JPH0289470A - Light beam printer - Google Patents

Abstract

PURPOSE:To always obtain a print output with high quality by providing a print density designation means and a means setting the operating condition of a photosensitive body through the designation of the said means. CONSTITUTION:A high voltage power supply circuit HVS1 26 uses a signal S1 so as to revise the quantity of charge given uniformly to the photosensitive drum 9 while switching a generating voltage. A circuit HVS2 receives a signal S2 to vary a bias voltage fed to a development sleeve. A circuit HVS3 receives a signal S3 to vary corona discharge quantity to transfer a development agent onto transfer paper. A device 29 receives a signal S4 to vary a temperature fixing thermally the development agent onto the transfer paper. A controller 30 receives a dot density request DCNG to output the signals S1-S4 thereby setting various conditions such as charging/development /transfer/fixing to optimum values. Thus, a print output with high quality is always obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light beam printer that enables switching control of print dot density.

(Prior Art) Conventionally, non-impact printers using electrophotographic processes include laser beam printers (hereinafter abbreviated as LBP) using laser diodes, LED printers using light emitting auto arrays as light sources, and liquid crystal printers. Liquid crystal printers using shutters are known. Among them,
LB that allows you to easily change the size of the dots in the output image
P uses a signal from an external device, a changeover switch, etc.
Some have variable dot density.

FIG. 8 shows the configuration of a conventional LBP in which the dot density can be switched. 1 is image data sent from an external device, etc., and is manually input to the video generator 2.

The video generator 2 develops the image data 1 into a bitmap based on the clock signal (image clock) sent from the oscillator 3, generates a video signal that is a modulation signal for the laser diode 5, and sends the video signal to the laser control circuit 4. send.

The oscillation frequency of the oscillator 3 is switched by a control signal sent from the control circuit 23. Therefore, the maximum frequency of the video signal is switched.

The laser control circuit 4 includes a laser diode 5
The drive current is modulated by the video signal, and the amount of laser light is switched by a control signal from the control circuit 23.

The modulated laser beam 12 is reflected by the rotating polygon mirror 6 and raster-scans the surface of the photosensitive drum 9.

The rotating polygon mirror 6 is controlled to rotate at a constant speed by a motor 7 and a motor control circuit 8 provided along its axial length.

The control circuit 8 is connected to the control circuit 23.
The rotation speed of the rotating polygon mirror 6 is switched by a control signal sent from the polygon mirror 6.

Next, an image forming operation by an electrophotographic process using the above-mentioned laser light source will be explained.

IO is a primary charger that performs positive corona discharge based on the voltage supplied from the high-voltage power supply circuit 11, and uniformly applies positive charge to the surface of the photosensitive drum 9. The photosensitive drum 9 rotates at a constant speed as shown by the arrow, and forms a latent image on its surface using the modulated laser beam 12, which is further developed in a developing device 13 with a developer, such as toner. The developer 13
A developing cylinder for adhering the toner to the surface of the photosensitive drum 9 is provided in close proximity to the surface of the photosensitive drum 9, and an electric field is generated in the developing section by the voltage supplied from the high-voltage power supply circuit 14 to perform development with the toner. The formed visible image is transferred by a transfer charger 17 onto the surface of the transfer paper 15 that is conveyed by a conveyance roller 16 .

The transfer charger 17 performs negative corona discharge based on the voltage supplied from the high-voltage power supply circuit 18, and causes the toner on the surface of the photosensitive drum 9 to adhere to the transfer paper 15.

The transfer paper 15 on which the image has been formed is sent to a fixing device 20 by a conveyor belt 19. A pair of rollers (hereinafter referred to as fixing rollers) provided in the fixing device 20 are controlled to a constant temperature by a heater and a fixing temperature control circuit 25 (not shown), and as the transfer paper 15 passes between the fixing rollers, The toner is thermally fixed on the transfer paper 15 and printing is completed. Further, after the transfer is completed, the toner remaining on the surface of the photosensitive drum 9 is cleaned by a cleaner 21, and the photosensitive drum 9 is further initialized by an exposure lamp 22.

Next, conventional dot density switching control with the above configuration will be explained. The control circuit 23 performs control by receiving dot density switching information from an external device.

In the conventional example described above, the dot density switching information is obtained by receiving a dot density command (DCNG) through the interface bus 24 with an external device.

Upon receiving the command, oscillator 3. Laser control circuit 4. A control signal corresponding to the dot density is given to the motor control circuit 8, and the dot density switching is completed.

[Problem to be solved by the invention]

However, in the conventional example described above, when switching the dot density, only the laser light intensity at the light source, the scanning speed, and the modulation frequency are controlled, so it is not possible to handle high density printing dots, and the printing quality is significantly reduced. It was expected to decrease.

SUMMARY OF THE INVENTION In view of the above-mentioned points, an object of the present invention is to provide a light beam printer that is configured to handle even high-density printing dots.

[Means to solve the problem]

In order to achieve such an object, the present invention provides a light beam printer device that controls an exposure means in accordance with recording information from an external device to record information on a photoreceptor, including a printing density specifying means for specifying the printing density of recorded information. and control means for setting operating conditions of the photoreceptor in response to the designation by the print density designation means.

[Function] According to the present invention, in a light beam printer that uses an electrophotographic process and can change the dot density of a light source that irradiates a photoreceptor according to external information, for example, the photoreceptor is means for changing the amount of charge uniformly applied to the developing sleeve; means for changing the bias voltage applied to the developing sleeve; means for changing the amount of corona discharge for transferring the developer to the transfer paper; By providing means for changing the temperature at which the agent is thermally fixed, various conditions of charging, development, transfer, and fixing are controlled to optimal values according to the dot density.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing the main configuration of an embodiment of the present invention. Note that the same parts as in FIG. 8 are given the same reference numerals.

Reference numeral 26 denotes a high-voltage power supply circuit 1 (hereinafter abbreviated as ■Vs 1) for changing the amount of charge on the photoreceptor. Said +1Vs
I (26) supplies a high voltage to the negative charger 101 to uniformly charge the photosensitive drum 9 by performing corona discharge. Moreover, HVSI (26) is the control circuit 30
The generated voltage is switched by a control signal Sl.

26 is a high-voltage power supply circuit 2 (hereinafter abbreviated as 11Vs2) constituting a means for changing the bias voltage applied to the developing sleeve, which applies a bias voltage to the developing sleeve of the developing device 13 and causes the developer to be applied to the photosensitive drum 9. Perform the development.

Furthermore, HVS2 (27) switches the generated voltage using the control signal S2 from the control circuit 30.

28 is a high-voltage power supply circuit 3 (hereinafter abbreviated as HVS3) that constitutes a means for changing the amount of corona discharge for transfer, and supplies a high voltage to the transfer charger 17 to form a toner image on the transfer paper 15. Perform the transcription. Also, 1lVs3(
28) switches the generated voltage according to the control signal S3 from the control circuit 30.

29 is a temperature control circuit (hereinafter abbreviated as FSC) which constitutes means for changing the temperature at which the developer is thermally fixed on the transfer paper; it detects the temperature of the fixing roller of the fixing device 20 and uses a heater to adjust the temperature Control the temperature. Further, the FSC 29 switches the temperature to be controlled by the control signal S4 from the control circuit 30.

The control circuit 30 outputs each of the control signals 5l-54 by receiving a dot density command (DCNG) from an external device (not shown) through the data bus 24.

Next, each of the above-mentioned control means will be specifically explained.

FIG. 2 is a block diagram showing the configuration of the control circuit 30. As shown in FIG. 31 is a microcomputer (hereinafter referred to as CPU)
It is equipped with a ROM 32 that stores programs and an rlAM 33 that temporarily stores data, and executes control. 24 is a data bus, and when CPυ31 receives the dot density command DCNG, it sends a control signal 5l-
54 is output according to the dot density. 55 to Sn are control signals used elsewhere.

FIG. 3 is a block diagram showing the configuration of IVsI (2B), and FIG. 4 is a block diagram showing the configuration of IIVS3 (28). IIVsI (26) and IIVS3 (28)
The IIVSI (26) in FIG. 3 will be explained here because they operate in substantially the same way, although the polarity of the output high voltage is different.

In FIG. 3, 34 is a reference voltage generator, which generates two different voltages.

35 is a switch circuit, and according to the control signal S1,
One of the reference voltages sent from the reference voltage generator 34 is sent to the inverting input of the differential amplifier 36. A feedback signal of primary charging high voltage +1vI is input to the non-inverting input of the differential amplifier 36. The output voltage of the differential amplifier 36 is determined according to the two inputs, and is input to the pulse width modulation circuit 37.

38 is an oscillation circuit, and the oscillation output is from the pulse width modulation circuit 3.
7, the pulse width is determined based on the output voltage of the differential amplifier 36, and the pulse width is input to the drive circuit 39. The drive circuit 39 is connected to the primary side of the high voltage transformer 40 and generates a high voltage on the secondary side of the high voltage transformer 40 using the modulated pulses. The secondary output of the high voltage transformer 40 is rectified and smoothed, and a high voltage 1-IV is supplied to the single charger IO.
Supply I.

Since the corona current in the primary charger 10 is fed back to the non-inverting input of the differential amplifier 36 through a resistor, the base voltage of the reference voltage generator 34 is increased. 1! Maintains a constant value depending on the voltage. Therefore, by switching the switch circuit 35 using the control signal Sl, the discharge amount of the negative charger IO is switched.

II V S 3 shown in FIG. 4 has a different polarity from +1VsI mentioned above, and the reference voltage generator 34'
The switch circuit 35' operates in the same manner as 4.
, the differential amplifier 36' is 36, the pulse width modulation circuit 37' is 37, the oscillation circuit 38' is 38, the drive circuit 39' is 39,
The high voltage transformer 40' performs the same operation as 40, and by reversing the polarity of the rectifying diode of the secondary output of the high voltage transformer 40' (generating high voltage HV3), the transfer charger is activated by the control signal S3. 17 corona current switching is performed.

FIG. 5 shows the bias voltage H applied to the developing sleeve of the developing device 13.
FIG. 2 is a block diagram showing the configuration of HV2 (27) that supplies V2. The bias voltage 11v2 is generated by combining the output voltages from the AC voltage generator and the DC voltage generator. The AC voltage generation section includes an oscillation circuit 41, an amplifier 42. Attenuator circuit 43. Drive circuit 44, high voltage transformer 45
It consists of

The oscillation output from the oscillation circuit 41 is amplified by the amplifier 42. The attenuator circuit 43 cuts the voltage level of the amplified oscillation output by using the control signal S2. The oscillation output that has passed through the attenuator circuit 43 is input to a drive circuit 44, causing a high voltage transformer 45 connected to the drive circuit 44 to oscillate. As a result, the high voltage transformer 4
AC voltage is generated on the 50 secondary side. Since the voltage level of the oscillation output that has passed through the attenuator circuit 43 is switched by the control signal S2, the AC voltage level generated by the high voltage transformer 45 is switched.

The DC voltage generator includes a reference voltage generator 46. Switch circuit 47. Differential amplifier 482 oscillation circuit 49. drive circuit 50,
It is composed of a high voltage transformer 51.

Reference voltage generator 46 generates two different voltages.

47 is a switch circuit, and according to the control signal S2,
One of the reference voltages sent from the reference voltage generator 34 is sent to the differential amplifier 48 . A feedback signal of the voltage generated by the high voltage transformer 5I is input to the other end of the differential amplifier 48. The output voltage of the differential amplifier 48 is determined depending on the two inputs. 5° is a drive circuit for the high voltage transformer 51, which oscillates the high voltage transformer 51 with the oscillation output of the oscillation circuit 49.

Further, the primary side current of the high voltage transformer 51 is controlled according to the output voltage of the differential amplifier 48 to generate a secondary side output voltage.

The secondary output of the high voltage transformer 51 is rectified and smoothed to become a DC voltage. The DC voltage is divided by a resistor and fed back to the differential amplifier 48, thereby maintaining a constant voltage according to the reference voltage of the reference voltage generator 46. Therefore, by switching the switch circuit 47 using the control signal S2, the DC voltage level generated by the high voltage transformer 51 is switched.

The AC voltage generated from the high voltage transformer 45 and the DC voltage are added to form the bias voltage 11v2, the voltage level of which is switched by the control signal S2.

FIG. 6 is a block diagram showing the configuration of the temperature control circuit (FSC) 29. A temperature detection sensor 52 is provided in the fixing device 20 and is composed of a resistor and a thermistor. That is, since the resistance value of the thermistor changes depending on the fixing temperature, the divided output voltage level also changes.

The output voltage of the temperature detection sensor 52 is input to a comparator 55 . A reference voltage selected by the reference voltage generator 53 and the switch circuit 54 is applied to the other input of the comparator 55, and is compared with the output voltage of the temperature detection sensor 52.

The relay circuit 56 operates according to the output result of the comparator 55,
AC to the halogen heater 58 provided in the fixing device 20
An operation of supplying voltage 57 is performed. Thereby, the fixing temperature is kept constant at the point where the output voltage of the temperature detection sensor 52 and the reference voltage of the reference voltage generator 53 match. Therefore, the fixing temperature is changed by switching the switch circuit 54 using the control signal S4.

In the above-described embodiment, the rotational speed of the photosensitive drum 9, that is, the printing speed of the transfer paper 15 was controlled as being fixed, but means for changing the printing speed may be combined.

FIG. 7 is a block diagram showing means for changing the printing speed. The same parts as in other drawings are given the same reference numerals. A conveyance motor 64 is a power scale for the photosensitive drum 9, conveyance roller 1B, conveyance belt 19, etc. in FIG. 1, and is controlled to rotate at a constant speed by a conveyance motor control circuit 66.

60 is an oscillation circuit, the oscillation output of which is frequency-divided by a frequency divider 61. The oscillation output frequency-divided by the frequency divider 61 is input to the PLI circuit 62 as a reference signal.

The PLL circuit 62 receives an output signal from a rotation sensor 65 that generates a pulse signal according to the rotation speed of the transport motor 64, performs phase control and frequency control, and performs PLL circuit 62.
An amplifier 63 provided at the output end of the L circuit 62 keeps the transport motor fi4 at a constant rotation speed.

The frequency divider 61 changes its frequency division ratio by control No. 3 SP sent from the control circuit 30. Therefore, base '1 of Pi circuit 62! The frequency of the A signal changes, and the rotation speed of the transport motor 64 also changes. Further, the CPU 31 simultaneously changes the interrupt cycle of the timer interrupt circuit 59 used for sequence control in response to the control signal ST.
Change sequence control.

It goes without saying that printing quality can be further improved by easily combining means for changing the printing speed as described above.

As described above, according to one embodiment of the present invention, in a light beam printer that uses an electrophotographic process and can change the dot density of a light source that irradiates a photoreceptor based on information from the outside, A means for changing the amount of charge uniformly applied to the photoconductor, a means for changing the bias voltage applied to the developing sleeve, a means for changing the amount of corona discharge for transferring developer to the transfer paper, and a transfer paper according to the information. By providing a means to change the temperature at which the developer is thermally fixed, the conditions for charging, development, transfer, and fixing can be controlled to optimal values according to the dot density, and printing is always possible even when the dot density is changed. You will be able to obtain high quality printouts.

(Effects of the Invention) As explained above, according to the present invention, high quality print output can always be obtained regardless of the size of the dot density.

[Brief explanation of the drawing]

1 is a diagram showing the main configuration of an embodiment of the present invention, FIG. 2 is a block diagram of the control circuit 30, FIG. 3 is a block diagram of the high voltage power supply circuit 26, and FIG. 4 is a block diagram of the high voltage power supply circuit 28. 5 is a block diagram of the high voltage power supply circuit 27, FIG. 6 is a block diagram of the temperature control circuit, FIG. 7 is a block diagram of the transport motor control circuit, and FIG. 8 is a block diagram of the conventional dot density switching method. FIG. 2 is a diagram showing a laser beam printer. lO... - charger, 13... developer, 17... transfer charger, 20... fixer, 26... high pressure? Four E source circuits 27... High voltage power supply circuit, 28... High voltage power supply circuit, 29... Temperature control circuit, 30... Control circuit.

Claims (1)

[Scope of Claims] 1) A light beam printer device that records information on a photoreceptor by controlling an exposure device according to recording information from an external device, comprising: a printing density specifying device that specifies a printing density of recorded information; 1. A light beam printer comprising: control means for setting operating conditions of a photoreceptor in response to designation by the density designation means. 2) Claim 1, wherein the printing density designation means includes at least means for changing the moving speed of the photoreceptor.
Optical beam printer as described in section.