GB1567937A

GB1567937A - Printing machines

Info

Publication number: GB1567937A
Application number: GB5134176A
Authority: GB
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 1975-12-11
Filing date: 1976-12-09
Publication date: 1980-05-21
Also published as: DE2656112C2; JPS52101105A; DE2656112A1

Description

(54) IMPROVEMENTS IN OR RELATING TO PRINTING MACHINES (71) We, RICOH COMPANY LIMITED, 3-6, Nakamagome 1-Chome, Ohta-Ku, Tokyo, Japan, a Japanese Body Corporate, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to printing machines.

According to the invention there is provided a printing machine for printing a preselected number of prints from each of a succession of printing masters, the printing machine comprising a reproduction unit for preparing fresh printing masters in succession from different originals, etching means for etching each master, a standby unit capable of storing a plurality of freshly etched printing masters, print means arranged to receive the etched masters in succession from the standby unit after a period of storage therein and to print from each the preselected number of prints, and control means including first means operative to provide an instantaneous count indicative of the number of prints yet to be produced from the master from which printing is taking place, and second means for triggering the reproduction unit to produce a fresh master when the instantaneous count reaches a first predetermined count, the first predetermined count being so selected that the reproduction step finishes when a second predetermined count is reached, and third means for feeding each reproduced master through the etching means to the standby unit, the second predetermined count being so selected that the said period of storage is related to the drying time of the etched master whereby the etched master has a predetermined dampness when used to produce said prints.

An offset printing press embodying the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a front elevation of the offset printing press; Figure 2a to c are illustrations of different counts appearing in the counter of the press of Figure 1; Figure 3 is a block diagram of a control circuit of the press of Figure 1 for controlling the operation during a reproduction step; Figure 4 is a timing diagram illustrating the timing of activating and stopping a master reproduction step relative to the printing process in the press of Figure 1; and Figure 5 is a block diagram of a control circuit for use in the press of Figure 1 in place of the control circuit of Figure 3.

The offset printing press of Figure 1 incorporates a reproduction unit 1. The process of the press can be divided into a reproduction step in which a printing master is prepared, an etching step where the master is etched, a master standby step where the master is temporarily stored, and a printing step. During the reproduction step, a sheet 3 is exposed to an original 0 through an optical system 2, and then developed in a developing unit 4 using a wet developer. After drying, the sheet is immersed in an etching solution 5 where it is subjected to the etching step to form a printing master. Then the master is received in a standby unit 7.The standby unit 7 is a device which stores a second master in a standby condition for a given time interval so that it can be mounted on the printing machine when a previous master wrapped around the outer surface of a master cylinder 8 is removed therefrom. The standby unit 7 can store one or more masters separated vertically from one another. When the standby unit 7 is driven vertically, the next master is fed for mounting on the outer surface of the master cylinder. The master once mounted on the master cylinder 8 is inked to form an inked image, which is then transferred onto a transfer cylinder 9. A printing paper passed between the transfer cylinder 9 and a pres sure cylinder 11 receives the ink image from the transfer cylinder and is then delivered into a container 13.After printing a pre determined number of prints, the master is removed from the master cylinder 8 and dis Ch;llged into a contliner 14.

.-s mentioned previously, the master is maintained in the standby unit 7 for a given time intcrval upon completion of the etching step. The degree of drying of the master or the etching solution thereon during such time interval has a great influence upon the print vluallity, since it is gcnerally accepted that in a slightly moistened condition the master pro ducts a favourable print quality.Thereforc, iii t'rder to achieve an optimum print quality the initiation or activation and stopping of the reproduction step is controlled so that the standby time poriend lor the master gencrally has a predetermined duration.

The reproductioll unit l of the printing machine shown in Figure 1 has a control panel 15 including a plurality of keys 16, which can be selectively operated to establish the total number ol rpints which are to be produced from a single master. When keys corresponding to a count of 125, for cxam- plc. are repressed, a count display 17 pro titles a corresponding display of "1 25" in its lozz er portion, as indicated in Figure 2 (a).At this point a button 18 designated as "ENTER" is depressed to transfer the dis play of "125" to the upper portion of the disl lay. Subsequently, as the printing step proceeds the number of prints yet to be pro duced. progressively decreases as indicated bv the counter. A signal is produced for the initiation of the preparation of a next master - b,- the reproduction unit when the number of remaining prints to be produced is reduced to a value less than 90 prints. The reproduction step is arranged to last for a sufficient period so that it terminates when the number of remaining prints has been reduced to 20 prints, for example.At this point, the said next master is subjected to an etching step and fed to the standby unit 7. It will be thus seen that the standby time period for the master corresponds to the time required for twenty prints to be produced. In other words, after a duration which corresponds to the standby time period has passed, the degree of drying, of the master will reach its optimum condition.

Figure 3 shows the control circuit which controls the activation and deactivation of the reproduction step. In this Figure, when a number of prints to be produced is keyed into the machine, three LATCH units momentar ily store the respective digits for example 125 and three DISPLAY units display the respective digits as shown in Figure 2(a).

When the button 18 on the control panel 15 is depressed, the digits are transferred through corresponding COUNTERs 21,22, 23 to upper DISPLAY units, which then indicate "125" in the upper portion of ilie counter display 17 as shown in Figure 2 (b).

A reset button 19 shown On the control panel 15 of Figure 1 functions to clcar the numeri- cal input entered into the lower portion ol the counter display 17 (see Figure 2 (a)).

Assuming that 125 prints are to he produced from a first master which is mounted on the master cylinder X shown in Figure 1, down pulses are applied to COUNlL'R's from the printing machine as the printing step proceeds. As a result the count in the upper portion of the count display 17 pr()g- ressively decreases as indicated in Figure 2 (c). A comparator 26 does not produce an output during the period while the count decreases from 125 to 91, but produces an output when the preset count of 90 is reached. The absence of an output during the time the count decreases from 125 to 91 inhibits the initiation of the reproduction step. However, when a preset count of 90 is reached, the output signal produced removes the inhibit in the reproduction step.Thus, the reproduction step is initiated to prepare a second master. When the second master is subjected to an etching step, it is fed into the standby unit 7 (Figure 1).

Figure 4 shows the relative timing relationship between the printing step and the master reproduction step. After the reproduction step is initiated, the operation of the reproduction step is interrupted by means of a timer or a master detection mechanism after the completion of the etching step. The interruption takes place in the following manner: When the second master is received in the standby unit 7, it is fed to be mounted on the cylinder 8 after a given standby time period. This standby period is the time interval which is required for the printing from the first master to be completed and the first master to be removed from the master cylinder 8. As mentioned, previously, the standby time period is selected so that an optimum degree of dampness of the second master is achieved.

Figure 5 is a block diagram of a control circuit for use in place of the circuit of Figure 3. Assuming that 125 prints are to be produced from the first master mounted on the master cylinder 8 of Figure 1, then as the printing step proceeds, down pulses from the printer is applied to COUNTERs as shown in Figure 5. The count displayed in the upper portion of the counter display 17 progressively decreases gradually, as indicated in Figure 2 (c). No output signal is produced until the count in the upper display reaches 100, namely, the lowest number having three digits, and an inverter 24 is utilized to derive therefrom a stop instruction for the rero- duction step. When the count changes from 100 to 99 or changes from a three-digit number to a two-digit number, the DIS PLAY corresponding to COUNTER 21 will change from 1 to 0.In response thereto, an output signal is produced which is inverted by the inverter 24 to remove the stop instructions for the reproduction step, thereby initiating the reproduction step to prepare a second master. Subsequent interruption of the reproduction step is similar to that described in conjunction with Figure 3.

While the control circuits have been described as controlling the timing of the preparation of a second master, they can be adapted to control the timing of the preparation of a third master while maintaining a second master in the standby unit 7, where only a low number of prints are required from each master or depending upon the copying condition or period and the etching condition or period during respective reproduction and etching steps.

While in the circuit control of Figure 5, the initiation of the reproduction step is initiated by a signal which is produced when the count changes from a three-digit to a two-digit number, the reproduction step can be initiated in response to a signal which is produced when the count changes from a two-digit to a single digit number.

In Figures 3 and 5, when all of the COUN TERs 21, 22 and 23 reach a count of 0, an AND circuit 25 responds by producing a zero print instruction, which interrupts the printing step. The automatic interruption of the printing step combined with the master being maintained in a condition for optimum print quality provides an automated printing machine.

WHAT WE CLAIM IS: 1. A printing machine for printing a preselected number of prints from each of a succession of printing masters, the printing machine comprising a reproduction unit for preparing fresh printing masters in succession from different originals, etching means for etching each master, a standby unit capable of storing a plurality of freshly etched printing masters, print means arranged to receive the etched masters in succession from the standby unit after a period of storage therein and to print from each of the preselected number of prints, and control means including first means operative to provide an instantaneous count indicative of the number of prints yet to be produced from the master from which printing is taking place, and second means for triggering the reproduction unit to produce a fresh master when the instantaneous count reaches a first predetermined count, the first predetermined count being so selected that the reproduction step finishes when a second predetermined count is reached, and third means for feeding each reproduced master through the etching means to the standby unit, the second predetermined count being so selected that the said period of storage is related to the drying time of the etched master whereby the etched master has a predetermined dampness when used to produce said prints.

2. A machine according to claim 1, wherein the preselected number has at least two digits in decimal form and wherein the second means is responsive to said instantaneous count to trigger the reproduction unit when the most significant digit of the instantaneous count becomes zero.

3. A printing machine according to claim 1 or claim 2, wherein the first means comprises a counter, and the second means comprises a comparator responsive to the instantaneous count of the counter and the first predetermined count to produce an output signal to trigger the reproduction unit when the count registered by the counter reaches the first predetermined count, the output signal from the comparator functioning to remove an inhibit instruction for the reproduction step.

4. A printing machine according to claim 2, including an inverter which produces an output signal in response to the down carry signal when the most significant digit of the instantaneous count reaches zero the output functioning to remove an inhibit instruction for the reproduction step and so triggering the reproduction unit.

5. A printing machine substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

100 to 99 or changes from a three-digit number to a two-digit number, the DIS PLAY corresponding to COUNTER 21 will change from 1 to 0. In response thereto, an output signal is produced which is inverted by the inverter 24 to remove the stop instructions for the reproduction step, thereby initiating the reproduction step to prepare a second master. Subsequent interruption of the reproduction step is similar to that described in conjunction with Figure 3.

While the control circuits have been described as controlling the timing of the preparation of a second master, they can be adapted to control the timing of the preparation of a third master while maintaining a second master in the standby unit 7, where only a low number of prints are required from each master or depending upon the copying condition or period and the etching condition or period during respective reproduction and etching steps.

While in the circuit control of Figure 5, the initiation of the reproduction step is initiated by a signal which is produced when the count changes from a three-digit to a two-digit number, the reproduction step can be initiated in response to a signal which is produced when the count changes from a two-digit to a single digit number.

In Figures 3 and 5, when all of the COUN TERs 21, 22 and 23 reach a count of 0, an AND circuit 25 responds by producing a zero print instruction, which interrupts the printing step. The automatic interruption of the printing step combined with the master being maintained in a condition for optimum print quality provides an automated printing machine.

WHAT WE CLAIM IS: 1. A printing machine for printing a preselected number of prints from each of a succession of printing masters, the printing machine comprising a reproduction unit for preparing fresh printing masters in succession from different originals, etching means for etching each master, a standby unit capable of storing a plurality of freshly etched printing masters, print means arranged to receive the etched masters in succession from the standby unit after a period of storage therein and to print from each of the preselected number of prints, and control means including first means operative to provide an instantaneous count indicative of the number of prints yet to be produced from the master from which printing is taking place, and second means for triggering the reproduction unit to produce a fresh master when the instantaneous count reaches a first predetermined count, the first predetermined count being so selected that the reproduction step finishes when a second predetermined count is reached, and third means for feeding each reproduced master through the etching means to the standby unit, the second predetermined count being so selected that the said period of storage is related to the drying time of the etched master whereby the etched master has a predetermined dampness when used to produce said prints.
2. A machine according to claim 1, wherein the preselected number has at least two digits in decimal form and wherein the second means is responsive to said instantaneous count to trigger the reproduction unit when the most significant digit of the instantaneous count becomes zero.
3. A printing machine according to claim 1 or claim 2, wherein the first means comprises a counter, and the second means comprises a comparator responsive to the instantaneous count of the counter and the first predetermined count to produce an output signal to trigger the reproduction unit when the count registered by the counter reaches the first predetermined count, the output signal from the comparator functioning to remove an inhibit instruction for the reproduction step.
4. A printing machine according to claim 2, including an inverter which produces an output signal in response to the down carry signal when the most significant digit of the instantaneous count reaches zero the output functioning to remove an inhibit instruction for the reproduction step and so triggering the reproduction unit.
5. A printing machine substantially as hereinbefore described with reference to the accompanying drawing.