component value are set to 55% or less of the case where the barcode data is not included, and the toner is transferred to the electrostatic latent image. And an image forming method comprising the steps of:

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