JPS5827159A - printing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing apparatus, and more particularly to a two-color printing apparatus using a liquid crystal optical writing unit in an optical writing signal generating section.

Recent advances in information processing technology have been remarkable, and along with this, printing devices, which are one of the output devices, have also improved.
High quality performance is required, including multi-color printing and combination with copying functions. In particular, in the case of two-color printing, high speed is required since several printing processes are used, and high resolution and high quality are also required. Conventional printing devices that satisfy this requirement include laser beam printers (LBPs) that use electrophotography and optical writing, and optical fiber tube (OF) printers that use electrophotography and optical writing.
T) There are printers, but both LBP and OFT are extremely expensive, which prevents their widespread use. In view of this situation, the present invention uses a liquid crystal optical writing unit in the optical signal generating section to achieve high speed performance.

The purpose is to realize a multi-color printing device that has high resolution, high quality, and is inexpensive.

Regarding the composition of liquid crystal light pulp, please refer to the patent application No. 56-704.
7 etc., but will be briefly explained.

First, FIGS. 1 and 2 show the basic structure of a liquid crystal panel.

The liquid crystal panel includes a liquid crystal composition 125 sealed between a glass substrate 117 having common signal electrodes 119 and 120, a glass substrate 118 having signal electrodes 121 and 122, and a spacer 126, and polarizing plates 1 on both sides of the glass substrate.
25 and 124. The common signal electrode consists of a transparent electrode 119 and an optically opaque metal electrode 120,
Signal electrodes 121 and 122 are transparent electrodes.

The polarizing plates 123 and 124 are arranged so that their polarization planes are perpendicular to each other. The light is modulated by a microshutter formed by the transparent portion 119 of the common electrode and the signal electrode. In the text below, there are parts where the shape of the transparent portion of the common electrode is expressed as a microshutter, but in this case, please interpret it as forming a microshutter together with the opposing signal electrode.

The liquid crystal composition to be encapsulated is a nematic liquid crystal shown in Table 1 of Japanese Patent Application No. 55-141085 containing an optically active substance 4-(2-meth).
ylbutyl) -4' -oyano biphe
A high-speed liquid crystal light pulp can be obtained by using a long period cholesteric liquid crystal obtained by adding 3% by weight of nyls. The frequency characteristics of the dielectric anisotropy of this liquid crystal are shown in FIG. The frequency at which the dielectric anisotropy is zero is called the crossover frequency and is expressed by fc. The frequency lower than fc is f
Let the high frequency be fh. The liquid crystal light pulp operates by applying signals of frequencies ft and fh to each signal electrode. In Fig. 4 Ch), the applied signal and (a)
This shows the response of light transmitted through liquid crystal light pulp.

A signal at time fh indicated by T2 and a signal at time fl- at T3 are applied. T1 is called a write period, T2 is called an opening time, and T3 is called a non-opening time. The liquid crystal light valve opens by applying the fh signal, and closes by the ft signal. By the method described above, it was possible to obtain liquid crystal light pulp at a revolutionary high speed. In the present invention, the cost is further reduced by driving this in a time division of /2 utility.

FIG. 5 is a schematic diagram of a liquid crystal panel constituting the optical write signal generating section, and FIG. 6 shows driving waveforms. This feature is common electrode 1
51 and 152, the signal electrodes 153 to 156 cross and oppose the two common electrodes, and each signal electrode is provided with two microshutters 161 to 168.

Reference numeral 157 is a mask for preventing light from leaking through the gap between the common electrodes, and light leaks through the gap 158, but this was designed to be sufficiently small, so there was no problem in practical use.

The driving method is to apply 172 to the common electrodes 151 and 152, respectively.
, 171, FOn signal 173 when opening the microshutter, and Foff signal 174 when closing it.
, are added to the signal electrodes 153-156. Common electrode signal 1
71 and 172 have a repetition period Tf, and Ta and Tt) are each half period. In the 72 time division, the first half 172 and the second half of one cycle of the common electrode signal 171 are respectively selected. The signal waveform of 171 is named 02, and the signal waveform of 172 is named 01. The selection signal is a high frequency fh with a frequency higher than the crossover frequency fo, and a low frequency f with a frequency and wave number lower than fo.
It consists of L, and the respective times are Th and To. When not selected, only the low frequency fL is available.

On the other hand, the signal waveforms applied to the signal electrode side are 173 for the microshutter opening signal (11'o, n) and 174 for the closing signal (poff). FOn,? off and half the period of the common electrode signal C1 or C2 (Ta or T
b). Open signal I! 'on has the same length Th as the high frequency part of cl (or 02) and has a high frequency part of opposite phase,
It is composed of a low frequency of 01 (or 02) and a low frequency of opposite phase. The closed signal Foffi is only a low frequency wave having an opposite phase to the low frequency fI of cz (or 02).

By applying the FOn and FOff signals to the signal electrodes, the microshutter selected by the common electrode signal is operated, and the other microshutter is closed. Based on the above principle, optical writing is performed based on time-series pixel signals. The microshutters are arranged in a staggered manner in the longitudinal direction at a pitch of tμ (of course, the sparkle between 161 and 163 is 2tμ), and the odd number rows of 161, 163, 165, 167, and the rows of 162.164, 166.168. The even-numbered columns are separated by 2.5 tμm. As described above, since the microshutters are driven in a time-division manner, for example, after writing to the odd-numbered columns of the microshutters, the even-numbered columns are written half a cycle later. The care light body (written part) is moved in the direction of the arrow at the writing cycle T.
Assuming that t μ rinsing is performed per fm wave, in order to write a normal pixel signal in the longitudinal direction for one line of input time-series pixel signals, the distance between the microshutter rows must be 2.5
Since the distance is μtn, 2
．． Even columns must be written after a delay of 5 cycles (2.5 T f m).

Next, when using the device for this purpose, no voltage is applied to the liquid crystal during standby. However, since the response of the liquid crystal used in the present invention immediately after voltage application is different from that in a steady state, an operation is performed to apply a low frequency to the liquid crystal for 0.2 to 1 second immediately before a write command is issued. This is called refresh, and by performing a refresh operation, a steady-state high-speed response can be obtained immediately after a write command is issued.

FIG. 7 shows a block diagram of the drive circuit, and FIG. 8 shows its signal waveform. Now, it is assumed that there are a total of N microshutters and the writing period is Tf, (8). A clock generated by a reference clock generator 181 is frequency-divided by a frequency divider 182, and a liquid crystal drive signal generator 183 generates various signals, an open signal 209. Close signal 210. Common electrode signals 211, 212 are created.

Among these, open signal 209. The close signal 210 is input to the open/close signal selection unit 1012, and the common electrode signals 212 and 211 are level-converted from a logic level to a liquid crystal drive voltage by the driver output unit 196, and are output to the common electrodes 1.2, respectively. The N pulse data generated by the clock generation section 184, the request clock 204, and the line start signal 203 indicating the beginning of one line of data generated by the control signal generation section are generated by a time series pixel signal generation section which is an external device. The data distribution unit 187 receives the data synchronized with the data request clock 2°4.

As mentioned earlier, the input data that is delayed by 2.5 cycles is sent to the buffer memory 189, and 2.
After a delay of 5 cycles, the other data is sent as is to the data distribution section 188, where the data is distributed to be sent to the interdigitally wired signal electrodes. Here, a RAM is used as the buffer memory, and the delay is delayed by 2.5 cycles using the address counter 186 and the 1 signal 213 from the control section 185. The data 207 and 208 distributed in this way are sent to the data transfer unit 190,
The transfer of the pulse generated by the clock generator 184 is transferred by the lock 205, and the transfer is completed by the control unit 1.
The data is latched by the data latch section 911 with the latch pulse 206 generated in step 85. Depending on the latched data, the open/close signal selector 912 selects the open signal 209 or the close signal 21.
0 is selected, the level is converted from the logic voltage to the liquid crystal drive voltage by the level converter 193, and the voltage is output from the output buffer 194 to the signal electrode.

When using an electrophotographic process, there is a time delay due to the charging process between the printing command and the actual writing on the photoreceptor, so a refresh operation is performed during this time. A ready signal and a start signal are received from the time-series pixel signal generation section 195 to the control section 185, and refresh signals 2 o 1. ,x.

A start signal 202 is generated. Refresh signal 201
While this is applied, only low frequency waves are applied to the liquid crystal.

Although optical writing was realized with the circuit configuration described above, the data transfer section, 1190. Data latch section 191° open/close signal selection section 192 level conversion section 193. Output buffer section 194
has been changed to engineering C. Each of the 101 electrodes was designed to drive 50 signal electrodes, and was mounted on a panel 221 as shown in FIG. These are hereinafter referred to as driver areas 0222 and 223, but
Driver box 0 consists of a 50-bit shift register, latch, signal selector, level shifter, and output buffer. FIG. 10 shows the configuration of the optical signal generator.

The optical signal generator includes a light source 231. such as a fluorescent lamp. Condensing lens 232. Polarizing plates 233, 236. LCD spring A/234
．． Imaging lens 238. It consists of a liquid crystal drive circuit 237, a driver area 0235, and a liquid crystal panel 324. The driver O235 is mounted on the mounting board 234. The light emitted from the light source is modulated by the liquid crystal light pulp. This optical signal 236 is imaged onto a photoreceptor 268 by an imaging lens 238 . An erect image can be obtained by using a gradient index rod lens array as the imaging lens.

FIG. 11 shows the principle of a two-color printing device using the above liquid crystal optical writing unit. First, in the first process, a photosensitive drum 302 is charged by a charger 301, and a negative image is optically written by a liquid crystal optical writing unit 303. 604 is a device that inputs time-series pixel signals to drive the liquid crystal.

The written electrostatic latent image is reversely developed by a developing device 305 that supplies toner colored in the first color, and further transferred onto paper 308 by a transfer unit 307 .

At this time, the developing machine 306 is not involved. Then photosensitive drum 3
02 is neutralized by an eraser lamp 310, residual toner is removed by a cleaner 311, and the first process is completed. On the other hand, the transferred paper 308 is transferred to the transport system 512, 313, 3
14 and is again sent to the transfer section.

Next, in the second process, the photosensitive drum 302 is charged again by the charger 301, and optical writing is performed by the liquid crystal optical writing unit 303. The negative latent image formed on the photosensitive drum is then reversely developed by a developing device 306 having toner colored in a second color different from the first color. At this time, the developing device 305 is retracted and does not participate in the development.

Next, the image is transferred again by the transfer unit 307 to the paper that has already been transferred to the first color in the first process, which has returned through the conveyance system 314 . After the transfer, the image is fixed by the fixing unit 309.
A colored impression is completed. Eraser lamp 3 for photosensitive drum
The static electricity is removed in step 10, and the two-color printing process is completed by cleaning with a cleaner 311.

As described above, by using the liquid crystal optical writing unit in the two-color printing process, it is possible to realize a two-color printing device that is high speed, high resolution, and high quality, while reducing costs.

[Brief explanation of drawings]

FIGS. 1 and 2 are diagrams of the principle of a liquid crystal panel. FIG. 3 is a diagram showing the frequency characteristics of dielectric anisotropy of the liquid crystal material used in the present invention. FIG. 4 is a diagram showing the response characteristics of the liquid crystal used in the present invention and the driving signals at that time. FIG. 5 shows an electrode pattern of a liquid crystal panel used in the present invention, which is used for time-division driving with a duty of '/2. FIG. 6 shows signal waveforms for using 1/2 date time division driving. FIGS. 7 and 8 show a block diagram of the liquid crystal drive circuit and timing charts of various signals. FIG. 9 shows the arrangement of the driver IO mounted on the liquid crystal panel. FIG. 10 shows a basic configuration diagram of an optical writing unit according to the present invention. 231...Light source 232...Condensing lens 233.236...Polarizing plate 234...Liquid crystal panel 235...Driver IC 237. . . . Liquid crystal drive circuit 238 . . . Imaging lens 239 . 303 is a liquid crystal optical writing unit, and 304 is a drive circuit. Applicant Suwa Seikosha Co., Ltd. Agent Patent Attorney Mogami Tsutomu-iri 5L'''' Figure 5, Figure 60

Claims (1)

[Claims] A printing device that uses an electrophotographic process, in which the first process involves developing with a toner colored with a first toner, and then developing with a toner colored with a second toner.
In this process, the toner is developed with a toner colored in a second color different from the first color, and is transferred onto the paper that has already been transferred in the first process, thereby achieving 2° color printing. In the printing device realized, the optical writing signal generating section is an optical writing unit consisting of a liquid crystal panel, a polarizing plate, a light source, a condensing lens, an imaging lens, and a liquid crystal drive circuit. .