JPH0410568Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a recording device using a liquid crystal shutter.

[Prior Art] A recording device that records by light using a liquid crystal optical shutter (hereinafter referred to as a liquid crystal printer) has been put into practical use as an alternative to an impact printer that prints mechanically.

In this liquid crystal printer, for example, a long liquid crystal cell is arranged near a photoreceptor drum used in electrophotographic copying, parallel to the rotation axis of the photoreceptor drum, and a large number of liquid crystal cells are arranged along the longitudinal direction of the photoreceptor drum. The microshutter is opened and closed according to the recording signal, the light from the light source installed near the liquid crystal cell is transmitted or blocked by the microshutter, and the light transmitted through the microshutter is transmitted to a 1-magnification imaging lens array ( For example, there is a product called Self-Ox Lens Array (trade name) that performs recording by forming an image on the surface of a photoreceptor drum.

In conventional liquid crystal printers, when performing optical recording on the photoreceptor drum as described above, the light source is turned on continuously, and the above-mentioned microshutter constantly irradiates light onto the liquid crystal cell while being driven to open and close. . The photoreceptor drum also rotates continuously, and the rotating photoreceptor drum is irradiated with transmitted light from the microshutter.

[Problems with conventional technology]

In the conventional recording apparatus as described above, a moving photoreceptor drum is irradiated with light transmitted through a microshutter for a predetermined period of time, so that one dot of white or black formed on the photoreceptor drum is The print becomes elongated due to the movement of the photoreceptor drum.
Moreover, since the opening and closing of the microshutter is performed by changing the alignment direction of the liquid crystal, the rise and fall of the opening and closing operations are slow. For this reason, a single dot of white or black print formed on the photoreceptor drum becomes a rectangular or oval print that extends in the direction of movement of the photoreceptor drum (sub-scanning direction), and furthermore, at both ends of the print, Printing is not clear because the amount of irradiation light is not sufficient.

Therefore, in conventional recording devices, the boundary between white or black print in the sub-scanning direction is sharper than in the longitudinal direction (main-scanning direction) of the liquid crystal cell, where printing is not related to the movement of the photoreceptor drum. Inferior. This is particularly noticeable when lines are recorded, with lines extending in the sub-scanning direction being recorded sharper than lines extending in the main-scanning direction.

[Purpose of invention]

In view of the above-mentioned conventional drawbacks, the present invention aims to provide a recording device that is capable of sharply recording lines extending in the main scanning direction as well as lines extending in the sub-scanning direction. .

[Key points of the idea]

In order to achieve the above object, the present invention includes a moving photoreceptor, a liquid crystal light shutter provided in a direction intersecting the moving direction of the photoreceptor, and a light source for illuminating the liquid crystal light shutter. In a recording device that performs optical recording by transmitting or blocking light by the liquid crystal light shutter and irradiating the transmitted light to the photoreceptor, the liquid crystal light shutter is used for dividing the writing cycle of the liquid crystal light shutter. A common electrode for supplying a division selection signal and a signal electrode for supplying an opening/closing signal to the liquid crystal light shutter are provided at a cross-opposed portion, and the liquid crystal light shutter is operated during a selection period in which the liquid crystal light shutter is selected by both electrodes. A drive signal that sets the open or closed state is applied, and a drive signal that continues the open or closed state is applied during a non-selection period following the selection period, and the light source sets or continues the open or closed state. The liquid crystal light shutter is characterized in that light is emitted during a period when the open or closed state of the liquid crystal light shutter is stable in response to a drive signal.

[Embodiments of the invention] Examples of the invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram of a liquid crystal printer, which is a recording device according to the present invention. In the figure, a charger 2, an optical recording section 3, a developing device 4, a transfer device 5, a cleaner 6, etc. are provided near the circumferential surface of the photoreceptor drum 1, and the photoreceptor drum 1 is moved in the direction of the arrow shown in the figure. Rotate to.

The optical recording section 3 is composed of a light source 7, a liquid crystal shutter unit 8, an imaging lens array 9, and a shutter drive circuit (not shown).The light emitted from the light source 7 is transmitted or blocked by a microshutter, which will be described later, provided in the liquid crystal shutter unit 8. The light transmitted through the microshutter is then imaged on the surface of the photoreceptor drum 1 by an imaging lens array 9 having an imaging function.

As shown in FIG. 2, the light source 7 includes a light transmission rod 7a made of transparent material such as quartz glass or acrylic.
A light diffusing section 7b is provided on the upper surface of the optical transmission rod 7a in the longitudinal direction of the optical transmission rod 7a, and a reflecting tube 7 is formed to cover the optical transmission rod 7a and form an opening 7c downward.
d, and a xenon lamp (not shown). The optical transmission rod 7 is transmitted through the above-mentioned opening 7c.
A and the upper surface of the liquid crystal shutter unit 8 are disposed to face each other, and the light from the xenon lamp from the direction of the arrow A propagates while being totally reflected on the inner wall surface of the light transmission rod 7a, and enters the light diffusion section 7b during propagation. The light is diffusely reflected, and a part of the diffusely reflected light is emitted from the opening 7c to a microshutter formed in the liquid crystal shutter unit 8. Further, the xenon lamp (not shown) is connected to a control circuit (not shown) that lights up intermittently at a period to be described later, and in synchronization with the intermittent lighting of the xenon lamp, intermittent light is also sent to the liquid crystal shutter unit 8 through the opening 7c. irradiated.

As shown in a partial perspective view in FIG. 3, the liquid crystal shutter unit 8 has two upper and lower glass substrates 11.
It is configured based on a and 11b. and,
A common electrode, which will be described later, is arranged on the lower surface of the upper glass substrate 11a, and a signal electrode, which will also be described later, is arranged on the upper surface of the lower glass substrate 11b. Both the common electrode and the signal electrode are made of a conductive material coated with chrome plating or the like that does not transmit light, but the intersection of each electrode constituting the microshutter 12 is made of a transparent conductive material.

In addition, in the liquid crystal printer of this embodiment, in order to open and close the micro-shutter 12 at high speed (for example, one writing period of 2 ms, which will be described later), a guest-host type liquid crystal agent is used in the micro-shutter 12, and drive is performed in two time divisions. is carried out, and a two-frequency driving method is used.

Among liquid crystals, this two-frequency driving method uses a liquid crystal agent whose dielectric anisotropy is reversed in polarity depending on the frequency of the applied electric field. The frequency at which the dielectric anisotropy becomes zero is called the crossing frequency _C , and a frequency _L lower than the crossing frequency _C and a frequency _H higher than the crossing frequency C are used to open and close each microshutter 12.

Also, because of the two-time division drive, the micro shutter 12
are arranged in two rows in a staggered manner.

Next, the configuration of each electrode will be explained using FIGS. 4a and 4b.

As described above, the common electrode formed on the lower surface of the upper glass substrate 11a is composed of two common electrodes 13a and 13b. Further, the signal electrodes provided on the upper surface of the lower glass substrate 11b include a large number of signal electrodes 14.
The pattern configuration is such that adjacent signal electrodes have their ends drawn out in opposite directions.

In addition, the common electrodes 13a and 13b and the signal electrode 14
As shown in FIG. 4b, the intersecting portions are composed of transparent members 15a, 15b (however, the common electrodes 13a, 13b are not shown) to allow light to pass through, and the microshutters 12a, 12b... It consists of

The operation of the liquid crystal printer configured as described above will be explained below.

First, the (image forming) operation by the photosensitive drum 1 will be explained using FIG.

When a waveform signal, which will be described later, is supplied from a control circuit (not shown) to the signal electrode 14 and the common electrodes 13a, 13b, the microshutters 12, 12a, 12b, . . .
is driven to open and close by this waveform signal, and transmits or blocks light emitted intermittently from the light source 7. Here, the light transmitted through the microshutter 11 is imaged on the surface of the photoreceptor drum 1 by the imaging lens array 9.

At this time, the photosensitive drum 1 is charged to a uniform potential by the charger 2 due to corona discharge, and is irradiated with recording light from the above-mentioned optical recording section 3 to form an electrostatic latent image on the surface. . In this way, the photosensitive drum 1
The electrostatic latent image formed on the surface of the photosensitive drum 1 is developed by the developing device 4 as the photosensitive drum 1 rotates in the direction of the arrow, and becomes a toner image, which is superimposed on the transfer paper 10 sent out from a paper feed section (not shown). The toner is transferred onto the transfer paper 10 by the corona discharge performed by the transfer device 5 .

The toner image transferred to the transfer paper 10 is thermally fixed onto the transfer paper 10 by a fixing section (not shown), and the toner image is transferred to the transfer paper 10.
0 is ejected to the outside of the liquid crystal printer. Further, toner remaining on the photoreceptor drum 1 without being transferred to the transfer paper 10 despite the corona discharge of the transfer device 5 is removed from the surface of the photoreceptor drum 1 by the cleaner 6 .

During the image forming operation as described above, the microshutter 12 has the common electrodes 13a, 13b,
Waveform signals shown in FIGS. 5a to 5e are supplied from the signal electrode 14, and the microshutter 12 is driven to open and close.

That is _, in the _first half period T _{w /} 2 shown _{in FIG} . It is supplied to the common electrode 13a.

In addition, the combined waveform signal of frequencies _H and _L is applied to the common electrode 1 during the first half period T _w /2 shown in the figure b, and the waveform signal of frequency _H is applied to the common electrode 1 during the latter half period T _w /2.
3b.

Further, c and d in the same figure are waveform signals supplied to the signal electrode 14, which are superimposed on the waveform signals a and b in the same figure mentioned above in the microshutter 12 to open or close the microshutter 11. This is a signal for The waveform signal c in the figure is a signal for setting the microshutter 12 to close, and the waveform signal d in the figure is a signal for setting the microshutter 12 to open.

However, the period T _{w /}
2 is a period for selecting opening/closing of the microshutter 12a (hereinafter referred to as a selection period), and a period T _w /2 in the latter half of the writing cycle T _w is a selection period of the microshutter 12b.

In other words, the first half of the writing period T _w is T _w /
In step 2, opening and closing of the microshutter 12a on the common electrode 13a is selected by supplying the waveform signal c or d in the figure to each signal electrode 14, and in the second half period T _w /2, the waveform signal shown in the figure c or d is supplied to each signal electrode 14. c.
Alternatively, opening/closing of the microshutter 12b on the common electrode 13b is selected by supplying the waveform signal d.

When a waveform signal as described above (a in the figure) is supplied, for example, to the common electrode 13a, and waveform signals shown in c and d in the figure are supplied to the signal electrode 14, each waveform signal supplied to the microshutter 12a is The superimposed waveforms are the waveforms shown in e to h in the figure.

That is, the micro shutter 12a has the above-mentioned
During the selection period in the first half of T _w , a superimposed waveform that sets opening and closing as shown in e or f in the same figure is applied, and the above-mentioned
A superimposed waveform as shown in g or h in the figure is applied during the non-selection period in the latter half of _Tw . In addition, a superimposed waveform as shown in e or f in the figure is applied to the microshutter 12b during the selection period in the latter half of the above-mentioned _Tw , and as shown in g or h in the figure during the non-selection period in the first half of the above-mentioned _Tw . The superimposed waveform shown will be applied.

It should be noted that when the superimposed waveform shown in g or h of the figure is supplied, the microshutter 12 continues in its previous open or closed state.

Therefore, the time-division drive of this embodiment not only keeps the microshutter 12 open or closed only during the allocated period as in normal time-division (two-time division) driving, but also keeps the microshutter 12 open or closed only during the allocated period. It is a drive that maintains the open or closed state set during the selection period even during the selection period, and in particular, such a drive is
It is called SD drive. Moreover, this driving method was developed in Japanese Patent Application Laid-open No.
143316, which is disclosed in detail.

Microshutter 1 is generated by such a superimposed waveform.
FIG. 6 shows the opening/closing response and amount of transmitted light of each microshutter 12a, 12b . For example, the microshutter 12a on one signal electrode 14 is driven to open, close, open, close, and the other microshutter 12b is opened.
The opening/closing response characteristics of the microshutters 12a and 12b when driven to open, close, and close are shown as 201 and 202 in FIGS.

In this embodiment, the light source 7 is lit intermittently by a xenon lamp. A signal 203 in c of the same figure indicates the lighting timing of the light source 7 described above. That is, the light is output at a predetermined time in one writing cycle _Tw , and as described above, this light irradiates each microshutter for a predetermined time T via the optical transmission rod 7a. Therefore, for example, the amount of transmitted light that passes through the microshutter 12a is when the above-mentioned 201 is open, and during the time T, and the amount of transmitted light is the amount of transmitted light that is transmitted through the microshutter 12a as shown in 204 (d) in the figure.
becomes. Further, the amount of transmitted light that passes through the microshutter 12b is when the above-mentioned 202 is open and during the time T, and the amount of transmitted light is 205 shown in the figure e.
becomes. Therefore, as shown at 201 and 202, the delay in the rise and fall of the opening and closing of the microshutter 12 is not used as transmitted light, and the transmitted light depends on the light emission of the xenon lamp, and the rise and fall of the transmitted light is The fall is also fast. Therefore, the rise and fall are fast, and the photosensitive drum 1 can be irradiated with intense light in an extremely short period of time.

Furthermore, by using SD drive as a time-division driving method, two shutters can be driven with one signal electrode, and even though the light source 7 is lit using time-division driving, one writing period T It is enough to light it once within _w .

In addition, in the above-mentioned embodiment, the micro shutter 12
Although the size of the microshutter 12a and the microshutter 12b have been described as being the same, the microshutter 12a
is irradiated during the non-selection period, whereas the microshutter 12b is irradiated during the selection period. As described above, even if the previous open/closed state is continued during the non-selection period, the amount of transmitted light is slightly smaller than when the opening is in the immediately previous non-selection period.

Therefore, the amount of transmitted light between the microshutters 12a and 12b is different, and in some cases this may appear as a difference in dot size on the image (the dot size is not directly determined by the shutter size, but is caused by flare light). It has been confirmed that this is determined by the amount of light transmitted through the shutter due to the influence of other factors). Therefore, in this case, the micro shutter 12
If the size of b is set slightly larger, there will be no difference in dot size, and a better image can be obtained.

In the above embodiment, a xenon lamp was used as the light source lamp, but the lamp is not limited to this, but any lamp that turns on and off at high speed and emits a sufficient amount of light may be used as well. It is possible to obtain images.

[Effect of idea]

As described in detail above, according to the present invention, recording dots in both the main scanning direction and the sub-scanning direction can be printed sharply, resulting in a good recorded image, which is particularly effective when recording lines.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the liquid crystal printer of this embodiment, Fig. 2 is a block diagram of the light source used in the liquid crystal printer of this embodiment, and Fig. 3 is a block diagram of the liquid crystal shutter unit used in the liquid crystal printer of this embodiment. , Figures 4a and 4b are electrode configuration diagrams of the liquid crystal shutter unit used in the liquid crystal printer of this embodiment, and Figures 5a to h
6 is a configuration diagram of a waveform signal supplied to the liquid crystal shutter unit, and FIGS. 6a to 6e are configuration diagrams showing the amount of light transmitted through the liquid crystal shutter unit. 1... Photosensitive drum, 3... Optical recording section, 7...
Light source, 7a... Optical transmission rod, 7c... Opening,
8...Liquid crystal shutter unit, 12...Micro shutter, 13a, 13b...Common electrode, 14...
...Signal electrode.

Claims (1)

[Claims for Utility Model Registration] A system comprising a moving photoreceptor, a liquid crystal light shutter provided in a direction intersecting the moving direction of the photoreceptor, and a light source for illuminating the liquid crystal light shutter, the light source emitting light from the light source. In a recording device that performs optical recording by irradiating the photoreceptor with transmitted light transmitted or blocked by the liquid crystal light shutter, the liquid crystal light shutter is provided with a time division selection signal for dividing a writing period of the liquid crystal light shutter. and a signal electrode that supplies an opening/closing signal to the liquid crystal light shutter. A drive signal that sets a state is applied, and a drive signal that continues the open or closed state is applied during a non-selection period following the selection period, and the light source is configured to apply a drive signal that sets or continues the open or closed state. A recording apparatus characterized in that the liquid crystal light shutter emits light during a period in which the open or closed state of the liquid crystal light shutter is stable.